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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 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 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 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
FXUS65 KCYS 211208
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
608 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116>118.

NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ





000
FXUS65 KCYS 211208
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
608 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116>118.

NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS65 KCYS 211208
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
608 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116>118.

NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS65 KCYS 211208
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
608 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116>118.

NE...NONE.
&&

$$

UPDATE...MAJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ





000
FXUS65 KCYS 211147
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
547 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116-117.

NE...NONE.
&&

$$

UPDATE...MJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ





000
FXUS65 KCYS 211147
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
547 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116-117.

NE...NONE.
&&

$$

UPDATE...MJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ





000
FXUS65 KCYS 211147
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
547 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116-117.

NE...NONE.
&&

$$

UPDATE...MJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS65 KCYS 211147
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
547 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.


&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116-117.

NE...NONE.
&&

$$

UPDATE...MJ
SHORT TERM...MAJ
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...MAJ
HYDROLOGY...MAJ




000
FXUS65 KCYS 211055
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.

&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

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




000
FXUS65 KCYS 211055
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.

&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

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





000
FXUS65 KCYS 211055
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT THU MAY 21 2015

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.

&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

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




000
FXUS65 KCYS 211051
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT THU MAY 21 2015

.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 PACIFIC NORTHWEST. 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. 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.

&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

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





000
FXUS65 KCYS 211051
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT THU MAY 21 2015

.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 PACIFIC NORTHWEST. 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. 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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG AND
LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND 4000
FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED TO
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING VISIBILITIES
4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE PREDAWN
HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS PREVAILS
FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH CEILINGS
FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN AT SIDNEY
THURSDAY EVENING.

&&

.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...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

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




000
FXUS65 KCYS 210650
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1250 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG
AND LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND
4000 FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED
TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING
VISIBILITIES 4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE
PRE DAWN HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS
PREVAILS FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH
CEILINGS FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN
AT SIDNEY THURSDAY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...RUBIN
FIRE WEATHER...ZF
HYDROLOGY...ZF





000
FXUS65 KCYS 210650
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1250 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG
AND LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND
4000 FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED
TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING
VISIBILITIES 4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE
PRE DAWN HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS
PREVAILS FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH
CEILINGS FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN
AT SIDNEY THURSDAY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...RUBIN
FIRE WEATHER...ZF
HYDROLOGY...ZF




000
FXUS65 KCYS 210650
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1250 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG
AND LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND
4000 FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED
TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING
VISIBILITIES 4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE
PRE DAWN HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS
PREVAILS FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH
CEILINGS FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN
AT SIDNEY THURSDAY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...RUBIN
FIRE WEATHER...ZF
HYDROLOGY...ZF





000
FXUS65 KCYS 210650
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1250 AM MDT THU MAY 21 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1246 AM MDT THU MAY 21 2015

WYOMING TAFS...MOUNTAINS MOSTLY OBSCURED. IFR PREVAILS IN FOG
AND LOW CLOUDS THROUGH MID MORNING...THEN VFR WITH CEILINGS AROUND
4000 FEET AGL. IN THE LATE AFTERNOON AND EARLY EVENING...ISOLATED
TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCING
VISIBILITIES 4 TO 6 MILES WITH OCCASIONAL MVFR CEILINGS.

NEBRASKA TAFS...VFR AND OCCASIONAL MVFR PREVAIL THROUGH THE
PRE DAWN HOURS...EXCEPT AT SIDNEY WHERE IFR IN FOG AND LOW CLOUDS
PREVAILS FROM 10Z TO 15Z. AFTER MID MORNING...VFR PREVAILS WITH
CEILINGS FROM 3000 TO 5000 FEET AGL...THEN MVFR DEVELOPS AGAIN
AT SIDNEY THURSDAY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THIS MORNING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...RUBIN
FIRE WEATHER...ZF
HYDROLOGY...ZF




000
FXUS65 KCYS 210313 AAB
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
913 PM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...ZF
HYDROLOGY...ZF





000
FXUS65 KCYS 210313 AAB
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
913 PM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...ZF
HYDROLOGY...ZF




000
FXUS65 KCYS 210313 AAB
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
913 PM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 913 PM MDT WED MAY 20 2015

NO MAJOR CHANGES FOR THE EVENING UPDATE. MOST OF THE LIGHT SHOWER
ACTIVITY FROM LATE AFTERNOON EARLY EVENING HAS DISSIPATED WITH THE
EXCEPTION OF SOME LIGHT TO MODERATE SHOWERS PERSISTING IN
SOUTHWESTERN CARBON COUNTY WY. AREAS OF DENSE FOG HAVE REDEVELOPED
OVER THE SUMMIT BETWEEN CHEYENNE AND LARAMIE...AND WILL CONTINUE
THE DENSE FOG ADVISORY THROUGH THURSDAY MORNING FOR THAT PART OF
THE SOUTH LARAMIE RANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...JG
SHORT TERM...ZF
LONG TERM...REC
AVIATION...JG
FIRE WEATHER...ZF
HYDROLOGY...ZF





000
FXUS65 KCYS 210016 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
616 PM MDT WED MAY 20 2015

.UPDATE...FOR 00Z AVIATION FORECAST RELEASE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

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




000
FXUS65 KCYS 210016 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
616 PM MDT WED MAY 20 2015

.UPDATE...FOR 00Z AVIATION FORECAST RELEASE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

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





000
FXUS65 KCYS 210016 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
616 PM MDT WED MAY 20 2015

.UPDATE...FOR 00Z AVIATION FORECAST RELEASE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 616 PM MDT WED MAY 20 2015

STARTING TO SEE CEILINGS LIFT TO VFR FLIGHT CATEGORY AT
CHADRON...SCOTTSBLUFF AND ALLIANCE WITH SIDNEY STILL IN MVFR A BIT
LONGER THROUGH 03Z. UPSLOPE FLOW AT CHEYENNE AND LARAMIE WILL
RESULT IN PROLONGED MVFR CEILINGS AROUND 1500 FT AGL THROUGH 03Z
THEN WE DROP THE CEILINGS TO IFR OR BELOW 1000 FT AGL AS UPSLOPE
FLOW STRENGTHENS A BIT OVERNIGHT...AND WE ALSO BRING IN SOME LIGHT
FOG FOR THOSE SITES TOWARD MORNING. A BIT MORE DRIER AIR WORKING
INTO RAWLINS AND THEY SHOULD STAY VFR THROUGH THE FORECAST PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL 10 AM MDT THURSDAY FOR WYZ116.

NE...NONE.
&&

$$

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





000
FXUS65 KCYS 202133
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
333 PM MDT WED MAY 20 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

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

$$

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




000
FXUS65 KCYS 202133
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
333 PM MDT WED MAY 20 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 243 PM MDT WED MAY 20 2015

SFC ANALYSIS SHOWS THE HIGH PRESSURE CENTER LOCATED NEAR THE PINE
RIDGE WITH EAST TO NORTHEAST UPSLOPE AND PERSISTENT LOW CLOUDS
ACROSS THE REGION.  IT HAS BEEN ANOTHER COOL DAY WITH TEMPS A GOOD
20 DEGREES BELOW NORMAL.  EXPIRED THE DENSE FOG ADVISORY FOR THE
SOUTH LARAMIE RANGE WITH WYDOT OBS SHOWING MOST VIS ABOVE 1 MILE.
THE HRRR DOES INDICATE VIS DROPPING BELOW ONE HALF MILE OVER THE
SOUTH LARAMIE RANGE BY 03Z.  THIS MAKES SENSE WITH SFC WINDS
REMAINING SOUTHEAST TO SOUTH OVERNIGHT.  HAVE AREAS OF FOG FROM
BUFORD TO THE SUMMIT BY EARLY TONIGHT AND CONTINUING THROUGH
THURSDAY MORING. WILL LET THE EVENING/NIGHT SHIFT MONITOR THE OBS
AND WEBCAMS OVER THE SUMMIT...AS DENSE FOG IS DEFINITELY POSSIBLE IN
THIS PATTERN.  SHOWERS DEVELOPING THIS AFTN ALONG AND WEST OF THE
LARAMIE RANGE HAVE BEEN STRUGGLING TO STAY TOGETHER IN THE VERY
STABLE AIRMASS OVER THE PLAINS.  KEPT ISOLATED TO SCATTERED SHOWERS
CONFINED TO MAINLY THE LARAMIE RANGE AND POINTS WEST THROUGH THE
EVENING.

