000
FXUS65 KRIW 181730
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1127 AM MDT SAT MAY 18 2013
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
A VERY UNSETTLED FEW DAYS EXPECTED ACROSS CENTRAL AND WYOMING. A FEW
SHOWERS LINGER OVER WESTERN WYOMING THIS MORNING...WITH A WEAK
BOUNDARY MOVING WEST THROUGH FREMONT COUNTY. WEBCAMS HAVE BEEN
INDICATING THE PRESENCE OF FOG ACROSS THE BIG HORN BASIN AND JOHNSON
COUNTY. PATCHY FOG WILL REMAIN IN THE FORECAST THROUGH THE MID
MORNING HOURS...WITH SHOWER ACTIVITY REMAINING FOR MUCH OF WESTERN
AND CENTRAL WYOMING.
A CIRCULATION EMBEDDED IN THE TROUGH OVER NORTHEASTERN UTAH
CONTINUES TO LIFT TOWARDS SOUTHWESTERN WYOMING WITH THE PROGRESSION
OF THE TROUGH. THIS CIRCULATION IS ANTICIPATED TO MOVE THROUGH MUCH
OF THE STATE TODAY. SHOWERS ARE EXPECTED THROUGH THE DAY...WITH
THUNDERSTORMS DEVELOPING IN THE LATE MORNING AND EARLY AFTERNOON
HOURS. INSTABILITY TO MOVE NORTHEAST THROUGH THE DAY...WITH THE BIG
HORN BASIN AND JOHNSON COUNTY AGAIN EXPECTED TO SEE THE GREATEST
AMOUNT OF INSTABILITY TODAY. ANY THUNDERSTORMS MAY CONTAIN GUSTY
WIND TODAY. IN ADDITION...STORMS ACROSS NORTHEASTERN WYOMING MAY
CONTAIN SMALL HAIL. STORMS MAY CONTAIN PERIOD OF HEAVY RAIN...WHICH
MAY RESULT IN LOCALIZED FLOODING.
NATIONAL GUIDANCE INDICATES A SLIGHT CHANCE FOR STRONG WIND AND
LARGE HAIL TO OCCUR...PRIMARILY ACROSS EASTERN JOHNSON COUNTY. AS
MENTIONED BEFORE....FLOODING WILL BE POSSIBLE...WITH MODELS
INDICATING THE HIGHEST PRECIPITABLE WATER VALUES ACROSS THIS AREA.
SPECIAL ATTENTION WILL CONTINUE TO BE PAID TO THE BURN SCAR
REGIONS...ESPECIALLY THE GILEAD BURN SCAR SHOULD SIGNIFICANT RAIN
FALL NEAR THE AREA. THE BIG HORN BASIN AND JOHNSON COUNTY ARE AGAIN
NOTED TO HAVE THE GREATEST CAPE AND LOWEST LIFTED INDEX VALUES
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. CONSEQUENTLY...IT IS
CERTAINLY NOT OUT OF THE QUESTION FOR A STORM OR TWO TO TURN SEVERE
ACROSS NORTHEASTERN WYOMING TODAY. NOTABLE CAPE AND LIFTED INDEX
VALUES SNEAK INTO NATRONA COUNTY DURING THE LATE AFTERNOON AND EARLY
EVENING HOURS. DAYLIGHT WILL BE FADING WITH THIS ARRIVAL...BUT SOME
STRONGER STORMS MAY OCCUR.
THUNDERSTORM ACTIVITY IS EXPECTED TO WANE WITH THE LOSS OF DAYLIGHT
THIS EVENING...WITH SHOWER ACTIVITY CONTINUING THROUGH THE OVERNIGHT
HOURS. PATCHY FOG DEVELOPMENT WILL AGAIN BE POSSIBLE ACROSS NORTHERN
WYOMING IN RESPONSE TO ANTICIPATED SHOWER ACTIVITY.
UNDER THE CONTINUED INFLUENCE OF THE TROUGH OF LOW
PRESSURE...THUNDERSTORMS WILL AGAIN BE POSSIBLE ON SUNDAY. A
NORTHWEST FLOW WILL BEGIN TO BUILD OVER THE AREA EARLY MONDAY
MORNING...THOUGH SOME INSTABILITY MAY KEEP ISOLATED THUNDERSTORM
ACTIVITY ACROSS THE SOUTHERN TWO THIRDS OF THE STATE ON MONDAY
AFTERNOON.
.LONG TERM...TUESDAY THROUGH SATURDAY
A REX BLOCK ACROSS SOUTHERN CANADA AND CENTRAL U.S. WILL GRADUALLY
WEAKEN BY LATE IN THE WEEK...WITH THE GENERAL FLOW ACROSS THE MUCH
OF THE CONUS REMAINING RATHER STAGNATE THROUGH THE EXTENDED. THERE
COULD BE SOME LINGERING LIGHT PRECIPITATION ACROSS THE EAST TUESDAY
ASSOCIATED WITH AN UPPER LOW NEAR SIOUX FALLS SOUTH DAKOTA.
HOWEVER...MODELS ARE SHOWING SOME WEAK RIDGING MOVING ACROSS THE
FORECAST AREA TUESDAY/TUESDAY NIGHT WHICH WOULD SUGGEST A DRYING
TREND AND THE BEGINNING OF A WARMING TREND.
FOR THE REST OF THE EXTENDED...ATTENTION TURNS TO A STRONG UPPER LOW
THAT MOVES INTO THE PACIFIC NORTHWEST TUESDAY/TUESDAY NIGHT. GLOBAL
MODELS KEEP THIS STRONG UPPER LOW AROUND THE PACIFIC NORTHWEST AREA
THROUGH SATURDAY. THIS WILL RESULT IN INCREASING SOUTH TO
SOUTHWESTERLY FLOW OVER THE REGION AND ABOVE AVERAGE
TEMPERATURES...AND POSSIBLY SOME STRONG CONVECTION AT TIMES.
