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000
FXUS65 KCYS 231009
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 AM MDT SAT MAY 23 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

TODAY...AREAS OF FOG CONTINUE ACROSS MANY LOCATIONS VIA OBSERVATIONS
AND LOOKING AT WEBCAMS...SO HAVE CONTINUED THROUGH 9 AM. VISIBILITIES
MAY BE SLOWLY IMPROVING OVER THE I-80 SUMMIT LOOKING AT WEBCAMS.

CHANCES FOR SHOWERS INCREASE THIS MORNING...AND ESPECIALLY THIS
AFTERNOON AS THE NEXT SHORTWAVE TROUGH MOVES OVERHEAD NEAR PEAK
HEATING.

FOR THIS AFTERNOON...IMPRESSIVE 850 MB THETA-E RIDGE AXIS EXTENDS
FROM NORTHEAST COLORADO AND SOUTHEAST WYOMING. THE COMBINATION OF
DECENT SHEAR AND MODERATE INSTABILITY ALONG WITH ADEQUATE MOISTURE
TO FUEL THE THUNDERSTORMS. ALTHOUGH SPC HAS A SLIGHT RISK OF SEVERE
THUNDERSTORMS OVER NORTHEAST COLORADO...WE MAY SEE A FEW STRONG TO
SEVERE STORMS OVER OUR SOUTHEAST COUNTIES...IF THERE ARE A FEW BREAKS
IN THE LOW CLOUD STRATUS.

TONIGHT...UPPER TROUGH ALOFT AND A WAVE MOVE ACROSS OUR COUNTIES...
SPARKING ANOTHER WIDESPREAD SHOWER EVENT ALONG WITH AREAS OF FOG.

SUNDAY...MORE SHOWERS AND A FEW THUNDERSTORMS ON TAP AS THE UPPER
TROUGH MOVES OVERHEAD AND INSTABILITY SHOWERS BECOME EVEN MORE
PRONOUNCED. SHEAR AND INSTABILITY WILL LESSEN...THEN WITH NEIGHBORLY
AGREEMENT...PRESENTING A LESSENING OF STRONG THUNDERSTORMS IN THE
AFTERNOON.

SUNDAY NIGHT/MONDAY...FLOW ALOFT BECOMES NORTHWEST AND WITH ADEQUATE
LOW AND MID LEVEL MOISTURE PER PROGS...DAYTIME HEATING...WILL SEE
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS IN THE
AFTERNOON. STORM STRENGTH SHOULD BE MINIMAL BASED ON CONVECTIVE
PARAMETERS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

ONLY SUBTLE DIFFERENCES WERE GLEANED FROM THE MEDIUM RANGE MODELS
COMPARED TO PREVIOUS RUNS. TROUGH RESPONSIBLE FOR THIS WEEKENDS
INCLEMENT WEATHER EXITS TOWARD THE UPPER MIDWEST...REPLACED BY A
SHORT WAVE RIDGE TUESDAY. SHOWER COVERAGE WILL DECREASE MONDAY
NIGHT...WITH A RETURN TO A MORE DIURNAL CONVECTIVE PATTERN TUESDAY
AS TEMPERATURES WARM. RIDGE BROADENS OVER THE GREAT PLAINS WITH A
TROUGH EJECTING EAST FROM CA TOWARD THE FOUR CORNERS BY THE END OF
THE WEEK. SURFACE PRESSURE PATTERN WILL BE WEAK WITH MAINLY LIGHT
AND VARIABLE WINDS. SHOWER/TSTORM COVERAGE FOR THE REMAINDER OF
THE WEEK WILL PRIMARILY BE SCATTERED DURING THE DAY AND ISOLATED
AT NIGHT. NOT LOOKING AT APPRECIABLE QPF BY ANY STRETCH. TEMPERATURES
WILL AVERAGE CLOSER TO SEASONAL NORMALS MID WEEK THEN COOL SOMEWHAT
FOR THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 300 AM MDT SAT MAY 23 2015

LATEST HRRR/SREF GUIDANCE FOCUSES THE LOWEST /LIFR-IFR/ CONDITIONS
FOR AIRFIELDS EAST OF THE LARAMIE RANGE THIS MORNING...WITH GRADUAL
IMPROVEMENT TO MVFR THIS AFTERNOON. VFR WITH LOCALIZED MVFR WILL
PREVAIL OUTSIDE THE MOUNTAINS WEST OF THE LARAMIE RANGE. MAINTAINED
VCTS FOR ALL AIRFIELDS THIS AFTERNOON/EVENING AS TSTM COVERAGE WILL
BE WIDELY SCATTERED. GUSTY WINDS...SMALL HAIL AND HEAVY RAIN WILL
BE POSSIBLE WITH THE STRONGER TSTMS.

&&

.FIRE WEATHER...
ISSUED AT 243 AM MDT SAT MAY 23 2015

MINIMAL ISSUES DUE TO WET GROUND AND PROGGED HUMIDITIES AND WINDS.

&&

.HYDROLOGY...
ISSUED AT 300 AM MDT SAT MAY 23 2015

WATER RELEASES FROM UPSTREAM GRAYROCKS RESERVOIR AND RUNOFF FROM
RAINFALL WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AROUND 7.5
FEET THROUGH THE WEEKEND. HIGH WATER LEVELS WILL CONTINUE AT
LARAMIE...CRESTING JUST BELOW FLOOD STAGE EARLY NEXT WEEK. SHOWER
COVERAGE WILL DECREASE NEXT WEEK...RETURNING TO A TYPICAL SCATTERED
DIURNAL PATTERN.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RUBIN
LONG TERM...JAMSKI
AVIATION...JAMSKI
FIRE WEATHER...RUBIN
HYDROLOGY...JAMSKI




000
FXUS65 KCYS 231009
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 AM MDT SAT MAY 23 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

TODAY...AREAS OF FOG CONTINUE ACROSS MANY LOCATIONS VIA OBSERVATIONS
AND LOOKING AT WEBCAMS...SO HAVE CONTINUED THROUGH 9 AM. VISIBILITIES
MAY BE SLOWLY IMPROVING OVER THE I-80 SUMMIT LOOKING AT WEBCAMS.

CHANCES FOR SHOWERS INCREASE THIS MORNING...AND ESPECIALLY THIS
AFTERNOON AS THE NEXT SHORTWAVE TROUGH MOVES OVERHEAD NEAR PEAK
HEATING.

FOR THIS AFTERNOON...IMPRESSIVE 850 MB THETA-E RIDGE AXIS EXTENDS
FROM NORTHEAST COLORADO AND SOUTHEAST WYOMING. THE COMBINATION OF
DECENT SHEAR AND MODERATE INSTABILITY ALONG WITH ADEQUATE MOISTURE
TO FUEL THE THUNDERSTORMS. ALTHOUGH SPC HAS A SLIGHT RISK OF SEVERE
THUNDERSTORMS OVER NORTHEAST COLORADO...WE MAY SEE A FEW STRONG TO
SEVERE STORMS OVER OUR SOUTHEAST COUNTIES...IF THERE ARE A FEW BREAKS
IN THE LOW CLOUD STRATUS.

TONIGHT...UPPER TROUGH ALOFT AND A WAVE MOVE ACROSS OUR COUNTIES...
SPARKING ANOTHER WIDESPREAD SHOWER EVENT ALONG WITH AREAS OF FOG.

SUNDAY...MORE SHOWERS AND A FEW THUNDERSTORMS ON TAP AS THE UPPER
TROUGH MOVES OVERHEAD AND INSTABILITY SHOWERS BECOME EVEN MORE
PRONOUNCED. SHEAR AND INSTABILITY WILL LESSEN...THEN WITH NEIGHBORLY
AGREEMENT...PRESENTING A LESSENING OF STRONG THUNDERSTORMS IN THE
AFTERNOON.

SUNDAY NIGHT/MONDAY...FLOW ALOFT BECOMES NORTHWEST AND WITH ADEQUATE
LOW AND MID LEVEL MOISTURE PER PROGS...DAYTIME HEATING...WILL SEE
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS IN THE
AFTERNOON. STORM STRENGTH SHOULD BE MINIMAL BASED ON CONVECTIVE
PARAMETERS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

ONLY SUBTLE DIFFERENCES WERE GLEANED FROM THE MEDIUM RANGE MODELS
COMPARED TO PREVIOUS RUNS. TROUGH RESPONSIBLE FOR THIS WEEKENDS
INCLEMENT WEATHER EXITS TOWARD THE UPPER MIDWEST...REPLACED BY A
SHORT WAVE RIDGE TUESDAY. SHOWER COVERAGE WILL DECREASE MONDAY
NIGHT...WITH A RETURN TO A MORE DIURNAL CONVECTIVE PATTERN TUESDAY
AS TEMPERATURES WARM. RIDGE BROADENS OVER THE GREAT PLAINS WITH A
TROUGH EJECTING EAST FROM CA TOWARD THE FOUR CORNERS BY THE END OF
THE WEEK. SURFACE PRESSURE PATTERN WILL BE WEAK WITH MAINLY LIGHT
AND VARIABLE WINDS. SHOWER/TSTORM COVERAGE FOR THE REMAINDER OF
THE WEEK WILL PRIMARILY BE SCATTERED DURING THE DAY AND ISOLATED
AT NIGHT. NOT LOOKING AT APPRECIABLE QPF BY ANY STRETCH. TEMPERATURES
WILL AVERAGE CLOSER TO SEASONAL NORMALS MID WEEK THEN COOL SOMEWHAT
FOR THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 300 AM MDT SAT MAY 23 2015

LATEST HRRR/SREF GUIDANCE FOCUSES THE LOWEST /LIFR-IFR/ CONDITIONS
FOR AIRFIELDS EAST OF THE LARAMIE RANGE THIS MORNING...WITH GRADUAL
IMPROVEMENT TO MVFR THIS AFTERNOON. VFR WITH LOCALIZED MVFR WILL
PREVAIL OUTSIDE THE MOUNTAINS WEST OF THE LARAMIE RANGE. MAINTAINED
VCTS FOR ALL AIRFIELDS THIS AFTERNOON/EVENING AS TSTM COVERAGE WILL
BE WIDELY SCATTERED. GUSTY WINDS...SMALL HAIL AND HEAVY RAIN WILL
BE POSSIBLE WITH THE STRONGER TSTMS.

&&

.FIRE WEATHER...
ISSUED AT 243 AM MDT SAT MAY 23 2015

MINIMAL ISSUES DUE TO WET GROUND AND PROGGED HUMIDITIES AND WINDS.

&&

.HYDROLOGY...
ISSUED AT 300 AM MDT SAT MAY 23 2015

WATER RELEASES FROM UPSTREAM GRAYROCKS RESERVOIR AND RUNOFF FROM
RAINFALL WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AROUND 7.5
FEET THROUGH THE WEEKEND. HIGH WATER LEVELS WILL CONTINUE AT
LARAMIE...CRESTING JUST BELOW FLOOD STAGE EARLY NEXT WEEK. SHOWER
COVERAGE WILL DECREASE NEXT WEEK...RETURNING TO A TYPICAL SCATTERED
DIURNAL PATTERN.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RUBIN
LONG TERM...JAMSKI
AVIATION...JAMSKI
FIRE WEATHER...RUBIN
HYDROLOGY...JAMSKI


  [top]

000
FXUS65 KRIW 230905
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
305 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

WV IMAGERY SHOWING LARGE UPR TROF ACROSS THE WRN CONUS WITH CLOSED
LOW OVR WRN AZ...EMBEDDED SW WITHIN CLOSED PORTION ROTATING
ANTI-CLOCKWISE THRU CNTRL WY AS WE SPEAK. SFC HAS GENERAL LOW P ACROSS
THE WEST...HIGH P TO THE EAST AND WEAK TROF/BOUNDARY STRETCHING FROM
CNTRL NE INTO NERN CO.

THE FCST FOR THE MEMORIAL DAY WEEKEND...UPR LOW MIGRATES FROM WEST
OF THE 4 CORNERS REGION SLOWLY TO THE N...CENTERING ACROSS WRN CO
BUT SPREADING OVR TOP OF WY BY DAY`S END TODAY. MID TO UPR LVL
VORTICITY WILL INCREASE WITH THE APPROACH OF THE UPR LOW. THE DAY
WILL BE MARKED BY SUFFICIENT BUOYANCY BUT LOW SHEAR THRU MUCH DEPTH.
DISORGANIZED SHOWERS WITH SOME EMBEDDED THUNDER BY AFTERNOON WILL BE
RELATIVELY SLOW MOVERS AGAIN...FROM S TO N AND 10 MPH +/- E OF THE
DIVIDE...SE TO NW/E TO W WEST OF THE DIVIDE. ML CAPE SHOULD TOP OUT
ACROSS THE CWA AT <=500 J/KG...BUT AVG 250 J/KG FOR MOST LOCATIONS.
PWS LOOK TO BE A BIT LESS THAN TODAY...BUT STILL AOA 0.60 E OF THE
DIVIDE...AOB 0.5 W OF THE DIVIDE...WITH HIGHEST VALUES SETTLING IN
OVR THE BIGHORN BASIN AND THE EXTREME ERN PORTIONS OF JOHNSON AND
NATRONA COUNTIES. EXPECTING SOME MID LVL DRYING THRU THE MORNING HRS
WITH BITS OF SUNSHINE POSSIBLE ACROSS THE SRN...CNTRL AND ERN FA.
THIS WILL INCREASE LL LAPSE RATES AND INSTABILITY OVR THESE
AREA...EMBEDDING A FEW THUNDERSTORMS AMIDST THE AMORPHOUS MASS OF
SHOWERS EXPECTED BY MID TO LATE AFTERNOON. ADDITIONALLY...WITH A
MODEST SFC LOW MOVING INTO WRN CO AND SRN WY...ERLY RETURN FLOW AND
SMALL WARM FRONT SETS UP ACROSS ERN AND CNTRL WY...ALLOWING FOR
TERRAIN INDUCED CONVERGENCE TO SET UP FROM THE ERN WIND RIVER
MOUNTAINS...EWD ALONG THE GREEN MOUNTAINS AND SOUTH ACROSS ERN
SWEETWATER COUNTY. THIS AREA WOULD LIKELY SEE A COUPLE OF THE
STRONGER STORMS OF THE DAY.

TONIGHT THROUGH SUNDAY...EARLY MORNING FOG WILL ALSO BE POSSIBLE OVR
MANY AREAS THROUGHOUT THE FCST. OTHERWISE...SFC CYCLOGENESIS TAKES
PLACE FROM ERN/NERN CO INTO SERN WY AND WRN NE. BETWEEN LOW TO MID
LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR MOISTURE FROM
ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY PLENTIFUL RAINFALL
WILL BE HAD OVER THE FAR ERN FA THRU THE DAY SUNDAY. THIS SYSTEM
CONTINUES TO LOOK COMPARATIVELY WARM...WITH H7 TEMPS REMAINING ABOVE
-1 DEG C THRU THE ENTIRE FCST PERIOD...AND REALLY ABOVE ZERO FOR
MOST OF THAT TIME.  GENERALLY...A TRACE TO AND INCH OR TWO WILL BE
POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS ABOVE 9500
FEET...WITH ONLY THE HIGHEST ELEVATIONS RECEIVING AN ISOLATED 3 OR
SO INCHES. STORM MOVEMENT IMPROVES SLIGHTLY...NOW REVERSING AND
BECOMING N TO S AT 15 TO 20 MPH. SEVERE WX WILL REMAIN MOSTLY EAST
TO SOUTHEAST OF FA THROUGH THE PERIOD WITH CONTINUED LOW SHEAR
CONDITIONS ONLY ABLE TO PROVIDE OCCASIONAL ISOLATED SMALL
HAIL...ESPECIALLY W OF THE DIVIDE.

SUNDAY NIGHT THRU MONDAY...SYSTEM PUSHES EWD INTO THE PLAINS WITH
TRANSITIONAL RIDGING TAKING PLACE ACROSS THE WRN FA WHILE THE ERN FA
IS FCST TO BE THE RECIPIENT OF A BACKSIDE UPR SW ROTATING AROUND THE
EXITING LOW...WITH BETTER SHOWER/THUNDER ACTIVITY/COVERAGE ACROSS
THE ERN CWA. OTHERWISE...A BIT WARMER AND MORE UNSTABLE WITH PERHAPS
AN BETTER SPRINKLING OF STRONGER THUNDERSTORMS MIXED IN WITH
SHOWERS. LOW SHEAR CONDITIONS ALSO PERSIST HOWEVER...KEEPING STORM
ORGANIZATION AT A MINIMUM...WHILE STORM MOTION IMPROVES EVEN
MORE...FROM THE NW TO SE AT 20 TO 25 MPH.

.LONG TERM...TUESDAY THROUGH SATURDAY

GFS MODEL CONTINUES ITS CONSISTENT FORECAST FOR TUESDAY THROUGH
FRIDAY. IT HAS A WEATHER SYSTEM SPINNING OVER THE PACIFIC NW STATES
WHICH CREATES SW FLOW ALOFT OVER WY TUE AND WED. THE SYSTEM MOVES
INTO IDAHO THURSDAY AND INTO NW WY FRIDAY...THEN ACROSS NORTHERN WY
FRIDAY NIGHT AND INTO WESTERN SOUTH DAKOTA NEXT SATURDAY AFTERNOON.
A DAILY CHANCE FOR SHOWERS AND STORMS IN THE AFTERNOON AND EVENING
HOURS WITH LINGERING SHOWERS LATE NIGHT AND MORNING HOURS TUESDAY
THROUGH FRIDAY. NEXT SATURDAY THE SHOWERS AND STORMS LOOK TO BE
MAINLY OVER THE NORTH WITH LESSER COVERAGE CENTRAL AND SOUTH. THE
ECMWF MODEL IS SIMILAR TO THE GFS MODEL WITH THE WEATHER PATTERN
THROUGH THURSDAY NIGHT. IT HAS A DIFFERENT TRACK ON FRIDAY BUT THE
TROUGH IS STILL MOVING THROUGH FRIDAY INTO FRI NIGHT. THEN THE ECMWF
MODEL IS ONLY SHOWING ISOLATED SHOWERS OR STORMS. THE FORECAST WILL
REFLECT A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON AND EVENING
WITH LESSER COVERAGE OF SHOWERS LATE NIGHT AND DURING THE MORNING.
NEXT SATURDAY WILL BE MOSTLY DRY IN THE SOUTHWEST WITH ISOLATED
COVERAGE FOR THE REST OF THE AREA. WILL HOWEVER KEEP A LITTLE CHANCE
OF PRECIP IN THE NORTHEAST ZONES NEXT SATURDAY. AS FOR HIGH TEMPS...
THERE WILL BE LITTLE CHANGE FROM DAY TO DAY WITH 60S TO LOWER 70S
FOR THE LOWER ELEVATIONS AND 40S AND 50S FOR THE MOUNTAINS. THESE
HIGHS ASSUME SOME SUNSHINE EACH DAY AND NOT A LOW OVERCAST DAY(S)
LIKE WE HAVE SEEN DURING THE PAST WEEK.

&&

.AVIATION.../12Z ISSUANCE/

CONFIDENCE IS LOW ON THE EXTENT/TIMING OF IFR/MVFR CONDITIONS FROM
LOW CEILINGS...FOG AND/OR RAIN THROUGH 00Z SUNDAY. A DRY SLOT IS
EXPECTED OVER MUCH OF SOUTHERN AND EASTERN SECTIONS THIS MORNING
LIMITING SHRA ACTIVITY...BUT FOG/LOW CEILINGS REMAIN POSSIBLE.
ANOTHER WAVE PUSHES OVER THE REGION SATURDAY AFTERNOON...WITH
SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS OVER THE
ENTIRE AREA IN THE AFTERNOON. A MORE WIDESPREAD AREA OF MVFR/IFR
CEILINGS WITH A MORE STEADY RAIN SHOULD DEVELOP EAST OF THE
DIVIDE...AND EASTERN SWEETWATER COUNTY TONIGHT. MOUNTAINS WILL BE
OBSCURED MUCH OF THE TIME. PLEASE SEE THE AVIATION WEATHER CENTER
FOR THE LATEST INFORMATION ON ICING FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...BRAUN




000
FXUS65 KRIW 230905
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
305 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

WV IMAGERY SHOWING LARGE UPR TROF ACROSS THE WRN CONUS WITH CLOSED
LOW OVR WRN AZ...EMBEDDED SW WITHIN CLOSED PORTION ROTATING
ANTI-CLOCKWISE THRU CNTRL WY AS WE SPEAK. SFC HAS GENERAL LOW P ACROSS
THE WEST...HIGH P TO THE EAST AND WEAK TROF/BOUNDARY STRETCHING FROM
CNTRL NE INTO NERN CO.

THE FCST FOR THE MEMORIAL DAY WEEKEND...UPR LOW MIGRATES FROM WEST
OF THE 4 CORNERS REGION SLOWLY TO THE N...CENTERING ACROSS WRN CO
BUT SPREADING OVR TOP OF WY BY DAY`S END TODAY. MID TO UPR LVL
VORTICITY WILL INCREASE WITH THE APPROACH OF THE UPR LOW. THE DAY
WILL BE MARKED BY SUFFICIENT BUOYANCY BUT LOW SHEAR THRU MUCH DEPTH.
DISORGANIZED SHOWERS WITH SOME EMBEDDED THUNDER BY AFTERNOON WILL BE
RELATIVELY SLOW MOVERS AGAIN...FROM S TO N AND 10 MPH +/- E OF THE
DIVIDE...SE TO NW/E TO W WEST OF THE DIVIDE. ML CAPE SHOULD TOP OUT
ACROSS THE CWA AT <=500 J/KG...BUT AVG 250 J/KG FOR MOST LOCATIONS.
PWS LOOK TO BE A BIT LESS THAN TODAY...BUT STILL AOA 0.60 E OF THE
DIVIDE...AOB 0.5 W OF THE DIVIDE...WITH HIGHEST VALUES SETTLING IN
OVR THE BIGHORN BASIN AND THE EXTREME ERN PORTIONS OF JOHNSON AND
NATRONA COUNTIES. EXPECTING SOME MID LVL DRYING THRU THE MORNING HRS
WITH BITS OF SUNSHINE POSSIBLE ACROSS THE SRN...CNTRL AND ERN FA.
THIS WILL INCREASE LL LAPSE RATES AND INSTABILITY OVR THESE
AREA...EMBEDDING A FEW THUNDERSTORMS AMIDST THE AMORPHOUS MASS OF
SHOWERS EXPECTED BY MID TO LATE AFTERNOON. ADDITIONALLY...WITH A
MODEST SFC LOW MOVING INTO WRN CO AND SRN WY...ERLY RETURN FLOW AND
SMALL WARM FRONT SETS UP ACROSS ERN AND CNTRL WY...ALLOWING FOR
TERRAIN INDUCED CONVERGENCE TO SET UP FROM THE ERN WIND RIVER
MOUNTAINS...EWD ALONG THE GREEN MOUNTAINS AND SOUTH ACROSS ERN
SWEETWATER COUNTY. THIS AREA WOULD LIKELY SEE A COUPLE OF THE
STRONGER STORMS OF THE DAY.

TONIGHT THROUGH SUNDAY...EARLY MORNING FOG WILL ALSO BE POSSIBLE OVR
MANY AREAS THROUGHOUT THE FCST. OTHERWISE...SFC CYCLOGENESIS TAKES
PLACE FROM ERN/NERN CO INTO SERN WY AND WRN NE. BETWEEN LOW TO MID
LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR MOISTURE FROM
ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY PLENTIFUL RAINFALL
WILL BE HAD OVER THE FAR ERN FA THRU THE DAY SUNDAY. THIS SYSTEM
CONTINUES TO LOOK COMPARATIVELY WARM...WITH H7 TEMPS REMAINING ABOVE
-1 DEG C THRU THE ENTIRE FCST PERIOD...AND REALLY ABOVE ZERO FOR
MOST OF THAT TIME.  GENERALLY...A TRACE TO AND INCH OR TWO WILL BE
POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS ABOVE 9500
FEET...WITH ONLY THE HIGHEST ELEVATIONS RECEIVING AN ISOLATED 3 OR
SO INCHES. STORM MOVEMENT IMPROVES SLIGHTLY...NOW REVERSING AND
BECOMING N TO S AT 15 TO 20 MPH. SEVERE WX WILL REMAIN MOSTLY EAST
TO SOUTHEAST OF FA THROUGH THE PERIOD WITH CONTINUED LOW SHEAR
CONDITIONS ONLY ABLE TO PROVIDE OCCASIONAL ISOLATED SMALL
HAIL...ESPECIALLY W OF THE DIVIDE.

SUNDAY NIGHT THRU MONDAY...SYSTEM PUSHES EWD INTO THE PLAINS WITH
TRANSITIONAL RIDGING TAKING PLACE ACROSS THE WRN FA WHILE THE ERN FA
IS FCST TO BE THE RECIPIENT OF A BACKSIDE UPR SW ROTATING AROUND THE
EXITING LOW...WITH BETTER SHOWER/THUNDER ACTIVITY/COVERAGE ACROSS
THE ERN CWA. OTHERWISE...A BIT WARMER AND MORE UNSTABLE WITH PERHAPS
AN BETTER SPRINKLING OF STRONGER THUNDERSTORMS MIXED IN WITH
SHOWERS. LOW SHEAR CONDITIONS ALSO PERSIST HOWEVER...KEEPING STORM
ORGANIZATION AT A MINIMUM...WHILE STORM MOTION IMPROVES EVEN
MORE...FROM THE NW TO SE AT 20 TO 25 MPH.