PATTERN DOES NOT CHANGE A WHOLE LOT BY THURSDAY.  LOW CLOUDS WILL BE
STUBBORN TO CLEAR YET AGAIN WITH MOIST SOUTHEAST LLVL FLOW.
SLIGHTLY BETTER INSTABILITY WILL EXIST ALONG THE LARAMIE RANGE (CAPE
VALUES OF 100-200 J/KG) BUT THIS IS LARGELY DEPENDENT ON SOME AFTN
CLEARING...WHICH IS QUESTIONABLE.  INSTABILITY REALLY DROPS OFF TO
THE EAST OF CHEYENNE SO EXPECTING STORMS TO REMAIN CONFINED IN
VICINITY OF THE LARAMIE RANGE.  A SHORTWAVE WILL EJECT NORTHWARD
FROM COLORADO BY LATE THURS NIGHT AND FRI MORNING.  WITH GOOD UPPER
LEVEL DIFLUENCE...MODELS HAVE BEEN CONSISTENT AT SHOWING WIDESPREAD
RAIN DEVELOPING OVER THE PLAINS BY FRI MORNING AND CONTINUING
THROUGH MUCH OF THE DAY.  THIS IS LOOKING LIKE ANOTHER 0.25-0.75
INCH MAINLY STRATIFORM RAIN EVENT FOR LOCATIONS TO THE EAST OF THE
LARAMIE RANGE.  DID LOWER HIGHS A FEW DEGREES ON FRI WITH HIGHS
STRUGGLING TO GET ABOVE THE MID 50S.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 243 PM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE SEVERE
WEATHER POTENTIAL SATURDAY.

SATURDAY-SATURDAY NIGHT:
LATEST LOOK AT THE GEM/GEFS ENSEMBLES AND ECMWF ARE SHOWING
REALLY GOOD AGREEMENT IN THE TRACK OF THE UPPER LEVEL TROF THIS
WEEKEND. THE MODELS ARE ALSO IN AGREEMENT IN SHOWING THIS CLOSED
UPPER TROF OPENING UP IN NORTHWEST COLORADO AND SENDING ITS FIRST
PIECE OF ENERGY INTO OUR REGION SATURDAY. HOWEVER...THERE IS QUITE
A BIT OF STANDARD DEVIATION IN THE PLACEMENT OF THE SURFACE LOW
AROUND 00Z SUNDAY. THE MEAN ENSEMBLES ARE SHOWING THE SURFACE LOW
DEVELOPING IN EASTERN COLORADO. HOWEVER...THERE IS SOME HINTS THAT
THIS SURFACE LOW MAY ACTUALLY DEVELOP FURTHER NORTH IN NORTHEAST
COLORADO AND LIFT NORTHEAST THROUGH THE NEBRASKA PANHANDLE. IF
THIS SURFACE LOW DEVELOPS FURTHER NORTH...WE MAY SEE WARMER
TEMPERATURES AND HIGHER LOW LEVEL MOISTURE BEING DRAWN INTO AREAS
EAST OF THE LARAMIE WHICH WILL RESULT IN HIGHER INSTABILITY. THIS
COULD SET THE STAGE FOR SEVERE WEATHER IN AREAS EAST OF THE
LARAMIE RANGE SATURDAY AFTN/EVE...ESPECIALLY WITH 0-6KM SHEAR
VALUES APPROACHING 40 TO 50 KTS. ANOTHER CONCERN IS WHETHER OR NOT
WE WILL SEE LOW CLOUDS. AT THIS POINT...IT DOES NOT APPEAR THAT
THE LOW CLOUDS WILL BE PRESENT...BUT WE WILL HAVE TO SEE HOW THAT
EVOLVES. IF THE LOW CLOUDS ARE NOT PRESENT...TEMPERATURES SHOULD
BE ABLE TO CLIMB TO THE 60S.

SUNDAY-SUNDAY NIGHT:
THE MODELS ARE SHOWING THE MAIN UPPER LEVEL TROF MOVING INTO THE
AREA ON SUNDAY IN ITS WEAKENED STATE. THERE IS A LITTLE MORE
UNCERTAINTY ON HOW THIS TROF WILL IMPACT THE AREA ON SUNDAY
AFTERNOON INTO SUNDAY EVENING. AT THIS POINT...IT APPEARS LIKE THE
MAIN CONVECTION SHOW WILL BE ON SATURDAY AFTERNOON/EVENING.
HOWEVER...IF WE DO NOT SEE MANY STORMS DURING THAT TIME...THEN
SUNDAY MAY BE A DAY TO WATCH AS WELL. IF WE DO SEE WIDESPREAD
CONVECTION ON SATURDAY THEN SUNDAY CHANCES MAY BE MUCH SMALLER.
FOR NOW...WE WILL STAY WITH THE MODEL BLENDS FOR CONSISTENCY SAKE.

MONDAY-WEDNESDAY:
MODELS/ENSEMBLES ARE IN PRETTY GOOD AGREEMENT IN SHOWING THE UPPER
LEVEL RIDGE BUILDING OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL
TROF MOVING INTO THE NORTHERN ROCKIES. THIS TROF WILL INDUCE UPPER
LEVEL DIFFLUENCE OVER THE AREA ON MONDAY AND TUESDAY WHICH COULD
SPARK SOME CONVECTION OVER THE MOUNTAINS WITH SOME OF THIS
CONVECTION POSSIBLY SPILLING OVER INTO THE PLAINS. OVERALL...IT
DOES NOT LOOK LIKE A REAL WET PATTERN...BUT WE CANNOT RULE OUT THE
AFTERNOON AND EVENING CONVECTION CHANCES OVER OUR AREA EITHER.
ALTHOUGH...TEMPERATURES WILL NOT BE TOO COOL WITH HIGHS CLIMBING
TO NEAR NORMAL READING WITH HIGHS MAINLY IN THE 60S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 243 PM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  TEMPERATURES WILL
REMAIN BELOW NORMAL AND AFTERNOON HUMIDITY VALUES WILL BE ABOVE 50
PERCENT.  THE BEST CHANCE OF WIDESPREAD WETTING RAIN WILL COME
THURSDAY NIGHT AND FRIDAY.

&&

.HYDROLOGY...
ISSUED AT 243 PM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE AND LARAMIE WILL CONTINUE TO RUN AT
RELATIVELY HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS
EXPECTED TO REMAIN WITHIN ITS BANKS. ANOTHER ROUND OF MODERATE TO
HEAVY RAINFALL IS EXPECTED OVER THE HIGH PLAINS AND POSSIBLY THE
LARAMIE VALLEY ON FRIDAY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK.

&&

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

$$

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





000
FXUS65 KCYS 201755
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1155 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 1059 AM MDT WED MAY 20 2015

LOWERED HIGHS FOR TODAY MAINLY FROM LARAMIE TO CHEYENNE AS LOW
CLOUDS WILL BE QUITE PERSISTENT INTO THE AFTERNOON. THE HRRR DOES
SHOW VIS IMPROVING OVER THE SOUTHERN LARAMIE RANGE AND THE
ARLINGTON AREA AFTER 18Z...AND WYDOT VIS IS SLOWLY STARTING TO
COME UP. DENSE FOG ADVISORY WILL PROBABLY BE EXPIRED AT NOON...BUT
WILL MONITOR OVER THE NEXT HOUR. WITH A STABLE AIRMASS OVER THE
PLAINS...SHOWERS AND AN ISOLATED TSTM WILL MAINLY BE CONFINED TO
THE SNOWY RANGE WESTWARD.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...REC
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 201755
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1155 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 1059 AM MDT WED MAY 20 2015

LOWERED HIGHS FOR TODAY MAINLY FROM LARAMIE TO CHEYENNE AS LOW
CLOUDS WILL BE QUITE PERSISTENT INTO THE AFTERNOON. THE HRRR DOES
SHOW VIS IMPROVING OVER THE SOUTHERN LARAMIE RANGE AND THE
ARLINGTON AREA AFTER 18Z...AND WYDOT VIS IS SLOWLY STARTING TO
COME UP. DENSE FOG ADVISORY WILL PROBABLY BE EXPIRED AT NOON...BUT
WILL MONITOR OVER THE NEXT HOUR. WITH A STABLE AIRMASS OVER THE
PLAINS...SHOWERS AND AN ISOLATED TSTM WILL MAINLY BE CONFINED TO
THE SNOWY RANGE WESTWARD.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...REC
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 201755
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1155 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 1059 AM MDT WED MAY 20 2015

LOWERED HIGHS FOR TODAY MAINLY FROM LARAMIE TO CHEYENNE AS LOW
CLOUDS WILL BE QUITE PERSISTENT INTO THE AFTERNOON. THE HRRR DOES
SHOW VIS IMPROVING OVER THE SOUTHERN LARAMIE RANGE AND THE
ARLINGTON AREA AFTER 18Z...AND WYDOT VIS IS SLOWLY STARTING TO
COME UP. DENSE FOG ADVISORY WILL PROBABLY BE EXPIRED AT NOON...BUT
WILL MONITOR OVER THE NEXT HOUR. WITH A STABLE AIRMASS OVER THE
PLAINS...SHOWERS AND AN ISOLATED TSTM WILL MAINLY BE CONFINED TO
THE SNOWY RANGE WESTWARD.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...REC
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 201755
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1155 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 1059 AM MDT WED MAY 20 2015