ON WEDNESDAY...MEDIUM RANGE MODELS ARE SHOWING A DECENT DIFLUENT
FLOW OVER THE FORECAST AREA AHEAD OF A SIGNIFICANT SHORTWAVE
ROTATING AROUND THE UPPER LOW. IN ADDITION...AT THE
SURFACE...MODELS ARE PROGGING A MOIST EAST/SOUTHEAST FLOW
DEVELOPING EAST OF THE DIVIDE. MODELS ARE SHOWING THE BULK OF
INSTABILITY/STEEP LAPSE RATES ON WEDNESDAY ACROSS THE
WEST/NORTHWEST. THUS COULD SEE SOME STRONG CONVECTION ACROSS THE
WEST/NORTHWEST WEDNESDAY...AND POSSIBLY FARTHER EAST IF MORE
INSTABILITY OCCURS THAN CURRENTLY FORECAST. THIS SYSTEM COULD ALSO
SURGE A COLD FRONT EASTWARD INTO WESTERN WYOMING LATE
WEDNESDAY/WEDNESDAY NIGHT...BUT QUICKLY RETREAT DURING THE DAY
BACK WEST/NORTHWEST THURSDAY. MODELS THEN SHOW A DRY SLOT MOVING
INTO SOUTHWEST WYOMING THURSDAY...BUT A CONTINUED MOIST
EAST/SOUTHEAST SURFACE FLOW ACROSS THE EXTREME EAST...WITH A
QUICKLY VEERING WIND PROFILE JUST ABOVE THE SURFACE. GLOBAL
MODELS ARE SHOWING THE BULK OF THE INSTABILITY THURSDAY ACROSS THE
EAST...WITH THE WEST FAIRLY STABLE. THUS THE BULK OF THE CONVECTION
SHOULD BE CONCENTRATED ACROSS THE NORTH AND EAST THURSDAY...WITH
SOME STRONG CONVECTION POSSIBLE ESPECIALLY ALONG AND NORTH AND
EAST OF THE PSEUDO DRY LINE/FRONT...WHICH SHOULD BE ACROSS JOHNSON
AND NATRONA COUNTY AS WELL AS THE BIG HORN BASIN. THE BASIC SET UP
WILL REMAIN THE SAME FRIDAY AND SATURDAY...WITH MODELS SHOWING THE
DRIER SOUTHWEST FLOW PUSHING EVER SO SLIGHTLY FARTHER EAST.
&&
.AVIATION.../18Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA...INCLUDING KJAC AS
ANOTHER UPPER LEVEL DISTURBANCE MOVES OVERHEAD IN SOUTH TO SOUTHWEST
FLOW. KJAC KBPI AND KPNA WILL CONTINUE TO BE IN AND OUT OF MVFR IFR
CONDITIONS THROUGH THE DAY WITH WIDESPREAD MOUNTAIN OBSCURATIONS
CONTINUING AND AFFECTING KJAC WITH BRIEF POSSIBLE BOUTS INTO IFR
CONDITIONS. MVFR CONDITIONS WILL ALSO POSSIBLE ACROSS THE BIGHORN
BASIN AND AT KWRL AND KCOD WHERE SHOWERS AND THUNDER WILL
OCCASSIONALY BRING CLOUD DECKS BELOW VFR CRITERIA.
SHOWERS AND SOME THUNDERSTORMS WILL INCREASE IN COVERAGE ACROSS THE
ENTIRE FORECAST AREA AFTER THIS AFTERNOON...SO WILL KEEP VCTS AND/OR
VCSH IN FORECAST FOR ALL TERMINALS TO ONE EXTENT OR ANOTHER.
SHOWERS AND THUNDERSTORMS WILL CLEAR FROM SOUTHWEST TO NORTHEAST
AFTER 03Z SUN...WITH SOME SHOWERS CONTINUING ACROSS THE NORTHEAST
AND IN THE KCPR AREA THROUGH SUNDAY MORNING.
&&
.FIRE WEATHER...
PATCHY MORNING FOG WILL BE POSSIBLE ACROSS THE BIG HORN BASIN AND
JOHNSON COUNTY TODAY IN RESPONSE TO PREVIOUS RAIN SHOWERS. ANOTHER
ROUND OF THUNDERSTORMS WILL OCCUR THIS AFTERNOON...WITH THE PRIME
SPOT AGAIN BEING FOUND OVER THE BIG HORN BASIN AND JOHNSON COUNTY.
STORMS IN THESE AREAS MAY PRODUCE GUSTY WIND AND SMALL HAIL...WITH A
FEW STORMS BECOMING STRONG. ISOLATED THUNDERSTORMS EXPECTED
ELSEWHERE...WITH GUSTY WIND POSSIBLE. THIS UNSETTLED PATTERN
CONTINUES THROUGH THE WEEKEND. NORTHWEST FLOW WILL BEGIN TO MOVE
OVER WESTERN WYOMING MONDAY MORNING...THOUGH THUNDERSTORMS MAY AGAIN
BE FOUND ACROSS CENTRAL AND SOUTHERN WYOMING.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...BRAUN
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 180954
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
354 AM MDT SAT MAY 18 2013
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
A VERY UNSETTLED FEW DAYS EXPECTED ACROSS CENTRAL AND WYOMING. A FEW
SHOWERS LINGER OVER WESTERN WYOMING THIS MORNING...WITH A WEAK
BOUNDARY MOVING WEST THROUGH FREMONT COUNTY. WEBCAMS HAVE BEEN
INDICATING THE PRESENCE OF FOG ACROSS THE BIG HORN BASIN AND JOHNSON
COUNTY. PATCHY FOG WILL REMAIN IN THE FORECAST THROUGH THE MID
MORNING HOURS...WITH SHOWER ACTIVITY REMAINING FOR MUCH OF WESTERN
AND CENTRAL WYOMING.