.LONG TERM...TUESDAY THROUGH SATURDAY

GFS MODEL CONTINUES ITS CONSISTENT FORECAST FOR TUESDAY THROUGH
FRIDAY. IT HAS A WEATHER SYSTEM SPINNING OVER THE PACIFIC NW STATES
WHICH CREATES SW FLOW ALOFT OVER WY TUE AND WED. THE SYSTEM MOVES
INTO IDAHO THURSDAY AND INTO NW WY FRIDAY...THEN ACROSS NORTHERN WY
FRIDAY NIGHT AND INTO WESTERN SOUTH DAKOTA NEXT SATURDAY AFTERNOON.
A DAILY CHANCE FOR SHOWERS AND STORMS IN THE AFTERNOON AND EVENING
HOURS WITH LINGERING SHOWERS LATE NIGHT AND MORNING HOURS TUESDAY
THROUGH FRIDAY. NEXT SATURDAY THE SHOWERS AND STORMS LOOK TO BE
MAINLY OVER THE NORTH WITH LESSER COVERAGE CENTRAL AND SOUTH. THE
ECMWF MODEL IS SIMILAR TO THE GFS MODEL WITH THE WEATHER PATTERN
THROUGH THURSDAY NIGHT. IT HAS A DIFFERENT TRACK ON FRIDAY BUT THE
TROUGH IS STILL MOVING THROUGH FRIDAY INTO FRI NIGHT. THEN THE ECMWF
MODEL IS ONLY SHOWING ISOLATED SHOWERS OR STORMS. THE FORECAST WILL
REFLECT A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON AND EVENING
WITH LESSER COVERAGE OF SHOWERS LATE NIGHT AND DURING THE MORNING.
NEXT SATURDAY WILL BE MOSTLY DRY IN THE SOUTHWEST WITH ISOLATED
COVERAGE FOR THE REST OF THE AREA. WILL HOWEVER KEEP A LITTLE CHANCE
OF PRECIP IN THE NORTHEAST ZONES NEXT SATURDAY. AS FOR HIGH TEMPS...
THERE WILL BE LITTLE CHANGE FROM DAY TO DAY WITH 60S TO LOWER 70S
FOR THE LOWER ELEVATIONS AND 40S AND 50S FOR THE MOUNTAINS. THESE
HIGHS ASSUME SOME SUNSHINE EACH DAY AND NOT A LOW OVERCAST DAY(S)
LIKE WE HAVE SEEN DURING THE PAST WEEK.

&&

.AVIATION.../12Z ISSUANCE/

CONFIDENCE IS LOW ON THE EXTENT/TIMING OF IFR/MVFR CONDITIONS FROM
LOW CEILINGS...FOG AND/OR RAIN THROUGH 00Z SUNDAY. A DRY SLOT IS
EXPECTED OVER MUCH OF SOUTHERN AND EASTERN SECTIONS THIS MORNING
LIMITING SHRA ACTIVITY...BUT FOG/LOW CEILINGS REMAIN POSSIBLE.
ANOTHER WAVE PUSHES OVER THE REGION SATURDAY AFTERNOON...WITH
SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS OVER THE
ENTIRE AREA IN THE AFTERNOON. A MORE WIDESPREAD AREA OF MVFR/IFR
CEILINGS WITH A MORE STEADY RAIN SHOULD DEVELOP EAST OF THE
DIVIDE...AND EASTERN SWEETWATER COUNTY TONIGHT. MOUNTAINS WILL BE
OBSCURED MUCH OF THE TIME. PLEASE SEE THE AVIATION WEATHER CENTER
FOR THE LATEST INFORMATION ON ICING FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...BRAUN





000
FXUS65 KRIW 230905
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
305 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

WV IMAGERY SHOWING LARGE UPR TROF ACROSS THE WRN CONUS WITH CLOSED
LOW OVR WRN AZ...EMBEDDED SW WITHIN CLOSED PORTION ROTATING
ANTI-CLOCKWISE THRU CNTRL WY AS WE SPEAK. SFC HAS GENERAL LOW P ACROSS
THE WEST...HIGH P TO THE EAST AND WEAK TROF/BOUNDARY STRETCHING FROM
CNTRL NE INTO NERN CO.

THE FCST FOR THE MEMORIAL DAY WEEKEND...UPR LOW MIGRATES FROM WEST
OF THE 4 CORNERS REGION SLOWLY TO THE N...CENTERING ACROSS WRN CO
BUT SPREADING OVR TOP OF WY BY DAY`S END TODAY. MID TO UPR LVL
VORTICITY WILL INCREASE WITH THE APPROACH OF THE UPR LOW. THE DAY
WILL BE MARKED BY SUFFICIENT BUOYANCY BUT LOW SHEAR THRU MUCH DEPTH.
DISORGANIZED SHOWERS WITH SOME EMBEDDED THUNDER BY AFTERNOON WILL BE
RELATIVELY SLOW MOVERS AGAIN...FROM S TO N AND 10 MPH +/- E OF THE
DIVIDE...SE TO NW/E TO W WEST OF THE DIVIDE. ML CAPE SHOULD TOP OUT
ACROSS THE CWA AT <=500 J/KG...BUT AVG 250 J/KG FOR MOST LOCATIONS.
PWS LOOK TO BE A BIT LESS THAN TODAY...BUT STILL AOA 0.60 E OF THE
DIVIDE...AOB 0.5 W OF THE DIVIDE...WITH HIGHEST VALUES SETTLING IN
OVR THE BIGHORN BASIN AND THE EXTREME ERN PORTIONS OF JOHNSON AND
NATRONA COUNTIES. EXPECTING SOME MID LVL DRYING THRU THE MORNING HRS
WITH BITS OF SUNSHINE POSSIBLE ACROSS THE SRN...CNTRL AND ERN FA.
THIS WILL INCREASE LL LAPSE RATES AND INSTABILITY OVR THESE
AREA...EMBEDDING A FEW THUNDERSTORMS AMIDST THE AMORPHOUS MASS OF
SHOWERS EXPECTED BY MID TO LATE AFTERNOON. ADDITIONALLY...WITH A
MODEST SFC LOW MOVING INTO WRN CO AND SRN WY...ERLY RETURN FLOW AND
SMALL WARM FRONT SETS UP ACROSS ERN AND CNTRL WY...ALLOWING FOR
TERRAIN INDUCED CONVERGENCE TO SET UP FROM THE ERN WIND RIVER
MOUNTAINS...EWD ALONG THE GREEN MOUNTAINS AND SOUTH ACROSS ERN
SWEETWATER COUNTY. THIS AREA WOULD LIKELY SEE A COUPLE OF THE
STRONGER STORMS OF THE DAY.

TONIGHT THROUGH SUNDAY...EARLY MORNING FOG WILL ALSO BE POSSIBLE OVR
MANY AREAS THROUGHOUT THE FCST. OTHERWISE...SFC CYCLOGENESIS TAKES
PLACE FROM ERN/NERN CO INTO SERN WY AND WRN NE. BETWEEN LOW TO MID
LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR MOISTURE FROM
ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY PLENTIFUL RAINFALL
WILL BE HAD OVER THE FAR ERN FA THRU THE DAY SUNDAY. THIS SYSTEM
CONTINUES TO LOOK COMPARATIVELY WARM...WITH H7 TEMPS REMAINING ABOVE
-1 DEG C THRU THE ENTIRE FCST PERIOD...AND REALLY ABOVE ZERO FOR
MOST OF THAT TIME.  GENERALLY...A TRACE TO AND INCH OR TWO WILL BE
POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS ABOVE 9500
FEET...WITH ONLY THE HIGHEST ELEVATIONS RECEIVING AN ISOLATED 3 OR
SO INCHES. STORM MOVEMENT IMPROVES SLIGHTLY...NOW REVERSING AND
BECOMING N TO S AT 15 TO 20 MPH. SEVERE WX WILL REMAIN MOSTLY EAST
TO SOUTHEAST OF FA THROUGH THE PERIOD WITH CONTINUED LOW SHEAR
CONDITIONS ONLY ABLE TO PROVIDE OCCASIONAL ISOLATED SMALL
HAIL...ESPECIALLY W OF THE DIVIDE.

SUNDAY NIGHT THRU MONDAY...SYSTEM PUSHES EWD INTO THE PLAINS WITH
TRANSITIONAL RIDGING TAKING PLACE ACROSS THE WRN FA WHILE THE ERN FA
IS FCST TO BE THE RECIPIENT OF A BACKSIDE UPR SW ROTATING AROUND THE
EXITING LOW...WITH BETTER SHOWER/THUNDER ACTIVITY/COVERAGE ACROSS
THE ERN CWA. OTHERWISE...A BIT WARMER AND MORE UNSTABLE WITH PERHAPS
AN BETTER SPRINKLING OF STRONGER THUNDERSTORMS MIXED IN WITH
SHOWERS. LOW SHEAR CONDITIONS ALSO PERSIST HOWEVER...KEEPING STORM
ORGANIZATION AT A MINIMUM...WHILE STORM MOTION IMPROVES EVEN
MORE...FROM THE NW TO SE AT 20 TO 25 MPH.

.LONG TERM...TUESDAY THROUGH SATURDAY

GFS MODEL CONTINUES ITS CONSISTENT FORECAST FOR TUESDAY THROUGH
FRIDAY. IT HAS A WEATHER SYSTEM SPINNING OVER THE PACIFIC NW STATES
WHICH CREATES SW FLOW ALOFT OVER WY TUE AND WED. THE SYSTEM MOVES
INTO IDAHO THURSDAY AND INTO NW WY FRIDAY...THEN ACROSS NORTHERN WY
FRIDAY NIGHT AND INTO WESTERN SOUTH DAKOTA NEXT SATURDAY AFTERNOON.
A DAILY CHANCE FOR SHOWERS AND STORMS IN THE AFTERNOON AND EVENING
HOURS WITH LINGERING SHOWERS LATE NIGHT AND MORNING HOURS TUESDAY
THROUGH FRIDAY. NEXT SATURDAY THE SHOWERS AND STORMS LOOK TO BE
MAINLY OVER THE NORTH WITH LESSER COVERAGE CENTRAL AND SOUTH. THE
ECMWF MODEL IS SIMILAR TO THE GFS MODEL WITH THE WEATHER PATTERN
THROUGH THURSDAY NIGHT. IT HAS A DIFFERENT TRACK ON FRIDAY BUT THE
TROUGH IS STILL MOVING THROUGH FRIDAY INTO FRI NIGHT. THEN THE ECMWF
MODEL IS ONLY SHOWING ISOLATED SHOWERS OR STORMS. THE FORECAST WILL
REFLECT A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON AND EVENING
WITH LESSER COVERAGE OF SHOWERS LATE NIGHT AND DURING THE MORNING.
NEXT SATURDAY WILL BE MOSTLY DRY IN THE SOUTHWEST WITH ISOLATED
COVERAGE FOR THE REST OF THE AREA. WILL HOWEVER KEEP A LITTLE CHANCE
OF PRECIP IN THE NORTHEAST ZONES NEXT SATURDAY. AS FOR HIGH TEMPS...
THERE WILL BE LITTLE CHANGE FROM DAY TO DAY WITH 60S TO LOWER 70S
FOR THE LOWER ELEVATIONS AND 40S AND 50S FOR THE MOUNTAINS. THESE
HIGHS ASSUME SOME SUNSHINE EACH DAY AND NOT A LOW OVERCAST DAY(S)
LIKE WE HAVE SEEN DURING THE PAST WEEK.

&&

.AVIATION.../12Z ISSUANCE/

CONFIDENCE IS LOW ON THE EXTENT/TIMING OF IFR/MVFR CONDITIONS FROM
LOW CEILINGS...FOG AND/OR RAIN THROUGH 00Z SUNDAY. A DRY SLOT IS
EXPECTED OVER MUCH OF SOUTHERN AND EASTERN SECTIONS THIS MORNING
LIMITING SHRA ACTIVITY...BUT FOG/LOW CEILINGS REMAIN POSSIBLE.
ANOTHER WAVE PUSHES OVER THE REGION SATURDAY AFTERNOON...WITH
SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS OVER THE
ENTIRE AREA IN THE AFTERNOON. A MORE WIDESPREAD AREA OF MVFR/IFR
CEILINGS WITH A MORE STEADY RAIN SHOULD DEVELOP EAST OF THE
DIVIDE...AND EASTERN SWEETWATER COUNTY TONIGHT. MOUNTAINS WILL BE
OBSCURED MUCH OF THE TIME. PLEASE SEE THE AVIATION WEATHER CENTER
FOR THE LATEST INFORMATION ON ICING FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...WM
FIRE WEATHER...BRAUN



  [top]

000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 230855
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
255 AM MDT SAT MAY 23 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

A LARGE UPPER LOW WAS NEARING THE 4-CORNERS REGION THIS MORNING
AS A 90-KT JET WAS MOVING ACROSS THE ERN ROCKIES. A LEAD SHORT-
WAVE TROUGH WAS MOVING OVER THE CWA BUT WAS GETTING DAMPED BY AN
UPPER-LEVEL RIDGE. THE RESULT WAS VIRTUALLY NO PCPN OVER THE
CWA...EXCEPT FOR A FEW SHRA OVER FAR SRN SECTIONS. FOR TODAY THE
UPPER LOW WILL SLOWLY APPROACH THE CWA AS LOW-LEVEL MOISTURE
SLOWLY INCREASES. GIVEN CONSIDERABLE MIDLEVEL CLOUD COVER THE
ATMOSPHERE WILL NOT DESTABILIZE VERY MUCH...AND THUS LAPSE RATES
AND CAPE WILL BE RATHER MODEST THIS AFTN. AS A RESULT...PCPN WILL
CONTINUE TO BE LIMITED TODAY. BY TONIGHT INTO SUNDAY...HOWEVER...
THE MODELS CONTINUE TO ADVERTISE MUCH BETTER LIFT MOVING ACROSS
THE CWA AS THE UPPER LOW MOVES TO ERN WY. THERE SHOULD BE A DECENT
BAND OF SHOWERS AND ISOLD TSRA MOVING NWD LATE TNGT AND ACROSS THE
AREA SUNDAY MRNG. BY LATE SUNDAY THE UPPER LOW WILL BE OVER ERN WY
WITH SOME CLEARING ACROSS WRN SD. THIS WILL ALLOW FOR MIDLEVEL
LAPSE RATES TO STEEPEN TO 6-7.5 C/KM WITH SBCAPE REACHING 1000
J/KG OVER SRN SD. ALTHOUGH DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
SUPER- CELLS...THE CAPE PROFILE IS RATHER SKINNY...AND THUS DO NOT
EXCEPT MUCH SEVERE WEATHER (CONSISTENT WITH THE MARGINAL OUTLOOK
FROM SPC). ON SUNDAY NIGHT THE UPPER LOW WILL MOVE EAST ACROSS THE
CWA... BRINGING ADDITIONAL SHRA/TSRA. HIGH TEMPS WILL CONTINUE TO
BE BELOW AVERAGE GIVEN THE CONSIDERABLE CLOUD COVER AND
PRECIPITATION...BUT OVERNIGHT LOWS WILL BE NEAR AVERAGE.

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 254 AM MDT SAT MAY 23 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON FEATURES THROUGH
EARLY NEXT WEEK. UPPER-LEVEL LOW WILL LIFT NORTH AND EAST INTO
CANADA ON MONDAY. LINGERING SHOWERS AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE ON MONDAY. HIGHS ON MEMORIAL DAY WILL BE IN THE
50S AND LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY THROUGH FRIDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT
ISSUED AT 254 AM MDT SAT MAY 23 2015

MVFR/IFR CIGS WILL EXPAND EARLY THIS MORNING...WITH
LOCAL LIFR CIGS/VSBY FOR THE HIGHER TERRAIN OF THE BLACK HILLS.
MVFR/IFR CONDITIONS WITH SCATTERED SHOWERS WILL PERSIST THROUGH THE
DAY. MORE STEADY RAIN AND CONTINUED IFR/LIFR CONDITIONS ARE EXPECTED
LATER TONIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS65 KCYS 230525
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1125 PM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIR MASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SURFACE UPSLOPE FLOW
OVERTOPPED BY DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL
DEPICTED BY MODELS FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM
FAR SE WY INTO THE SRN NE PANHANDLE WITH CAPES FROM ABOUT
1000-1500 J/KG. THIS ALONG WITH DECENT SHEAR MAY LEAD TO A FEW
STRONG TO SEVERE STORMS THOUGH CONVECTION MAY BE ELEVATED. HAIL
WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROUGH SHOULD
CONTINUE TO LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK
OF THE SHOWERS EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON
ITS HEELS ANOTHER UPPER LEVEL TROUGH IS EXPECTED TO SPIN INTO THE
NORTHERN ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER
LEVEL DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING A
LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S FOR
MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE HIGH
PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL DAY
WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROUGH DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A RESULT...
WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY.
HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD FAVOR WARMER
TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS PAST WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1118 PM MDT FRI MAY 22 2015

MOIST SOUTHEASTERLY FLOW OVER SOUTHEAST WY AND WESTERN NE WILL
MAINTAIN LOW IFR TO IFR IN STRATUS AND AREAS OF FOG THROUGH
MIDDAY SATURDAY. VFR CONDITIONS WILL PREVAIL AT RAWLINS AND
SARATOGA WITH THE MOUNTAINS OBSCURED. MODELS KEEP IFR TO MVFR
CEILINGS AROUND THROUGH EARLY AFTERNOON WITH SCATTERED TSRA
DEVELOPING MID TO LATE AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...MAJ
FIRE WEATHER...RE
HYDROLOGY...RE




000
FXUS65 KRIW 230515 CCA
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1115 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS. IN ADDITION...A WEAK 700MB
CIRCULATION WILL DRIFT FROM WESTERN WYOMING THIS EVENING TO
NORTHEAST WY LATER SATURDAY...ADDING TO THE
CONVERGENCE/LIFT...ENHANCING PRECIP AMOUNTS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

CONFIDENCE IS LOW ON THE EXTENT/TIMING OF IFR/MVFR CONDITIONS FROM
LOW CEILINGS...FOG AND/OR RAIN THROUGH 00Z SUNDAY. A DRY SLOT IS
EXPECTED PUSH NORTHWARD AND IMPACT MUCH OF SOUTHERN AND EASTERN
SECTIONS THROUGH SATURDAY MORNING LIMITING SHRA ACTIVITY...BUT
FOG/LOW CEILINGS REMAIN POSSIBLE. ANOTHER WAVE PUSHES OVER THE
REGION SATURDAY AFTERNOON...WITH SCATTERED TO NUMEROUS SHOWERS WITH
ISOLATED THUNDERSTORMS OVER THE ENTIRE AREA IN THE AFTERNOON. A MORE
WIDESPREAD AREA OF MVFR/IFR CEILINGS WITH A MORE STEADY RAIN SHOULD
DEVELOP EAST OF THE DIVIDE...AND EASTERN SWEETWATER COUNTY SATURDAY
NIGHT. MOUNTAINS WILL BE OBSCURED MUCH OF THE TIME. PLEASE SEE THE
AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON ICING
FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...WM
FIRE WEATHER...LIPSON












000
FXUS65 KRIW 230515 CCA
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1115 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS. IN ADDITION...A WEAK 700MB
CIRCULATION WILL DRIFT FROM WESTERN WYOMING THIS EVENING TO
NORTHEAST WY LATER SATURDAY...ADDING TO THE
CONVERGENCE/LIFT...ENHANCING PRECIP AMOUNTS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../06Z ISSUANCE/

CONFIDENCE IS LOW ON THE EXTENT/TIMING OF IFR/MVFR CONDITIONS FROM
LOW CEILINGS...FOG AND/OR RAIN THROUGH 00Z SUNDAY. A DRY SLOT IS
EXPECTED PUSH NORTHWARD AND IMPACT MUCH OF SOUTHERN AND EASTERN
SECTIONS THROUGH SATURDAY MORNING LIMITING SHRA ACTIVITY...BUT
FOG/LOW CEILINGS REMAIN POSSIBLE. ANOTHER WAVE PUSHES OVER THE
REGION SATURDAY AFTERNOON...WITH SCATTERED TO NUMEROUS SHOWERS WITH
ISOLATED THUNDERSTORMS OVER THE ENTIRE AREA IN THE AFTERNOON. A MORE
WIDESPREAD AREA OF MVFR/IFR CEILINGS WITH A MORE STEADY RAIN SHOULD
DEVELOP EAST OF THE DIVIDE...AND EASTERN SWEETWATER COUNTY SATURDAY
NIGHT. MOUNTAINS WILL BE OBSCURED MUCH OF THE TIME. PLEASE SEE THE
AVIATION WEATHER CENTER FOR THE LATEST INFORMATION ON ICING
FORECASTS.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...WM
FIRE WEATHER...LIPSON











000
FXUS63 KUNR 230512
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1112 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM MDT FRI MAY 22 2015

MVFR/IFR CIGS WILL EXPAND OVERNIGHT...WITH LOCAL LIFR CIGS/VSBY
FOR THE HIGHER TERRAIN OF THE BLACK HILLS. MVFR/IFR CONDITIONS
WILL PERSIST THROUGH SATURDAY. SCATTERED SHOWERS WILL SPREAD
ACROSS THE AREA SATURDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7



000
FXUS63 KUNR 230512
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1112 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM MDT FRI MAY 22 2015

MVFR/IFR CIGS WILL EXPAND OVERNIGHT...WITH LOCAL LIFR CIGS/VSBY
FOR THE HIGHER TERRAIN OF THE BLACK HILLS. MVFR/IFR CONDITIONS
WILL PERSIST THROUGH SATURDAY. SCATTERED SHOWERS WILL SPREAD
ACROSS THE AREA SATURDAY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS65 KCYS 230057 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
657 PM MDT FRI MAY 22 2015

.UPDATE...FOR EVENING AVIATION UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 657 PM MDT FRI MAY 22 2015

RAIN ACTIVITY CONTINUE TO DIMINISH ACROSS THE AREA...BUT
SOUTHEASTERLY UPSLOPE FLOW FROM LARAMIE EAST WILL KEEP LOW CLOUDS
IN THE FORECAST THROUGH MID-DAY TOMORROW FOR MOST SITES EXCEPT
FOR RAWLINS. BROUGHT LIFR VISIBILITIES/CEILINGS IN FOR CHEYENNE
AND SIDNEY LATE THIS EVENING THROUGH MID MORNING...AND LIFR
CEILINGS IN FOR ALL OTHER SITES EXCEPT RAWLINS. MODELS INSISTING
MOST OF THE LOW CLOUDS WILL STICK AROUND THROUGH EARLY
AFTERNOON...THEN AS BREAKS START OCCURRING WE SHOULD SEE SCATTERED
THUNDERSTORMS DEVELOP IN THE LATE AFTERNOON HOURS ACROSS SOUTHEAST
WYOMING AND THE SOUTHERN NEBRASKA PANHANDLE.

&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...RE
HYDROLOGY...RE




000
FXUS65 KCYS 230057 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
657 PM MDT FRI MAY 22 2015

.UPDATE...FOR EVENING AVIATION UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 657 PM MDT FRI MAY 22 2015

RAIN ACTIVITY CONTINUE TO DIMINISH ACROSS THE AREA...BUT
SOUTHEASTERLY UPSLOPE FLOW FROM LARAMIE EAST WILL KEEP LOW CLOUDS
IN THE FORECAST THROUGH MID-DAY TOMORROW FOR MOST SITES EXCEPT
FOR RAWLINS. BROUGHT LIFR VISIBILITIES/CEILINGS IN FOR CHEYENNE
AND SIDNEY LATE THIS EVENING THROUGH MID MORNING...AND LIFR
CEILINGS IN FOR ALL OTHER SITES EXCEPT RAWLINS. MODELS INSISTING
MOST OF THE LOW CLOUDS WILL STICK AROUND THROUGH EARLY
AFTERNOON...THEN AS BREAKS START OCCURRING WE SHOULD SEE SCATTERED
THUNDERSTORMS DEVELOP IN THE LATE AFTERNOON HOURS ACROSS SOUTHEAST
WYOMING AND THE SOUTHERN NEBRASKA PANHANDLE.

&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS65 KCYS 230057 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
657 PM MDT FRI MAY 22 2015

.UPDATE...FOR EVENING AVIATION UPDATE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 657 PM MDT FRI MAY 22 2015

RAIN ACTIVITY CONTINUE TO DIMINISH ACROSS THE AREA...BUT
SOUTHEASTERLY UPSLOPE FLOW FROM LARAMIE EAST WILL KEEP LOW CLOUDS
IN THE FORECAST THROUGH MID-DAY TOMORROW FOR MOST SITES EXCEPT
FOR RAWLINS. BROUGHT LIFR VISIBILITIES/CEILINGS IN FOR CHEYENNE
AND SIDNEY LATE THIS EVENING THROUGH MID MORNING...AND LIFR
CEILINGS IN FOR ALL OTHER SITES EXCEPT RAWLINS. MODELS INSISTING
MOST OF THE LOW CLOUDS WILL STICK AROUND THROUGH EARLY
AFTERNOON...THEN AS BREAKS START OCCURRING WE SHOULD SEE SCATTERED
THUNDERSTORMS DEVELOP IN THE LATE AFTERNOON HOURS ACROSS SOUTHEAST
WYOMING AND THE SOUTHERN NEBRASKA PANHANDLE.

&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7



000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS63 KUNR 222306
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
506 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 504 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS EVENING. OTHERWISE...VFR CONDITIONS
ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING. SCATTERED
SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING... MOSTLY
ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN SD...WITH
MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY AND
WESTERN SD OVERNIGHT. MVFR/IFR CONDITIONS WITH SHOWERS WILL
PERSIST THROUGH SATURDAY AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...7




000
FXUS65 KCYS 222118
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
318 PM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.


&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.


&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS65 KCYS 222118
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
318 PM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.


&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.


&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS65 KCYS 222118
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
318 PM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.


&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.


&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS65 KCYS 222118
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
318 PM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 315 PM MDT FRI MAY 22 2015

SHORTWAVE LIFTING NORTHEAST FROM NORTHEAST COLORADO INTO WESTERN
NEBRASKA NOW WITH SOME CLEARING NOTED OVER EASTERN COLORADO. RAIN
AND CLOUDS HAVE KEPT THE AIRMASS RATHER STABLE OVER THE CWA WITH
NO STORMS NOTED SO FAR. A FEW NOT OUT OF THE QUESTION OUT WEST FOR
THE REST OF THE AFTERNOON.