LOWERED HIGHS FOR TODAY MAINLY FROM LARAMIE TO CHEYENNE AS LOW
CLOUDS WILL BE QUITE PERSISTENT INTO THE AFTERNOON. THE HRRR DOES
SHOW VIS IMPROVING OVER THE SOUTHERN LARAMIE RANGE AND THE
ARLINGTON AREA AFTER 18Z...AND WYDOT VIS IS SLOWLY STARTING TO
COME UP. DENSE FOG ADVISORY WILL PROBABLY BE EXPIRED AT NOON...BUT
WILL MONITOR OVER THE NEXT HOUR. WITH A STABLE AIRMASS OVER THE
PLAINS...SHOWERS AND AN ISOLATED TSTM WILL MAINLY BE CONFINED TO
THE SNOWY RANGE WESTWARD.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1059 AM MDT WED MAY 20 2015

THE MAIN CONCERN WITH THIS TAF ISSUANCE IS THE TIMING OF WHEN THE
IFR/MVFR CEILINGS WILL BEGIN TO CLEAR OUT.

LATEST SURFACE ANALYSIS WAS SHOWING COLD AIR DAMMING PERSISTING ALONG
THE LEE SIDE OF THE LARAMIE RANGE AROUND LUNCHTIME. THE MODELS ARE
CURRENTLY TOO FAST IN MOVING THIS CANADIAN SURFACE HIGH EAST THIS
AFTERNOON. AS A RESULT...WE ARE EXPECTING THE LOW CEILINGS TO
HANG ON TO MUCH OF THE AREA THIS AFTERNOON. THE LOWEST CEILINGS
ARE AROUND CYS (AROUND 800FT) AND POINTS WEST TO THE I-80 SUMMIT
WHERE THEY ARE STILL EXPERIENCING DENSE FOG. THIS SURFACE HIGH
SHOULD GRADUALLY SHIFT EAST LATE THIS AFTERNOON INTO THIS EVENING.
HOWEVER...WE ARE NOT CONFIDENT THAT CYS CEILINGS WILL CLIMB VERY
MUCH DUE TO THE EASTERLY FLOW KICKING IN. WE ARE LITTLE MORE
CONFIDENT THAT THE LOWER CEILINGS SHOULD BEGIN TO SCOUR OUT FROM
NORTH TO SOUTH ACROSS THE PANHANDLE SITES LATE THIS AFTERNOON
BASED ON THE LATEST SATELLITE TRENDS. HOWEVER...THERE IS A
POSSIBILITY THAT SOME PATCHY FOG COULD DEVELOP IN ITS WAKE.
OTHERWISE...WEAK ISENTROPIC ASCENT WILL BRING SOME VFR CEILINGS
INTO THE AREA AFTER MIDNIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...REC
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 201340
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
740 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 735 AM MDT WED MAY 20 2015

LATEST LOOK AT THE WEB CAMS AND OBS WERE SHOWING THE VISIBILITY
BELOW A QUARTER OF A MILE BETWEEN MILE MARKERS 262 AND 280 AND
BETWEEN VEDAUWOO AND BUFORD ON INTERSTATE 80. DO NOT SEE THESE
AREAS CLEARING OUT VERY QUICKLY THIS MORNING DUE TO THE INFLUENCE
OF THE CANADIAN HIGH IN THE NEBRASKA PANHANDLE. AS A RESULT...WE
ARE GOING TO ISSUE A DENSE FOG ADVISORY FOR THESE AREAS THROUGH
NOON.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 340 AM MDT WED MAY 20 2015

WIDESPREAD IFR TO MVFR DUE TO LOW CIGS ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA PANHANDLE. VERY LITTLE IMPROVEMENT IN POOR
AVIATION CONDITIONS THROUGH WEDNESDAY AFTERNOON AS EASTERLY
UPSLOPE WINDS CONTINUE TO PRODUCE LOW CIGS AND EVEN SOME FOG. ANY
IMPROVEMENT TO IFR EAST OF THE LARAMIE RANGE TODAY WILL LIKELY
GIVE WAY TO LOWER CIGS AGAIN TONIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...REC
SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 201340
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
740 AM MDT WED MAY 20 2015

.UPDATE...
ISSUED AT 735 AM MDT WED MAY 20 2015

LATEST LOOK AT THE WEB CAMS AND OBS WERE SHOWING THE VISIBILITY
BELOW A QUARTER OF A MILE BETWEEN MILE MARKERS 262 AND 280 AND
BETWEEN VEDAUWOO AND BUFORD ON INTERSTATE 80. DO NOT SEE THESE
AREAS CLEARING OUT VERY QUICKLY THIS MORNING DUE TO THE INFLUENCE
OF THE CANADIAN HIGH IN THE NEBRASKA PANHANDLE. AS A RESULT...WE
ARE GOING TO ISSUE A DENSE FOG ADVISORY FOR THESE AREAS THROUGH
NOON.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 340 AM MDT WED MAY 20 2015

WIDESPREAD IFR TO MVFR DUE TO LOW CIGS ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA PANHANDLE. VERY LITTLE IMPROVEMENT IN POOR
AVIATION CONDITIONS THROUGH WEDNESDAY AFTERNOON AS EASTERLY
UPSLOPE WINDS CONTINUE TO PRODUCE LOW CIGS AND EVEN SOME FOG. ANY
IMPROVEMENT TO IFR EAST OF THE LARAMIE RANGE TODAY WILL LIKELY
GIVE WAY TO LOWER CIGS AGAIN TONIGHT.


&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...DENSE FOG ADVISORY UNTIL NOON MDT TODAY FOR WYZ110-116.

NE...NONE.
&&

$$

UPDATE...REC
SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 201010
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
410 AM MDT WED MAY 20 2015

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 340 AM MDT WED MAY 20 2015

WIDESPREAD IFR TO MVFR DUE TO LOW CIGS ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA PANHANDLE. VERY LITTLE IMPROVEMENT IN POOR
AVIATION CONDITIONS THROUGH WEDNESDAY AFTERNOON AS EASTERLY
UPSLOPE WINDS CONTINUE TO PRODUCE LOW CIGS AND EVEN SOME FOG. ANY
IMPROVEMENT TO IFR EAST OF THE LARAMIE RANGE TODAY WILL LIKELY
GIVE WAY TO LOWER CIGS AGAIN TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

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

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 201010
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
410 AM MDT WED MAY 20 2015

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 346 AM MDT WED MAY 20 2015

THE PACIFIC STORM SYSTEM WHICH BROUGHT RAIN AND EVEN SOME SNOW TO
THE REGION YESTERDAY IS CURRENTLY WEAKENING AND MOVING EASTWARD
OVER THE NORTHERN PLAINS THIS MORNING. THERE IS STILL SOME LIGHT
SNOW BEING REPORTED ACROSS PORTIONS OF FAR EASTERN WYOMING AND
WESTERN NEBRASKA...BUT ACCUMULATIONS HAVE BEEN MINIMAL. OF MORE
SIGNIFICANCE IS THE FREEZING DRIZZLE NEAR THE RIDGE TOPS AND ALONG
THE LARAMIE RANGE...WITH CHEYENNE REPORTING FREEZING DRIZZLE
THROUGH MOST OF THE NIGHT. THERE HAVE BEEN A FEW REPORTS OF BLACK
ICE ON THE ROADWAYS...BUT SO FAR IT HAS BEEN RELATIVELY ISOLATED
WITH MAINLY JUST WET ROADWAYS. WILL CONTINUE TO KEEP AN EYE ON
THIS AS TEMPERATURES CONTINUE TO LOWER THROUGH THE UPPER 20S EARLY
THIS MORNING. HIGH TEMPERATURES TODAY WILL STRUGGLE TO REACH THE
MID TO UPPER 40S DUE TO A PERSISTENT LOW CLOUD DECK AND EVEN SOME
PATCHY FOG/DRIZZLE ALONG THE SOUTH FACING RIDGES.
EVENTUALLY...WINDS WILL SHIFT INTO THE EAST TO NORTHEAST TODAY
WITH CLOUD CEILINGS INCREASING A BIT BY THE AFTERNOON. NOT MUCH
SUN TODAY...WITH VALLEY LOCATIONS WEST OF THE LARAMIE RANGE HAVING
THE BEST CHANCE TO SEE SOME SUNSHINE. WITH SO MUCH MOISTURE AND
NEARLY SATURATED LOW TO MIDLEVELS...IT WILL NOT TAKE MUCH
INSTABILITY TO GENERATE SOME LIGHT SHOWERS. KEPT POP BETWEEN 20 TO
40 PERCENT FOR NOW...WITH SHOWERS LIKELY IN THE MOUNTAINS.