A CIRCULATION EMBEDDED IN THE TROUGH OVER NORTHEASTERN UTAH
CONTINUES TO LIFT TOWARDS SOUTHWESTERN WYOMING WITH THE PROGRESSION
OF THE TROUGH. THIS CIRCULATION IS ANTICIPATED TO MOVE THROUGH MUCH
OF THE STATE TODAY. SHOWERS ARE EXPECTED THROUGH THE DAY...WITH
THUNDERSTORMS DEVELOPING IN THE LATE MORNING AND EARLY AFTERNOON
HOURS. INSTABILITY TO MOVE NORTHEAST THROUGH THE DAY...WITH THE BIG
HORN BASIN AND JOHNSON COUNTY AGAIN EXPECTED TO SEE THE GREATEST
AMOUNT OF INSTABILITY TODAY. ANY THUNDERSTORMS MAY CONTAIN GUSTY
WIND TODAY. IN ADDITION...STORMS ACROSS NORTHEASTERN WYOMING MAY
CONTAIN SMALL HAIL. STORMS MAY CONTAIN PERIOD OF HEAVY RAIN...WHICH
MAY RESULT IN LOCALIZED FLOODING.
NATIONAL GUIDANCE INDICATES A SLIGHT CHANCE FOR STRONG WIND AND
LARGE HAIL TO OCCUR...PRIMARILY ACROSS EASTERN JOHNSON COUNTY. AS
MENTIONED BEFORE....FLOODING WILL BE POSSIBLE...WITH MODELS
INDICATING THE HIGHEST PRECIPITABLE WATER VALUES ACROSS THIS AREA.
SPECIAL ATTENTION WILL CONTINUE TO BE PAID TO THE BURN SCAR
REGIONS...ESPECIALLY THE GILEAD BURN SCAR SHOULD SIGNIFICANT RAIN
FALL NEAR THE AREA. THE BIG HORN BASIN AND JOHNSON COUNTY ARE AGAIN
NOTED TO HAVE THE GREATEST CAPE AND LOWEST LIFTED INDEX VALUES
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. CONSEQUENTLY...IT IS
CERTAINLY NOT OUT OF THE QUESTION FOR A STORM OR TWO TO TURN SEVERE
ACROSS NORTHEASTERN WYOMING TODAY. NOTABLE CAPE AND LIFTED INDEX
VALUES SNEAK INTO NATRONA COUNTY DURING THE LATE AFTERNOON AND EARLY
EVENING HOURS. DAYLIGHT WILL BE FADING WITH THIS ARRIVAL...BUT SOME
STRONGER STORMS MAY OCCUR.
THUNDERSTORM ACTIVITY IS EXPECTED TO WANE WITH THE LOSS OF DAYLIGHT
THIS EVENING...WITH SHOWER ACTIVITY CONTINUING THROUGH THE OVERNIGHT
HOURS. PATCHY FOG DEVELOPMENT WILL AGAIN BE POSSIBLE ACROSS NORTHERN
WYOMING IN RESPONSE TO ANTICIPATED SHOWER ACTIVITY.
UNDER THE CONTINUED INFLUENCE OF THE TROUGH OF LOW
PRESSURE...THUNDERSTORMS WILL AGAIN BE POSSIBLE ON SUNDAY. A
NORTHWEST FLOW WILL BEGIN TO BUILD OVER THE AREA EARLY MONDAY
MORNING...THOUGH SOME INSTABILITY MAY KEEP ISOLATED THUNDERSTORM
ACTIVITY ACROSS THE SOUTHERN TWO THIRDS OF THE STATE ON MONDAY
AFTERNOON.
.LONG TERM...TUESDAY THROUGH SATURDAY
A REX BLOCK ACROSS SOUTHERN CANADA AND CENTRAL U.S. WILL GRADUALLY
WEAKEN BY LATE IN THE WEEK...WITH THE GENERAL FLOW ACROSS THE MUCH
OF THE CONUS REMAINING RATHER STAGNATE THROUGH THE EXTENDED. THERE
COULD BE SOME LINGERING LIGHT PRECIPITATION ACROSS THE EAST TUESDAY
ASSOCIATED WITH AN UPPER LOW NEAR SIOUX FALLS SOUTH DAKOTA.
HOWEVER...MODELS ARE SHOWING SOME WEAK RIDGING MOVING ACROSS THE
FORECAST AREA TUESDAY/TUESDAY NIGHT WHICH WOULD SUGGEST A DRYING
TREND AND THE BEGINNING OF A WARMING TREND.
FOR THE REST OF THE EXTENDED...ATTENTION TURNS TO A STRONG UPPER LOW
THAT MOVES INTO THE PACIFIC NORTHWEST TUESDAY/TUESDAY NIGHT. GLOBAL
MODELS KEEP THIS STRONG UPPER LOW AROUND THE PACIFIC NORTHWEST AREA
THROUGH SATURDAY. THIS WILL RESULT IN INCREASING SOUTH TO SOUTHWESTERLY
FLOW OVER THE REGION AND ABOVE AVERAGE TEMPERATURES...AND POSSIBLY
SOME STRONG CONVECTION AT TIMES.