SHOULD SEE SHOWERS BECOME MORE SCATTERED IN NATURE TONIGHT AS THE
INITIAL WAVE LIFTS NORTHEAST AND AWAY FROM THE AREA WITH A
MINIMUM IN COVERAGE LATER TONIGHT INTO SAT MORNING. MAIN UPPER
LOW CURRENTLY SOUTH OF LAS VEGAS NV WILL LIFT SLOWLY NORTHEAST
THROUGH SATURDAY AND ARRIVE OVER NW COLORADO BY LATE SAT
AFTERNOON. EXPECT YET ANOTHER ROUND OF CONVECTION TO DEVELOP OVER
MUCH OF THE CWA SAT AFTERNOON UNDER SFC UPSLOPE FLOW OVERTOPPED BY
DIFFLUENT UPPER FLOW. BETTER INSTABILITY STILL DEPICTED BY MODELS
FOR A RELATIVELY SHORT TIME SAT AFTERNOON FROM FAR SE WY INTO THE
SRN PANHANDLE WITH CAPES FROM ABOUT 1000-1500 J/KG. THIS ALONG
WITH DECENT SHEAR MAY LEAD TO A FEW STRONGER STORMS THOUGH
CONVECTION MAY BE ELEVATED. HAIL WOULD BE THE MAIN THREAT.

FAIRLY WIDESPREAD RAIN AND SHOWERS LIKELY TO CONTINUE SAT NIGHT
INTO SUNDAY AS THE UPPER LOW TREKS SLOWLY NORTHEAST ACROSS THE
CWA. A DRIER NORTHWEST TO WESTERLY FLOW ARRIVES LATE SUNDAY WHICH
WILL DECREASE SHOWER ACTIVITY.

TEMPS REMAINING COOL TO MILD GIVEN THE CLOUDS AND PCPN WITH MAXS
BELOW SEASONAL NORMS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 315 PM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE UPPER LEVEL WAVES MOVING THROUGH THE REGION NEXT WEEK.

MONDAY-MONDAY NIGHT:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IS SHOWING ANOTHER WEAK
POTENTIAL VORTICITY ANOMALY MOVING THROUGH THE FORECAST AREA
MONDAY MORNING. THIS FEATURE MAY TRIGGER A FEW SHOWERS AS IT
PASSES THROUGH. OTHERWISE...THIS UPPER LEVEL TROF SHOULD CONTINUE TO
LIFT NORTHEAST INTO NORTHERN PLAINS AND TAKE THE BULK OF THE SHOWERS
EAST OF THE FORECAST AREA BY MIDDAY. HOWEVER...ON ITS HEELS
ANOTHER UPPER LEVEL TROF IS EXPECTED TO SPIN INTO THE NORTHERN
ROCKIES. AHEAD OF THIS FEATURE...THERE WILL BE SOME UPPER LEVEL
DIFFLUENCE WHICH MAY BE ENOUGH TO INITIATE A FEW SHOWERS AND
THUNDERSTORMS MAINLY WEST OF THE LARAMIE RANGE. ELSEWHERE...WE MAY
SEE SOME SUNSHINE UNLESS WE SEE A STRONGER SURFACE HIGH BUILD ON
THE LEE SIDE OF THE LARAMIE RANGE. NOT REAL CONFIDENT THIS WILL
OCCUR...BUT THERE A FEW CANADIAN/GEM ENSEMBLES THAT ARE DEPICTING
A LITTLE STRONGER SURFACE HIGH THAN WHAT DEPICTED ON THE
OPERATIONAL MODELS. IF THE WEAKER HIGH DEVELOPS...WE ARE LOOKING
A LITTLE WARMER TEMPERATURES WITH HIGHS FINALLY REACHING THE 60S
FOR MUCH OF THE AREA. ON THE OTHER HAND...IF THE STRONGER SURFACE
HIGH PLUNGES INTO THE AREA...WE MAY SEE ANOTHER CLOUDY AND COOL
DAY WITH HIGHS ONLY REACHING THE 50S EAST OF THE LARAMIE RANGE.

TUESDAY-FRIDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT IN SHOWING THE NEXT UPPER
LEVEL TROF DEVELOPING OVER THE NORTHERN ROCKIES AND SLOWLY
SHIFTING EASTWARD THROUGH THE WEEK. THIS FEATURE WILL KEEP OUR
PATTERN PRETTY UNSETTLED THROUGH MUCH OF THE WEEK. AS A
RESULT...WE WILL HAVE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS
EACH DAY. HOWEVER...THE GOOD NEWS IS THAT THIS PATTERN SHOULD
FAVOR A BIT WARMER TEMPERATURES COMPARED TO WHAT WE HAVE SEEN THIS
PAST WEEK.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.


&&

.FIRE WEATHER...
ISSUED AT 315 PM MDT FRI MAY 22 2015

WIDESPREAD WETTING RAINS EXPECTED THROUGH SATURDAY EVENING BEFORE
PRECIPITATION DECREASES AND BECOMES MORE SCATTERED INTO EARLY NEXT
WEEK. NO CONCERNS SEEN INTO EARLY NEXT WEEK WITH FUELS MOIST AND
WEATHER CONDITIONS NON-CRITICAL.

&&

.HYDROLOGY...
ISSUED AT 315 PM MDT FRI MAY 22 2015

RELEASES FROM GRAYROCKS AND CONTINUED RUNOFF FROM AREA RAINFALL
WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AT MINOR FLOOD STAGE
THROUGH THE WEEKEND. RAIN LIKELY TO CONTINUE THROUGH LATE SATURDAY
THEN ACTIVITY SHOULD DECREASE AND BE MORE SCATTERED IN NATURE INTO
EARLY NEXT WEEK.


&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...RE
HYDROLOGY...RE



000
FXUS63 KUNR 222106
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
306 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS AFTERNOON AND EVENING. OTHERWISE...VFR
CONDITIONS ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING.
SCATTERED SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING...
MOSTLY ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN
SD...WITH MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY
AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...26



000
FXUS63 KUNR 222106
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
306 PM MDT FRI MAY 22 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 238 PM MDT FRI MAY 22 2015

THE UPPER LOW CURRENTLY LOCATED OVER THE SWRN CONUS WILL CONTINUE
TO AFFECT THE WEATHER OVER THE FORECAST AREA THROUGH THE WEEKEND.
12Z SOUNDINGS AND MODEL FORECASTS INDICATE A 110KT 300MB JET
STREAK ROUNDING THE UPPER LOW WILL MOVE NORTHWARD TOWARD THE
FORECAST AREA TONIGHT. THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT
AS IT MOVES SLOWLY NORTH ACROSS THE CWA TONIGHT. FORCING WILL BE
RELATIVELY WEAK WITH THE BEST LIFT PASSING TO THE EAST OF THE
FORECAST AREA. THE E-W ORIENTED BAND OF RAIN OVER NRN NEBRASKA IS
EXPECTED TO PUSH SLIGHTLY NORTHWARD INTO THE SWRN AND SC SD PARTS
OF THE FORECAST AREA LATE THIS AFTN-EARLY THIS EVENING. ISOLD-SCT
SHOWERS ARE EXPECTED OVER NERN WY AND PARTS OF FAR WRN SD TONIGHT.

SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA BY MID-DAY. A SHORT-WAVE TROUGH WILL APPROACH THE
FORECAST AREA FROM THE SOUTH DURING THE DAY...WITH INCREASING
PWATS AND SBCAPES OF 250-500 J/KG...MAINLY OVER THE SRN HALF OF
THE FA. EXPECT SCT SHRA/TSRA ACROSS THE CWA INCREASING IN COVERAGE
DURING THE AFTN. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER JET
STREAK AND SHORTWAVE TROUGH ACROSS THE AREA INCREASING THE
SYNOPTIC SCALE LIFT. THIS WILL LEAD TO A GOOD ROUND OF PCPN THAT
WILL PERSIST INTO SUNDAY. WILL KEEP THE ESF GOING FOR THE HEAVY
RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT ON
FEATURES THROUGH EARLY NEXT WEEK. UPPER LEVEL LOW WILL LIFT NORTH
AND EAST ACROSS THE REGION ON SUNDAY AND GRADUALLY WEAKEN AS IT
MOVES NORTHEAST OF THE AREA SUNDAY NIGHT AND MONDAY. FAIRLY
WIDESPREAD AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
AND MOVE ACROSS THE AREA ON SUNDAY. LOCALLY HEAVY RAINFALL IS
POSSIBLE...BUT THREAT FOR SEVERE STORMS LOOKS MINIMAL AT THIS POINT.
SHOWERS WILL TAPER OFF IN COVERAGE AND INTENSITY SUNDAY NIGHT INTO
MONDAY. HIGHS ON SUNDAY AND MEMORIAL DAY WILL BE IN THE 50S AND
LOWER 60S.

BEHIND THE SYSTEM...FLOW ALOFT WILL BE FROM THE WEST-SOUTHWEST NEXT
WEEK. THIS WILL KEEP ACTIVE WEATHER PATTERN IN PLACE...WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEK. THE
BETTER CHANCES AT THIS POINT LOOK TO BE WEDNESDAY AND THURSDAY.
TEMPERATURES WILL RETURN TO NEAR AVERAGE LEVELS IN MOST AREAS FOR
TUESDAY AND THE REST OF THE WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 238 PM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL
SLOWLY PUSH NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHERN
SD...AND THE BLACK HILLS THIS AFTERNOON AND EVENING. OTHERWISE...VFR
CONDITIONS ARE EXPECTED ELSEWHERE THROUGH THE EARLY EVENING.
SCATTERED SHOWERS WILL CONTINUE TONIGHT INTO SATURDAY MORNING...
MOSTLY ACROSS NORTHEAST WY...THE BLACK HILLS...AND SOUTHERN
SD...WITH MVFR/IFR CONDITIONS DEVELOPING ACROSS MUCH OF NORTHEAST WY
AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...26
AVIATION...26




000
FXUS65 KRIW 222105 CCA
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
259 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS. IN ADDITION...A WEAK 700MB
CIRCULATION WILL DRIFT FROM WESTERN WYOMING THIS EVENING TO
NORTHEAST WY LATER SATURDAY...ADDING TO THE
CONVERGENCE/LIFT...ENHANCING PRECIP AMOUNTS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN WHERE CLOUD BASES WILL BE BETWEEN 3
AND 4K IN SOME AREAS...NORTHERLY TO EASTERLY LOW LEVEL MOIST FLOW
WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR MUCH OF
THE EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM MOVING
INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY THIS
EVENING WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE
EXPECTED AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST
ON AND OFF THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE
ATMOSPHERE WILL BECOME MORE UNSTABLE GIVING RISE TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY
RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM COLORADO...UTAH
AND IDAHO RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN OBSCURATIONS/LOCALLY
HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING WITH LINGERING SHOWERS THEREAFTER. IN
ADDITION...THERE WILL BE PATCHES OF CLOUDS WITH BASES RANGING
FROM 3 TO 4K THROUGHOUT THE REGION. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO MOVE IN FROM THE SOUTH SATURDAY AS THE LOW PRESSURE
CENTER NEAR LAS VEGAS TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON








000
FXUS65 KRIW 222105 CCA
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
259 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS. IN ADDITION...A WEAK 700MB
CIRCULATION WILL DRIFT FROM WESTERN WYOMING THIS EVENING TO
NORTHEAST WY LATER SATURDAY...ADDING TO THE
CONVERGENCE/LIFT...ENHANCING PRECIP AMOUNTS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN WHERE CLOUD BASES WILL BE BETWEEN 3
AND 4K IN SOME AREAS...NORTHERLY TO EASTERLY LOW LEVEL MOIST FLOW
WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR MUCH OF
THE EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM MOVING
INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY THIS
EVENING WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE
EXPECTED AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST
ON AND OFF THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE
ATMOSPHERE WILL BECOME MORE UNSTABLE GIVING RISE TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY
RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM COLORADO...UTAH
AND IDAHO RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN OBSCURATIONS/LOCALLY
HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING WITH LINGERING SHOWERS THEREAFTER. IN
ADDITION...THERE WILL BE PATCHES OF CLOUDS WITH BASES RANGING
FROM 3 TO 4K THROUGHOUT THE REGION. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO MOVE IN FROM THE SOUTH SATURDAY AS THE LOW PRESSURE
CENTER NEAR LAS VEGAS TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON









000
FXUS65 KRIW 222059
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
259 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN WHERE CLOUD BASES WILL BE BETWEEN 3
AND 4K IN SOME AREAS...NORTHERLY TO EASTERLY LOW LEVEL MOIST FLOW
WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR MUCH OF
THE EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM MOVING
INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY THIS
EVENING WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE
EXPECTED AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST
ON AND OFF THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE
ATMOSPHERE WILL BECOME MORE UNSTABLE GIVING RISE TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY
RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM COLORADO...UTAH
AND IDAHO RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN OBSCURATIONS/LOCALLY
HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING WITH LINGERING SHOWERS THEREAFTER. IN
ADDITION...THERE WILL BE PATCHES OF CLOUDS WITH BASES RANGING
FROM 3 TO 4K THROUGHOUT THE REGION. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO MOVE IN FROM THE SOUTH SATURDAY AS THE LOW PRESSURE
CENTER NEAR LAS VEGAS TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON






000
FXUS65 KRIW 222059
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
259 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN WHERE CLOUD BASES WILL BE BETWEEN 3
AND 4K IN SOME AREAS...NORTHERLY TO EASTERLY LOW LEVEL MOIST FLOW
WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR MUCH OF
THE EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM MOVING
INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY THIS
EVENING WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE
EXPECTED AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST
ON AND OFF THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE
ATMOSPHERE WILL BECOME MORE UNSTABLE GIVING RISE TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY
RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM COLORADO...UTAH
AND IDAHO RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN OBSCURATIONS/LOCALLY
HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING WITH LINGERING SHOWERS THEREAFTER. IN
ADDITION...THERE WILL BE PATCHES OF CLOUDS WITH BASES RANGING
FROM 3 TO 4K THROUGHOUT THE REGION. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO MOVE IN FROM THE SOUTH SATURDAY AS THE LOW PRESSURE
CENTER NEAR LAS VEGAS TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON





000
FXUS65 KRIW 222059
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
259 PM MDT FRI MAY 22 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

...WET UNSETTLED PATTERN TO CONTINUE...

LOW CLOUDS AND COOL TEMPERATURES EAST OF THE DIVIDE ARE PREVALENT
ALONG AND SOUTH OF THE OWL CREEK MTNS AND ALONG AND EAST OF THE BIG
HORN MTNS INCLUDING AREAS ACROSS THE WIND RIVER BASIN INTO NATRONA
AND JOHNSON COUNTIES. A COOL NORTHEASTERLY FLOW IS FEEDING LOW LEVEL
MOISTURE INTO THESE AREAS AND FOR THIS REASON...DO NOT EXPECT MUCH
IN THE WAY OF THUNDERSTORMS FOR THE REMAINDER OF THIS AFTERNOON AND
EVENING IN THESE AREAS. THE AIRMASS IS MUCH MORE UNSTABLE WEST OF
THE DIVIDE. THE BIG HORN BASIN HAS RECEIVED MORE SUNSHINE THEN THE
REST OF THE AREA EAST OF THE DIVIDE SO THIS AREA COULD ALSO BE
PRIMED FOR MORE THUNDERSTORM ACTIVITY FOR THE REST OF TODAY. A
THUNDERSTORM HAS ALREADY FORMED NEAR MEETEETSE WITH OTHER T STORMS
PREVALENT WEST OF THE DIVIDE. CURRENTLY THE MAIN CIRCULATION OF OUR
NEXT CLOSED LOW APPEARS TO BE OVER THE NEVADA/CALIFORNIA/ARIZONA
TRIPLE POINT. THE SSW SOMEWHAT DIFLUENT FLOW WILL ENCOURAGE
THUNDERSTORM DEVELOPMENT FOR THE REST OF TODAY EXCEPT IN THE
AFOREMENTIONED STABLE AREAS. THE LOW WILL TRAVEL TO UTAH TONIGHT AND
THEN TOWARD WYOMING SATURDAY ALONG WITH A TROUGH TROUGH EXTENDING TO
WYOMING OUT AHEAD OF IT. SOME SNOW IS EXPECTED TO FALL ABOVE 9500
FEET OR SO LATE TONIGHT WITH UP TO AN INCH AND A HALF OF SNOW
EXPECTED AT THESE ELEVATIONS IN THE WIND RIVER RANGE AFTER MIDNIGHT
TONIGHT. MORE WIDESPREAD THUNDERSTORM ACTIVITY IS EXPECTED SATURDAY
WITH SOMEWHAT MILDER TEMPS EXPECTED THANKS TO THE SSW FLOW AHEAD OF
THE APPROACHING LOW BEFORE SHORT LIVED COOLER AIR FLOWS IN AROUND
THE BACKSIDE OF THE LOW. HOWEVER...THE STRONGEST STORMS SHOULD HOLD
OFF UNTIL AFTER 21Z SATURDAY SINCE WITH AREAS EAST OF THE DIVIDE
STILL CONTENDING WITH A COOL MOIST EASTERLY FLOW MAKING IT DIFFICULT
TO TAKE ADVANTAGE OF MUCH SOLAR INSULATION AT LEAST UNTIL THEN AS
SFC CYCLOGENESIS TAKES PLACE IN SE CO. AS HAS BEEN THE CASE THESE
LAST COUPLE OF WEEKS...ANY THUNDERSTORMS THAT DO FORM WILL LIKELY
PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL GIVEN THE LOW LEVEL LC
AND LOW ELEVATION WET BULB ZEROS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE SLOWLY
EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL WYOMING
WITH SOUTHWEST FLOW ALOFT OVER THE AREA.  THE AIRMASS WILL BE
UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN MOUNTAINS
AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE EVENING.
SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL LINGER INTO
SUNDAY MORNING.  A CANADIAN COLD FRONT WILL SLIDE SOUTH THROUGH MUCH
OF THE AREA AS THE UPPER LOW DRIFTS SLOWLY EAST OVER THE COLD
FRONT.  SHOWERS WILL BE WIDESPREAD ACROSS THE AREA WITH COOL
TEMPERATURES.  ENOUGH INSTABILITY WILL BE OVER THE AREA IN THE
EVENING TO SUPPORT ISOLATED THUNDERSTORMS WITH SMALL HAIL.  SNOW
LEVELS WILL LOWER THROUGH SATURDAY NIGHT DOWN TO AROUND 7500 FEET.
SUNDAY WILL BE COOL AND REMAINING SHOWERY WITH A FEW ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO
THE EAST AS ANOTHER INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL
DECREASE THROUGH SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING
OVER THE WESTERN MOUNTAINS.  LESS MOISTURE WILL BE OVER THE AREA ON
MONDAY BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS.  MONDAY NIGHT WILL SEE
A SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH WILL
SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY AND
TUESDAY NIGHT WITH MORE SHOWERS...ESPECIALLY OVER THE WESTERN AND
NORTHERN MOUNTAINS.  TEMPERATURES SHOULD BE SLIGHTLY WARMER.  THE
TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE NORTH AND
EAST ACROSS THE AREA WITH INCREASING SHOWERS AND ISOLATED
THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING.  THE TROUGH WILL
BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN COLD FRONT
MOVES SOUTH BRINGING GENERAL COOLING.  THE FLOW ALOFT WILL BECOME
ZONAL THURSDAY AND FRIDAY WITH DRYING AND WARMING.  THIS WILL KEEP
SOME SHOWERS AND ISOLATED THUNDERSTORMS IN THE WESTERN AND NORTHERN
MOUNTAINS. MODELS BEGIN TO DIVERGE WITH THE FASTER MOVING SHORT WAVE
TROUGHS IN THE ZONAL FLOW WHICH DECREASES THE CONFIDENCE IN THE
STRENGTH AND TIMING OF PRECIPITATION.

&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN WHERE CLOUD BASES WILL BE BETWEEN 3
AND 4K IN SOME AREAS...NORTHERLY TO EASTERLY LOW LEVEL MOIST FLOW
WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR MUCH OF
THE EVENING AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM MOVING
INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY THIS
EVENING WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE
EXPECTED AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST
ON AND OFF THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE
ATMOSPHERE WILL BECOME MORE UNSTABLE GIVING RISE TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY
RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM COLORADO...UTAH
AND IDAHO RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN OBSCURATIONS/LOCALLY
HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING WITH LINGERING SHOWERS THEREAFTER. IN
ADDITION...THERE WILL BE PATCHES OF CLOUDS WITH BASES RANGING
FROM 3 TO 4K THROUGHOUT THE REGION. ANOTHER ROUND OF THUNDERSTORMS
IS EXPECTED TO MOVE IN FROM THE SOUTH SATURDAY AS THE LOW PRESSURE
CENTER NEAR LAS VEGAS TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON






000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI




000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KCYS 221758
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1158 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1144 AM MDT FRI MAY 22 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
SHOWERS WILL MOVE OUT OF THE AREA THIS AFTERNOON AND LOW CEILINGS
AGAIN TONIGHT.

LATEST RADAR LOOP WAS SHOWING DRIER AIR STARTING TO FILTER INTO
THE NEBRASKA PANHANDLE. HOWEVER...THIS DRY SLOT WAS BEGINNING TO
FILL BACK IN WITH MORE LIGHT RAIN DURING THE LAST COUPLE OF VOLUME
SCANS. WE BASED OUR TAF ON POTENTIAL DRYING THIS AFTERNOON...BUT
WE WILL HAVE TO WATCH RADAR TRENDS TO SEE IF THIS DRY SLOT CAN
REMAIN IN TACT. OTHERWISE...MVFR CEILINGS WILL BE THE TREND THIS
AFTERNOON WITH GUSTY SOUTHEAST FLOW. THE NEXT CONCERN TONIGHT
WILL BE THE POTENTIAL FOR LOWER CEILINGS FILTERING BACK INTO THE
AREA ONCE AGAIN. MEANWHILE...THE UPPER LEVEL TROF BEGINS TO MOVE
INTO WESTERN COLORADO FROM THE GREAT BASIN. THIS FEATURE WILL
INDUCE SURFACE LOW PRESSURE EAST OF THE COLORADO FRONT RANGE
TOMORROW MORNING. AS A RESULT...THE SURFACE FLOW SHOULD BECOME
EASTERLY AND BRING IFR CEILINGS TO MUCH OF THE AREA TONIGHT WITH
THE LIFR CEILINGS POSSIBLE AROUND CYS. THESE LOW CEILINGS SHOULD
GRADUALLY CLIMB AFTER DAYBREAK...BUT MAY HANG ON THROUGH THE MUCH
OF THE MORNING.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...REC
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KRIW 221757
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1156 AM MDT FRI MAY 22 2015

TODAY THROUGH SUNDAY NIGHT

WV IMAGERY SHOWING LARGE DEEP TROF WRN CONUS...CLOSED LOW OVR
CALIFORNIA...SW RIDGE CNTRL CONUS...DEEP TROF ERN CONUS. WEAK SW
MOVING NWD THRU CNTRL WY THIS EVENING...WITH STRONGER SW TO THE
SOUTH...ROTATING ANTI-CLOCKWISE AROUND THE CLOSED LOW...SPREADING
OVR COLORADO. SFC HAS HIGH P CNTRL CONUS...LOW P AND NEARLY
STATIONARY FRONT WEST OF WY...DRAPED FROM NRN ID...SWD THRU UT AND
INTO WRN NM. ISOLATED TO WIDELY SCATTERED SHOWERS SPRINKLED AROUND
THE FA TONIGHT.

THRU TODAY...SW CURRENTLY OVR COLORADO WILL CONTINUE TO
ROTATE NWD ACROSS WY THIS AFTERNOON/EVENING/OVERNIGHT...WITH SW AXIS
BISECTING WY FROM SW TO NE BY THIS TIME TOMORROW. THIS WILL AID IN
KICKING OFF ANOTHER BATCH OF SHRA/TSRA. OTHERWISE...LL ERN FLOW
ACROSS MOST OF THE AREA E OF THE DIVIDE WILL STRENGTHEN...KEEPING
GOOD AMOUNTS OF LL MOISTURE ACROSS THE FA...WHILE MORE MID/UPR LVL
MOISTURE MOVES INTO THE REGION FROM THE SOUTH. DIRECTIONAL AND SPEED
SHEAR NOT PARTICULARLY IMPRESSIVE WITH RATHER WEAK MID/UPR FLOW IN
PLACE. BUOYANCY WILL BE MODEST WITH ML CAPE RANGING FROM 300 TO 500
J/KG FOR MOST OF THE CNTRL AND WRN FA...WEAKER TO THE EAST. STRONGER
STORMS OF THE DAY CURRENTLY LOOK TO FORM ACROSS THE FAR WEST...FROM
N OF JACKSON S TO AROUND KEMMERER WHERE WHERE SOME MARGINALLY
BETTER CHANCES FOR SUNSHINE WILL OCCUR...ALONG WITH CHCS FOR MAINLY
SMALL HAIL.

THE REST OF THE FCST FOR THE MEMORIAL DAY WEEKEND...COOL AND WET.
UPR LOW MIGRATES FROM NEAR THE 4 CORNERS REGION TO THE NRN HIGH
PLAINS BY THE END OF THE FCST...WHILE SFC CYCLOGENESIS TAKES PLACE
FROM ERN/NERN CO INTO THE CNTRL PLAINS THRU THE SAME PERIOD. BETWEEN
LOW TO MID LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR
MOISTURE FROM ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY
PLENTIFUL RAINFALL AND SOME SNOWFALL WILL BE HAD OVER THE SAME
PERIOD. THIS WILL...HOWEVER...BE A COMPARATIVELY WARM SYSTEM THE WAY
IT STANDS NOW WITH H7 TEMPS NOT DROPPING AT ANY ONE TIME TO MUCH
LESS THAN -1/-2DEG C...AND EVEN THEN FOR ONLY SHORT PERIODS AS THE
UPR LOW ROTATES ACROSS THE STATE. SUNDAY MORNING WILL LIKELY SEE THE
COLD TEMPS OVR THE NW FCST QUAD...BUT WITH LITTLE ATTENDING SNOWFALL
AS THE SYSTEM PULLS AWAY. GENERALLY...A TRACE TO AND INCH OR TWO
WILL BE POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS AND ONLY
ACROSS THE HIGHEST ELEVATIONS...ISOLATED 3 INCHES. SEVERE WX SHOULD
REMAIN MOSTLY EAST TO SOUTHEAST OF FA THROUGH THE PERIOD WITH ONLY
ISOLATED SMALL HAIL A SMALL THREAT THROUGHOUT. EARLY MORNING FOG
WILL ALSO BE POSSIBLE OVR MANY AREAS THROUGHOUT THE FCST.
.SHORT TERM...