TONIGHT WILL BE MORE OF THE SAME...BUT WITH LESS CLOUD COVER OVER
THE NORTHERN AND WESTERN PORTION OF THE FORECAST AREA. MODELS SHOW
WINDS SHIFTING BACK INTO THE SOUTH OR SOUTHEAST...RESULTING IN
ANOTHER ROUND OF FOG AND/OR DRIZZLE FOR THE CHEYENNE AND PINE
RIDGE...ALONG WITH THE EASTERN FOOTHILLS OF THE LARAMIE RANGE. DO
NOT EXPECT THIS STRATUS DECK TO MAKE IT WEST OF THE LARAMIE
RANGE...SO LARAMIE AND RAWLINS MAY JUST BE PARTLY CLOUDY TONIGHT
BUT RELATIVELY COLD. MAY NEED A FROST OR FREEZE ADVISORY FOR
PORTIONS OF THE NORTHERN NEBRASKA PANHANDLE AS LOW TEMPERATURES
ARE PROGGED TO BE NEAR OR JUST BELOW FREEZING AT CHADRON AND
ALLIANCE...WHICH IS OVER ONE WEEK PAST THE AVERAGE LAST FREEZE.
IT IS UNCLEAR HOW MUCH CLOUDINESS WILL BE PRESENT IN THESE
AREAS...SO WILL HOLD OFF ON ANY HEADLINES FOR NOW.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO LOW 60S. THERE
SHOULD BE A BREAK IN THE PRECIPITATION ACROSS THE AREA DUE TO THE
MIDLEVEL SUBSIDENCE ASSOCIATED WITH THE RIDGE ALOFT. THE BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED HOWEVER...AS ALL MODELS
INDICATE ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND ISOLATED TSTORMS
LATE ON THURSDAY AND INTO THURSDAY EVENING. WILL HAVE TO WATCH THE
NEXT SIGNIFICANT SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE
SOUTHWEST LATE THURSDAY AND INTO FRIDAY. MODELS SHOW THIS
SHORTWAVE MOVING ACROSS COLORADO AND WYOMING EARLY ON FRIDAY
BRINGING ANOTHER ROUND OF RAINFALL AND MOUNTAIN SNOWS DUE TO A
LARGE AREA OF UPPER LEVEL DIFFLUENCE. SNOWLEVELS SHOULD BE
BETWEEN 7500 TO 8500 FEET THIS TIME AROUND...SO DO NOT EXPECT ANY
SNOW FLAKES OVER THE HIGH PLAINS AT THIS TIME. THIS SYSTEM HAS A
BETTER CHANCE TO CONTAIN HEAVIER RAIN SHOWERS COMPARED TO
YESTERDAYS SYSTEM...MAINLY BECAUSE OF THE CONDITIONAL INSTABILITY
ALOFT SHOWN BY MODEL SOUNDINGS. AFTER THE MAIN AREA OF
PRECIPITATION...EXPECT PARTIAL CLEARING SKIES FRIDAY AFTERNOON.
WITH THE COLD POOL ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH
OVERHEAD...IT WILL NOT TAKE MUCH TO TRIGGER SCATTERED SHOWERS AND
TSTORMS LATE IN THE AFTERNOON EVEN AFTER THE TROUGH MOVES
NORTHWARD...WHICH IS TYPICAL THIS TIME OF THE YEAR. CONTINUED
INCREASING POP BETWEEN 60 TO 80 PERCENT...ESPECIALLY ALONG AND
EAST OF THE LARAMIE RANGE.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM MDT WED MAY 20 2015

ACTIVITY WEATHER PATTERN TO REMAIN IN PLACE THROUGH THE LONG TERM
FORECAST PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL EXIST
EVERY DAY AS COOL UNSTABLE AIR ALOFT REMAINS IN PLACE ALONG WITH
SEVERAL DISTURBANCES WHICH WILL MOVE ACROSS THE FORECAST AREA
INTO EARLY NEXT WEEK. DIFFICULT TO PINPOINT THE BEST CHANCES FOR
PRECIPITATION GIVEN THE FACT IT IS TOUGH FOR THE MODELS TO RESOLVE
A NEARLY CONTINUOUS STREAM OF UPPER DISTURBANCES...BUT SAFE TO
SAY AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE COMMON DUE TO
DIURNAL HEATING PRODUCING INSTABILITY MANY DAYS. NOT OVERLY
CONCERNED ABOUT SEVERE THUNDERSTORMS THROUGH THE PERIOD BUT IF
THERE IS A DAY TO WATCH IT IS SATURDAY. AT THIS TIME IT LOOKS AT
THROUGH THE BOUNDARY LAYER MAY STAY CAPPED WHILE A DISTURBANCE
MOVES ACROSS THE AREA EARLY IN THE DAY...BUT ELEVATED CONVECTION
MAY BE POSSIBLE TOO. SOMETHING TO KEEP AN EYE ON THE NEXT FEW
DAYS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 340 AM MDT WED MAY 20 2015

WIDESPREAD IFR TO MVFR DUE TO LOW CIGS ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA PANHANDLE. VERY LITTLE IMPROVEMENT IN POOR
AVIATION CONDITIONS THROUGH WEDNESDAY AFTERNOON AS EASTERLY
UPSLOPE WINDS CONTINUE TO PRODUCE LOW CIGS AND EVEN SOME FOG. ANY
IMPROVEMENT TO IFR EAST OF THE LARAMIE RANGE TODAY WILL LIKELY
GIVE WAY TO LOWER CIGS AGAIN TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 246 AM MDT WED MAY 20 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY
COOL TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW
IS EXPECTED OVER THE MOUNTAINS EARLY TODAY AND ON FRIDAY. DAYTIME
RELATIVE HUMIDITIES ACROSS THE HIGH VALLEYS AND HIGH PLAINS WILL
LIKELY NOT LOWER BELOW 50 PERCENT UNTIL EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 246 AM MDT WED MAY 20 2015

LARAMIE RIVER AT FORT LARAMIE WILL CONTINUE TO RUN AT RELATIVELY
HIGH LEVELS THROUGH THIS WEEK...BUT AT THIS TIME IS EXPECTED TO
REMAIN WITHIN ITS BANKS. THE PACIFIC STORM SYSTEM WHICH PUSHED
ACROSS THE REGION YESTERDAY DID NOT IMPACT RIVER LEVELS TOO MUCH
ACROSS THE AREA. HOWEVER...ANOTHER PACIFIC SYSTEM ON FRIDAY MAY
BRING MODERATE TO HEAVY RAINFALL AMOUNTS TO THE HIGH PLAINS AND
POSSIBLY THE LARAMIE VALLEY...SO WILL NEED TO CONTINUE TO MONITOR
THE LARAMIE RIVER THROUGH LATE THIS WEEK. THE LARAMIE RIVER AT
LARAMIE IS FORECAST TO FALL BELOW ACTION STAGE THIS WEEKEND OR
EARLY NEXT WEEK.

&&

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

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 200550
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1141 PM MDT TUE MAY 19 2015

LIGHT SNOW SHOWERS WILL LINGER OVER FAR SOUTHEAST WYOMING AND THE
NEBRAKSA PANHANDLE TONIGHT WITH FOG AND MIST DEVELOPING AS THE
SNOW ENDS. WIDESPREAD IFR DUE TO LOW CIGS ALONG AND WEST OF THE
LARAMIE RANGE. WEST OF THE LARAMIE RANGE MAINLY MVFR WITH LOCALLY
IFR. VERY LITTLE IMPROVEMENT IN POOR AVIATION CONDITIONS THROUGH
WEDNESDAY AFTERNOON EASTERLY UPSLOPE WINDS CONTINUE TO PRODUCE LOW
CIGS AND EVEN SOME FOG. DENSE FOG MAY OCCUR ALONG THE LARAMIE
RANGE THROUGH MUCH OF WEDNESDAY AND INTO WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...SML
FIRE WEATHER...ZF