ON WEDNESDAY...MEDIUM RANGE MODELS ARE SHOWING A DECENT DIFLUENT
FLOW OVER THE FORECAST AREA AHEAD OF A SIGNIFICANT SHORTWAVE
ROTATING AROUND THE UPPER LOW. IN ADDITION...AT THE
SURFACE...MODELS ARE PROGGING A MOIST EAST/SOUTHEAST FLOW
DEVELOPING EAST OF THE DIVIDE. MODELS ARE SHOWING THE BULK OF
INSTABILITY/STEEP LAPSE RATES ON WEDNESDAY ACROSS THE
WEST/NORTHWEST. THUS COULD SEE SOME STRONG CONVECTION ACROSS THE
WEST/NORTHWEST WEDNESDAY...AND POSSIBLY FARTHER EAST IF MORE
INSTABILITY OCCURS THAN CURRENTLY FORECAST. THIS SYSTEM COULD ALSO
SURGE A COLD FRONT EASTWARD INTO WESTERN WYOMING LATE
WEDNESDAY/WEDNESDAY NIGHT...BUT QUICKLY RETREAT DURING THE DAY
BACK WEST/NORTHWEST THURSDAY. MODELS THEN SHOW A DRY SLOT MOVING
INTO SOUTHWEST WYOMING THURSDAY...BUT A CONTINUED MOIST
EAST/SOUTHEAST SURFACE FLOW ACROSS THE EXTREME EAST...WITH A
QUICKLY VEERING WIND PROFILE JUST ABOVE THE SURFACE. GLOBAL
MODELS ARE SHOWING THE BULK OF THE INSTABILITY THURSDAY ACROSS THE
EAST...WITH THE WEST FAIRLY STABLE. THUS THE BULK OF THE CONVECTION
SHOULD BE CONCENTRATED ACROSS THE NORTH AND EAST THURSDAY...WITH
SOME STRONG CONVECTION POSSIBLE ESPECIALLY ALONG AND NORTH AND
EAST OF THE PSEUDO DRY LINE/FRONT...WHICH SHOULD BE ACROSS JOHNSON
AND NATRONA COUNTY AS WELL AS THE BIG HORN BASIN. THE BASIC SET UP
WILL REMAIN THE SAME FRIDAY AND SATURDAY...WITH MODELS SHOWING THE
DRIER SOUTHWEST FLOW PUSHING EVER SO SLIGHTLY FARTHER EAST.
&&
.AVIATION.../12Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA AS ANOTHER WAVE MOVES
OVERHEAD IN SOUTHWEST FLOW...KJAC KBPI AND KPNA WILL CONTINUE TO
BE IN AND OUT OF MVFR TO IFR CONDITIONS THROUGH THE MORNING WITH
WIDESPREAD MOUNTAIN OBSCURATIONS ONGOING. MVFR TO IFR CONDITIONS
ARE ALSO POSSIBLE ACROSS THE BIGHORN BASIN AND AT KBYG THROUGH THE
EARLY MORNING HOURS AS FOG FORMS IN LOCATIONS WHERE HEAVY
RAIN FELL WITH THE STORMS ON FRIDAY AFTERNOON.
SHOWERS AND SOME STORMS WILL INCREASE IN COVERAGE ACROSS THE
ENTIRE FORECAST AREA AFTER 18Z...SO WILL KEEP VCTS AND VCSH IN
FORECAST FOR ALL TERMINALS. THE HIGHEST BASED STORMS WILL BE VCNTY
KCPR BETWEEN 20Z SAT AND 02Z SUN...THE THREAT FOR DOWNBURST WINDS
WILL BE GREATEST AT THIS TIME. SHOWERS AND THUNDERSTORMS WILL CLEAR
FROM SOUTHWEST TO NORTHEAST AFTER 03Z SUN...WITH SOME SHOWERS
CONTINUING ACROSS THE NORTHEAST AND IN THE KCPR AREA THROUGH THE END
OF THE TAF PERIOD.
&&
.FIRE WEATHER...
PATCHY MORNING FOG WILL BE POSSIBLE ACROSS THE BIG HORN BASIN AND
JOHNSON COUNTY TODAY IN RESPONSE TO PREVIOUS RAIN SHOWERS. ANOTHER
ROUND OF THUNDERSTORMS WILL OCCUR THIS AFTERNOON...WITH THE PRIME
SPOT AGAIN BEING FOUND OVER THE BIG HORN BASIN AND JOHNSON COUNTY.
STORMS IN THESE AREAS MAY PRODUCE GUSTY WIND AND SMALL HAIL...WITH A
FEW STORMS BECOMING STRONG. ISOLATED THUNDERSTORMS EXPECTED
ELSEWHERE...WITH GUSTY WIND POSSIBLE. THIS UNSETTLED PATTERN
CONTINUES THROUGH THE WEEKEND. NORTHWEST FLOW WILL BEGIN TO MOVE
OVER WESTERN WYOMING MONDAY MORNING...THOUGH THUNDERSTORMS MAY AGAIN
BE FOUND ACROSS CENTRAL AND SOUTHERN WYOMING.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...ALLEN
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 180527 AAA
AFDRIW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
1127 PM MDT FRI MAY 17 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY
TODAY...MORNING LINGERING SHOWERS OVER THE WRN AND NWRN BORDER
REGIONS THIS MORNING GIVING WAY TO SHOWERS WITH SOME THUNDER RUNNING
DIAGONALLY FROM THE EVANSTON AREA NE TO SHERIDAN. LOOKS A BIT SPLIT
AS FAR AS HIGH TEMPS GO TOO...THE 70 DEG DEMARCATION LINE RUNS FROM
AROUND ROCK SPRINGS WY ON THE SOUTH TO JUST WEST OF LOVELL WYO ON
THE NORTH WITH 50 TO 60 DEG HIGHS PREVALENT ACROSS THE MOUNTAINS.
LOWER MID AND UPPER 70S TO NEAR 80 WILL BE COMMON EAST OF THIS LINE.
SPLIT SHORTWAVE ACTIVITY...ONE EXITING NEAR NWRN TO NRN WY WITH
ANOTHER JUST MOVING INTO THE STATE FROM THE SW. BEST INSTABILITY
SHOWING UP NEAR THE SOUTHERN BIG HORNS AND INTERSECTION WITH THE OWL
CREEK RANGE...BOTH ML AND SFC. LINE BETWEEN THERMOPOLIS AND
EDGERTON...INCLUDING SOME OF HOT SPRINGS...WASHAKIE...AND JOHNSON
COUNTIES... LOOKS TO HAVE THE BEST ABILITY TO PRODUCE SOMEWHAT
STRONGER CONVECTION LATER IN THE DAY AS LL MOISTURE AND CONVERGENCE
WILL BE MAXIMIZED HERE...IN ADDITION TO H85 TO H5 SHEAR OF 35 TO 40
KTS. POSSIBLE MARGINAL SEVERE WITH HALF TO THREE QUARTER INCH HAIL
AND STRONG OUTFLOW WINDS. ADDITIONALLY...BIG HORN COUNTY MAY ALSO
GET OUTFLOW DOMINATED LINE TYPE CONVECTION AS T-STORMS DEVELOPING
OFF THE ABSAROKA MOUNTAINS MOVE THROUGH. AFTERNOON DCAPE VALUES ARE
HOVERING BETWEEN 600 AND 700 J/KG FOR MOST AREAS...WHICH WILL PUT
THE CONVECTIVE ACTIVITY TODAY IN A NARROW MARGINALLY SEVERE
WIND...UP TO 55 MPH...CATEGORY THIS AFTERNOON. ELSEWHERE...PRECIP
MODE WILL BE WEAK TO MODERATELY CONVECTIVE WITH RELATIVELY LOW
INSTABILITIES...BUT THE ELEVATED TERRAIN TOGETHER WITH STRONGER JET
LEVEL WINDS NEAR 80KTS FLOWING OVER THIS PART OF THE CWA WILL BE THE
PREFERRED AREA FOR EARLY INITIATION TODAY.