.LONG TERM...MONDAY THROUGH FRIDAY

THE LONG RANGE MODELS ARE IN MODEST AGREEMENT WITH THE WEATHER
PATTERN MONDAY THROUGH FRIDAY. MEMORIAL DAY WILL BE DRIER FOR MOST
PLACES WITH MAINLY ISOLATED AFTERNOON SHOWERS OR STORMS. ACTIVITY
COULD BE A LITTLE MORE NUMEROUS IN THE FAR WEST LATE IN THE DAY INTO
MONDAY EVENING. HIGH TEMPS ON MEMORIAL DAY WILL BE AT OR SLIGHTLY
BELOW NORMAL WITH 50S AND 60S...40S TO LOW 50S FOR THE MOUNTAINS.

FOR TUESDAY THROUGH THURSDAY...A WEATHER SYSTEM SETTLES INTO THE
PACIFIC NW PER THE GFS MODEL AND MOVES INTO IDAHO THURSDAY NIGHT.
THEN IT BRINGS THE WEATHER SYSTEM THROUGH THE REGION FRIDAY. THE
ECMWF MODEL IS A BIT DIFFERENT AND FASTER AS IT DROPS THE WEATHER
SYSTEM INTO IDAHO TUESDAY NIGHT AND ACROSS THE ROCKIES WED NIGHT
AND THURSDAY MORNING. THEN THE ECMWF MODEL HAS FAIRLY QUIET
WEATHER FOR NEXT FRIDAY. BOTH MODELS HAVE BEEN CONSISTENT IN THEIR
TIMING THE PAST FEW MODEL RUNS. WILL LEAN TOWARD THE GFS SOLUTION
TONIGHT. THIS MEANS A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON
AND EVENING FROM TUE THROUGH FRI. COVERAGE SHOULD INCREASE OVER
THE WEST AND NORTH LATER NEXT WEEK AS THE SYSTEM GETS CLOSER AND
EVENTUALLY PASSES THROUGH THE AREA. WILL SEE HOW THINGS LOOK
TONIGHT AND SEE IF ANY CHANGES ARE NEEDED. AS FOR HIGH TEMPS TUE
THROUGH FRI...LITTLE DAY TO DAY CHANGE WITH 60S TO LOW 70S AND 50S
FOR THE MOUNTAINS. OF COURSE TOO MUCH CLOUD COVER WILL PRODUCE
COOLER THAN FORECASTED HIGHS.

&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN...NORTHERLY TO EASTERLY LOW LEVEL
MOIST FLOW WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR
MUCH OF THE AFTERNOON AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM
MOVING INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY
WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE EXPECTED
AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST ON AND OFF
THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE ATMOSPHERE WILL
BECOME MORE UNSTABLE RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL START THE AFTERNOON OUT...EXCEPT FOR KRKS WHERE
OCCASIONAL MVFR CONDITIONS DUE TO LOW CIGS WILL OCCUR...BEFORE
ANOTHER ROUND OF SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM
COLORADO AND UTAH RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN
OBSCURATIONS/LOCALLY HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS
WILL CONTINUE WELL INTO THE EVENING WITH LINGERING SHOWERS
THEREAFTER. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO MOVE IN
FROM THE SOUTH SATURDAY AS THE LOW PRESSURE CENTER NEAR LAS VEGAS
TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...LIPSON
FIRE WEATHER...BRAUN








000
FXUS65 KRIW 221757
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1156 AM MDT FRI MAY 22 2015

TODAY THROUGH SUNDAY NIGHT

WV IMAGERY SHOWING LARGE DEEP TROF WRN CONUS...CLOSED LOW OVR
CALIFORNIA...SW RIDGE CNTRL CONUS...DEEP TROF ERN CONUS. WEAK SW
MOVING NWD THRU CNTRL WY THIS EVENING...WITH STRONGER SW TO THE
SOUTH...ROTATING ANTI-CLOCKWISE AROUND THE CLOSED LOW...SPREADING
OVR COLORADO. SFC HAS HIGH P CNTRL CONUS...LOW P AND NEARLY
STATIONARY FRONT WEST OF WY...DRAPED FROM NRN ID...SWD THRU UT AND
INTO WRN NM. ISOLATED TO WIDELY SCATTERED SHOWERS SPRINKLED AROUND
THE FA TONIGHT.

THRU TODAY...SW CURRENTLY OVR COLORADO WILL CONTINUE TO
ROTATE NWD ACROSS WY THIS AFTERNOON/EVENING/OVERNIGHT...WITH SW AXIS
BISECTING WY FROM SW TO NE BY THIS TIME TOMORROW. THIS WILL AID IN
KICKING OFF ANOTHER BATCH OF SHRA/TSRA. OTHERWISE...LL ERN FLOW
ACROSS MOST OF THE AREA E OF THE DIVIDE WILL STRENGTHEN...KEEPING
GOOD AMOUNTS OF LL MOISTURE ACROSS THE FA...WHILE MORE MID/UPR LVL
MOISTURE MOVES INTO THE REGION FROM THE SOUTH. DIRECTIONAL AND SPEED
SHEAR NOT PARTICULARLY IMPRESSIVE WITH RATHER WEAK MID/UPR FLOW IN
PLACE. BUOYANCY WILL BE MODEST WITH ML CAPE RANGING FROM 300 TO 500
J/KG FOR MOST OF THE CNTRL AND WRN FA...WEAKER TO THE EAST. STRONGER
STORMS OF THE DAY CURRENTLY LOOK TO FORM ACROSS THE FAR WEST...FROM
N OF JACKSON S TO AROUND KEMMERER WHERE WHERE SOME MARGINALLY
BETTER CHANCES FOR SUNSHINE WILL OCCUR...ALONG WITH CHCS FOR MAINLY
SMALL HAIL.

THE REST OF THE FCST FOR THE MEMORIAL DAY WEEKEND...COOL AND WET.
UPR LOW MIGRATES FROM NEAR THE 4 CORNERS REGION TO THE NRN HIGH
PLAINS BY THE END OF THE FCST...WHILE SFC CYCLOGENESIS TAKES PLACE
FROM ERN/NERN CO INTO THE CNTRL PLAINS THRU THE SAME PERIOD. BETWEEN
LOW TO MID LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR
MOISTURE FROM ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY
PLENTIFUL RAINFALL AND SOME SNOWFALL WILL BE HAD OVER THE SAME
PERIOD. THIS WILL...HOWEVER...BE A COMPARATIVELY WARM SYSTEM THE WAY
IT STANDS NOW WITH H7 TEMPS NOT DROPPING AT ANY ONE TIME TO MUCH
LESS THAN -1/-2DEG C...AND EVEN THEN FOR ONLY SHORT PERIODS AS THE
UPR LOW ROTATES ACROSS THE STATE. SUNDAY MORNING WILL LIKELY SEE THE
COLD TEMPS OVR THE NW FCST QUAD...BUT WITH LITTLE ATTENDING SNOWFALL
AS THE SYSTEM PULLS AWAY. GENERALLY...A TRACE TO AND INCH OR TWO
WILL BE POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS AND ONLY
ACROSS THE HIGHEST ELEVATIONS...ISOLATED 3 INCHES. SEVERE WX SHOULD
REMAIN MOSTLY EAST TO SOUTHEAST OF FA THROUGH THE PERIOD WITH ONLY
ISOLATED SMALL HAIL A SMALL THREAT THROUGHOUT. EARLY MORNING FOG
WILL ALSO BE POSSIBLE OVR MANY AREAS THROUGHOUT THE FCST.
.SHORT TERM...

.LONG TERM...MONDAY THROUGH FRIDAY

THE LONG RANGE MODELS ARE IN MODEST AGREEMENT WITH THE WEATHER
PATTERN MONDAY THROUGH FRIDAY. MEMORIAL DAY WILL BE DRIER FOR MOST
PLACES WITH MAINLY ISOLATED AFTERNOON SHOWERS OR STORMS. ACTIVITY
COULD BE A LITTLE MORE NUMEROUS IN THE FAR WEST LATE IN THE DAY INTO
MONDAY EVENING. HIGH TEMPS ON MEMORIAL DAY WILL BE AT OR SLIGHTLY
BELOW NORMAL WITH 50S AND 60S...40S TO LOW 50S FOR THE MOUNTAINS.

FOR TUESDAY THROUGH THURSDAY...A WEATHER SYSTEM SETTLES INTO THE
PACIFIC NW PER THE GFS MODEL AND MOVES INTO IDAHO THURSDAY NIGHT.
THEN IT BRINGS THE WEATHER SYSTEM THROUGH THE REGION FRIDAY. THE
ECMWF MODEL IS A BIT DIFFERENT AND FASTER AS IT DROPS THE WEATHER
SYSTEM INTO IDAHO TUESDAY NIGHT AND ACROSS THE ROCKIES WED NIGHT
AND THURSDAY MORNING. THEN THE ECMWF MODEL HAS FAIRLY QUIET
WEATHER FOR NEXT FRIDAY. BOTH MODELS HAVE BEEN CONSISTENT IN THEIR
TIMING THE PAST FEW MODEL RUNS. WILL LEAN TOWARD THE GFS SOLUTION
TONIGHT. THIS MEANS A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON
AND EVENING FROM TUE THROUGH FRI. COVERAGE SHOULD INCREASE OVER
THE WEST AND NORTH LATER NEXT WEEK AS THE SYSTEM GETS CLOSER AND
EVENTUALLY PASSES THROUGH THE AREA. WILL SEE HOW THINGS LOOK
TONIGHT AND SEE IF ANY CHANGES ARE NEEDED. AS FOR HIGH TEMPS TUE
THROUGH FRI...LITTLE DAY TO DAY CHANGE WITH 60S TO LOW 70S AND 50S
FOR THE MOUNTAINS. OF COURSE TOO MUCH CLOUD COVER WILL PRODUCE
COOLER THAN FORECASTED HIGHS.

&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN...NORTHERLY TO EASTERLY LOW LEVEL
MOIST FLOW WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR
MUCH OF THE AFTERNOON AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM
MOVING INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY
WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE EXPECTED
AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST ON AND OFF
THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE ATMOSPHERE WILL
BECOME MORE UNSTABLE RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL START THE AFTERNOON OUT...EXCEPT FOR KRKS WHERE
OCCASIONAL MVFR CONDITIONS DUE TO LOW CIGS WILL OCCUR...BEFORE
ANOTHER ROUND OF SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM
COLORADO AND UTAH RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN
OBSCURATIONS/LOCALLY HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS
WILL CONTINUE WELL INTO THE EVENING WITH LINGERING SHOWERS
THEREAFTER. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO MOVE IN
FROM THE SOUTH SATURDAY AS THE LOW PRESSURE CENTER NEAR LAS VEGAS
TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...LIPSON
FIRE WEATHER...BRAUN








000
FXUS65 KRIW 221757
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1156 AM MDT FRI MAY 22 2015

TODAY THROUGH SUNDAY NIGHT

WV IMAGERY SHOWING LARGE DEEP TROF WRN CONUS...CLOSED LOW OVR
CALIFORNIA...SW RIDGE CNTRL CONUS...DEEP TROF ERN CONUS. WEAK SW
MOVING NWD THRU CNTRL WY THIS EVENING...WITH STRONGER SW TO THE
SOUTH...ROTATING ANTI-CLOCKWISE AROUND THE CLOSED LOW...SPREADING
OVR COLORADO. SFC HAS HIGH P CNTRL CONUS...LOW P AND NEARLY
STATIONARY FRONT WEST OF WY...DRAPED FROM NRN ID...SWD THRU UT AND
INTO WRN NM. ISOLATED TO WIDELY SCATTERED SHOWERS SPRINKLED AROUND
THE FA TONIGHT.

THRU TODAY...SW CURRENTLY OVR COLORADO WILL CONTINUE TO
ROTATE NWD ACROSS WY THIS AFTERNOON/EVENING/OVERNIGHT...WITH SW AXIS
BISECTING WY FROM SW TO NE BY THIS TIME TOMORROW. THIS WILL AID IN
KICKING OFF ANOTHER BATCH OF SHRA/TSRA. OTHERWISE...LL ERN FLOW
ACROSS MOST OF THE AREA E OF THE DIVIDE WILL STRENGTHEN...KEEPING
GOOD AMOUNTS OF LL MOISTURE ACROSS THE FA...WHILE MORE MID/UPR LVL
MOISTURE MOVES INTO THE REGION FROM THE SOUTH. DIRECTIONAL AND SPEED
SHEAR NOT PARTICULARLY IMPRESSIVE WITH RATHER WEAK MID/UPR FLOW IN
PLACE. BUOYANCY WILL BE MODEST WITH ML CAPE RANGING FROM 300 TO 500
J/KG FOR MOST OF THE CNTRL AND WRN FA...WEAKER TO THE EAST. STRONGER
STORMS OF THE DAY CURRENTLY LOOK TO FORM ACROSS THE FAR WEST...FROM
N OF JACKSON S TO AROUND KEMMERER WHERE WHERE SOME MARGINALLY
BETTER CHANCES FOR SUNSHINE WILL OCCUR...ALONG WITH CHCS FOR MAINLY
SMALL HAIL.

THE REST OF THE FCST FOR THE MEMORIAL DAY WEEKEND...COOL AND WET.
UPR LOW MIGRATES FROM NEAR THE 4 CORNERS REGION TO THE NRN HIGH
PLAINS BY THE END OF THE FCST...WHILE SFC CYCLOGENESIS TAKES PLACE
FROM ERN/NERN CO INTO THE CNTRL PLAINS THRU THE SAME PERIOD. BETWEEN
LOW TO MID LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR
MOISTURE FROM ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY
PLENTIFUL RAINFALL AND SOME SNOWFALL WILL BE HAD OVER THE SAME
PERIOD. THIS WILL...HOWEVER...BE A COMPARATIVELY WARM SYSTEM THE WAY
IT STANDS NOW WITH H7 TEMPS NOT DROPPING AT ANY ONE TIME TO MUCH
LESS THAN -1/-2DEG C...AND EVEN THEN FOR ONLY SHORT PERIODS AS THE
UPR LOW ROTATES ACROSS THE STATE. SUNDAY MORNING WILL LIKELY SEE THE
COLD TEMPS OVR THE NW FCST QUAD...BUT WITH LITTLE ATTENDING SNOWFALL
AS THE SYSTEM PULLS AWAY. GENERALLY...A TRACE TO AND INCH OR TWO
WILL BE POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS AND ONLY
ACROSS THE HIGHEST ELEVATIONS...ISOLATED 3 INCHES. SEVERE WX SHOULD
REMAIN MOSTLY EAST TO SOUTHEAST OF FA THROUGH THE PERIOD WITH ONLY
ISOLATED SMALL HAIL A SMALL THREAT THROUGHOUT. EARLY MORNING FOG
WILL ALSO BE POSSIBLE OVR MANY AREAS THROUGHOUT THE FCST.
.SHORT TERM...

.LONG TERM...MONDAY THROUGH FRIDAY

THE LONG RANGE MODELS ARE IN MODEST AGREEMENT WITH THE WEATHER
PATTERN MONDAY THROUGH FRIDAY. MEMORIAL DAY WILL BE DRIER FOR MOST
PLACES WITH MAINLY ISOLATED AFTERNOON SHOWERS OR STORMS. ACTIVITY
COULD BE A LITTLE MORE NUMEROUS IN THE FAR WEST LATE IN THE DAY INTO
MONDAY EVENING. HIGH TEMPS ON MEMORIAL DAY WILL BE AT OR SLIGHTLY
BELOW NORMAL WITH 50S AND 60S...40S TO LOW 50S FOR THE MOUNTAINS.

FOR TUESDAY THROUGH THURSDAY...A WEATHER SYSTEM SETTLES INTO THE
PACIFIC NW PER THE GFS MODEL AND MOVES INTO IDAHO THURSDAY NIGHT.
THEN IT BRINGS THE WEATHER SYSTEM THROUGH THE REGION FRIDAY. THE
ECMWF MODEL IS A BIT DIFFERENT AND FASTER AS IT DROPS THE WEATHER
SYSTEM INTO IDAHO TUESDAY NIGHT AND ACROSS THE ROCKIES WED NIGHT
AND THURSDAY MORNING. THEN THE ECMWF MODEL HAS FAIRLY QUIET
WEATHER FOR NEXT FRIDAY. BOTH MODELS HAVE BEEN CONSISTENT IN THEIR
TIMING THE PAST FEW MODEL RUNS. WILL LEAN TOWARD THE GFS SOLUTION
TONIGHT. THIS MEANS A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON
AND EVENING FROM TUE THROUGH FRI. COVERAGE SHOULD INCREASE OVER
THE WEST AND NORTH LATER NEXT WEEK AS THE SYSTEM GETS CLOSER AND
EVENTUALLY PASSES THROUGH THE AREA. WILL SEE HOW THINGS LOOK
TONIGHT AND SEE IF ANY CHANGES ARE NEEDED. AS FOR HIGH TEMPS TUE
THROUGH FRI...LITTLE DAY TO DAY CHANGE WITH 60S TO LOW 70S AND 50S
FOR THE MOUNTAINS. OF COURSE TOO MUCH CLOUD COVER WILL PRODUCE
COOLER THAN FORECASTED HIGHS.

&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXCEPT FOR THE BIG HORN BASIN...NORTHERLY TO EASTERLY LOW LEVEL
MOIST FLOW WILL KEEP LOW CLOUDS/MVFR/IFR/MTN OBSCURATIONS AROUND FOR
MUCH OF THE AFTERNOON AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM
MOVING INTO THE AREA FROM THE SOUTHERN GREAT BASIN AREA. INSTABILITY
WILL BE RELATIVELY WEAK SO MAINLY JUST RAIN SHOWERS ARE EXPECTED
AROUND THE AREA. THESE CONDITIONS ARE EXPECTED TO PERSIST ON AND OFF
THROUGH ABOUT 21Z SATURDAY AFTER WHICH TIME THE ATMOSPHERE WILL
BECOME MORE UNSTABLE RESULTING IN SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS ACCOMPANIED BY LOCALLY HEAVY RAIN AND SMALL HAIL.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS WILL START THE AFTERNOON OUT...EXCEPT FOR KRKS WHERE
OCCASIONAL MVFR CONDITIONS DUE TO LOW CIGS WILL OCCUR...BEFORE
ANOTHER ROUND OF SCATTERED TO NUMEROUS THUNDERSTORMS MOVE IN FROM
COLORADO AND UTAH RESULTING IN LOCAL MVFR/IFR CONDITIONS/MTN
OBSCURATIONS/LOCALLY HEAVY RAIN AND SMALL HAIL. THESE THUNDERSTORMS
WILL CONTINUE WELL INTO THE EVENING WITH LINGERING SHOWERS
THEREAFTER. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO MOVE IN
FROM THE SOUTH SATURDAY AS THE LOW PRESSURE CENTER NEAR LAS VEGAS
TRACKS NORTHEAST TO WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...LIPSON
FIRE WEATHER...BRAUN









000
FXUS63 KUNR 221727
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1127 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 1127 AM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL SLOWLY PUSH
NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHWEST SD...AND
THE BLACK HILLS THIS AFTERNOON. OTHERWISE...VFR CONDITIONS ARE
EXPECTED ELSEWHERE THROUGH THE AFTERNOON. SCATTERED SHOWERS WILL
CONTINUE TONIGHT INTO SATURDAY MORNING...MOSTLY ACROSS NORTHEAST
WY...THE BLACK HILLS...AND SOUTHERN SD...WITH MVFR/IFR CONDITIONS
DEVELOPING ACROSS MUCH OF NORTHEAST WY AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...26



000
FXUS63 KUNR 221727
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1127 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 1127 AM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL SLOWLY PUSH
NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHWEST SD...AND
THE BLACK HILLS THIS AFTERNOON. OTHERWISE...VFR CONDITIONS ARE
EXPECTED ELSEWHERE THROUGH THE AFTERNOON. SCATTERED SHOWERS WILL
CONTINUE TONIGHT INTO SATURDAY MORNING...MOSTLY ACROSS NORTHEAST
WY...THE BLACK HILLS...AND SOUTHERN SD...WITH MVFR/IFR CONDITIONS
DEVELOPING ACROSS MUCH OF NORTHEAST WY AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...26



000
FXUS63 KUNR 221727
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1127 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 1127 AM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL SLOWLY PUSH
NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHWEST SD...AND
THE BLACK HILLS THIS AFTERNOON. OTHERWISE...VFR CONDITIONS ARE
EXPECTED ELSEWHERE THROUGH THE AFTERNOON. SCATTERED SHOWERS WILL
CONTINUE TONIGHT INTO SATURDAY MORNING...MOSTLY ACROSS NORTHEAST
WY...THE BLACK HILLS...AND SOUTHERN SD...WITH MVFR/IFR CONDITIONS
DEVELOPING ACROSS MUCH OF NORTHEAST WY AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...26




000
FXUS63 KUNR 221727
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1127 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SATURDAY
ISSUED AT 1127 AM MDT FRI MAY 22 2015

SCATTERED SHOWERS AND AREAS OF MVFR CONDITIONS WILL SLOWLY PUSH
NORTH INTO SOUTHERN PORTIONS OF NORTHEAST WY...SOUTHWEST SD...AND
THE BLACK HILLS THIS AFTERNOON. OTHERWISE...VFR CONDITIONS ARE
EXPECTED ELSEWHERE THROUGH THE AFTERNOON. SCATTERED SHOWERS WILL
CONTINUE TONIGHT INTO SATURDAY MORNING...MOSTLY ACROSS NORTHEAST
WY...THE BLACK HILLS...AND SOUTHERN SD...WITH MVFR/IFR CONDITIONS
DEVELOPING ACROSS MUCH OF NORTHEAST WY AND WESTERN SD OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...26




000
FXUS63 KUNR 221550
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
950 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 221550
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
950 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS63 KUNR 221550
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
950 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 221550
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
950 AM MDT FRI MAY 22 2015

.UPDATE...
ISSUED AT 940 AM MDT FRI MAY 22 2015

LATEST SAT IMAGES SHOW THE LEADING SHORTWAVE ALONG WITH THE
ASSOCIATED THICK CLOUD COVER AND PRECIPITATION MOVING NORTHWARD
INTO NEBRASKA LATE THIS MORNING. THE PRECIPITATION WILL HAVE TO
OVERCOME WEAKENING FORCING AS IT MOVES NORTHWARD BUT IT STILL
LOOKS LIKE RAIN SHOWERS WILL BE LIKELY ALONG THE SD/NEB BORDER
THIS AFTERNOON. THERE IS A CHANCE OF SHOWERS AND POSSIBLY A FEW
THUNDERSTORMS OVER NORTHEASTERN WYOMING THIS AFTN WHERE WEAK CAPE
DEVELOPS TODAY. THERE IS ALSO A CHANCE OF SHOWERS OVER THE BLACK
HILLS AND THE REST OF SOUTHWESTERN AND SOUTH CENTRAL SOUTH DAKOTA.
THE CHANCE OF SHOWERS DECREASES QUICKLY NORTH OF THOSE AREAS THIS
AFTN.

&&

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS63 KUNR 221130
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
530 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 221130
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
530 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 221130
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
530 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS63 KUNR 221130
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
530 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM MDT FRI MAY 22 2015

LIGHT RAIN SHOWERS WITH IFR/MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA THIS MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED EAST OF THE BLACK HILLS
TODAY. CONDITIONS WILL DETERIORATE TONIGHT ACROSS THE AREA AS THE
NEXT WEATHER SYSTEM MOVES IN. IFR/MVFR CEILINGS WITH LIGHT RAIN
SHOWERS WILL ENTER SOUTHERN AND WESTERN PORTIONS OF SOUTH DAKOTA
AND NORTHEAST WYOMING BY MID EVENING...AND SPREAD NORTH AND EAST
THROUGH THE NIGHT...WITH WIDESPREAD MVFR/IFR CONDITIONS AFTER
MIDNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS65 KCYS 221028
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
428 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG. MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI




000
FXUS65 KCYS 221028
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
428 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG. MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI




000
FXUS65 KCYS 221028
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
428 AM MDT FRI MAY 22 2015

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 425 AM MDT FRI MAY 22 2015

A WELL PRONOUNCED LARGE SCALE PATTERN DOMINATED NORTH AMERICA WITH
TROUGHS OVER SOUTHEAST CANADA/NEW ENGLAND AND ACROSS THE WESTERN
CONUS. IN BETWEEN WAS A UPPER RIDGE FROM THE NORTHWEST GULF OF
MEXICO INTO THE NORTHERN GREAT PLAINS. SEVERAL SHORT WAVES WERE
ROTATING AROUND THE LATTER TROUGH...WITH ONE LIFTING NORTH INTO
CO AND ANOTHER ACCOMPANYING THE UPPER LOW OVER SOUTHERN CA. THE
SURFACE ANALYSIS SHOWED TWO FRONTS...ONE BORDERING NEW ENGLAND
ACROSS THE SOUTHERN GREAT LAKES AND INTO THE DAKOTAS...AND THE
OTHER FROM THE NORTHERN GULF COAST EXTENDING NORTHWEST INTO ID.
REGIONAL RADARS INDICATED A LARGE COVERAGE OF SHOWERS AND A FEW
TSTORMS FROM EASTERN UT ACROSS CO AND WESTERN KS SPREADING
NORTHWARD AHEAD OF THE INITIAL SHORT WAVE. ISOLATED LIGHT SHOWERS
HAD ALSO DEVELOPED ALONG AND WEST OF THE LARAMIE RANGE. MOIST
SOUTHEAST FLOW RESULTED IN FAIRLY WIDESPREAD STRATUS AND AREAS
OF FOG OVER SOUTHEAST WY. LOWEST VISIBILITY WAS NEAR THE I-80
SUMMIT AND IN THE VICINITY OF CHEYENNE. THE COVERAGE OF DENSE FOG
WILL NOT BE AS WIDESPREAD AS THURSDAY MORNING WITH THE PRESENCE OF
SHOWER ACTIVITY AND A MORE MIXED BOUNDARY LAYER.