000
FXUS65 KCYS 200550
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1141 PM MDT TUE MAY 19 2015

LIGHT SNOW SHOWERS WILL LINGER OVER FAR SOUTHEAST WYOMING AND THE
NEBRAKSA PANHANDLE TONIGHT WITH FOG AND MIST DEVELOPING AS THE
SNOW ENDS. WIDESPREAD IFR DUE TO LOW CIGS ALONG AND WEST OF THE
LARAMIE RANGE. WEST OF THE LARAMIE RANGE MAINLY MVFR WITH LOCALLY
IFR. VERY LITTLE IMPROVEMENT IN POOR AVIATION CONDITIONS THROUGH
WEDNESDAY AFTERNOON EASTERLY UPSLOPE WINDS CONTINUE TO PRODUCE LOW
CIGS AND EVEN SOME FOG. DENSE FOG MAY OCCUR ALONG THE LARAMIE
RANGE THROUGH MUCH OF WEDNESDAY AND INTO WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...SML
FIRE WEATHER...ZF





000
FXUS65 KCYS 200550
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1141 PM MDT TUE MAY 19 2015

LIGHT SNOW SHOWERS WILL LINGER OVER FAR SOUTHEAST WYOMING AND THE
NEBRAKSA PANHANDLE TONIGHT WITH FOG AND MIST DEVELOPING AS THE
SNOW ENDS. WIDESPREAD IFR DUE TO LOW CIGS ALONG AND WEST OF THE
LARAMIE RANGE. WEST OF THE LARAMIE RANGE MAINLY MVFR WITH LOCALLY
IFR. VERY LITTLE IMPROVEMENT IN POOR AVIATION CONDITIONS THROUGH
WEDNESDAY AFTERNOON EASTERLY UPSLOPE WINDS CONTINUE TO PRODUCE LOW
CIGS AND EVEN SOME FOG. DENSE FOG MAY OCCUR ALONG THE LARAMIE
RANGE THROUGH MUCH OF WEDNESDAY AND INTO WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...SML
FIRE WEATHER...ZF




000
FXUS65 KCYS 200550
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1141 PM MDT TUE MAY 19 2015

LIGHT SNOW SHOWERS WILL LINGER OVER FAR SOUTHEAST WYOMING AND THE
NEBRAKSA PANHANDLE TONIGHT WITH FOG AND MIST DEVELOPING AS THE
SNOW ENDS. WIDESPREAD IFR DUE TO LOW CIGS ALONG AND WEST OF THE
LARAMIE RANGE. WEST OF THE LARAMIE RANGE MAINLY MVFR WITH LOCALLY
IFR. VERY LITTLE IMPROVEMENT IN POOR AVIATION CONDITIONS THROUGH
WEDNESDAY AFTERNOON EASTERLY UPSLOPE WINDS CONTINUE TO PRODUCE LOW
CIGS AND EVEN SOME FOG. DENSE FOG MAY OCCUR ALONG THE LARAMIE
RANGE THROUGH MUCH OF WEDNESDAY AND INTO WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...SML
FIRE WEATHER...ZF




000
FXUS65 KCYS 200037
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
637 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 626 PM MDT TUE MAY 19 2015

VERY POOR AVIATION CONDITIONS WILL PERSIST FOR THE FIRST 12-18
HOURS OF THIS TAF CYCLE AS A BROAD AREA OF LOW PRESSURE SPINS
ACROSS THE INTERMOUNTAIN WEST. MOISTURE ASSOCIATED WITH THIS LOW
PRESSURE AREA ALONG WITH LLVL UPSLOPE WILL CONTINUE TO PRODUCE
WIDESPREAD IFR/MVFR CIGS AND VSBYS THRU THE NIGHT. ADDITIONALLY...
POCKETS OF -SN AND -RA CAN CONTINUE TO BE EXPECTED AT LEAST
THROUGH AROUND 06-12Z. EXPECT SOME DRIER AIR TO BEGIN MOVING IN AT
THAT TIME AND SHOULD SEE CONDITIONS BEGIN TO SLOWLY IMPROVE 12-18Z
AND ESPECIALLY AFTER 18Z WEDNESDAY. MOUNTAINS WILL BE OBSCURED
THROUGH AT LEAST 18Z WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 200037
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
637 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 626 PM MDT TUE MAY 19 2015

VERY POOR AVIATION CONDITIONS WILL PERSIST FOR THE FIRST 12-18
HOURS OF THIS TAF CYCLE AS A BROAD AREA OF LOW PRESSURE SPINS
ACROSS THE INTERMOUNTAIN WEST. MOISTURE ASSOCIATED WITH THIS LOW
PRESSURE AREA ALONG WITH LLVL UPSLOPE WILL CONTINUE TO PRODUCE
WIDESPREAD IFR/MVFR CIGS AND VSBYS THRU THE NIGHT. ADDITIONALLY...
POCKETS OF -SN AND -RA CAN CONTINUE TO BE EXPECTED AT LEAST
THROUGH AROUND 06-12Z. EXPECT SOME DRIER AIR TO BEGIN MOVING IN AT
THAT TIME AND SHOULD SEE CONDITIONS BEGIN TO SLOWLY IMPROVE 12-18Z
AND ESPECIALLY AFTER 18Z WEDNESDAY. MOUNTAINS WILL BE OBSCURED
THROUGH AT LEAST 18Z WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...ZF





000
FXUS65 KCYS 200037
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
637 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 626 PM MDT TUE MAY 19 2015

VERY POOR AVIATION CONDITIONS WILL PERSIST FOR THE FIRST 12-18
HOURS OF THIS TAF CYCLE AS A BROAD AREA OF LOW PRESSURE SPINS
ACROSS THE INTERMOUNTAIN WEST. MOISTURE ASSOCIATED WITH THIS LOW
PRESSURE AREA ALONG WITH LLVL UPSLOPE WILL CONTINUE TO PRODUCE
WIDESPREAD IFR/MVFR CIGS AND VSBYS THRU THE NIGHT. ADDITIONALLY...
POCKETS OF -SN AND -RA CAN CONTINUE TO BE EXPECTED AT LEAST
THROUGH AROUND 06-12Z. EXPECT SOME DRIER AIR TO BEGIN MOVING IN AT
THAT TIME AND SHOULD SEE CONDITIONS BEGIN TO SLOWLY IMPROVE 12-18Z
AND ESPECIALLY AFTER 18Z WEDNESDAY. MOUNTAINS WILL BE OBSCURED
THROUGH AT LEAST 18Z WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...ZF




000
FXUS65 KCYS 200037
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
637 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 626 PM MDT TUE MAY 19 2015

VERY POOR AVIATION CONDITIONS WILL PERSIST FOR THE FIRST 12-18
HOURS OF THIS TAF CYCLE AS A BROAD AREA OF LOW PRESSURE SPINS
ACROSS THE INTERMOUNTAIN WEST. MOISTURE ASSOCIATED WITH THIS LOW
PRESSURE AREA ALONG WITH LLVL UPSLOPE WILL CONTINUE TO PRODUCE
WIDESPREAD IFR/MVFR CIGS AND VSBYS THRU THE NIGHT. ADDITIONALLY...
POCKETS OF -SN AND -RA CAN CONTINUE TO BE EXPECTED AT LEAST
THROUGH AROUND 06-12Z. EXPECT SOME DRIER AIR TO BEGIN MOVING IN AT
THAT TIME AND SHOULD SEE CONDITIONS BEGIN TO SLOWLY IMPROVE 12-18Z
AND ESPECIALLY AFTER 18Z WEDNESDAY. MOUNTAINS WILL BE OBSCURED
THROUGH AT LEAST 18Z WEDNESDAY.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...ZF





000
FXUS65 KCYS 192209
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 252 PM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF FOG AND MIXED LIGHT PRECIPITATION. EXCEPTION WILL BE
RAWLINS WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH
LATE EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN
RISE TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF
THE DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...ZF




000
FXUS65 KCYS 192209
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 252 PM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF FOG AND MIXED LIGHT PRECIPITATION. EXCEPTION WILL BE
RAWLINS WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH
LATE EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN
RISE TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF
THE DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...ZF





000
FXUS65 KCYS 192209
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 252 PM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF FOG AND MIXED LIGHT PRECIPITATION. EXCEPTION WILL BE
RAWLINS WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH
LATE EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN
RISE TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF
THE DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...ZF




000
FXUS65 KCYS 192209
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
409 PM MDT TUE MAY 19 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