WRN CONUS TROF BECOMING MORE NEGATIVELY TILTED TODAY THROUGH
TOMORROW. AS IT DOES...WE WILL LOSE MUCH OF THE UPPER LEVEL
SUPPORT/FLOW...SHIFTING OVER FAR EASTERN CWA. ALSO...CLOUD COVER AND
COOL MOIST CONDITIONS OVER WESTERN 3/4RDS OF FA WILL KEEP OVERALL
INSTABILITY ON THE LOW SIDE COMPARED WITH TODAY. JOHNSON COUNTY
HOWEVER WILL ONCE AGAIN HAVE THE BEST SHOT AT PRODUCING STRONGER
THUNDER SATURDAY. OTHERWISE...EXPECT SCATTERED SHOWERS AND ISOLATED
THUNDER OVER MOST AREAS...WITH LESS PRCIP AND AREAL COVERAGE OVER
THE SOUTH CENTRAL AND SOUTHWEST CWA.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
THE MAIN DIGGING NEGATIVELY TILTED TROUGH SHOULD BE OVER OUR CWA BY
SATURDAY NIGHT BEFORE CLOSING OFF BY 18Z SUNDAY. ON SATURDAY NIGHT
MOST OF THE PRECIP WILL BE CONFINED TO CENTRAL AND NORTHERN WYOMING.
THEN AS THE LOW CLOSES OFF OVER THE EASTERN HALF OF
WYOMING...MOISTURE AND COLD AIR WILL WRAP AROUND THE CLOSED LOW
SPREADING PRECIP INTO SOUTHERN WYOMING. THE COOLING TREND WILL
CONTINUE ON SUNDAY. H7 TEMPS WILL COOL DOWN TO BETWEEN -3 AND -4C IN
NW WYOMING BY SUNDAY WITH SNOW LEVELS GETTING DOWN TO 6500 FEET
THERE. ELSEWHERE...SNOW LEVELS SHOULD BE AROUND 8K. ON SUNDAY NIGHT
CYCLOGENESIS WILL TAKE PLACE AT H7 AND ABOVE OVER SOUTH DAKOTA WHICH
WILL DEEPEN THE NORTHERLY UPSLOPE FLOW EAST OF THE DIVIDE. THE
UPSLOPE COMPONENT WILL LOWER THE SNOW LEVEL DOWN TO 7500 FEET DUE TO
ADIABATIC COOLING ALONG THE EAST SLOPE OF THE WIND RIVER...ABSAROKA
AND BIG HORN MOUNTAINS SUNDAY NIGHT. CONVERSELY...SNOW LEVELS SHOULD
BE UP AS HIGH AS 9K ALONG THE WEST SLOPE OF THE WIND RIVER MTNS
SUNDAY NIGHT DUE TO DOWNSLOPE FLOW THERE. THESE SNOW LEVELS SHOULD
PERSIST THROUGH MONDAY WITH THE PRECIP BECOMING MORE STRATIFORM EAST
OF THE DIVIDE AS THE UPSLOPE DEEPENS. THE MOST SNOWFALL SHOULD FALL
ALONG THE EAST SLOPE OF THE WIND RIVER MTNS WHERE THE ORIENTATION OF
THE MOUNTAIN RANGE WILL BE BETTER SUITED TO FORCING THE NORTHERLY
FLOW INTO AN UPSLOPE COMPONENT WHERE AT LEAST 4 TO 5 INCHES OF SNOW
IS EXPECTED SUNDAY NIGHT INTO MONDAY. THE BIG HORN AND ABSAROKA MTNS
SHOULD SEE 2 TO 3 INCHES. ON MONDAY NIGHT THE PRECIP SHOULD START TO
WIND DOWN. ON TUESDAY A SHORT LIVED RIDGE OF HIGH PRESSURE WILL
PROVIDE A PRECIP FREE DAY AND SLIGHTLY MILDER TEMPS. THEN BY
WEDNESDAY A STRONG CLOSED LOW MIGRATING DOWN ALONG THE CANADIAN
PACIFIC COAST WILL SET UP SHOP OVER THE PACIFIC NORTHWEST. THE FIRST
SHORTWAVE THAT THIS CIRCULATION WILL EJECT TOWARD THE NORTHEAST WILL
PROVIDE A SHOT OF THUNDERSTORMS TO NW WYOMING FOR WEDNESDAY. A
SURFACE BASED SOUTHEAST FLOW PROVIDING AMPLE LOW LEVEL MOISTURE
COMBINING WITH INSTABILITY WILL RESULT IN THUNDERSTORM DEVELOPMENT
IN JOHNSON COUNTY AND THE BIG HORN MTNS AS WELL WEDNESDAY. THE NEXT
SUCH EJECTED SHORTWAVE WILL PROVIDE ANOTHER SHOT OF T STORMS FOR NW
WYOMING NEXT FRIDAY WITH SOUTHEAST SURFACE WINDS FEEDING LOW LEVEL
MOISTURE INTO JOHNSON COUNTY AND THE BIG HORN MOUNTAINS FOR
THUNDERSTORMS THERE AS WELL. THE SOUTHWEST STEERING FLOW OUT AHEAD
OF THIS CLOSED LOW IN THE PACIFIC NW WILL PROVIDE A WARMING TREND
FOR THE CWA THROUGH NEXT WEEK. THE EURO AND THE GFS BOTH SUPPORT
THIS TREND.