THE NUMERICAL MODELS HAVE BEEN CONSISTENT WITH THE LARGE SCALE
PATTERN...PROGGING THE WESTERN CONUS UPPER TROUGH TO SLOWLY
TRANSLATE EAST TOWARD THE ROCKIES AND HIGH PLAINS THIS WEEKEND.
THE SHORT WAVE TRACKING NORTH ACROSS CO WILL BRING NUMEROUS
SHOWERS. ISOLATED THUNDER WILL DEVELOP ALONG/WEST OF THE LARAMIE
RANGE EARLY AFTERNOON AND EXTEND EAST ONTO MOST OF THE PLAINS
BY LATE AFTERNOON. SHOWER COVERAGE WILL DIMINISH TONIGHT AS THE
SHORT WAVE EXITS NORTH OF THE CWA. IT WILL BE ANOTHER COOL DAY
AS HIGH TEMPERATURES REMAIN IN THE 40S AND 50S.

SATURDAY IS STILL LOOKING LIKE AN ACTIVE DAY FOR THUNDERSTORMS
AS THE SECOND MORE POTENT SHORT WAVE APPROACHES THE CWA. THE
MODELS SHOW A SURFACE LOW FORMING OVER NORTHEAST CO BY SATURDAY
AFTERNOON WITH A TROUGH EXTENDING NORTH-SOUTH ACROSS THE EASTERN
PLAINS. A STRENGTHENING SOUTH-SOUTHEAST BOUNDARY LAYER FLOW WILL
DRAW RICH GULF MOISTURE NORTHWARD ACROSS THE EASTERN PLAINS
SATURDAY AFTERNOON...WITH THE NOSE OF THE THETA-E RIDGE EXTENDING
INTO SOUTHEAST WY AND WESTERN NE. THE NAM AND SREF ARE MORE
BULLISH WITH THE INSTABILITY COMPARED TO THE ECMWF AND GFS WITH
SBCAPES NEAR 1500 J/KG ACROSS THE AFOREMENTIONED AREA. VEERING
WIND PROFILE EAST OF THE LARAMIE RANGE WITH BULK SHEAR VALUES
OF 30-40 KT SUGGEST THE POTENTIAL FOR ISOLATED SUPERCELL STORMS
WITH LARGE HAIL THE PRIMARY THREAT. AN ISOLATED BRIEF TORNADO
CANNOT BE RULED OUT...ESPECIALLY NEAR THE CO BORDER CLOSER TO
THE SURFACE LOW. THE SPC DAY2 OUTLOOK SHOWS A MARGINAL RISK FOR
SEVERE STORMS ALONG AND EAST OF A CHEYENNE-SCOTTSBLUFF-ALLIANCE
LINE. WILL HIGHLIGHT THE SEVERE THREAT IN THE HWO AND WEATHER
STORY. LATER SHIFTS CAN FINE TUNE THE DETAILS BEFORE INTRODUCING
SEVERE WORDING IN THE ZONE FORECASTS. IT WILL BE MILDER SATURDAY
WITH HIGHS IN THE 50S AND 60S.

THE SEVERE STORM RISK MAY EXTEND INTO EARLY SATURDAY EVENING
FOR WESTERN NE BEFORE ENDING WITH DESTABILIZATION AND EXIT OF THE
SHORT WAVE SATURDAY NIGHT. WRAP-AROUND MOISTURE AND COOL AIR
ALOFT SATURDAY NIGHT AND SUNDAY WILL PROMOTE GOOD CHANCES FOR
MORE SHOWERS AND ISOLATED AFTERNOON THUNDERSTORMS. SOMEWHAT COOLER
TEMPERATURES ARE ALSO EXPECTED IN THE WAKE OF THE UPPER LOW.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 325 AM MDT FRI MAY 22 2015

SUNDAY NIGHT/MONDAY...THE UPPER TROUGH WILL SLOWLY MOVE NORTH OF OUR
COUNTIES DURING THE DAYLIGHT HOURS...WITH MOST OF THE UPWARD
VERTICAL MOTION UP IN COLORADO...THOUGH THERE WILL BE A FAIR SHARE
ACROSS SOUTHEAST WYOMING WITH ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS.

TUESDAY...DESPITE THE RIDGING ALOFT...PRESENCE OF STRONG THERMAL
HEATING AND ADEQUATE LOW AND MID LEVEL MOISTURE...WILL SEE ISOLATED
TO SCATTERED THUNDERSTORMS SOUTH OF A DOUGLAS TO KIMBALL LINE.

WEDNESDAY/THURSDAY...SOUTHWEST FLOW ALOFT IN FULL SWING WITH SEVERAL
WEAK EMBEDDED SHORTWAVE TROUGH ALOFT HELPING TO PRODUCE ISOLATED TO
WIDELY SCATTERED AFTERNOON AND IMPENDING THUNDERSTORMS.

FRIDAY...LESS THUNDERSTORM COVERAGE DUE TO WEST SOUTHWEST FLOW ALOFT
LIKELY STABILIZING THE ATMOSPHERE AND LESS AND LESS LOW AND MID
LEVEL MOISTURE TO ACT AS FUEL TO GENERATE THUNDERSTORMS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG. MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 318 AM MDT FRI MAY 22 2015

A UPPER LEVEL LOW PRESSURE SYSTEM AND ITS ACCOMPANYING DISTURBANCES
OVER THE SOUTHWEST U.S. WILL GRADUALLY MOVE NORTHEAST TOWARD THE
CENTRAL ROCKIES DURING THE NEXT 24 TO 48 HOURS. SHOWERS AND ISOLATED
THUNDERSTORMS WILL BECOME MORE WIDESPREAD TODAY. THE SHOWERS WILL
DECREASE TONIGHT AS ONE DISTURBANCE EXITS THE DISTRICTS THEN INCREASE
ONCE AGAIN SATURDAY WITH THE APPROACH OF A STRONGER DISTURBANCE. A
SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER NORTHEAST COLORADO
SATURDAY WITH A BETTER CHANCE FOR THUNDERSTORMS. A FEW STRONG TO
SEVERE THUNDERSTORMS WILL BE POSSIBLE SATURDAY AFTERNOON AND EARLY
EVENING FOR THE SOUTHEAST WYOMING PLAINS INTO MUCH OF WESTERN
NEBRASKA. THE WET PATTERN WILL LINGER INTO SUNDAY BEFORE SOMEWHAT
DRIER AND WARMER CONDITIONS ARRIVE NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 325 AM MDT FRI MAY 22 2015

ONGOING WATER RELEASES FROM THE GRAYROCKS RESERVOIR WITH RECENT
RAINFALL PUSHED THE LARAMIE RIVER NEAR FORT LARAMIE ABOVE FLOOD
STAGE. THE RIVER HAS STEADIED AT 7.13 FT OVERNIGHT AND IS FORECAST
TO REMAIN AT 7.1 FT THROUGH THE WEEKEND BEFORE FALLING BELOW FLOOD
STAGE LATE MONDAY. AT LARAMIE...THE RIVER WAS AT 7.35 FT AND IS
FORECAST TO SLOWLY RISE TO 7.8 FT MONDAY THEN FALL TO 7.5 FT
TUESDAY. BASIN AVERAGE RAINFALL OVER THE LARAMIE RIVER IS PROJECTED
TO RANGE FROM A HALF INCH TO AN INCH TODAY THROUGH SUNDAY. THE
LOWER NORTH PLATTE RIVER BASIN COULD RECEIVE ONE TO ONE AND HALF
INCHES OF RAIN FOR THE SAME PERIOD...WHICH WILL RESULT IN SLOW
RISES DOWNSTREAM FROM FORT LARAMIE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...JAMSKI
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...JAMSKI
HYDROLOGY...JAMSKI



000
FXUS65 KRIW 220942
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
342 AM MDT FRI MAY 22 2015

TODAY THROUGH SUNDAY NIGHT

WV IMAGERY SHOWING LARGE DEEP TROF WRN CONUS...CLOSED LOW OVR
CALIFORNIA...SW RIDGE CNTRL CONUS...DEEP TROF ERN CONUS. WEAK SW
MOVING NWD THRU CNTRL WY THIS EVENING...WITH STRONGER SW TO THE
SOUTH...ROTATING ANTI-CLOCKWISE AROUND THE CLOSED LOW...SPREADING
OVR COLORADO. SFC HAS HIGH P CNTRL CONUS...LOW P AND NEARLY
STATIONARY FRONT WEST OF WY...DRAPED FROM NRN ID...SWD THRU UT AND
INTO WRN NM. ISOLATED TO WIDELY SCATTERED SHOWERS SPRINKLED AROUND
THE FA TONIGHT.

THRU TODAY...SW CURRENTLY OVR COLORADO WILL CONTINUE TO
ROTATE NWD ACROSS WY THIS AFTERNOON/EVENING/OVERNIGHT...WITH SW AXIS
BISECTING WY FROM SW TO NE BY THIS TIME TOMORROW. THIS WILL AID IN
KICKING OFF ANOTHER BATCH OF SHRA/TSRA. OTHERWISE...LL ERN FLOW
ACROSS MOST OF THE AREA E OF THE DIVIDE WILL STRENGTHEN...KEEPING
GOOD AMOUNTS OF LL MOISTURE ACROSS THE FA...WHILE MORE MID/UPR LVL
MOISTURE MOVES INTO THE REGION FROM THE SOUTH. DIRECTIONAL AND SPEED
SHEAR NOT PARTICULARLY IMPRESSIVE WITH RATHER WEAK MID/UPR FLOW IN
PLACE. BUOYANCY WILL BE MODEST WITH ML CAPE RANGING FROM 300 TO 500
J/KG FOR MOST OF THE CNTRL AND WRN FA...WEAKER TO THE EAST. STRONGER
STORMS OF THE DAY CURRENTLY LOOK TO FORM ACROSS THE FAR WEST...FROM
N OF JACKSON S TO AROUND KEMMERER WHERE WHERE SOME MARGINALLY
BETTER CHANCES FOR SUNSHINE WILL OCCUR...ALONG WITH CHCS FOR MAINLY
SMALL HAIL.

THE REST OF THE FCST FOR THE MEMORIAL DAY WEEKEND...COOL AND WET.
UPR LOW MIGRATES FROM NEAR THE 4 CORNERS REGION TO THE NRN HIGH
PLAINS BY THE END OF THE FCST...WHILE SFC CYCLOGENESIS TAKES PLACE
FROM ERN/NERN CO INTO THE CNTRL PLAINS THRU THE SAME PERIOD. BETWEEN
LOW TO MID LVL MOISTURE RETURN AROUND THE SFC LOW...AND MID UPR
MOISTURE FROM ACCOMPANYING THE UPR WAVE/CLOSED LOW...RELATIVELY
PLENTIFUL RAINFALL AND SOME SNOWFALL WILL BE HAD OVER THE SAME
PERIOD. THIS WILL...HOWEVER...BE A COMPARATIVELY WARM SYSTEM THE WAY
IT STANDS NOW WITH H7 TEMPS NOT DROPPING AT ANY ONE TIME TO MUCH
LESS THAN -1/-2DEG C...AND EVEN THEN FOR ONLY SHORT PERIODS AS THE
UPR LOW ROTATES ACROSS THE STATE. SUNDAY MORNING WILL LIKELY SEE THE
COLD TEMPS OVR THE NW FCST QUAD...BUT WITH LITTLE ATTENDING SNOWFALL
AS THE SYSTEM PULLS AWAY. GENERALLY...A TRACE TO AND INCH OR TWO
WILL BE POSSIBLE DURING THE COLDEST PORTION OF THE NIGHTS AND ONLY
ACROSS THE HIGHEST ELEVATIONS...ISOLATED 3 INCHES. SEVERE WX SHOULD
REMAIN MOSTLY EAST TO SOUTHEAST OF FA THROUGH THE PERIOD WITH ONLY
ISOLATED SMALL HAIL A SMALL THREAT THROUGHOUT. EARLY MORNING FOG
WILL ALSO BE POSSIBLE OVR MANY AREAS THROUGHOUT THE FCST.
.SHORT TERM...

.LONG TERM...MONDAY THROUGH FRIDAY

THE LONG RANGE MODELS ARE IN MODEST AGREEMENT WITH THE WEATHER
PATTERN MONDAY THROUGH FRIDAY. MEMORIAL DAY WILL BE DRIER FOR MOST
PLACES WITH MAINLY ISOLATED AFTERNOON SHOWERS OR STORMS. ACTIVITY
COULD BE A LITTLE MORE NUMEROUS IN THE FAR WEST LATE IN THE DAY INTO
MONDAY EVENING. HIGH TEMPS ON MEMORIAL DAY WILL BE AT OR SLIGHTLY
BELOW NORMAL WITH 50S AND 60S...40S TO LOW 50S FOR THE MOUNTAINS.

FOR TUESDAY THROUGH THURSDAY...A WEATHER SYSTEM SETTLES INTO THE
PACIFIC NW PER THE GFS MODEL AND MOVES INTO IDAHO THURSDAY NIGHT.
THEN IT BRINGS THE WEATHER SYSTEM THROUGH THE REGION FRIDAY. THE
ECMWF MODEL IS A BIT DIFFERENT AND FASTER AS IT DROPS THE WEATHER
SYSTEM INTO IDAHO TUESDAY NIGHT AND ACROSS THE ROCKIES WED NIGHT
AND THURSDAY MORNING. THEN THE ECMWF MODEL HAS FAIRLY QUIET
WEATHER FOR NEXT FRIDAY. BOTH MODELS HAVE BEEN CONSISTENT IN THEIR
TIMING THE PAST FEW MODEL RUNS. WILL LEAN TOWARD THE GFS SOLUTION
TONIGHT. THIS MEANS A CHANCE OF SHOWERS AND STORMS EACH AFTERNOON
AND EVENING FROM TUE THROUGH FRI. COVERAGE SHOULD INCREASE OVER
THE WEST AND NORTH LATER NEXT WEEK AS THE SYSTEM GETS CLOSER AND
EVENTUALLY PASSES THROUGH THE AREA. WILL SEE HOW THINGS LOOK
TONIGHT AND SEE IF ANY CHANGES ARE NEEDED. AS FOR HIGH TEMPS TUE
THROUGH FRI...LITTLE DAY TO DAY CHANGE WITH 60S TO LOW 70S AND 50S
FOR THE MOUNTAINS. OF COURSE TOO MUCH CLOUD COVER WILL PRODUCE
COOLER THAN FORECASTED HIGHS.

&&

.AVIATION.../12Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

EXPECT CONDITIONS TO BE VFR THROUGH AT LEAST 00Z/SAT AT ALL
TERMINALS. WEST-EAST ORIENTED AREA OF CONVECTION WILL LIFT NORTH
ACROSS THE FORECAST AREAS BETWEEN 21Z/FRI AND 03Z/SAT...SIMILAR TO
WHAT WAS SEEN THURSDAY. INSTABILITY LOOKS A LITTLE MORE FAVORABLE
FOR WEAK CONVECTION AT KCPR. MAIN HAZARD WITH THE SHOWERS AND STORMS
WILL BE HEAVY RAIN. MID-LEVEL CIRCULATION ALONG THE WESTERN WYOMING
BORDER AT 00Z. CONVERGENCE AXIS WILL PINWHEEL NORTH DURING THE
EVENING AND PROVIDE PERHAPS A BETTER PERIOD OF WIDESPREAD SHOWERS
AND STORMS. PLENTY OF ENERGY AND MOISTURE TO WORK WITH THROUGH AT
LEAST 06Z/SAT. HAVE KEPT VCSH AT MANY TERMINALS BUT COULD SEE MORE
DEFINITIVE PERIOD OF PREVAILING -SHRA BETWEEN 00Z-06Z/SAT. LEFT EXIT
REGION OF 100KT+ JET MAY ALSO ASSIST LIFT FRIDAY EVENING...
ESPECIALLY ACROSS CENTRAL WYOMING. MOUNTAIN TOP OBSCURATIONS WILL BE
WIDESPREAD ABOVE ABOUT 9K-10K MSL THROUGHOUT MUCH OF THE FORECAST
PERIOD...ESPECIALLY ALONG THE WIND RIVER RANGE AND THE SOUTHERN
PORTIONS OF THE ABSAROKA AND BIGHORN RANGES.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

STEADY STREAM OF SHORTWAVE ENERGY WILL HEAD NORTH ACROSS THE
FORECAST AREA TODAY. VFR CONDITIONS WILL LARGELY BE THE RULE THROUGH
00Z/SAT...WITH THE EXCEPTION BEING MVFR CONDITIONS WITH THE
STRONGEST STORMS LATE TODAY. SHORTWAVE IN SOUTHERN COLORADO WILL
CONTINUE TO LIFT AS THE KICKER UPPER LOW MOVES EAST. EXPECT
CONVECTION TO ORIENT IN A WEST-EAST BAND ACROSS FAR SOUTHERN WYOMING
BY 18Z TODAY. SIMILAR TO THURSDAY...THIS AREA OF CONVECTION WILL LIFT
NORTH THROUGH 00Z/SAT. THEREFORE...HAVE VCTS BY 19Z/FRI AT KRKS AND
BY 21Z/FRI AT KBPI...KPNA...AND KJAC. MAIN HAZARD WILL BE HEAVY
RAIN. AFTER 00Z/SAT...700MB CIRCULATION AND LOW-LEVEL SOUTHERLY FLOW
MAY ENHANCE PRECIPITATION ACROSS THE GREEN RIVER BASIN FROM KBPI TO
KPNA. THIS WOULD BE THE MOST LIKELY PERIOD OF MVFR CONDITIONS AT
THESE TWO TERMINALS. MOUNTAIN TOP OBSCURATIONS WILL BE COMMON
THROUGH THE FORECAST PERIOD WITH LOWERING CEILINGS AFTER 00Z/SAT.

&&

.FIRE WEATHER...

FIRE DANGER LOW AND WILL REMAIN LOW THROUGH THE HOLIDAY WEEKEND
AS COOL AND RELATIVELY WET WEATHER REMAINS IN PLACE AS YET ANOTHER
VIGOROUS UPPER LEVEL SYSTEM ROTATES ACROSS THE REGION. WIDESPREAD
PRECIPITATION WITH LIGHT MOUNTAIN SNOW IS EXPECTED EACH DAY...WITH
EMBEDDED THUNDERSTORMS POSSIBLE EACH AFTERNOON AND EARLY EVENING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BRAUN
LONG TERM...AR
AVIATION...CNJ
FIRE WEATHER...BRAUN





000
FXUS63 KUNR 220929
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
329 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 327 AM MDT FRI MAY 22 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST WY...SOUTH-
WEST SD...AND THE BLACK HILLS AREA EARLY THIS MORNING. OTHERWISE
VFR CONDITIONS ARE EXPECTED THROUGH TODAY. CONDITIONS WILL
DETERIORATE LATE TONIGHT ACROSS THE AREA AS THE NEXT WEATHER
SYSTEM MOVES IN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 220929
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
329 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 327 AM MDT FRI MAY 22 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST WY...SOUTH-
WEST SD...AND THE BLACK HILLS AREA EARLY THIS MORNING. OTHERWISE
VFR CONDITIONS ARE EXPECTED THROUGH TODAY. CONDITIONS WILL
DETERIORATE LATE TONIGHT ACROSS THE AREA AS THE NEXT WEATHER
SYSTEM MOVES IN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 220929
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
329 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 327 AM MDT FRI MAY 22 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST WY...SOUTH-
WEST SD...AND THE BLACK HILLS AREA EARLY THIS MORNING. OTHERWISE
VFR CONDITIONS ARE EXPECTED THROUGH TODAY. CONDITIONS WILL
DETERIORATE LATE TONIGHT ACROSS THE AREA AS THE NEXT WEATHER
SYSTEM MOVES IN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 220929
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
329 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 327 AM MDT FRI MAY 22 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST WY...SOUTH-
WEST SD...AND THE BLACK HILLS AREA EARLY THIS MORNING. OTHERWISE
VFR CONDITIONS ARE EXPECTED THROUGH TODAY. CONDITIONS WILL
DETERIORATE LATE TONIGHT ACROSS THE AREA AS THE NEXT WEATHER
SYSTEM MOVES IN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15




000
FXUS63 KUNR 220929
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
329 AM MDT FRI MAY 22 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
ISSUED AT 327 AM MDT FRI MAY 22 2015

THE LARGE UPPER LOW OVER THE SWRN CONUS...PER WATER VAPOR
IMAGERY...WILL BE THE MAIN PLAYER FOR OUR WEATHER THROUGH THE
WEEKEND. LATEST OBS SHOWED A 100-KT 300-MB JET STREAK ROUNDING THE
BASE OF THE UPPER LOW...JUST SOUTHWEST OF CA. IN ADDITION...AN
UPPER LOW TO THE SOUTHEAST OF THE HUDSON BAY WILL HELP MAINTAIN A
CONFLUENT ZONE OVER THE NERN CWA...WHICH WILL HELP LIMIT THE NWD
EXTENT OF SHOWERS THROUGH TNGT.

FOR TODAY...A LEAD SHORT-WAVE TROUGH OVER SERN CO EARLY THIS MRNG
WILL MOVE TO NEAR KCDR BY 24Z. AS IT MOVES NORTH IT WILL ENCOUNTER
THE CONFLUENT UPPER FLOW AND GRADUALLY SHEAR OUT...WITH FORCING
DIMINISHING W/TIME PER THE WEAKENING Q-VECTOR CONVERGENCE. THUS...
WILL KEEP POPS CONFINED MOSTLY TO THE SWRN CWA. IN ADDITION...CAPE
WILL BE MARGINAL FOR TSTMS EXCEPT FOR PARTS OF NERN WY.

FOR TNGT...THE LEAD SHORT-WAVE TROUGH WILL SHEAR OUT AS IT MOVES
SLOWLY NORTH ACROSS THE CWA. FORCING WILL BE WEAK WITH THE BEST Q-
VECTOR CONVERGENCE GOING EAST OF THE CWA. AS A RESULT...ONLY EXPECT
SCT SHRA OVER SRN SECTIONS OF THE AREA...WITH LIMITED PCPN AMOUNTS.

ON SATURDAY...SOUTHWEST FLOW ALOFT WILL STRENGTHEN AS THE HUDSON BAY
AREA LOW MOVES SOUTHEAST AND THE SWRN CONUS LOW MOVES TO THE FOUR-
CORNERS AREA. ANOTHER SHORT-WAVE TROUGH WILL APPROACH THE CWA DURING
THE DAY...WITH INCREASING PWATS AND SBCAPES OF 500-750 J/KG...MAINLY
OVER THE SRN HALF OF THE AREA. AS A RESULT...EXPECT SCT SHRA/TSRA
ACROSS THE CWA. THE SEVERE POTENTIAL WILL BE LOW BECAUSE OF THE
LIMITED BUOYANCY AND MODEST MIDLEVEL LAPSE RATES.

ON SATURDAY NIGHT THE MODELS AGREE ON BRINGING A STRONGER SHORT-WAVE
TROUGH ACROSS THE AREA WITH NOTABLE DIFFERENTIAL CVA AND Q-VECTOR
CONVERGENCE IN THE 500-300MB LAYER...ALONG WITH LOW-LEVEL FGEN. THIS
SHOULD LEAD TO A GOOD ROUND OF PCPN THAT WILL PERSIST AFTER 12Z SUN.
WILL KEEP THE ESF GOING FOR THE HEAVY RAIN POTENTIAL.