UPPER LEVEL TROUGH AXIS IS CURRENTLY ALONG THE COLORADO BORDER AND
SWINGING NORTHWARD. CLOUD TOPS HAVE WARMED IN AREAS ALONG
INTERSTATE 80 AND THE PRECIPITATION IS BECOMING MORE
SHOWERY/CONVECTIVE IN NATURE. A HEAVIER SHOWER JUST MOVED OVER THE
INTERSTATE 80 SUMMIT WITH SOME SNOW ACCUMULATING BRIEFLY ON THE
ROAD. DECIDED TO CANCEL THE WINTER WEATHER ADVISORY FOR THE
SOUTHERN LARAMIE RANGE AS WIDESPREAD SNOW ACCUMULATION ON ROADS IS
UNLIKELY EXCEPT DURING THE BRIEF HEAVIER SNOW SHOWERS...WHICH ARE
EXPECTED TO BECOME LESS NUMEROUS DURING THE EVENING. MAIN REGION
OF PRECIP WILL SHIFT NORTHWARD INTO THE NORTHERN HALF OF THE CWA
BY LATER THIS EVENING...ALTHOUGH NOT EXPECTING RATES TO BE AS HIGH
AS THIS AFTERNOON. THE COLDEST AIR AT LOWER ELEVATIONS IS
CURRENTLY OVER THE NEBRASKA PANHANDLE WHERE SFC TEMPS ARE 32-35F
AND SNOW IS FALLING. CURRENT THINKING IS THAT LIGHT SNOW WILL
MAINLY ACCUMULATE ON GRASSY SURFACES THROUGH EARLY TONIGHT AS ROAD
TEMPS REMAIN RATHER WARM. LARGE SCALE LIFT REALLY BEGINS TO
DECREASE AFTER 06Z WITH LIGHT SNOW SHOWERS STILL POSSIBLE THROUGH
SUNRISE OVER CONVERSE/NIOBRARA COUNTIES AND INTO THE NORTHERN
PANHANDLE. WITH THE SFC HIGH REMAINING ANCHORED JUST TO THE EAST
OF THE CWA THROUGH THE NIGHT AND EAST TO SOUTHEAST SFC
WINDS...AREAS OF FOG WILL PROBABLY DEVELOP ONCE AGAIN FROM THE
SUMMIT TO CHEYENNE.

IT WILL BE COOL AND CLOUDY AND STABLE OVER THE REGION ON WED. LOW
CLOUDS WILL BE PERSISTENT IN THE LLVL UPSLOPE FLOW TO THE EAST OF
THE LARAMIE RANGE. THE MODELS SHOW ONLY VERY WEAK INSTABILITY OVER
CARBON AND ALBANY COUNTIES...SO WILL KEEP THUNDER OUT OF THE FCST.
WED COULD BE THE ONLY DAY OUT OF THE NEXT FEW WHERE PRECIP IS
ABSENT TO THE EAST OF THE LARAMIE RANGE. TEMPS WARM AROUND 10
DEGREES ON THURS AND SFC DEWPOINTS RISE SOME...SO INSTABILITY WILL
BE QUITE A BIT HIGHER. THE GFS SHOWS CAPE VALUES UP TO 500-750
J/KG ALONG THE LARAMIE RANGE DURING THE AFTN. CONVECTION WILL
STRUGGLE TO PUSH TOO FAR EASTWARD OFF THE LARAMIE RANGE AT THE
AIRMASS BECOMES MORE STABLE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 252 PM MDT TUE MAY 19 2015

BY FRIDAY WE TREND BACK TO A WETTER PATTERN AS AN UPPER LOW ROLLS
UP OUT OF CALIFORNIA AND CROSSES WYOMING AND WESTERN NEBRASKA
BEFORE OPENING UP AND LIFTING NORTHEAST OF THE AREA. THIS NEXT
SYSTEM OVER THE WEEKEND LOOKS WARMER IN THE MODELS...AND MAIN
CONCERNS WILL BE COVERAGES OF SHOWERS/THUNDERSTORMS FRIDAY THROUGH
SUNDAY AS THE SYSTEM CROSSES THE REGION. THE GFS STILL POINTS TO A
POTENTIAL FOR A FEW SUPERCELLS EAST OF THE LARAMIE RANGE INTO
WESTERN NEBRASKA ON SATURDAY AFTERNOON AS A SURFACE LOW DEEPENS
OVER NORTHEASTERN COLORADO BACKING OF THE LOW LEVEL WINDS AND
INCREASING THE LOW LEVEL SHEAR PROFILES...SOMETHING WE WILL HAVE
TO MONITOR WITH SUBSEQUENT FORECASTS. OVERALL OUR HIGHEST POPS
WILL BE FRIDAY THROUGH SATURDAY WITH LIKELY POPS OVER THE EASTERN
2/3RDS OF THE AREA...AND MOSTLY CHANCE POPS OUT WEST. BY MONDAY WE
TREND POPS BACK DOWN TO SLIGHT CHANCE FOR MOST AREAS AS THE UPPER
SYSTEM LIFTS OUT TO THE NORTHEAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 252 PM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF FOG AND MIXED LIGHT PRECIPITATION. EXCEPTION WILL BE
RAWLINS WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH
LATE EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN
RISE TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF
THE DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 252 PM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THROUGH THE WEEKEND.  A COOL AND SOMEWHAT
WET PATTERN WILL REMAIN IN PLACE.  RAIN AND SNOW SHOWERS WILL COME
TO AN END BY LATE TONIGHT.  THE NEXT CHANCE OF WIDESPREAD WETTING
PRECIPITATION WILL COME THURSDAY NIGHT AND FRIDAY MORNING.  MINIMUM
AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 50 PERCENT.

&&

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

$$

SHORT TERM...ZF
LONG TERM...JG
AVIATION...JG
FIRE WEATHER...ZF





000
FXUS65 KCYS 191750 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 AM MDT TUE MAY 19 2015

.UPDATE...
ISSUED AT 1150 AM MDT TUE MAY 19 2015

BACK EDGE OF THE COLDEST CLOUD TOPS AND HEAVIEST PRECIP IS
CURRENTLY MOVING NORTHWARD TOWARD THE COLORADO BORDER. EXPECTING
PRECIP RATES TO DROP OFF ALONG INTERSTATE 80 AFTER 18Z.  TEMPS TO
THE EAST OF THE LARAMIE RANGE HAVE MOSTLY STAYED ABOVE
35F...KEEPING THE PRECIP AS PREDOMINANTLY RAIN. SNOW ACCUMULATIONS
OVER THE SOUTHERN LARAMIE RANGE HAVE BEEN LESS THAN A FEW INCHES
AS MUCH OF THE HIGHER REFLECTIVITY HAS REMAINED OVER LARAMIE
COUNTY AND POINTS EASTWARD. WILL KEEP THE WINTER WEATHER ADVISORY
GOING FOR THE SOUTHERN LARAMIE RANGE THROUGH THE AFTERNOON...EVEN
THROUGH RATES WILL BE LIGHT AND ACCUMULATIONS MAINLY ON THE GRASSY
SURFACES.

&&

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1150 AM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF LIGHT PRECIPITATION WITH FOG. EXCEPTION WILL BE RAWLINS
WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH LATE
EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN RISE
TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF THE
DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...JG
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 191750 AAA
AFDCYS

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 AM MDT TUE MAY 19 2015

.UPDATE...
ISSUED AT 1150 AM MDT TUE MAY 19 2015

BACK EDGE OF THE COLDEST CLOUD TOPS AND HEAVIEST PRECIP IS
CURRENTLY MOVING NORTHWARD TOWARD THE COLORADO BORDER. EXPECTING
PRECIP RATES TO DROP OFF ALONG INTERSTATE 80 AFTER 18Z.  TEMPS TO
THE EAST OF THE LARAMIE RANGE HAVE MOSTLY STAYED ABOVE
35F...KEEPING THE PRECIP AS PREDOMINANTLY RAIN. SNOW ACCUMULATIONS
OVER THE SOUTHERN LARAMIE RANGE HAVE BEEN LESS THAN A FEW INCHES
AS MUCH OF THE HIGHER REFLECTIVITY HAS REMAINED OVER LARAMIE
COUNTY AND POINTS EASTWARD. WILL KEEP THE WINTER WEATHER ADVISORY
GOING FOR THE SOUTHERN LARAMIE RANGE THROUGH THE AFTERNOON...EVEN
THROUGH RATES WILL BE LIGHT AND ACCUMULATIONS MAINLY ON THE GRASSY
SURFACES.