.AVIATION.../06Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA AS ANOTHER WAVE MOVES
OVERHEAD IN SOUTHWEST FLOW...KJAC KBPI AND KPNA WILL CONTINUE TO
BE IN AND OUT OF MVFR TO IFR CONDITIONS THROUGH THE MORNING WITH
WIDESPREAD MOUNTAIN OBSCURATIONS ONGOING. MVFR TO IFR CONDITIONS
ARE ALSO POSSIBLE ACROSS THE BIGHORN BASIN AND AT KBYG THROUGH THE
MORNING HOURS AS FOG BEGINS TO FORM IN LOCATIONS WHERE HEAVY RAIN
FELL WITH THE STORMS ON FRIDAY AFTERNOON.
SHOWERS AND SOME STORMS WILL INCREASE IN COVERAGE ACROSS THE
ENTIRE FORECAST AREA AFTER 18Z...SO WILL KEEP VCTS AND VCSH IN
FORECAST FOR ALL TERMINALS. THE HIGHEST BASED STORMS WILL BE VCNTY
KCPR BETWEEN 20Z SAT AND 02Z SUN...THE THREAT FOR DOWNBURST WINDS
WILL BE GREATEST AT THIS TIME.
.FIRE WEATHER...
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS CONTINUE TODAY AS ANOTHER
COUPLE UPPER LEVEL DISTURBANCES MOVE THROUGH THE REGION...ESPECIALLY
ACROSS THE WESTERN HALF OF THE CWA. THESE STORMS WILL PRESENT AT
TIMES...BRIEF STRONG ERRATIC WINDS...SMALL HAIL AND OCCASIONAL TO
FREQUENT LIGHTNING. AMBIENT WINDS WILL ALSO BECOME STRONG AND QUITE
GUSTY THIS AFTERNOON...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES...EAST OF A LINE FROM ROCK SPRINGS TO MUDDY GAP AND ON TO
CASPER. AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
SATURDAY AND SUNDAY...HOWEVER COOLER HIGH TEMPERATURES...MORE
MOISTURE IN THE AREA AND EXITING INSTABILITY - LESS CHANCES FOR
LIGHTNING SATURDAY AND SUNDAY - WILL LIMIT FIRE DANGERS THIS
WEEKEND AND INTO THE BEGINNING OF NEXT WEEK.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...ALLEN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 172159
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
359 PM MDT FRI MAY 17 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY
TODAY...MORNING LINGERING SHOWERS OVER THE WRN AND NWRN BORDER
REGIONS THIS MORNING GIVING WAY TO SHOWERS WITH SOME THUNDER RUNNING
DIAGONALLY FROM THE EVANSTON AREA NE TO SHERIDAN. LOOKS A BIT SPLIT
AS FAR AS HIGH TEMPS GO TOO...THE 70 DEG DEMARCATION LINE RUNS FROM
AROUND ROCK SPRINGS WY ON THE SOUTH TO JUST WEST OF LOVELL WYO ON
THE NORTH WITH 50 TO 60 DEG HIGHS PREVALENT ACROSS THE MOUNTAINS.
LOWER MID AND UPPER 70S TO NEAR 80 WILL BE COMMON EAST OF THIS LINE.
SPLIT SHORTWAVE ACTIVITY...ONE EXITING NEAR NWRN TO NRN WY WITH
ANOTHER JUST MOVING INTO THE STATE FROM THE SW. BEST INSTABILITY
SHOWING UP NEAR THE SOUTHERN BIG HORNS AND INTERSECTION WITH THE OWL
CREEK RANGE...BOTH ML AND SFC. LINE BETWEEN THERMOPOLIS AND
EDGERTON...INCLUDING SOME OF HOT SPRINGS...WASHAKIE...AND JOHNSON
COUNTIES... LOOKS TO HAVE THE BEST ABILITY TO PRODUCE SOMEWHAT
STRONGER CONVECTION LATER IN THE DAY AS LL MOISTURE AND CONVERGENCE
WILL BE MAXIMIZED HERE...IN ADDITION TO H85 TO H5 SHEAR OF 35 TO 40
KTS. POSSIBLE MARGINAL SEVERE WITH HALF TO THREE QUARTER INCH HAIL
AND STRONG OUTFLOW WINDS. ADDITIONALLY...BIG HORN COUNTY MAY ALSO
GET OUTFLOW DOMINATED LINE TYPE CONVECTION AS T-STORMS DEVELOPING
OFF THE ABSOROKA MOUNTAINS MOVE THROUGH. AFTERNOON DCAPE VALUES ARE
HOVERING BETWEEN 600 AND 700 J/KG FOR MOST AREAS...WHICH WILL PUT
THE CONVECTIVE ACTIVITY TODAY IN A NARROW MARGINALLY SEVERE
WIND...UP TO 55 MPH...CATEGORY THIS AFTERNOON. ELSEWHERE...PRECIP
MODE WILL BE WEAK TO MODERATELY CONVECTIVE WITH RELATIVELY LOW
INSTABILITIES...BUT THE ELEVATED TERRAIN TOGETHER WITH STRONGER JET
LEVEL WINDS NEAR 80KTS FLOWING OVER THIS PART OF THE CWA WILL BE THE
PREFERRED AREA FOR EARLY INITIATION TODAY.