.LONG TERM...SUNDAY THROUGH THURSDAY
ISSUED AT 327 AM MDT FRI MAY 22 2015

UPPER LEVEL LOW LIFTS OUT OF THE WESTERN TROF AND CROSSES THE
NORTHERN PLAINS ON SUNDAY...BRINGING WIDESPREAD PRECIPITATION TO
THE AREA. BEST PRECIP CHANCES ON SUNDAY WILL BE ACROSS NORTHEAST
WYOMING...ACROSS THE BLACK HILLS...AND INTO NORTHWEST SOUTH
DAKOTA...WHERE A QUARTER TO ONE HALF INCH OF RAINFALL IS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION ON MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS AN ACTIVE UPPER-LEVEL
PATTERN CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE
OVER THE WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE
TEMPERATURES BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING
ISSUED AT 327 AM MDT FRI MAY 22 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST WY...SOUTH-
WEST SD...AND THE BLACK HILLS AREA EARLY THIS MORNING. OTHERWISE
VFR CONDITIONS ARE EXPECTED THROUGH TODAY. CONDITIONS WILL
DETERIORATE LATE TONIGHT ACROSS THE AREA AS THE NEXT WEATHER
SYSTEM MOVES IN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...BUNKERS
LONG TERM...15
AVIATION...15



000
FXUS65 KCYS 220619
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1219 AM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG.  MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...RUBIN
FIRE WEATHER...RE



000
FXUS65 KCYS 220619
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1219 AM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG.  MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...RUBIN
FIRE WEATHER...RE



000
FXUS65 KCYS 220619
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1219 AM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG.  MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...RUBIN
FIRE WEATHER...RE




000
FXUS65 KCYS 220619
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1219 AM MDT FRI MAY 22 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1217 AM MDT FRI MAY 22 2015

WIDESPREAD IFR AND MVFR THROUGH THE PRE DAWN HOURS IN FOG...LOW
CLOUDS AND RAIN...THEN CONDITIONS IMPROVING SLOWLY DURING THE
DAY WITH VFR AND MVFR AT MOST LOCALES...THEN IFR AND MVFR AGAIN
FRIDAY EVENING AS CEILINGS AND VISIBILITIES LOWER ALONG WITH
AREAS OF FOG.  MOUNTAINS OBSCURED.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...RUBIN
FIRE WEATHER...RE




000
FXUS65 KRIW 220530
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL
LEVELS BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

CONDITIONS THROUGH 21Z/FRI WILL BE VFR AT ALL TERMINALS. SHORTWAVE
ENERGY WILL ROTATE NORTH AHEAD OF MORE IMPRESSIVE SHORTWAVE OVER
NORTHERN NEW MEXICO. EXPECT THAT SHOWERS OVER THE BIG HORN BASIN
WILL DISSIPATE LATE TONIGHT WHILE KRIW AND KLND COULD SEE ISOLATED
WEAK CONVECTION THROUGH THE OVERNIGHT HOURS. ENERGY WITH THE MORE
VIGOROUS SHORTWAVE WILL REACH CENTRAL WYOMING IN THE 20Z-22Z/FRI
TIMEFRAME. THE EVOLUTION MAY BE VERY SIMILAR TO THURSDAY. APPEARS
THERE COULD BE A LITTLE MORE INSTABILITY TO GENERATE AT LEAST
SHOWERS AT KCPR...WHEREAS STABLE AIR LIMITED THAT THURSDAY. 700MB
LOW SHOULD BE ALONG THE WESTERN WYOMING BORDER BY 00Z/SAT. PLENTY OF
ENERGY AND MOISTURE AVAILABLE TO KEEP SHOWERS AND ISOLATED
THUNDERSTORMS GOING THROUGH 06Z/SAT. HAVE KEPT VCSH AT MANY
TERMINALS BUT COULD SEE MORE DEFINITIVE PERIOD OF PREVAILING -SHRA
BETWEEN 00Z-06Z/SAT. THERE COULD ALSO BE SOME AID FROM THE LEFT EXIT
REGION OF THE JET DURING THAT SPAN. MOUNTAIN TOP OBSCURATIONS WILL
BE WIDESPREAD ABOVE ABOUT 9K-10K MSL THROUGHOUT MUCH OF THE FORECAST
PERIOD...ESPECIALLY ALONG THE WIND RIVER RANGE AND THE SOUTHERN
PORTIONS OF THE ABSAROKA AND BIGHORN RANGES.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

YET MORE SHORTWAVE ENERGY ROTATING NORTH TONIGHT. CLOUD TOPS ARE
ALREADY COOLING AHEAD OF VIGOROUS SHORTWAVE OVER NORTHERN NEW MEXICO
PER IR IMAGERY. CONVECTION IS LIKELY TO CONTINUE THROUGH THE
NIGHT...WITH VFR CONDITIONS LARGELY THE RULE. COULD SEE SOME
LOCALIZED MVFR WITH THE STRONGER CONVECTION AND IN THE GREEN RIVER
VALLEY AROUND KBPI AND KPNA. NEW MEXICO SHORTWAVE WILL LIFT NORTH
DURING THE DAY AS LARGER UPPER LOW TO THE WEST MOVES FARTHER INLAND.
CONVECTION MAY AGAIN ORIENT WEST-EAST ACROSS FAR SOUTHERN WYOMING BY
18Z/FRI. SIMILAR TO THURSDAY...THIS AREA OF CONVECTION WILL LIFT
NORTH THROUGH 00Z/SAT. THEREFORE...HAVE VCTS BY 19Z/FRI AT KRKS AND
BY 21Z/FRI AT KBPI...KPNA...AND KJAC. CERTAINLY COULD BE A FAIRLY
STEADY PERIOD OF RAIN...ESPECIALLY AT KBPI AND KPNA...DURING THE
LATE AFTERNOON HOURS FRIDAY. MOUNTAIN TOP OBSCURATIONS WILL BE
COMMON THROUGH THE FORECAST PERIOD WITH LOWERING CEILINGS AFTER
00Z/SAT.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...CNJ
FIRE WEATHER...LIPSON











000
FXUS65 KRIW 220530
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL
LEVELS BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

CONDITIONS THROUGH 21Z/FRI WILL BE VFR AT ALL TERMINALS. SHORTWAVE
ENERGY WILL ROTATE NORTH AHEAD OF MORE IMPRESSIVE SHORTWAVE OVER
NORTHERN NEW MEXICO. EXPECT THAT SHOWERS OVER THE BIG HORN BASIN
WILL DISSIPATE LATE TONIGHT WHILE KRIW AND KLND COULD SEE ISOLATED
WEAK CONVECTION THROUGH THE OVERNIGHT HOURS. ENERGY WITH THE MORE
VIGOROUS SHORTWAVE WILL REACH CENTRAL WYOMING IN THE 20Z-22Z/FRI
TIMEFRAME. THE EVOLUTION MAY BE VERY SIMILAR TO THURSDAY. APPEARS
THERE COULD BE A LITTLE MORE INSTABILITY TO GENERATE AT LEAST
SHOWERS AT KCPR...WHEREAS STABLE AIR LIMITED THAT THURSDAY. 700MB
LOW SHOULD BE ALONG THE WESTERN WYOMING BORDER BY 00Z/SAT. PLENTY OF
ENERGY AND MOISTURE AVAILABLE TO KEEP SHOWERS AND ISOLATED
THUNDERSTORMS GOING THROUGH 06Z/SAT. HAVE KEPT VCSH AT MANY
TERMINALS BUT COULD SEE MORE DEFINITIVE PERIOD OF PREVAILING -SHRA
BETWEEN 00Z-06Z/SAT. THERE COULD ALSO BE SOME AID FROM THE LEFT EXIT
REGION OF THE JET DURING THAT SPAN. MOUNTAIN TOP OBSCURATIONS WILL
BE WIDESPREAD ABOVE ABOUT 9K-10K MSL THROUGHOUT MUCH OF THE FORECAST
PERIOD...ESPECIALLY ALONG THE WIND RIVER RANGE AND THE SOUTHERN
PORTIONS OF THE ABSAROKA AND BIGHORN RANGES.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

YET MORE SHORTWAVE ENERGY ROTATING NORTH TONIGHT. CLOUD TOPS ARE
ALREADY COOLING AHEAD OF VIGOROUS SHORTWAVE OVER NORTHERN NEW MEXICO
PER IR IMAGERY. CONVECTION IS LIKELY TO CONTINUE THROUGH THE
NIGHT...WITH VFR CONDITIONS LARGELY THE RULE. COULD SEE SOME
LOCALIZED MVFR WITH THE STRONGER CONVECTION AND IN THE GREEN RIVER
VALLEY AROUND KBPI AND KPNA. NEW MEXICO SHORTWAVE WILL LIFT NORTH
DURING THE DAY AS LARGER UPPER LOW TO THE WEST MOVES FARTHER INLAND.
CONVECTION MAY AGAIN ORIENT WEST-EAST ACROSS FAR SOUTHERN WYOMING BY
18Z/FRI. SIMILAR TO THURSDAY...THIS AREA OF CONVECTION WILL LIFT
NORTH THROUGH 00Z/SAT. THEREFORE...HAVE VCTS BY 19Z/FRI AT KRKS AND
BY 21Z/FRI AT KBPI...KPNA...AND KJAC. CERTAINLY COULD BE A FAIRLY
STEADY PERIOD OF RAIN...ESPECIALLY AT KBPI AND KPNA...DURING THE
LATE AFTERNOON HOURS FRIDAY. MOUNTAIN TOP OBSCURATIONS WILL BE
COMMON THROUGH THE FORECAST PERIOD WITH LOWERING CEILINGS AFTER
00Z/SAT.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...CNJ
FIRE WEATHER...LIPSON










000
FXUS65 KRIW 220530
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL
LEVELS BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

CONDITIONS THROUGH 21Z/FRI WILL BE VFR AT ALL TERMINALS. SHORTWAVE
ENERGY WILL ROTATE NORTH AHEAD OF MORE IMPRESSIVE SHORTWAVE OVER
NORTHERN NEW MEXICO. EXPECT THAT SHOWERS OVER THE BIG HORN BASIN
WILL DISSIPATE LATE TONIGHT WHILE KRIW AND KLND COULD SEE ISOLATED
WEAK CONVECTION THROUGH THE OVERNIGHT HOURS. ENERGY WITH THE MORE
VIGOROUS SHORTWAVE WILL REACH CENTRAL WYOMING IN THE 20Z-22Z/FRI
TIMEFRAME. THE EVOLUTION MAY BE VERY SIMILAR TO THURSDAY. APPEARS
THERE COULD BE A LITTLE MORE INSTABILITY TO GENERATE AT LEAST
SHOWERS AT KCPR...WHEREAS STABLE AIR LIMITED THAT THURSDAY. 700MB
LOW SHOULD BE ALONG THE WESTERN WYOMING BORDER BY 00Z/SAT. PLENTY OF
ENERGY AND MOISTURE AVAILABLE TO KEEP SHOWERS AND ISOLATED
THUNDERSTORMS GOING THROUGH 06Z/SAT. HAVE KEPT VCSH AT MANY
TERMINALS BUT COULD SEE MORE DEFINITIVE PERIOD OF PREVAILING -SHRA
BETWEEN 00Z-06Z/SAT. THERE COULD ALSO BE SOME AID FROM THE LEFT EXIT
REGION OF THE JET DURING THAT SPAN. MOUNTAIN TOP OBSCURATIONS WILL
BE WIDESPREAD ABOVE ABOUT 9K-10K MSL THROUGHOUT MUCH OF THE FORECAST
PERIOD...ESPECIALLY ALONG THE WIND RIVER RANGE AND THE SOUTHERN
PORTIONS OF THE ABSAROKA AND BIGHORN RANGES.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

YET MORE SHORTWAVE ENERGY ROTATING NORTH TONIGHT. CLOUD TOPS ARE
ALREADY COOLING AHEAD OF VIGOROUS SHORTWAVE OVER NORTHERN NEW MEXICO
PER IR IMAGERY. CONVECTION IS LIKELY TO CONTINUE THROUGH THE
NIGHT...WITH VFR CONDITIONS LARGELY THE RULE. COULD SEE SOME
LOCALIZED MVFR WITH THE STRONGER CONVECTION AND IN THE GREEN RIVER
VALLEY AROUND KBPI AND KPNA. NEW MEXICO SHORTWAVE WILL LIFT NORTH
DURING THE DAY AS LARGER UPPER LOW TO THE WEST MOVES FARTHER INLAND.
CONVECTION MAY AGAIN ORIENT WEST-EAST ACROSS FAR SOUTHERN WYOMING BY
18Z/FRI. SIMILAR TO THURSDAY...THIS AREA OF CONVECTION WILL LIFT
NORTH THROUGH 00Z/SAT. THEREFORE...HAVE VCTS BY 19Z/FRI AT KRKS AND
BY 21Z/FRI AT KBPI...KPNA...AND KJAC. CERTAINLY COULD BE A FAIRLY
STEADY PERIOD OF RAIN...ESPECIALLY AT KBPI AND KPNA...DURING THE
LATE AFTERNOON HOURS FRIDAY. MOUNTAIN TOP OBSCURATIONS WILL BE
COMMON THROUGH THE FORECAST PERIOD WITH LOWERING CEILINGS AFTER
00Z/SAT.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...CNJ
FIRE WEATHER...LIPSON











000
FXUS65 KRIW 220530
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL
LEVELS BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../06Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

CONDITIONS THROUGH 21Z/FRI WILL BE VFR AT ALL TERMINALS. SHORTWAVE
ENERGY WILL ROTATE NORTH AHEAD OF MORE IMPRESSIVE SHORTWAVE OVER
NORTHERN NEW MEXICO. EXPECT THAT SHOWERS OVER THE BIG HORN BASIN
WILL DISSIPATE LATE TONIGHT WHILE KRIW AND KLND COULD SEE ISOLATED
WEAK CONVECTION THROUGH THE OVERNIGHT HOURS. ENERGY WITH THE MORE
VIGOROUS SHORTWAVE WILL REACH CENTRAL WYOMING IN THE 20Z-22Z/FRI
TIMEFRAME. THE EVOLUTION MAY BE VERY SIMILAR TO THURSDAY. APPEARS
THERE COULD BE A LITTLE MORE INSTABILITY TO GENERATE AT LEAST
SHOWERS AT KCPR...WHEREAS STABLE AIR LIMITED THAT THURSDAY. 700MB
LOW SHOULD BE ALONG THE WESTERN WYOMING BORDER BY 00Z/SAT. PLENTY OF
ENERGY AND MOISTURE AVAILABLE TO KEEP SHOWERS AND ISOLATED
THUNDERSTORMS GOING THROUGH 06Z/SAT. HAVE KEPT VCSH AT MANY
TERMINALS BUT COULD SEE MORE DEFINITIVE PERIOD OF PREVAILING -SHRA
BETWEEN 00Z-06Z/SAT. THERE COULD ALSO BE SOME AID FROM THE LEFT EXIT
REGION OF THE JET DURING THAT SPAN. MOUNTAIN TOP OBSCURATIONS WILL
BE WIDESPREAD ABOVE ABOUT 9K-10K MSL THROUGHOUT MUCH OF THE FORECAST
PERIOD...ESPECIALLY ALONG THE WIND RIVER RANGE AND THE SOUTHERN
PORTIONS OF THE ABSAROKA AND BIGHORN RANGES.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

YET MORE SHORTWAVE ENERGY ROTATING NORTH TONIGHT. CLOUD TOPS ARE
ALREADY COOLING AHEAD OF VIGOROUS SHORTWAVE OVER NORTHERN NEW MEXICO
PER IR IMAGERY. CONVECTION IS LIKELY TO CONTINUE THROUGH THE
NIGHT...WITH VFR CONDITIONS LARGELY THE RULE. COULD SEE SOME
LOCALIZED MVFR WITH THE STRONGER CONVECTION AND IN THE GREEN RIVER
VALLEY AROUND KBPI AND KPNA. NEW MEXICO SHORTWAVE WILL LIFT NORTH
DURING THE DAY AS LARGER UPPER LOW TO THE WEST MOVES FARTHER INLAND.
CONVECTION MAY AGAIN ORIENT WEST-EAST ACROSS FAR SOUTHERN WYOMING BY
18Z/FRI. SIMILAR TO THURSDAY...THIS AREA OF CONVECTION WILL LIFT
NORTH THROUGH 00Z/SAT. THEREFORE...HAVE VCTS BY 19Z/FRI AT KRKS AND
BY 21Z/FRI AT KBPI...KPNA...AND KJAC. CERTAINLY COULD BE A FAIRLY
STEADY PERIOD OF RAIN...ESPECIALLY AT KBPI AND KPNA...DURING THE
LATE AFTERNOON HOURS FRIDAY. MOUNTAIN TOP OBSCURATIONS WILL BE
COMMON THROUGH THE FORECAST PERIOD WITH LOWERING CEILINGS AFTER
00Z/SAT.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...CNJ
FIRE WEATHER...LIPSON










000
FXUS63 KUNR 220515
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1115 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1114 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
INCREASING COVERAGE OF SHOWERS ON FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7



000
FXUS63 KUNR 220515
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1115 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1114 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
INCREASING COVERAGE OF SHOWERS ON FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7



000
FXUS63 KUNR 220515
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1115 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1114 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
INCREASING COVERAGE OF SHOWERS ON FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 220515
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1115 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1114 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
INCREASING COVERAGE OF SHOWERS ON FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE



000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE



000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE



000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE



000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE




000
FXUS65 KCYS 220044
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
644 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM MDT THU MAY 21 2015

A VFR START TO THE MOST OF THE TAF SITES THIS EVENING...WITH KCYS
THE ONE EXCEPTION WITH PREVAILING MVFR CONDITINS. THE FIRST BAND
OF SHOWERS ALONG WITH A FEW WEAK EMBEDDED THUNDERSTORMS WILL
CONTINUE TO WEAKEN AS IT LIFTS NORTH THIS EVENING. THE NEXT WAVE
OF PRECIPITATION WILL LIFT NORTH ACROSS COLORADO DURING THE
OVERNIGHT HOURS...REACHING VERY CLOSE TO THE CO/WY STATELINE BY
AROUND 08Z. AS THIS OCCURS...CONDITIONS WILL DETERIORATE AT
AIRFIELDS. A FAIRLY WIDESPREAD PERIOD OF MVFR/IFR CONDITIONS ARE
EXPECTED AS THIS BAND OF SHOWERS MOVES THROUGH TOMORROW MORNING
AND INTO EARLY AFTERNOON. MOST OF THE ACTION WILL MOVE OUT OF THE
AREA BY LATE TOMORROW AFTERNOON...WITH CONDITIONS IMPROVING
SOMEWHAT AT THAT TIME.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...CAH
FIRE WEATHER...RE



000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7




000
FXUS63 KUNR 212348
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
548 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO
TONIGHT. MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE
SOUTHWEST OF THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND
BOUNDARY LAYER FLOW SHOULD KEEP TEMPERATURES TOO WARM FOR ANY
FROST DEVELOPMENT ON THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 545 PM MDT THU MAY 21 2015

3000-5000FT AGL CIGS SPREADING INTO NORTHEAST WYOMING/SOUTHWEST
SOUTH DAKOTA THIS EVENING...WILL CONTINUE TO MOVE NORTHWARD
OVERNIGHT. MVFR CIGS EXPECTED AROUND THE BLACK HILLS.
SHOWERS/THUNDERSTORMS ON TAP FOR FRIDAY...WITH MVFR/LCL IFR
CONDITIONS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...7



000
FXUS65 KCYS 212148
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
348 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...ZF
FIRE WEATHER...RE




000
FXUS65 KCYS 212148
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
348 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...ZF
FIRE WEATHER...RE



000
FXUS65 KCYS 212148
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
348 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...ZF
FIRE WEATHER...RE



000
FXUS65 KCYS 212148
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
348 PM MDT THU MAY 21 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 340 PM MDT THU MAY 21 2015

MILD AND UNSETTLED WEATHER WILL CONTINUE OVER THE CWA WITH A
COUPLE ENHANCED PERIODS OF SHOWERS AND SOME THUNDERSTORMS OVER
MUCH OF THE CWA. UPPER LOW NEAR THE SOCAL COAST WILL MOVE INLAND
OVERNIGHT THEN MOVE SLOWLY NORTHEAST INTO WRN COLORADO BY LATE
SATURDAY. A COUPLE OF SHORTWAVE WILL LIFT OUT NORTHEAST AHEAD OF
THIS LOW AND PASS ACROSS THE REGION BRINGING INCREASED CONVECTIVE
ACTIVITY. THE FIRST ONE...CURRENTLY OVER AZ...WILL TURN NORTHEAST
AND APPROACH THE CWA OVERNIGHT WITH SHOWERS SPREADING ACROSS MUCH
OF THE CWA AHEAD OF IT...AIDED BY SOME UPPER DIFFLUENCE. ACTIVITY
WILL PERSIST THROUGH FRIDAY BEFORE WANING SOME FRIDAY NIGHT. A
SECOND WAVE WILL THEN APPROACH ON SATURDAY WITH ANOTHER ROUND OF
CONVECTION INITIATING SATURDAY AFTERNOON. INSTABILITIES RATHER LOW
ON FRIDAY SO NOT MUCH IN THE WAY OF STORMS EXPECTED. HIGHER
INSTABILITY PROGGED SATURDAY AFTERNOON WITH CAPES FROM 1000-2000
J/KG OVER FAR SE WY INTO THE SW NEB PANHANDLE SO A FEW STRONGER
STORMS A POSSIBILITY THEN. SHEAR WILL BE SOMEWHAT HIGHER AS SFC
WINDS TURN MORE NORTHEASTERLY IN RESPONSE TO LEE CYCLONE
DEVELOPING OVER ERN COLORADO. MORE SHOWERY WEATHER FOR SAT EVENING
WITH A FEW STORMS MAINLY OVER THE PANHANDLE.

OTHER CONCERN IS FOR SOME FOG FORMATION AGAIN TONIGHT OVER AND
NEAR THE LARAMIE RANGES. RAIN MAY HELP TO REDUCE THIS HOWEVER.

.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 340 PM MDT THU MAY 21 2015

SUNDAY WILL LIKELY BE THE MOST UNSETTLED DAY OF THE EXTENDED
PERIOD WITH A WARMING AND DRYING TREND BY EARLY NEXT WEEK. COLD
FRONT WILL PUSH ACROSS THE REGION ON SUN MORNING WITH NORTHERLY
WINDS AND SCATTERED SHOWERS DURING THE AFTN. THERE IS NOT AS MUCH
INSTABILITY AS SAT BEHIND THE FRONT...HOWEVER COULD SEE A FEW
TSTMS OVER THE NEBRASKA PANHANDLE. UPPER TROUGH OVER THE CWA ON
SUNDAY WILL WEAKEN AND SHIFT EASTWARD INTO THE CENTRAL PLAINS FOR
MON. LOOKS LIKE WE WILL FINALLY BEGIN TO WARM UP BY MEMORIAL DAY
AND MORE SO BY TUES AND WED. WE MAY ACTUALLY BE BACK TO NORMAL
TEMPS FOR THE FIRST TIME IN A WHILE.  SHORTWAVE RIDGE WILL MOVE
OVERHEAD ON TUES AND THEN FLOW ALOFT WILL BECOME MORE
SOUTHWESTERLY BY WED. WITH THE WARMER TEMPS...AFTN INSTABILITY
WILL BE HIGHER THAN THE PAST FEW WEEKS...SO WILL SEE MORE NORMAL
LATE MAY CONVECTIVE PATTERN. AT LEAST THROUGH MIDWEEK IT DOES NOT
APPEAR THAT STORMS WILL BE TOO NUMEROUS (ONLY AN ISOLATED TO
SCATTERED COVERAGE) WITH SVR POTENTIAL RATHER LOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 329 PM MDT THU MAY 21 2015

NO CONCERNS SEEN THROUGH THE WEEKEND WITH A MILD AND MOIST WEATHER
PATTERN CONTINUING OVER THE AREA. MANY AREAS LIKELY TO RECEIVE
WETTING RAINS OVER THE NEXT COUPLE DAYS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...ZF
AVIATION...ZF
FIRE WEATHER...RE




000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON







000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON







000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON







000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON







000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON







000
FXUS65 KRIW 212104
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
304 PM MDT THU MAY 21 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

AREAS OF LOW CLOUDS AND FOG HAVE LIFTED INTO A LOW CUMULUS CLOUD
DECK BETWEEN 3 AND 4K AS ABUNDANT GROUND MOISTURE CONTINUES TO
CONTRIBUTE TO THE LOWER AIRMASS AS TEMPS AND CORRESPONDING LCLS
RISE. THE STUBBORN HIGH IN WESTERN CANADA HAS DIVERTED ANOTHER
CLOSED LOW SOUTH TO OFF THE CALIFORNIA COAST. THE CIRCULATION
AROUND THIS LOW IS ARRIVING AS A SOUTH SOUTHWEST DIFLUENT FLOW
ACROSS WYOMING OUT AHEAD OF IT. SCATTERED THUNDERSTORMS UNDERNEATH
THIS FLOW HAVE ERUPTED ACROSS YELLOWSTONE PARK/ABSAROKAS AS WELL AS
ACROSS SOUTHWEST WY WHERE A SHORTWAVE/VORT LOBE IS TRACKING NORTH
NORTHEAST WITHIN THE SSW DIFLUENT FLOW IN SOUTHERN WY. WITH THE
RELATIVELY LOW LCL AND LOW WET BULB ZERO...MANY OF THESE CELLS
COULD PRODUCE LOCALLY HEAVY RAINFALL AND SMALL HAIL. AS THIS
SHORTWAVE TRACKS NNE...THE TREND WILL BE FOR MORE STORM CELLS TO
DEVELOP ACROSS THE REST OF NORTHERN AND ALSO CENTRAL AND EASTERN
PORTIONS OF THE CWA. TONIGHT THE LOW CENTER WILL TRACK EAST ACROSS
SOUTHERN CALIFORNIA ALONG WITH A WEAK TROUGH EXTENDING NORTHEAST
FROM THE LOW NORTHEAST INTO WYOMING. WITH THE TROUGHINESS OVHD
FRIDAY...EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS CENTRAL AND
SOUTHERN WY FRIDAY BY LATE MORNING. THE STORMS WILL BE LAST TO
ARRIVE IN NORTH CENTRAL AND NORTHEAST WY WHERE MORE SOLAR
INSULATION WILL TAKE PLACE THROUGH THE LATER AFTERNOON HOURS FOR
FEWER...LATER BUT STRONGER THUNDERSTORMS AS THE TROUGHINESS
CONTINUES TO EXTEND NORTHEAST. TEMPS WILL WARM UP TO MORE SEASONAL LEVELS
BY FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

A PACIFIC LOW PRESSURE TROUGH OVER THE GREAT BASIN WILL MOVE
SLOWLY EAST SPREADING PACIFIC MOISTURE INTO WESTERN AND CENTRAL
WYOMING WITH SOUTHWEST FLOW ALOFT OVER THE AREA. THE AIRMASS WILL
BE UNSTABLE WITH SHOWERS...RATHER WIDESPREAD OVER THE WESTERN
MOUNTAINS AND ISOLATED THUNDERSTORMS PASSING THROUGH DURING THE
EVENING. SHOWERS WITH SOME SNOW IN THE HIGHER MOUNTAINS WILL
LINGER INTO SATURDAY MORNING. A CANADIAN COLD FRONT WILL SLIDE
SOUTH THROUGH MUCH OF THE ARA ON SATURDAY AS THE UPPER LOW DRIFTS
SLOWLY EAST OVER THE COLD FRONT. SHOWERS WILL BE WIDESPREAD ACROSS
THE AREA WITH COOL TEMPERATURES. ENOUGH INSTABILITY WILL BE OVER
THE AREA SATURDAY AFTERNOON AND EVENING TO SUPPORT ISOLATED
THUNDERSTORMS WITH SMALL HAIL. SNOW LEVELS WILL LOWER THROUGH
SATURDAY NIGHT DOWN TO AROUND 8000 FEET. SUNDAY WILL BE COOL AND
REMAINING SHOWERY WITH A FEW ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS AS THE UPPER LEVEL LOW EXITS TO THE EAST AS ANOTHER
INTENSIFIES OVER THE GREAT BASIN. SHOWERS WILL DECREASE THROUGH
SUNDAY NIGHT AND MONDAY MORNING WITH SOME LINGERING OVER THE
WESTERN MOUNTAINS. LESS MOISTURE WILL BE OVER THE AREA ON MONDAY
BUT SCATTERED MOUNTAIN SHOWERS CAN BE EXPECTED AGAIN WITH ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS. MONDAY NIGHT WILL SEE A
SIGNIFICANT DECREASE IN SHOWERS BUT SOME WILL LINGER OVER THE
WESTERN MOUNTAINS INTO TUESDAY MORNING. THE GREAT BASIN TROUGH
WILL SPREAD INCREASING MOISTURE INTO THE SOUTH AND WEST TUESDAY
AND TUESDAY NIGHT WITH MORE SHOWERS... ESPECIALLY OVER THE WESTERN
AND NORTHERN MOUNTAINS. TEMPERATURES SHOULD BE SLIGHTLY WARMER.
THE TROUGH WILL REMAIN TO THE WEST SPREADING PACIFIC MOISTURE
NORTH AND EAST ACROSS THE AREA WITH INCREASING SHOWERS AND
ISOLATED THUNDERSTORMS WEDNESDAY AND WEDNESDAY EVENING. THE TROUGH
WILL BEGIN MOVING EAST OVER THE AREA AGAIN AS ANOTHER CANADIAN
COLD FRONT MOVES SOUTH BRINGING GENERAL COOLING.