&&

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1150 AM MDT TUE MAY 19 2015

FOR THE NOON AVIATION PACKAGE WE CONTINUE WITH IFR/LIFR CEILINGS AT
ALL AIRPORT SITES ACROSS SOUTHEAST WYOMING AND THE WESTERN
NEBRASKA PANHANDLE THROUGH THE OVERNIGHT PERIOD DUE TO PROLONGED
PERIODS OF LIGHT PRECIPITATION WITH FOG. EXCEPTION WILL BE RAWLINS
WHERE THEY WILL PREVAIL AT MVFR FLIGHT CATEGORY THROUGH LATE
EVENING IN LIGHT PRECIPITATION AND LOWERED CEILINGS...THEN RISE
TO VFR TOWARDS MIDNIGHT AS DRIER AIRMASS ON THE BACKSIDE OF THE
DEPARTING LOW PRESSURE SYSTEM MOVES IN.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.
&&

$$

UPDATE...ZF
SHORT TERM...TJT
LONG TERM...SML
AVIATION...JG
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 191245
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
645 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 640 AM MDT TUE MAY 19 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TODAY. RAIN WILL CHANGE TO SNOW OVER THE MOUNTAINS OF
SOUTHEAST WYOMING TONIGHT WITH SOME SNOW SPREADING INTO THE
PLAINS OF A PERIOD OF TIME. WIDESPREAD MVFR TO IFR ACROSS THE
AREA DUE TO THE RAIN AND SNOW. LIFR POSSIBLE ALONG AND EAST OF
THE LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 4000 FEET MSL. AS PRECIPITATION WINDS DOWN THIS
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA THROUGH TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.

&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 191245
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
645 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 640 AM MDT TUE MAY 19 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TODAY. RAIN WILL CHANGE TO SNOW OVER THE MOUNTAINS OF
SOUTHEAST WYOMING TONIGHT WITH SOME SNOW SPREADING INTO THE
PLAINS OF A PERIOD OF TIME. WIDESPREAD MVFR TO IFR ACROSS THE
AREA DUE TO THE RAIN AND SNOW. LIFR POSSIBLE ALONG AND EAST OF
THE LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 4000 FEET MSL. AS PRECIPITATION WINDS DOWN THIS
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA THROUGH TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.

&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 191245
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
645 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 640 AM MDT TUE MAY 19 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TODAY. RAIN WILL CHANGE TO SNOW OVER THE MOUNTAINS OF
SOUTHEAST WYOMING TONIGHT WITH SOME SNOW SPREADING INTO THE
PLAINS OF A PERIOD OF TIME. WIDESPREAD MVFR TO IFR ACROSS THE
AREA DUE TO THE RAIN AND SNOW. LIFR POSSIBLE ALONG AND EAST OF
THE LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 4000 FEET MSL. AS PRECIPITATION WINDS DOWN THIS
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA THROUGH TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.

&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 191013
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
413 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.


.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1149 PM MDT MON MAY 18 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TUESDAY. SHOWERS WILL DEVELOP ACROSS THE AREA TONIGHT WITH
WIDESPREAD PRECIPITATION THROUGH THE DAY TUESDAY. RAIN WILL CHANGE
TO SNOW OVER THE MOUNTAINS OF SOUTHEAST WYOMING TONIGHT WITH SNOW
SPREADING INTO THE PLAINS AFTER SUNRISE TUESDAY. WIDESPREAD MVFR
TO IFR ACROSS THE AREA. LIFR POSSIBLE ALONG AND EAST OF THE
LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 3500 FEET MSL. AS PRECIPITATION WINDS DOWN TUESDAY
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.
&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT




000
FXUS65 KCYS 191013
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
413 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.


.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1149 PM MDT MON MAY 18 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TUESDAY. SHOWERS WILL DEVELOP ACROSS THE AREA TONIGHT WITH
WIDESPREAD PRECIPITATION THROUGH THE DAY TUESDAY. RAIN WILL CHANGE
TO SNOW OVER THE MOUNTAINS OF SOUTHEAST WYOMING TONIGHT WITH SNOW
SPREADING INTO THE PLAINS AFTER SUNRISE TUESDAY. WIDESPREAD MVFR
TO IFR ACROSS THE AREA. LIFR POSSIBLE ALONG AND EAST OF THE
LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 3500 FEET MSL. AS PRECIPITATION WINDS DOWN TUESDAY
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.
&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT





000
FXUS65 KCYS 191013
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
413 AM MDT TUE MAY 19 2015

.SHORT TERM...(TODAY AND THURSDAY)
ISSUED AT 402 AM MDT TUE MAY 19 2015

VERY TRICKY FORECAST TODAY ACROSS THE AREA...AND ESPECIALLY THE
HIGH PLAINS. THE MAIN FORECAST CONCERN WILL BE WHEN RAIN CHANGES
TO SNOW ACROSS THE AREA AND HOW MUCH...IF ANY...ACCUMULATES.
CURRENT KCYS AND KFTG RADAR LOOPS SHOW A VAST INCREASE IN
PRECIPITATION COVERAGE OVER COLORADO AS A LARGE SHIELD OF
PRECIPITATION DEVELOPS ACROSS THE ROCKY MOUNTAINS AND COLORADO
PLAINS AT THIS HOUR. THIS PRECIPITATION IS QUICKLY EXPANDING
NORTH...BUT ALSO EXTENDS SOUTHWARD INTO SOUTHERN COLORADO DUE
STRONG UPPER LEVEL DIFLUENCE AHEAD OF A PACIFIC JET. MOST OF
SOUTHEAST WYOMING AND WESTERN NEBRASKA WILL BE IN THIS AREA OF
UPPER LEVEL DIFLUENCE THROUGH THE DAY IN ADDITION TO JET DYNAMICS
FROM THE APPROACHING PACIFIC JET. IN ADDITION...A STRONG SURFACE
HIGH OVER THE NORTHERN PLAINS WILL REMAIN IN PLACE AND ACTUALLY
INTENSIFY AND SHIFT WESTWARD TODAY AND TONIGHT...WITH ADDITIONAL
FRONTOGENESIS ALONG SOUTHERN WYOMING AND CENTRAL COLORADO AS
COOLER AIR MOVES INTO THE REGION. WIDESPREAD PRECIP AMOUNTS
BETWEEN 0.50 TO 1.00 LIQUID CAN BE EXPECTED FROM THE LARAMIE RANGE
EASTWARD...WITH LESSER AMOUNTS WEST OF THE LARAMIE RANGE. WOULD
NOT BE SURPRISED TO SEE SOME LOCATIONS RECEIVE 1.50 LIQUID BY
TONIGHT ACROSS THE HIGH PLAINS. AS THE SURFACE HIGH STRENGTHENS
AND THE UPPER LEVEL DISTURBANCE MOVES NORTHEAST...MODELS SHOW
700MB TEMPERATURES LOWERING BETWEEN -3C TO -5C EAST OF THE FRONTAL
BOUNDARY...WHICH SHOULD BE JUST WEST OF THE LARAMIE RANGE. MODEL
SOUNDINGS SHOW NEARLY ISOTHERMAL TEMPERATURES FROM 700MB DOWN TO
THE SURFACE. THIS SUGGESTS THE POTENTIAL FOR HEAVY SNOW ACROSS
MOST OF THE HIGH PLAINS EVEN THOUGH CURRENT TEMPERATURES ARE IN
THE 40S TO LOW 50S. EVEN THE I80 SUMMIT IS HOVERING AROUND 35
DEGREES. MODELS SHOW THESE TEMPERATURES FALLING STEADILY TODAY
WITH RAIN CHANGING TO SNOW. DO NOT EXPECT MUCH SNOW WEST OF THE
LARAMIE RANGE DUE TO THE SHALLOW DEPTH OF THE COLD AIR.

IN TERMS OF IMPACT...SHOULD BE MINOR TO MODERATE ACROSS THE AREA
DUE TO THE TIME OF YEAR AND THE SNOWFALL MAINLY OCCURRING DURING
THE DAY. HOWEVER...THESE IS SOME UNCERTAINTY WITH SOME ENSEMBLE
MEMBERS SUGGESTING HIGH SNOWFALL RATES AND ACCUMULATING SNOW DOWN
TO 4500 FEET. WILL HAVE TO KEEP AN EYE ON PERSISTENT
MODERATE/HEAVY SNOWFALL RATES AS THE RAIN CHANGES TO SNOW ACROSS
THE AREA. IF THESE HEAVY SNOWFALL RATES PERSIST AND BECOME THE
NORM...MAY BE LOOKING AT LOCALLY SIGNIFICANT SNOW ACCUMULATIONS
WITH HEAVY SNOW BANDS MOVING ACROSS THE AREA FROM SOUTH TO NORTH.
NOT CONFIDENT ENOUGH IN THIS SCENARIO TO EXPAND THE WINTER
WEATHER ADVISORY THOUGH...SO ONLY KEPT THE ADVISORY GOING FOR THE
I80 SUMMIT WHICH AS THE BEST POTENTIAL IN SEEING HEAVY SNOWFALL
AND ACCUMULATING SNOWFALL ON THE ROADWAYS. FURTHER EAST...1 TO 4
INCHES MAY ACCUMULATE ON GRASSY SURFACES BEFORE MELTING IN BETWEEN
BANDS...WITH VERY LITTLE ACCUMULATION ON THE ROADWAYS. WILL WATCH
THESE TRENDS THROUGH THE MORNING AND ADJUST ACCORDINGLY. WILL HAVE
TO ALSO MONITOR RIVER LEVELS AND POTENTIAL FLASH FLOODING IF SNOW
LEVELS DO NOT LOWER...AS THE LARAMIE RIVER AND AREA CREEKS AND
STREAMS REMAIN HIGH.