WRN CONUS TROF BECOMING MORE NEGATIVELY TILTED TODAY THROUGH
TOMORROW. AS IT DOES...WE WILL LOSE MUCH OF THE UPPER LEVEL
SUPPORT/FLOW...SHIFTING OVER FAR EASTERN CWA. ALSO...CLOUD COVER AND
COOL MOIST CONDITIONS OVER WESTERN 3/4RDS OF FA WILL KEEP OVERALL
INSTABILITY ON THE LOW SIDE COMPARED WITH TODAY. JOHNSON COUNTY
HOWEVER WILL ONCE AGAIN HAVE THE BEST SHOT AT PRODUCING STRONGER
THUNDER SATURDAY. OTHERWISE...EXPECT SCATTERED SHOWERS AND ISOLATED
THUNDER OVER MOST AREAS...WITH LESS PRCIP AND AREAL COVERAGE OVER
THE SOUTH CENTRAL AND SOUTHWEST CWA.
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
THE MAIN DIGGING NEGATIVELY TILTED TROUGH SHOULD BE OVER OUR CWA BY
SATURDAY NIGHT BEFORE CLOSING OFF BY 18Z SUNDAY. ON SATURDAY NIGHT
MOST OF THE PRECIP WILL BE CONFINED TO CENTRAL AND NORTHERN WYOMING.
THEN AS THE LOW CLOSES OFF OVER THE EASTERN HALF OF
WYOMING...MOISTURE AND COLD AIR WILL WRAP AROUND THE CLOSED LOW
SPREADING PRECIP INTO SOUTHERN WYOMING. THE COOLING TREND WILL
CONTINUE ON SUNDAY. H7 TEMPS WILL COOL DOWN TO BETWEEN -3 AND -4C IN
NW WYOMING BY SUNDAY WITH SNOW LEVELS GETTING DOWN TO 6500 FEET
THERE. ELSEWHERE...SNOW LEVELS SHOULD BE AROUND 8K. ON SUNDAY NIGHT
CYCLOGENESIS WILL TAKE PLACE AT H7 AND ABOVE OVER SOUTH DAKOTA WHICH
WILL DEEPEN THE NORTHERLY UPSLOPE FLOW EAST OF THE DIVIDE. THE
UPSLOPE COMPONENT WILL LOWER THE SNOW LEVEL DOWN TO 7500 FEET DUE TO
ADIABATIC COOLING ALONG THE EAST SLOPE OF THE WIND RIVER...ABSAROKA
AND BIG HORN MOUNTAINS SUNDAY NIGHT. CONVERSELY...SNOW LEVELS SHOULD
BE UP AS HIGH AS 9K ALONG THE WEST SLOPE OF THE WIND RIVER MTNS
SUNDAY NIGHT DUE TO DOWNSLOPE FLOW THERE. THESE SNOW LEVELS SHOULD
PERSIST THROUGH MONDAY WITH THE PRECIP BECOMING MORE STRATIFORM EAST
OF THE DIVIDE AS THE UPSLOPE DEEPENS. THE MOST SNOWFALL SHOULD FALL
ALONG THE EAST SLOPE OF THE WIND RIVER MTNS WHERE THE ORIENTATION OF
THE MOUNTAIN RANGE WILL BE BETTER SUITED TO FORCING THE NORTHERLY
FLOW INTO AN UPSLOPE COMPONENT WHERE AT LEAST 4 TO 5 INCHES OF SNOW
IS EXPECTED SUNDAY NIGHT INTO MONDAY. THE BIG HORN AND ABSAROKA MTNS
SHOULD SEE 2 TO 3 INCHES. ON MONDAY NIGHT THE PRECIP SHOULD START TO
WIND DOWN. ON TUESDAY A SHORT LIVED RIDGE OF HIGH PRESSURE WILL
PROVIDE A PRECIP FREE DAY AND SLIGHTLY MILDER TEMPS. THEN BY
WEDNESDAY A STRONG CLOSED LOW MIGRATING DOWN ALONG THE CANADIAN
PACIFIC COAST WILL SET UP SHOP OVER THE PACIFIC NORTHWEST. THE FIRST
SHORTWAVE THAT THIS CIRCULATION WILL EJECT TOWARD THE NORTHEAST WILL
PROVIDE A SHOT OF THUNDERSTORMS TO NW WYOMING FOR WEDNESDAY. A
SURFACE BASED SOUTHEAST FLOW PROVIDING AMPLE LOW LEVEL MOISTURE
COMBINING WITH INSTABILITY WILL RESULT IN THUNDERSTORM DEVELOPMENT
IN JOHNSON COUNTY AND THE BIG HORN MTNS AS WELL WEDNESDAY. THE NEXT
SUCH EJECTED SHORTWAVE WILL PROVIDE ANOTHER SHOT OF T STORMS FOR NW
WYOMING NEXT FRIDAY WITH SOUTHEAST SURFACE WINDS FEEDING LOW LEVEL
MOISTURE INTO JOHNSON COUNTY AND THE BIG HORN MOUNTAINS FOR
THUNDERSTORMS THERE AS WELL. THE SOUTHWEST STEERING FLOW OUT AHEAD
OF THIS CLOSED LOW IN THE PACIFIC NW WILL PROVIDE A WARMING TREND
FOR THE CWA THROUGH NEXT WEEK. THE EURO AND THE GFS BOTH SUPPORT
THIS TREND.
&&
.AVIATION.../00Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA AS ANOTHER WAVE MOVES
OVERHEAD IN SOUTHWEST FLOW...KJAC HAS BEEN IN AND OUT OF MVFR TO IFR
CONDITIONS THROUGH THE MORNING WITH WIDESPREAD MOUNTAIN OBSCURATIONS
ONGOING. SOME CLEARING HAS TAKEN PLACE THIS MORNING AROUND KBPI AND
KPNA AS A RIDGE OF HIGH PRESSURE BATTLES THE TROF TO THE WEST.
TRICKY FORECAST AT KBPI AND KPNA AS THEY WILL LAY JUST ON THE
INFLECTION POINT BETWEEN THE TWO DIFFERING AIR MASSES.