&&

.AVIATION.../00Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MOSTLY VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST PERIOD.
THE NEXT IN A SERIES OF SHORTWAVES IS APPROACHING SOUTHWEST WYOMING
THIS AFTERNOON. FAVORABLE INSTABILITY AND DYNAMICS WILL BE TO THE
SOUTHWEST OVER SOUTHWEST WYOMING. ISOLATED THUNDERSTORMS WILL
MAINLY BE CONFINED TO THE HIGHER TERRAIN AFTER 22Z THIS AFTERNOON AND
IS EXPECTED TO DISSIPATE WITH THE SETTING SUN. NOT EXPECTING ANY
THUNDERSTORMS TO SPEAK OF IN THE NORTH CENTRAL...NORTHEAST AND EAST
CWA FOR THE REST OF TODAY WHERE THE AIR IS MUCH MORE STABLE. HAVE
LINGERED VCSH INTO THE 06Z- 08Z/FRI TIME FRAME ACROSS CENTRAL
WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY IMPACTING KWRL OR
KCOD. EXPECT ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS TO DEVELOP
FRIDAY AS ANOTHER PIECE OF ENERGY SPREADS NORTHEAST FROM A LOW
CENTER IN THE DESERT SOUTHWEST. EXPECT AN EARLY SHOW OF SHOWER
DEVELOPMENT ALONG WITH ISOLATED THUNDERSTORMS. LATER...FEWER BUT
STRONGER THUNDERSTORMS ARE EXPECTED IN THE BIG HORN
BASIN...JOHSNON AND NATRONA COUNTIES AFTER 21Z FRIDAY. EXPECT MVFR
CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR MTN OBSCURATIONS
FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

THE NEXT IN A SERIES OF SHORTWAVES WILL ROTATE NORTH THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP...MOSTLY OVER THE HIGHER TERRAIN...WITH DEVELOPMENT
OCCURRING THROUGH 23Z TODAY. LIFTED INDICES AND CAPE ARE
SUFFICIENT TO GENERATE SOME ADDITIONAL WIDELY SCATTERED
THUNDERSTORMS AFTER 23Z THIS AFTERNOON. SIMILAR TO LAST
NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL ABOUT 04Z/FRI
WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI. CLOUD
HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE FROM SOUTHWEST
WYOMING. EXPECT MVFR CONDITIONS FROM LOW CLOUDS AND LOCAL MVFR/IFR
MTN OBSCURATIONS FROM SHOWER AND THUNDERSTORM ACTIVITY FRIDAY.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE FOR THE REST OF THIS
AFTERNOON AND EVENING. DEEPER MOISTURE WILL MOVE TOWARD THE AREA
FOR FRIDAY AND BRING ANOTHER CHANCE OF A WETTING RAIN FROM FRIDAY
INTO FRIDAY NIGHT. THERE WILL BE A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS WELL. SNOW LEVELS
WILL DROP TO 8000 FEET LATE SATURDAY NIGHT AND SUNDAY MORNING.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...LIPSON
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...LIPSON








000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE



000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE



000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE



000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE



000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE



000
FXUS63 KUNR 212043
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
243 PM MDT THU MAY 21 2015

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 225 PM MDT THU MAY 21 2015

CURRENT UPPER ANALYSIS SHOWS A HIGH AMPLITUDE RIDGE OVER THE GREAT
PLAINS WITH AN UPPER LOW MOVING ONSHORE THE CALIFORNIA COAST.
SOUTHEASTERLY UPSLOPE SFC FLOW OVER THE GREAT PLAINS IS COMBINING
WITH MID/HIGH LEVEL MOISTURE TO THE EAST OF THE UPPER LOW/TROUGH
TO PRODUCE SHOWERS OVER MUCH OF THE ROCKIES THIS AFTN.

FOR TNGT...SOUTHEASTERLY SFC FLOW WILL CONTINUE OVER THE FORECAST
AREA WITH A SLIGHT STRENGTHENING OF THE 850-MB WINDS AS THE
BOUNDARLY LAYER DECOUPLES THIS EVENING. A SHORT-WAVE TROUGH WILL
EJECT NORTHEASTWARD FROM THE UPPER LOW AND WILL CROSS COLORADO TONIGHT.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD KEEP TEMPERATURES TOO WARM FOR ANY FROST DEVELOPMENT ON
THE PLAINS OVERNIGHT.

ON FRIDAY/FRIDAY NIGHT...THE SHORT-WAVE TROUGH WILL SLOWLY CROSS
THE NEB PANHANDLE...WITH NORTHWARD PROGRESS BEING SLOWED BY AN UPPER-
LEVEL NW-SE ORIENTED CONFLUENT ZONE. A NARROW ZONE OF
MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE SRN CWA.
INSTABILITY IS EXPECTED TO BE WEAK...SO HAVE KEPT THE THUNDER
POTENTIAL CLOSEST TO THE BOUNDARY OVER NERN WYOMING ON FRIDAY
AFTN/EVE. ON FRIDAY NIGHT...THE SHORT- WAVE TROUGH WILL MOVE
NORTHEASTWARD ACROSS THE FORECAST AREA. SOME ISENTROPIC LIFT IS
PRESENT IN THE LOW-MID LEVELS...BUT THE WAVE WILL ENCOUNTER DRY
AIR TO THE NORTH...SO WILL KEEP ONLY LOW POPS OVER THE NORTHERN
CWA...HIGHEST POPS ACROSS THE SOUTH.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED
WEATHER THROUGH THE HOLIDAY WEEKEND AS UPPER LEVEL SYSTEM SLOWLY
TRACKS ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. WITH THE
LEFT EXIT REGION OF THE UPPER JET MOVING OVER THE CWA...IT STILL
LOOKS LIKE THE HEAVIER AND MORE WIDESPREAD RAINFALL WILL BE LATE
SATURDAY INTO SUNDAY. BEST INSTABILITY AND SHEAR FOR STRONGER STORMS
WILL BE FROM SOUTHWEST INTO CENTRAL SD ON SATURDAY...SHIFTING
EASTWARD FOR SUNDAY. MODELS DIFFER ON THE LOCATION OF THE HEAVIER
PRECIP BUT ARE GENERALLY SHOWING 0.5 TO 1.5 INCHES BY SUNDAY
NIGHT...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE.

THIS SYSTEM WILL GRADUALLY EXIT THE REGION MONDAY...BUT PRECIP
CHANCES WILL CONTINUE THROUGH THE WEEK AS THE ACTIVE PATTERN
CONTINUES. TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE
WEEKEND...WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES
BY THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 225 PM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...POJORLIE




000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS











000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS












000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS











000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS











000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS











000
FXUS65 KRIW 211753
AFDRIW

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE RIVERTON WY
1154 AM MDT THU MAY 21 2015

.SHORT TERM...THURSDAY THROUGH SATURDAY NIGHT

THE ACTIVE WEATHER PATTERN LOOKS TO CONTINUE INTO THE FIRST PART OF
THE HOLIDAY WEEKEND. AS OF RIGHT...WE STILL GAVE A FEW LIGHT SHOWERS
MAINLY WEST OF THE DIVIDE BUT NOTHING OF CONSEQUENCE. THIS LOOKS TO
BE ON OF THE QUIETEST TIMES OF THE SHORT TERM FORECAST PERIOD.
THINGS WILL BECOME MORE ACTIVE THIS AFTERNOON AS ANOTHER SHORTWAVE
APPROACHES THE AREA FROM THE SOUTH AND WEST AND BRINGS ANOTHER ROUND
OF SHOWERS AND THUNDERSTORMS. MUCH LIKE YESTERDAY...THE VAST
MAJORITY OF THESE LOOK TO STAY WEST OF THE DIVIDE. ALSO...WITH MORE
SOUTHERLY FLOW AND MORE SUNSHINE THAN YESTERDAY...TEMPERATURES
SHOULD WARM UP CLOSER TO NORMAL LEVELS...BUT STILL RATHER CHILLY FOR
THIS TIME OF YEAR. A FEW OF THESE STORMS COULD SNEAK EAST OF THE
DIVIDE...BUT MOST AREAS EAST OF THE DIVIDE SHOULD REMAIN MAINLY DRY
MOST OF THE TIME. MOST SHOWERS SHOULD WANE AFTER MIDNIGHT ALTHOUGH A
FEW COULD LINGER AS A DEEPER PUSH OF MOISTURE MOVES TOWARDS THE
AREA.

THE AFOREMENTIONED PUSH OF MOISTURE WILL BEGIN TO PUSH NORTHWARD
ACROSS THE AREA IN THE MORNING...BUT THE BEST CHANCE OF RAIN WILL BE
DURING THE AFTERNOON. AS OF THIS TIME...THE BEST CHANCE OF SHOWERS
WILL BE ACROSS CENTRAL PORTIONS OF THE AREA WITH LESSER CHANCES
FURTHER NORTH. AS FOR THE CHANCE OF ANY STRONGER STORMS...THE BEST
CHANCE WOULD BE FURTHER NORTH WHERE THE START OF THE RAIN WOULD BE
LATER AND THERE COULD BE SOME MORNING SUNSHINE THAT COULD
DESTABILIZE THINGS SOMEWHAT. BY LATER FRIDAY NIGHT...AN INTERESTING
SCENARIO AS BOTH THE NAM AND THE GFS SHOW A DRY SLOT TRYING TO WORK
INTO THE AREA...ALTHOUGH THE NAM IS MORE PRONOUNCED WITH IT THAT THE
GFS IS.

AND THIS LEADS US TO THE QUESTION OF SATURDAY. IF THE MODELS ARE TO
BE BELIEVED...MUCH OF SATURDAY MORNING COULD BE DRY EAST OF THE
DIVIDE...ESPECIALLY THE FURTHER EAST YOU GO. THERE COULD EVEN BE
SOME CLEARING. AND THIS LEADS TO THE POSSIBILITY OF MORE CONVECTIVE
PRECIPITATION RATHER THAN STRATIFORM. AGAIN...IT DEPENDS OF THE
MODEL. THE GFS IS COOLER BUT STILL HAS NEGATIVE LIFTED INDICES AND
UP TO 300 J/KG OF CAPE IN HE AFTERNOON. MEANWHILE...THE
NAM..ALTHOUGH IT TENDS TO OVERDO INSTABILITY A BIT...IT IS SHOWING
AROUND 1000 J/KG OF CAPE OVER PORTIONS OF THE AREA ALONG WITH LIFTED
INDICES DROPPING TO AS LOW AS -5. THE NEW STORM PREDICTION CENTER DAY
3 OUTLOOK BRINGS A MARGINAL AREA INTO SOUTHEASTERN WYOMING AS
WELL. THERE IS ALSO A DECENT JET NEAR THE AREA AND WITH THE LOW
NEAR BY THERE WILL BE SOME DIRECTIONAL SHEAR AROUND. AGAIN...THE
BIG X FACTOR WILL BE HOW MUCH SUNSHINE AND DESTABILIZATION THERE
IS. SOMETHING TO WATCH. BY SATURDAY NIGHT...AGAIN THE QUESTION IS
WHETHER OR NOT THE S WORD WILL ENTER THE FORECAST AGAIN. THIS
SYSTEM STILL LOOKS WARMER THAN THE LAST ONE. THE GFS IS THE
COLDEST WITH -1 CELSIUS AT 700 MILLIBARS WHICH WOULD BRING SNOW
LEVELS DOWN TO AROUND 8000 FEET. THE NAM IS WARMER WITH LEVELS
CLOSER TO 9000 FEET. THE GFS WAS CLOSER LAST TIME THOUGH.
CONTINUITY HAD THIS REPRESENTED FAIRLY WELL SO WE MADE FEW
CHANGES.

.LONG TERM...SUNDAY THROUGH THURSDAY

SUNDAY WILL SEE THE WEATHER SYSTEM MOVE SLOWLY INTO EASTERN WY BY
00Z MONDAY. RAIN WILL BE MORE LIKELY IN THE EASTERN ZONES SUNDAY
WITH SCATTERED RAIN SHOWERS ELSEWHERE. THE WEATHER SYSTEM MOVES OUT
SUNDAY NIGHT WITH SHOWER ACTIVITY DECREASING. MONDAY LOOKS DRIER
CENTRAL AND EAST WITH A WEST FLOW ALOFT. SHOULD SEE SLIGHT CHANCE
FOR SHOWERS AND STORMS OVER MUCH OF THE REGION MON AFTERNOON AND
EVENING. FLOW ALOFT TURNS TO THE WEST SOUTHWEST FOR TUESDAY. DO NOT
SEE A WEATHER DISTURBANCE IN THE FLOW ON TUE BUT THERE IS ENOUGH
MOISTURE AND INSTABILITY FOR CONVECTION TO FIRE UP IN THE WEST AND
SOUTHWEST. ONLY ISOLATED ACTIVITY FOR THE REST OF THE AREA. WEDNESDAY
AND THURSDAY WILL SEE A SOUTHWEST FLOW ALOFT PER THE GFS MODEL
WITH A DECENT WEATHER DISTURBANCE ON THURS PM AND NIGHT. THEN A
POTENTIAL WEATHER DISTURBANCE AGAIN NEXT THURSDAY. THE ECMWF MODEL
IS A TAD DIFFERENT NEXT WED AND THURS WITH LESS POTENT WEATHER
SYSTEMS IN THE FLOW. WILL KEEP THE SCATTERED SHOWERS AND ISOLATED
STORMS IN THE FORECAST BOTH DAYS. AS FOR TEMPS...A COOL DAY ON
SUNDAY THEN WARMING UP A FEW DEGREES FOR MON AND TUE. THEN MAYBE A
LITTLE COOLER WED AND NEXT THURS DUE TO MORE CLOUDS AND MORE
COVERAGE OF SHOWERS/STORMS.


&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z OVER THE NORTH CENTRAL AND
NORTHEAST WIND RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM
THE EDGES. OTHERWISE VFR CEILINGS WILL PREVAIL THROUGH THE FORECAST
PERIOD. OVERALL EXPECT LESS CLOUD COVER FOR A CHUNK OF TODAY WHICH
WILL AID MIXING AND LIFT CEILINGS. THE NEXT IN A SERIES OF
SHORTWAVES WILL APPROACH SOUTHWEST WYOMING THIS AFTERNOON. FAVORABLE
INSTABILITY AND DYNAMICS WILL BE TO THE SOUTHWEST OVER SOUTHWEST
WYOMING. ISOLATED THUNDERSTORMS WILL MAINLY BE CONFINED TO THE
HIGHER TERRAIN AFTER 22Z/THU AND IS EXPECTED TO DISSIPATE WITH THE
SETTING SUN. HAVE LINGERED VCSH INTO THE 06Z-08Z/FRI TIME FRAME
ACROSS CENTRAL WYOMING...WITH LITTLE IF ANY SHOWER ACTIVITY
IMPACTING KWRL OR KCOD.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

MVFR CIGS WILL PERSIST UNTIL ABOUT 19Z ACROSS THE WESTERN PORTION OF
THE GREEN RIVER BASIN BEFORE THIS AREA OF CLOUDS SHRINKS FROM THE
EDGES. A SMALL PATCH OF LINGERING IFR CIGS WILL VANISH OVER
SWEETWATER COUNTY JUST IN TIME FOR A HIGHER DECK OF VFR CLOUDINESS
MOVING IN FROM THE SOUTH WHICH SHOULD DELAY ANY CONVECTIVE ACTIVITY
THERE UNTIL MAINLY AFTER 22Z THIS AFTERNOON. THE NEXT IN A SERIES OF
SHORTWAVES WILL ROTATE NORTH THIS AFTERNOON. SHOWERS WILL BE MOST
NUMEROUS OVER THE HIGHER TERRAIN...WITH DEVELOPMENT OCCURRING
BETWEEN 22Z-23Z TODAY. LIFTED INDICES AND CAPE ARE SUFFICIENT TO
GENERATE WIDELY SCATTERED THUNDERSTORMS AFTER 22Z THIS AFTERNOON.
SIMILAR TO LAST NIGHT...THE SHOWERS AND STORMS WILL CONTINUE UNTIL
ABOUT 04Z/FRI WITH SOME SHOWERS LINGERING UNTIL WELL AFTER 06Z/FRI.
CLOUD HEIGHTS OVERNIGHT TONIGHT INTO FRIDAY WILL BE LOWER...ALBEIT
VFR/MVFR...AS A RESULT OF THE INCREASED LOW-LEVEL MOISTURE ACROSS
SOUTHWEST WYOMING.

&&

.FIRE WEATHER...

FIRE DANGER RELATIVELY LOW AS SEASONAL TO COOL AND RELATIVELY MOIST
CONDITIONS PERSIST. A WEAK UPPER LEVEL DISTURBANCE WILL BRING
ISOLATED CONVECTION MAINLY WEST OF THE DIVIDE TODAY. DEEPER MOISTURE
WILL MOVE TOWARD THE AREA FOR FRIDAY AND BRING ANOTHER CHANCE OF A
WETTING RAIN FROM FRIDAY INTO FRIDAY NIGHT. THERE WILL BE A CHANCE
OF SHOWERS AND THUNDERSTORMS THAT WILL PERSIST INTO SATURDAY AS
WELL.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HATTINGS
LONG TERM...AR
AVIATION...CNJ/LIPSON
FIRE WEATHER...HATTINGS











000
FXUS65 KCYS 211753
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1153 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 605 AM MDT THU MAY 21 2015

WENT AHEAD AND EXPANDED THE DENSE FOG ADVISORY EAST TO INCLUDE
CENTRAL LARAMIE COUNTY AND THE CHEYENNE AREA AS VISIBILITIES
TANKED TO LESS THAN A QUARTER MILE.

UPDATE ISSUED AT 543 AM MDT THU MAY 21 2015

LATEST CHECK OF WYDOT WEB CAMS INDICATED THAT THE DENSE FOG HAD
SPREAD EAST TOWARD CHEYENNE WITH VISIBILITIES AT A QUARTER MILE
OR LESS. IN A RECENT UPDATE...ADDED THE SOUTH LARAMIE RANGE
FOOTHILLS TO THE DENSE FOG ADVISORY. VISIBILITY AT CHEYENNE
RECENTLY DROPPED TO A QUARTER MILE.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 445 AM MDT THU MAY 21 2015

PREDAWN WATER VAPOR LOOP DEPICTED A LONG WAVE TROUGH AXIS ALONG
THE PACIFIC COAST WITH EMBEDDED CLOSED CIRCULATIONS. DIFFLUENT
FLOW ALOFT WAS INCREASING BETWEEN THE TROUGH AND DOWNSTREAM UPPER
RIDGE FROM THE SOUTHERN HIGH PLAINS TO WYOMING. THE SURFACE
ANALYSIS SHOWED A RIDGE CENTERED OVER THE GREAT PLAINS...WITH A
WAVY STATIONARY FRONT FROM THE SOUTHERN ATLANTIC COAST THROUGH THE
DEEP SOUTH AND NORTHWEST INTO THE NORTHERN ROCKIES. MID AND HIGH
LEVEL MOISTURE WAS SPREADING NORTHEAST FROM THE FOUR CORNERS.
PERSISTENT MOIST LOW LEVEL EASTERLY FLOW PRODUCED AREAS OF LOW
STRATUS...DRIZZLE AND FOG ALONG THE I-80 CORRIDOR. THE DENSEST FOG
EXTENDED FROM THE SUMMIT EAST TO BUFORD PER THE WYDOT WEB CAMS. THE
FOG WILL LIKELY PERSIST THROUGH LATE THIS MORNING.

LATEST DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT PROGGING
THE UPPER RIDGE OVER THE CWA TO TRANSLATE EAST INTO THE CENTRAL
AND SOUTHERN GREAT PLAINS AS THE MAIN UPPER LOW OFF THE WEST COAST
OF CA TRACKS SOUTHEAST TOWARD THE DESERT SOUTHWEST DURING THE NEXT
24 TO 48 HOURS. THIS WILL PLACE THE FRONT RANGE AND HIGH PLAINS
IN THE DIFFLUENT FLOW ALOFT WITH SEVERAL PIECES OF SHORTWAVE ENERGY
EJECTING NORTHEAST ACROSS THE REGION. TIMING OF THESE SMALLER
FEATURES AND THEIR INFLUENCE ON CONVECTION ARE USUALLY DIFFICULT
TO RESOLVE. AS THE CENTER OF THE SURFACE RIDGE SLIDES SOUTHEAST
AND WEAK CYCLOGENESIS DEVELOPS OVER EASTERN CO...SOUTHEASTERLY
FLOW WILL CONTINUE TO DRAW LOW LEVEL GULF MOISTURE NORTHWESTWARD
WITH MID/UPPER LEVEL PACIFIC MOISTURE FROM THE SOUTHWEST.

LIGHT SHOWERS WILL DEVELOP LATE THIS MORNING ALONG AND WEST OF
THE LARAMIE RANGE...GRADUALLY SPREADING EAST INTO SOUTHEAST WY
THIS AFTERNOON. INSTABILITY WILL GENERALLY BE WEAK (LESS THAN 500
J/KG SBCAPE) WITH ISOLATED THUNDER POSSIBLE. HIGH TEMPERATURES
WILL MODERATE INTO THE 50S. SHOWERS/ISOLATED THUNDER BECOME
MORE WIDESPREAD THIS EVENING AND OVERNIGHT TONIGHT AS A SHORTWAVE
LIFTS NORTHEAST ACROSS THE CWA. SHOWERS/ISOLATED AFTERNOON THUNDER
ARE LIKELY FRIDAY WITH THE POTENTIAL FOR MODERATE TO LOCALLY HEAVY
RAIN OVER SOUTHEAST WY AND SOUTHERN NE PANHANDLE. COULD SEE BETWEEN
ONE HALF AND ONE INCH QPF IN THESE AREAS. IT WILL BE SLIGHTLY COOLER
FRIDAY WITH HIGHS IN THE MID 40S TO MID 50S.

THE MODELS CONTINUE TO TREND TOWARD AN ACTIVE CONVECTIVE DAY
ON SATURDAY AS THE MAIN UPPER LOW MOVES NORTHEAST OVER THE FOUR
CORNERS. THERE ARE DIFFERENCES WITH RESPECT TO TO THE TRACK AND
STRENGTH OF THE SURFACE LOW. AT NOON SATURDAY...THE GFS PLACES THE
LOW JUST SOUTH OF CHEYENNE WHILE THE ECMWF IS NEAR PUEBLO. IF THE
GFS PANS OUT...THERE WILL BE AN MARGINAL RISK FOR STRONG TO
POSSIBLY SEVERE TSTORMS AS FAR NORTH AS CHEYENNE AND SIDNEY WITH
SBCAPES 500-1000 J/KG...DEW POINTS 40S-LOW 50S AND MODEST 0-6KM
SHEAR. CONVERSELY... THE ECMWF SOLUTION WOULD RESULT IN A MORE
STABLE EASTERLY LOW LEVEL FLOW. BETTER CHANCES FOR STRONG TO
SEVERE TSTORMS APPEAR TO BE OVER NORTHEAST CO CLOSER TO THE
INTERSECTION OF THE SURFACE LOW AND TROUGH. WILL SEE A DECREASE IN
THE SHOWERS SATURDAY MORNING...THEN BECOME WIDESPREAD IN THE
AFTERNOON. HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES WARMER
SATURDAY WITH LOW TO MID 60S FOR THE PLAINS.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 415 AM MDT THU MAY 21 2015

SATURDAY NIGHT...UPPER TROUGH PIVOTS ACROSS SOUTHEAST WYOMING WITH
SOME INDICATIONS OF DRY SLOTTING...THOUGH LOOKS LIKE THERE WILL BE
ENOUGH LOW LEVEL CONVERGENCE AND LOW AND MID LEVEL MOISTURE PRESENT
TO SPARK SCATTERED THUNDERSTORMS...SOME STRONG TO SEVERE IN THE
EVENING...MAINLY EAST OF I-25.

SUNDAY...SCATTERED TO NUMEROUS SHOWER COVERAGE WITH ISOLATED
THUNDERSTORMS WITH ADEQUATE MOISTURE PRESENT AND SYSTEM DYNAMICS
MOVING OVERHEAD.

MONDAY...FLOW ALOFT TURNS MORE WEST...WITH SOME SLOW DRYING.
NEVERTHELESS...STILL ENOUGH MOISTURE AND DYNAMICS TO PRODUCE
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS FROM RAWLINS TO
LARAMIE.

TUESDAY...WEAK RIDGE ALOFT...THOUGH WITH ADEQUATE LOW AND MID LEVEL
MOISTURE...AND A LOW LEVEL CONVERGENCE AXIS EVIDENT AT THE SURFACE...
WILL MAINTAIN SCATTERED AFTERNOON AND EVENING COVERAGE.

WEDNESDAY...NEXT SHORTWAVE TROUGH APPROACHES FROM THE GREAT BASIN
STATES. A COLD FRONT WILL ENTER OUR NORTHERN COUNTIES. AGAIN...LOOKS
LIKE A DAY WITH SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON
AND EVENING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 345 AM MDT THU MAY 21 2015

THE PERSISTENT COOL AND MOIST UPSLOPE PATTERN WILL PRECLUDE FIRE
WEATHER CONCERNS THROUGH THE WEEKEND. BEST CHANCES FOR WIDESPREAD
WETTING RAIN WILL BE TONIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 400 AM MDT THU MAY 21 2015

WATER LEVELS WILL REMAIN HIGH ALONG THE LARAMIE RIVER AT FORT LARAMIE
AND LARAMIE FOR THE NEXT SEVERAL DAYS. FORT LARAMIE IS FORECAST TO
COME WITHIN A TENTH OF A FOOT OF FLOOD STAGE (7 FT) THROUGH THE
WEEKEND. MODERATE TO LOCALLY HEAVY RAIN WILL BE POSSIBLE FOR THE HIGH
PLAINS AND POSSIBLY LARAMIE VALLEY TONIGHT AND FRIDAY...WHICH MAY
RESULT IN FURTHER RISES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...ZF
FIRE WEATHER...MAJ
HYDROLOGY...MAJ



000
FXUS65 KCYS 211753
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1153 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 605 AM MDT THU MAY 21 2015

WENT AHEAD AND EXPANDED THE DENSE FOG ADVISORY EAST TO INCLUDE
CENTRAL LARAMIE COUNTY AND THE CHEYENNE AREA AS VISIBILITIES
TANKED TO LESS THAN A QUARTER MILE.