BY TONIGHT...THE UPPER LEVEL DISTURBANCE LIFTS NORTH AND EAST INTO
THE DAKOTAS AND WEAKENS. HEAVY PRECIP RATES SHOULD COME TO AN END
BY MIDNIGHT WITH SNOWFALL BECOMING LIGHTER AND MORE SHOWERY IN
NATURE. DECENT AMOUNT OF COLD AIR ACROSS THE HIGH PLAINS...SO CAN
NOT RULE OUT ADDITIONAL LIGHT SNOW ACCUMULATIONS. DRIZZLE AND FOG
MAY BECOME A PROBLEM ALONG THE SOUTH FACING RIDGES SUCH AS THE
CHEYENNE RIDGE FROM CHEYENNE TO SIDNEY TONIGHT AND INTO EARLY
WEDNESDAY. HIGH TEMPERATURES TODAY AND WEDNESDAY WILL BE 20 TO 30
DEGREES BELOW NORMAL. ALTHOUGH PRECIPITATION WILL GENERALLY COME
TO AN END BY WEDNESDAY...UPSLOPE FLOW AND THE REMNANT STATIONARY
FRONT ALONG THE LARAMIE RANGE WILL RESULT IN SCATTERED SHOWERS AND
ISOLATED THUNDER OVER WYOMING.

WARMER TEMPERATURES ARE EXPECTED ON THURSDAY AS A SHORT WAVE
RIDGES MOVES ACROSS THE AREA. TEMPERATURES WILL STILL BE BELOW
NORMAL THOUGH AND GENERALLY IN THE MID 50S TO MID 60S. BREAK IN
THE PRECIPITATION WILL BE SHORT LIVED...AS ALL MODELS INDICATE
ANOTHER PACIFIC STORM SYSTEM MOVING TOWARDS THE AREA.
INITIALLY...EXPECT A ROUND OF SCATTERED SHOWERS AND TSTORMS LATE
ON THURSDAY WITH THE POTENTIAL FOR STRONG TSTORMS AS FORECAST CAPE
VALUES CLIMB NEAR 1000 J/KG ALONG WITH PLENTY OF UPPER LEVEL
DIFLUENCE AHEAD OF THE NEXT PACIFIC STORM. INCREASED POP BETWEEN
40 TO 60 PERCENT ACROSS SOUTHEAST WYOMING THURSDAY AFTERNOON.


.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 AM MDT TUE MAY 19 2015

IF YOU ARE LOOKING FOR A BREAK IN THE COOL AND WET WEATHER
PATTERN...YOU MAY BE WAITING FOR A WHILE. EXTENDED MODELS SHOW NO
SIGN OF CURRENT WEATHER PATTERN CHANGING ANYTIME SOON. THE HEMISPHERIC
LONGWAVE PATTERN WILL REMAIN LOCKED IN PLACE WITH MANY BLOCKING
FEATURES ACROSS THE NORTHERN HEMISPHERE. NOT THE LEAST BEING THE
HIGH OVER LOW BLOCK ACROSS WESTERN CANADA AND WESTERN CONUS
RESPECTFULLY. A CONTINUOUS STREAM OF PACIFIC SYSTEMS WILL SLIDE
UNDER THE UPPER LEVEL HIGH OVER WESTERN CANADA DURING THE FORECAST
PERIOD AND BEYOND. THIS MEANS CHANCES FOR SHOWERS NEARLY
EVERYDAY...ALONG WITH THUNDERSTORMS AND EVEN THE POTENTIAL FOR
SNOW ON OCCASION.

THE NEXT CHANCE FOR SNOW OUTSIDE OF THE MOUNTAIN MAY COME AGAIN AS
EARLY AS FRIDAY. AT THIS TIME KEPT THE MENTION OF SNOW OUT OF THE
GRIDS BUT WILL HAVE TO KEEP A CLOSE EYE ON THE TRACK AND STRENGTH
OF THE SHORTWAVE TROUGH WHICH IS PROGGED TO MOVE OVER THE AREA
FRIDAY. THE NUMERICAL MODELS ARE WARM ENOUGH TO KEEP PRECIPITATION
AS RAIN BUT THE MODELS HAVE HAD A WARM BIAS WITH THE LAST FEW
SYSTEMS. THIS VERY WELL MAY AGAIN BE THE CASE FRIDAY.
FORTUNATELY...BASED ON THE CURRENT MODEL TIMING THE HEAVIEST
PRECIPITATION WOULD BE DURING THE DAYTIME HOURS...MAKING
ACCUMULATIONS OF SNOW UNLIKELY...ESPECIALLY OVER ROADWAYS.

ECMWF AND GFS SHOWING DISTINCT DIFFERENCES IN THE PLACEMENT OF YET
ANOTHER DISTURBANCE SATURDAY. THE GFS IS SLIGHTLY SLOWER AND MUCH
FARTHER WEST WITH SHORTWAVE ENERGY. NOT CONFIDENT IN ANY ONE
SOLUTION AT THIS TIME...BUT THE DIFFERENCE HAVE SIGNIFICANT
FORECAST IMPLICATIONS. THE ECMWF SOLUTION SUGGESTS COOLER
TEMPERATURES WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS...AND VERY LITTLE CHANCE FOR SEVERE THUNDERSTORMS.
THE WARMER GFS WOULD SUGGEST A CHANCE FOR SOME SEVERE STORMS INTO
THE PLAINS LATE SATURDAY. BY SUNDAY THE BOTH MODELS PUSH THE MAIN
DYNAMICS INTO THE PLAINS...OF COURSE ANOTHER SYSTEM WILL BE HOT
ON ITS HEALS DROPPING SOUTH ACROSS THE INTERMOUNTAIN WEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1149 PM MDT MON MAY 18 2015

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE ACROSS THE FORECAST
AREA TUESDAY. SHOWERS WILL DEVELOP ACROSS THE AREA TONIGHT WITH
WIDESPREAD PRECIPITATION THROUGH THE DAY TUESDAY. RAIN WILL CHANGE
TO SNOW OVER THE MOUNTAINS OF SOUTHEAST WYOMING TONIGHT WITH SNOW
SPREADING INTO THE PLAINS AFTER SUNRISE TUESDAY. WIDESPREAD MVFR
TO IFR ACROSS THE AREA. LIFR POSSIBLE ALONG AND EAST OF THE
LARAMIE RANGE AS SNOW DEVELOPS WITH SNOW BEING HEAVY AT TIMES
MAINLY ABOVE 3500 FEET MSL. AS PRECIPITATION WINDS DOWN TUESDAY
EVENING...WIDESPREAD STRATUS...FOG...AND DRIZZLE WILL OCCUR OVER
THE AREA.

&&

.FIRE WEATHER...
ISSUED AT 302 AM MDT TUE MAY 19 2015

NO FIRE WEATHER CONCERNS THIS WEEK DUE TO UNSEASONABLY COOL
TEMPERATURES AND HIGH CHANCES OF PRECIPITATION. EVEN SOME SNOW IS
EXPECTED OVER THE MOUNTAINS AND PORTIONS OF THE HIGH PLAINS EARLY
THIS WEEK. DAYTIME RELATIVE HUMIDITIES WILL LIKELY NOT LOWER BELOW
50 PERCENT UNTIL LATE THIS WEEKEND OR EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 302 AM MDT TUE MAY 19 2015

LARAMIE RIVER WILL CONTINUE TO RUN AT RELATIVELY HIGH LEVELS
THROUGH THIS WEEK BUT AT THIS TIME IS EXPECTED TO REMAIN WITHIN
ITS BANKS. HOWEVER...THE FIRST OF A SERIES OF PACIFIC STORMS WILL
IMPACT THE REGION TODAY AND INTO TONIGHT. WILL HAVE TO CLOSELY
MONITOR HOW MUCH PRECIPITATION WILL FALL AS A STRONG AREA OF LOW
PRESSURE MOVES ACROSS THE AREA...WITH ANOTHER POSSIBLE BY THE END
OF THE WEEK. HIGHEST PRECIPITATION AMOUNTS ARE LIKELY ACROSS THE
PLAINS WHICH COULD BE ENOUGH TO PUSH THE LARAMIE RIVER AT FORT
LARAMIE INTO MINOR FLOODING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ116.

NE...NONE.
&&

$$

SHORT TERM...TJT
LONG TERM...SML
AVIATION...SML
FIRE WEATHER...TJT
HYDROLOGY...TJT




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