UPDATE ISSUED AT 543 AM MDT THU MAY 21 2015

LATEST CHECK OF WYDOT WEB CAMS INDICATED THAT THE DENSE FOG HAD
SPREAD EAST TOWARD CHEYENNE WITH VISIBILITIES AT A QUARTER MILE
OR LESS. IN A RECENT UPDATE...ADDED THE SOUTH LARAMIE RANGE
FOOTHILLS TO THE DENSE FOG ADVISORY. VISIBILITY AT CHEYENNE
RECENTLY DROPPED TO A QUARTER MILE.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 445 AM MDT THU MAY 21 2015

PREDAWN WATER VAPOR LOOP DEPICTED A LONG WAVE TROUGH AXIS ALONG
THE PACIFIC COAST WITH EMBEDDED CLOSED CIRCULATIONS. DIFFLUENT
FLOW ALOFT WAS INCREASING BETWEEN THE TROUGH AND DOWNSTREAM UPPER
RIDGE FROM THE SOUTHERN HIGH PLAINS TO WYOMING. THE SURFACE
ANALYSIS SHOWED A RIDGE CENTERED OVER THE GREAT PLAINS...WITH A
WAVY STATIONARY FRONT FROM THE SOUTHERN ATLANTIC COAST THROUGH THE
DEEP SOUTH AND NORTHWEST INTO THE NORTHERN ROCKIES. MID AND HIGH
LEVEL MOISTURE WAS SPREADING NORTHEAST FROM THE FOUR CORNERS.
PERSISTENT MOIST LOW LEVEL EASTERLY FLOW PRODUCED AREAS OF LOW
STRATUS...DRIZZLE AND FOG ALONG THE I-80 CORRIDOR. THE DENSEST FOG
EXTENDED FROM THE SUMMIT EAST TO BUFORD PER THE WYDOT WEB CAMS. THE
FOG WILL LIKELY PERSIST THROUGH LATE THIS MORNING.

LATEST DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT PROGGING
THE UPPER RIDGE OVER THE CWA TO TRANSLATE EAST INTO THE CENTRAL
AND SOUTHERN GREAT PLAINS AS THE MAIN UPPER LOW OFF THE WEST COAST
OF CA TRACKS SOUTHEAST TOWARD THE DESERT SOUTHWEST DURING THE NEXT
24 TO 48 HOURS. THIS WILL PLACE THE FRONT RANGE AND HIGH PLAINS
IN THE DIFFLUENT FLOW ALOFT WITH SEVERAL PIECES OF SHORTWAVE ENERGY
EJECTING NORTHEAST ACROSS THE REGION. TIMING OF THESE SMALLER
FEATURES AND THEIR INFLUENCE ON CONVECTION ARE USUALLY DIFFICULT
TO RESOLVE. AS THE CENTER OF THE SURFACE RIDGE SLIDES SOUTHEAST
AND WEAK CYCLOGENESIS DEVELOPS OVER EASTERN CO...SOUTHEASTERLY
FLOW WILL CONTINUE TO DRAW LOW LEVEL GULF MOISTURE NORTHWESTWARD
WITH MID/UPPER LEVEL PACIFIC MOISTURE FROM THE SOUTHWEST.

LIGHT SHOWERS WILL DEVELOP LATE THIS MORNING ALONG AND WEST OF
THE LARAMIE RANGE...GRADUALLY SPREADING EAST INTO SOUTHEAST WY
THIS AFTERNOON. INSTABILITY WILL GENERALLY BE WEAK (LESS THAN 500
J/KG SBCAPE) WITH ISOLATED THUNDER POSSIBLE. HIGH TEMPERATURES
WILL MODERATE INTO THE 50S. SHOWERS/ISOLATED THUNDER BECOME
MORE WIDESPREAD THIS EVENING AND OVERNIGHT TONIGHT AS A SHORTWAVE
LIFTS NORTHEAST ACROSS THE CWA. SHOWERS/ISOLATED AFTERNOON THUNDER
ARE LIKELY FRIDAY WITH THE POTENTIAL FOR MODERATE TO LOCALLY HEAVY
RAIN OVER SOUTHEAST WY AND SOUTHERN NE PANHANDLE. COULD SEE BETWEEN
ONE HALF AND ONE INCH QPF IN THESE AREAS. IT WILL BE SLIGHTLY COOLER
FRIDAY WITH HIGHS IN THE MID 40S TO MID 50S.

THE MODELS CONTINUE TO TREND TOWARD AN ACTIVE CONVECTIVE DAY
ON SATURDAY AS THE MAIN UPPER LOW MOVES NORTHEAST OVER THE FOUR
CORNERS. THERE ARE DIFFERENCES WITH RESPECT TO TO THE TRACK AND
STRENGTH OF THE SURFACE LOW. AT NOON SATURDAY...THE GFS PLACES THE
LOW JUST SOUTH OF CHEYENNE WHILE THE ECMWF IS NEAR PUEBLO. IF THE
GFS PANS OUT...THERE WILL BE AN MARGINAL RISK FOR STRONG TO
POSSIBLY SEVERE TSTORMS AS FAR NORTH AS CHEYENNE AND SIDNEY WITH
SBCAPES 500-1000 J/KG...DEW POINTS 40S-LOW 50S AND MODEST 0-6KM
SHEAR. CONVERSELY... THE ECMWF SOLUTION WOULD RESULT IN A MORE
STABLE EASTERLY LOW LEVEL FLOW. BETTER CHANCES FOR STRONG TO
SEVERE TSTORMS APPEAR TO BE OVER NORTHEAST CO CLOSER TO THE
INTERSECTION OF THE SURFACE LOW AND TROUGH. WILL SEE A DECREASE IN
THE SHOWERS SATURDAY MORNING...THEN BECOME WIDESPREAD IN THE
AFTERNOON. HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES WARMER
SATURDAY WITH LOW TO MID 60S FOR THE PLAINS.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 415 AM MDT THU MAY 21 2015

SATURDAY NIGHT...UPPER TROUGH PIVOTS ACROSS SOUTHEAST WYOMING WITH
SOME INDICATIONS OF DRY SLOTTING...THOUGH LOOKS LIKE THERE WILL BE
ENOUGH LOW LEVEL CONVERGENCE AND LOW AND MID LEVEL MOISTURE PRESENT
TO SPARK SCATTERED THUNDERSTORMS...SOME STRONG TO SEVERE IN THE
EVENING...MAINLY EAST OF I-25.

SUNDAY...SCATTERED TO NUMEROUS SHOWER COVERAGE WITH ISOLATED
THUNDERSTORMS WITH ADEQUATE MOISTURE PRESENT AND SYSTEM DYNAMICS
MOVING OVERHEAD.

MONDAY...FLOW ALOFT TURNS MORE WEST...WITH SOME SLOW DRYING.
NEVERTHELESS...STILL ENOUGH MOISTURE AND DYNAMICS TO PRODUCE
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS FROM RAWLINS TO
LARAMIE.

TUESDAY...WEAK RIDGE ALOFT...THOUGH WITH ADEQUATE LOW AND MID LEVEL
MOISTURE...AND A LOW LEVEL CONVERGENCE AXIS EVIDENT AT THE SURFACE...
WILL MAINTAIN SCATTERED AFTERNOON AND EVENING COVERAGE.

WEDNESDAY...NEXT SHORTWAVE TROUGH APPROACHES FROM THE GREAT BASIN
STATES. A COLD FRONT WILL ENTER OUR NORTHERN COUNTIES. AGAIN...LOOKS
LIKE A DAY WITH SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON
AND EVENING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 345 AM MDT THU MAY 21 2015

THE PERSISTENT COOL AND MOIST UPSLOPE PATTERN WILL PRECLUDE FIRE
WEATHER CONCERNS THROUGH THE WEEKEND. BEST CHANCES FOR WIDESPREAD
WETTING RAIN WILL BE TONIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 400 AM MDT THU MAY 21 2015

WATER LEVELS WILL REMAIN HIGH ALONG THE LARAMIE RIVER AT FORT LARAMIE
AND LARAMIE FOR THE NEXT SEVERAL DAYS. FORT LARAMIE IS FORECAST TO
COME WITHIN A TENTH OF A FOOT OF FLOOD STAGE (7 FT) THROUGH THE
WEEKEND. MODERATE TO LOCALLY HEAVY RAIN WILL BE POSSIBLE FOR THE HIGH
PLAINS AND POSSIBLY LARAMIE VALLEY TONIGHT AND FRIDAY...WHICH MAY
RESULT IN FURTHER RISES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...ZF
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS65 KCYS 211753
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1153 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 605 AM MDT THU MAY 21 2015

WENT AHEAD AND EXPANDED THE DENSE FOG ADVISORY EAST TO INCLUDE
CENTRAL LARAMIE COUNTY AND THE CHEYENNE AREA AS VISIBILITIES
TANKED TO LESS THAN A QUARTER MILE.

UPDATE ISSUED AT 543 AM MDT THU MAY 21 2015

LATEST CHECK OF WYDOT WEB CAMS INDICATED THAT THE DENSE FOG HAD
SPREAD EAST TOWARD CHEYENNE WITH VISIBILITIES AT A QUARTER MILE
OR LESS. IN A RECENT UPDATE...ADDED THE SOUTH LARAMIE RANGE
FOOTHILLS TO THE DENSE FOG ADVISORY. VISIBILITY AT CHEYENNE
RECENTLY DROPPED TO A QUARTER MILE.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 445 AM MDT THU MAY 21 2015

PREDAWN WATER VAPOR LOOP DEPICTED A LONG WAVE TROUGH AXIS ALONG
THE PACIFIC COAST WITH EMBEDDED CLOSED CIRCULATIONS. DIFFLUENT
FLOW ALOFT WAS INCREASING BETWEEN THE TROUGH AND DOWNSTREAM UPPER
RIDGE FROM THE SOUTHERN HIGH PLAINS TO WYOMING. THE SURFACE
ANALYSIS SHOWED A RIDGE CENTERED OVER THE GREAT PLAINS...WITH A
WAVY STATIONARY FRONT FROM THE SOUTHERN ATLANTIC COAST THROUGH THE
DEEP SOUTH AND NORTHWEST INTO THE NORTHERN ROCKIES. MID AND HIGH
LEVEL MOISTURE WAS SPREADING NORTHEAST FROM THE FOUR CORNERS.
PERSISTENT MOIST LOW LEVEL EASTERLY FLOW PRODUCED AREAS OF LOW
STRATUS...DRIZZLE AND FOG ALONG THE I-80 CORRIDOR. THE DENSEST FOG
EXTENDED FROM THE SUMMIT EAST TO BUFORD PER THE WYDOT WEB CAMS. THE
FOG WILL LIKELY PERSIST THROUGH LATE THIS MORNING.

LATEST DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT PROGGING
THE UPPER RIDGE OVER THE CWA TO TRANSLATE EAST INTO THE CENTRAL
AND SOUTHERN GREAT PLAINS AS THE MAIN UPPER LOW OFF THE WEST COAST
OF CA TRACKS SOUTHEAST TOWARD THE DESERT SOUTHWEST DURING THE NEXT
24 TO 48 HOURS. THIS WILL PLACE THE FRONT RANGE AND HIGH PLAINS
IN THE DIFFLUENT FLOW ALOFT WITH SEVERAL PIECES OF SHORTWAVE ENERGY
EJECTING NORTHEAST ACROSS THE REGION. TIMING OF THESE SMALLER
FEATURES AND THEIR INFLUENCE ON CONVECTION ARE USUALLY DIFFICULT
TO RESOLVE. AS THE CENTER OF THE SURFACE RIDGE SLIDES SOUTHEAST
AND WEAK CYCLOGENESIS DEVELOPS OVER EASTERN CO...SOUTHEASTERLY
FLOW WILL CONTINUE TO DRAW LOW LEVEL GULF MOISTURE NORTHWESTWARD
WITH MID/UPPER LEVEL PACIFIC MOISTURE FROM THE SOUTHWEST.

LIGHT SHOWERS WILL DEVELOP LATE THIS MORNING ALONG AND WEST OF
THE LARAMIE RANGE...GRADUALLY SPREADING EAST INTO SOUTHEAST WY
THIS AFTERNOON. INSTABILITY WILL GENERALLY BE WEAK (LESS THAN 500
J/KG SBCAPE) WITH ISOLATED THUNDER POSSIBLE. HIGH TEMPERATURES
WILL MODERATE INTO THE 50S. SHOWERS/ISOLATED THUNDER BECOME
MORE WIDESPREAD THIS EVENING AND OVERNIGHT TONIGHT AS A SHORTWAVE
LIFTS NORTHEAST ACROSS THE CWA. SHOWERS/ISOLATED AFTERNOON THUNDER
ARE LIKELY FRIDAY WITH THE POTENTIAL FOR MODERATE TO LOCALLY HEAVY
RAIN OVER SOUTHEAST WY AND SOUTHERN NE PANHANDLE. COULD SEE BETWEEN
ONE HALF AND ONE INCH QPF IN THESE AREAS. IT WILL BE SLIGHTLY COOLER
FRIDAY WITH HIGHS IN THE MID 40S TO MID 50S.

THE MODELS CONTINUE TO TREND TOWARD AN ACTIVE CONVECTIVE DAY
ON SATURDAY AS THE MAIN UPPER LOW MOVES NORTHEAST OVER THE FOUR
CORNERS. THERE ARE DIFFERENCES WITH RESPECT TO TO THE TRACK AND
STRENGTH OF THE SURFACE LOW. AT NOON SATURDAY...THE GFS PLACES THE
LOW JUST SOUTH OF CHEYENNE WHILE THE ECMWF IS NEAR PUEBLO. IF THE
GFS PANS OUT...THERE WILL BE AN MARGINAL RISK FOR STRONG TO
POSSIBLY SEVERE TSTORMS AS FAR NORTH AS CHEYENNE AND SIDNEY WITH
SBCAPES 500-1000 J/KG...DEW POINTS 40S-LOW 50S AND MODEST 0-6KM
SHEAR. CONVERSELY... THE ECMWF SOLUTION WOULD RESULT IN A MORE
STABLE EASTERLY LOW LEVEL FLOW. BETTER CHANCES FOR STRONG TO
SEVERE TSTORMS APPEAR TO BE OVER NORTHEAST CO CLOSER TO THE
INTERSECTION OF THE SURFACE LOW AND TROUGH. WILL SEE A DECREASE IN
THE SHOWERS SATURDAY MORNING...THEN BECOME WIDESPREAD IN THE
AFTERNOON. HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES WARMER
SATURDAY WITH LOW TO MID 60S FOR THE PLAINS.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 415 AM MDT THU MAY 21 2015

SATURDAY NIGHT...UPPER TROUGH PIVOTS ACROSS SOUTHEAST WYOMING WITH
SOME INDICATIONS OF DRY SLOTTING...THOUGH LOOKS LIKE THERE WILL BE
ENOUGH LOW LEVEL CONVERGENCE AND LOW AND MID LEVEL MOISTURE PRESENT
TO SPARK SCATTERED THUNDERSTORMS...SOME STRONG TO SEVERE IN THE
EVENING...MAINLY EAST OF I-25.

SUNDAY...SCATTERED TO NUMEROUS SHOWER COVERAGE WITH ISOLATED
THUNDERSTORMS WITH ADEQUATE MOISTURE PRESENT AND SYSTEM DYNAMICS
MOVING OVERHEAD.

MONDAY...FLOW ALOFT TURNS MORE WEST...WITH SOME SLOW DRYING.
NEVERTHELESS...STILL ENOUGH MOISTURE AND DYNAMICS TO PRODUCE
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS FROM RAWLINS TO
LARAMIE.

TUESDAY...WEAK RIDGE ALOFT...THOUGH WITH ADEQUATE LOW AND MID LEVEL
MOISTURE...AND A LOW LEVEL CONVERGENCE AXIS EVIDENT AT THE SURFACE...
WILL MAINTAIN SCATTERED AFTERNOON AND EVENING COVERAGE.

WEDNESDAY...NEXT SHORTWAVE TROUGH APPROACHES FROM THE GREAT BASIN
STATES. A COLD FRONT WILL ENTER OUR NORTHERN COUNTIES. AGAIN...LOOKS
LIKE A DAY WITH SCATTERED SHOWERS AND THUNDERSTORMS IN THE AFTERNOON
AND EVENING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1144 AM MDT THU MAY 21 2015

WITH MOIST SOUTH TO SOUTHEASTERLY WINDS IN PLACE...LOW CLOUDS WILL
BE PERSISTENT THROUGH THE AFTERNOON ACROSS THE PLAINS. WILL KEEP
IFR CIGS FOR CYS THROUGH 20Z. BRIEF MVFR CIGS WILL BE POSSIBLE
OVER THE NEBRASKA PANHANDLE...HOWEVER CURRENT THINKING IS IT WILL
BE PREVAILING VFR CIGS. A LARGE AREA OF MOSTLY LIGHT RAIN WILL
MOVE ACROSS THE COLORADO BORDER AND INTO THE REGION BY LATE
TONIGHT AND FRI MORNING. CIGS WILL LOWER WITH THE RAIN AND VIS
WILL BE REDUCED TO MVFR WITHIN POCKETS OF MODERATE RAIN.

&&

.FIRE WEATHER...
ISSUED AT 345 AM MDT THU MAY 21 2015

THE PERSISTENT COOL AND MOIST UPSLOPE PATTERN WILL PRECLUDE FIRE
WEATHER CONCERNS THROUGH THE WEEKEND. BEST CHANCES FOR WIDESPREAD
WETTING RAIN WILL BE TONIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 400 AM MDT THU MAY 21 2015

WATER LEVELS WILL REMAIN HIGH ALONG THE LARAMIE RIVER AT FORT LARAMIE
AND LARAMIE FOR THE NEXT SEVERAL DAYS. FORT LARAMIE IS FORECAST TO
COME WITHIN A TENTH OF A FOOT OF FLOOD STAGE (7 FT) THROUGH THE
WEEKEND. MODERATE TO LOCALLY HEAVY RAIN WILL BE POSSIBLE FOR THE HIGH
PLAINS AND POSSIBLY LARAMIE VALLEY TONIGHT AND FRIDAY...WHICH MAY
RESULT IN FURTHER RISES.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...ZF
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS63 KUNR 211734
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1134 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1107 AM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...POJORLIE




000
FXUS63 KUNR 211734
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1134 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1107 AM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...POJORLIE




000
FXUS63 KUNR 211734
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1134 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1107 AM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...POJORLIE




000
FXUS63 KUNR 211734
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1134 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1107 AM MDT THU MAY 21 2015

RAIN SHOWERS WITH MVFR CIGS WILL PUSH INTO NORTHEAST
WY...SOUTHWEST SD...AND THE BLACK HILLS AREA EARLY FRIDAY MORNING.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...POJORLIE




000
FXUS63 KUNR 211554
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
954 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 524 AM MDT THU MAY 21 2015

PATCHY FOG CAN BE EXPECTED ACROSS THE BLACK HILLS EARLY
THIS MORNING. AREAS OF MVFR CIGS WILL ALSO DRIFT INTO NORTHEAST WY
AND FAR SOUTHWEST SD EARLY THIS MORNING BEFORE DISSIPATING.
OTHERWISE...VFR CONDITIONS WILL CONTINUE ACROSS THE AREA TODAY INTO
TONIGHT.



&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...26



000
FXUS63 KUNR 211554
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
954 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 951 AM MDT THU MAY 21 2015

LATEST OBSERVATIONS SHOW HIGH PRESSURE OVER WESTERN SOUTH DAKOTA
RESULTING IN SUNNY SKIES. SOUTHERLY WINDS HAVE PUSHED AN AREA OF
LOW STRATUS INTO PARTS OF NORTHEASTERN WYOMING...WHICH IS EXPECTED
TO DISSIPATE OVER THE NEXT COUPLE OF HOURS DUE TO INCREASED MIXING
WITH DIURNAL HEATING. FORECAST REMAINS ON TRACK SO NO UPDATES
PLANNED ATTM.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 300 AM MDT THU MAY 21 2015

A RATHER COMPLEX UPPER PATTERN EXISTS WITH A LARGE-SCALE RIDGE
COVERING WRN CANADA BUT WITH A TROUGH UNDERCUTTING IT OVER THE
SWRN CONUS. A DEEP HUDSON BAY LOW WAS ASSOCIATED WITH A MEAN
TROUGH OVER ERN NOAM. THE RESULT OVER THE BLKHLS AREA WAS CON-
FLUENT UPPER FLOW AND SUBSIDENCE...WITH A DEFORMATION ZONE OVER
THE SWRN CWA...AND A SURFACE HIGH OVER WRN NEB THAT WAS ASSOCIATED
WITH SOME FROSTY CONDITIONS OVER SWRN SD/NERN WY. THE INTERPLAY
BETWEEN THE UPPER LOWS OVER THE SWRN CONUS AND HUDSON BAY WILL BE
THE LARGE-SCALE DRIVER OF OUR WEATHER THROUGH AT LEAST EARLY
SATURDAY.

FOR TODAY...THE SFC HIGH WILL MOVE SOUTH WITH RETURN SOUTHEAST SFC
FLOW DEVELOPING. 850-MB TEMPS WILL RISE 4-6C AND WILL HELP TEMPS
RISE BACK INTO THE 60S FOR A CHANGE. THE CONFLUENT UPPER FLOW AND
DEFORMATION ZONE WILL KEEP FAIR SKIES OVER MOST OF THE CWA...EXCEPT
FOR THE SWRN THIRD OR SO. FOR TNGT...SOUTHEAST SFC FLOW CONTINUES
WITH A 1O-KT STRENGTHENING OF THE 850-MB WINDS. A SHORT-WAVE TROUGH
IS PROGGED TO EJECT NORTHEAST ACROSS CO TO NEAR KDEN BY 12Z THU.
MOISTURE AND LIFT WILL REMAIN CONFINED MOSTLY TO THE SOUTHWEST OF
THE CWA THROUGH 12Z. 850-MB TEMPS OF 8-10C AND BOUNDARY LAYER FLOW
SHOULD PRECLUDE ADDITIONAL FROST.

FOR FRIDAY...THE SHORT-WAVE TROUGH WILL PROGRESS SLOWLY ACROSS THE
NEB PANHANDLE...BEING SLOWED BY THE UPPER-LEVEL CONFLUENT ZONE. A
NARROW ZONE OF MOISTURE/LIFT WILL FAVOR THE HIGHEST POPS ACROSS THE
SRN CWA...AND THIS WILL STRUGGLE TO MAKE IT NORTH AGAINST THE DRY
AIR AND DEFORMATION ZONE. CAPE AND INSTABILITY PROGS ARE QUITE
MEAGER...SO HAVE CUT BACK ON THE THUNDER POTENTIAL FOR FRIDAY. ON
FRIDAY NIGHT...THE SHORT-WAVE TROUGH SHOULD PROGRESS ACROSS THE
CWA. SOME ISENTROPIC LIFT AT LOW-LEVELS IS NOTED...BUT THE WAVE
WILL ENCOUNTER DRY AIR TO THE NORTH...SO HAVE TRIMMED BACK POPS
FROM THE PREVIOUS FORECAST. CAPE ALSO IS MINIMAL...THUS HAVE CUT
BACK ON COVERAGE OF THUNDER.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 300 AM MDT THU MAY 21 2015

MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT ON UNSETTLED WEATHER
THROUGH THE HOLIDAY WEEKEND AS UPPER-LEVEL SYSTEM SLOWLY TRACKS
ACROSS THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS. HOWEVER...THE
VARIOUS MODELS STILL DIFFER ON SPECIFICS SUCH AS TIMING AND
COVERAGE OF BEST PCPN CHANCES SATURDAY AND SUNDAY. MAJORITY OF 00Z
MODELS LEANING MORE TOWARD THE LATE AFTERNOON AND NIGHTTIME HOURS
FOR ANY HEAVIER AND MORE WIDESPREAD RAINFALL ON SATURDAY...WITH
THE BEST INSTABILITY OVER FAR SOUTHERN PORTIONS OF THE CWA DURING
THE AFTERNOON AND EVENING. THIS WOULD LIKELY LIMIT THE THREAT FOR
ANY STRONGER STORMS TO MOSTLY AREAS SOUTHEAST OF THE BLACK
HILLS...AND ESPECIALLY OVER NEB...AS SOUTHERLY LOW-LEVEL JET
INTENSIFIES THERE IN THE EVENING. THE THREAT FOR HEAVY RAINFALL
LOOKS MORE LOCALIZED AT THIS POINT...MOSTLY TO THE EAST OF THE
BLACK HILLS. SUNDAY LOOKS SIMILAR WITH REGARD TO ANY THREAT FOR
STRONGER STORMS. AS THE UPPER LOW MOVES INTO THE NORTHERN HIGH
PLAINS ON SUNDAY...THE BETTER COVERAGE FOR RAINFALL WOULD MOST
LIKELY SHIFT TO NORTHERN PORTIONS OF THE CWA.

AS THE SYSTEM WEAKENS AND EXITS THE AREA SUNDAY NIGHT INTO
MONDAY...WEST-SOUTHWEST FLOW ALOFT WILL BRING WEAKER DISTURBANCES
ACROSS THE AREA EARLY NEXT WEEK...WITH ISOLATED TO SCATTERED SHOWER
AND THUNDERSTORM ACTIVITY EXPECTED MONDAY THROUGH WEDNESDAY.
TEMPERATURES WILL CONTINUE TO BE BELOW AVERAGE OVER THE WEEKEND...
WITH A GRADUAL WARMING TREND TO NEAR AVERAGE TEMPERATURES BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 524 AM MDT THU MAY 21 2015

PATCHY FOG CAN BE EXPECTED ACROSS THE BLACK HILLS EARLY
THIS MORNING. AREAS OF MVFR CIGS WILL ALSO DRIFT INTO NORTHEAST WY
AND FAR SOUTHWEST SD EARLY THIS MORNING BEFORE DISSIPATING.
OTHERWISE...VFR CONDITIONS WILL CONTINUE ACROSS THE AREA TODAY INTO
TONIGHT.



&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

UPDATE...10
SHORT TERM...BUNKERS
LONG TERM...26
AVIATION...26




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