HOWEVER...SHOWERS AND SOME STORMS WILL INCREASE IN COVERAGE AFTER
22Z...SO WILL KEEP VCTS AND VCSH IN FORECAST FOR THOSE TWO
TERMINALS. OTHERWISE...SHOWERS WILL CONTINUE ON AND OCCASIONALLY
OFF THROUGH THE TAF PERIOD AT KJAC AS A COLD FRONT PUSHES IN AND
STALLS IN ADDITION TO AN UPPER LEVEL SHORTWAVE MOVING OVERHEAD FOR MUCH OF
THE DAY.
AT ALL OTHER TERMINALS...SCATTERED CONVECTION IS EXPECTED TO RETURN
FROM NOW THROUGH THE EVENING TODAY EXCEPT KCPR AND KRKS WHERE MOSTLY
DRY SOUTHWEST WINDS COULD GUST AS HIGH AS 35 KTS IN THE AFTERNOON.
AN ISOLATED SHOWER OR TWO CANNOT BE RULED OUT NEAR KRKS IF THEY ARE
INITIATED OFF THE UNITAH MOUNTAINS. HOWEVER...OVERALL CONDITIONS ARE
NOT CONDUCIVE TO MAINTAINING THUNDERSTORMS FROM KRKS TO KCPR. STORMS
TODAY WILL FAVOR THE BIG HORN VALLEY AND ADJACENT MOUNTAINS...AND
THE WIND RIVER MOUNTAINS AND VALLEY SECONDLY. STORMS THAT DO FORM
WILL HAVE VERY GUSTY AND ERRATIC OUTFLOWS...ESPECIALLY FROM 18-00Z.
A COLD FRONT MOVES THROUGH FROM WEST TO EAST THROUGH THE FORECAST
PERIOD.
&&
.FIRE WEATHER...
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS CONTINUE TODAY AS ANOTHER
COUPLE UPPER LEVEL DISTURBANCES MOVE THROUGH THE REGION...ESPECIALLY
ACROSS THE WESTERN HALF OF THE CWA. THESE STORMS WILL PRESNT AT
TIMES...BRIEF STRONG ERRATIC WINDS...SMALL HAIL AND OCCASSIONAL TO
FREQUENT LIGHTNING. AMBIENT WINDS WILL ALSO BECOME STRONG AND QUITE
GUSTY THIS AFTERNOON...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES...EAST OF A LINE FROM ROCK SPRINGS TO MUDDY GAP AND ONE TO
CASPER. AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
SATURDAY AND SUNDAY...HOWEVER COOLER HIGH TEMPERATURES...MOSRE
MOISTURE IN THE AREA AND EXITING INSTABILITY - LESS CHANCES FOR
LIGHTNING SATURDAY AND SUNDAY - WILL LIMIT FIRE DANGERS THIS WEEKEND
AND INTO THE BEGINNING OF NEXT WEEK.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...BRAUN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 172143
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
343 PM MDT FRI MAY 17 2013
.SHORT TERM...TONIGHT THROUGH SATURDAY
TODAY...MORNING LINGERING SHOWERS OVER THE WRN AND NWRN BORDER
REGIONS THIS MORNING GIVING WAY TO SHOWERS WITH SOME THUNDER RUNNING
DIAGONALLY FROM THE EVANSTON AREA NE TO SHERIDAN. LOOKS A BIT SPLIT
AS FAR AS HIGH TEMPS GO TOO...THE 70 DEG DEMARCATION LINE RUNS FROM
AROUND ROCK SPRINGS WY ON THE SOUTH TO JUST WEST OF LOVELL WYO ON
THE NORTH WITH 50 TO 60 DEG HIGHS PREVALENT ACROSS THE MOUNTAINS.
LOWER MID AND UPPER 70S TO NEAR 80 WILL BE COMMON EAST OF THIS LINE.
SPLIT SHORTWAVE ACTIVITY...ONE EXITING NEAR NWRN TO NRN WY WITH
ANOTHER JUST MOVING INTO THE STATE FROM THE SW. BEST INSTABILITY
SHOWING UP NEAR THE SOUTHERN BIG HORNS AND INTERSECTION WITH THE OWL
CREEK RANGE...BOTH ML AND SFC. LINE BETWEEN THERMOPOLIS AND
EDGERTON...INCLUDING SOME OF HOT SPRINGS...WASHAKIE...AND JOHNSON
COUNTIES... LOOKS TO HAVE THE BEST ABILITY TO PRODUCE SOMEWHAT
STRONGER CONVECTION LATER IN THE DAY AS LL MOISTURE AND CONVERGENCE
WILL BE MAXIMIZED HERE...IN ADDITION TO H85 TO H5 SHEAR OF 35 TO 40
KTS. POSSIBLE MARGINAL SEVERE WITH HALF TO THREE QUARTER INCH HAIL
AND STRONG OUTFLOW WINDS. ADDITIONALLY...BIG HORN COUNTY MAY ALSO
GET OUTFLOW DOMINATED LINE TYPE CONVECTION AS T-STORMS DEVELOPING
OFF THE ABSOROKA MOUNTAINS MOVE THROUGH. AFTERNOON DCAPE VALUES ARE
HOVERING BETWEEN 600 AND 700 J/KG FOR MOST AREAS...WHICH WILL PUT
THE CONVECTIVE ACTIVITY TODAY IN A NARROW MARGINALLY SEVERE
WIND...UP TO 55 MPH...CATEGORY THIS AFTERNOON. ELSEWHERE...PRECIP
MODE WILL BE WEAK TO MODERATELY CONVECTIVE WITH RELATIVELY LOW
INSTABILITIES...BUT THE ELEVATED TERRAIN TOGETHER WITH STRONGER JET
LEVEL WINDS NEAR 80KTS FLOWING OVER THIS PART OF THE CWA WILL BE THE
PREFERRED AREA FOR EARLY INITIATION TODAY.
WRN CONUS TROF BECOMING MORE NEGATIVELY TILTED TODAY THROUGH
TOMORROW. AS IT DOES...WE WILL LOSE MUCH OF THE UPPER LEVEL
SUPPORT/FLOW...SHIFTING OVER FAR EASTERN CWA. ALSO...CLOUD COVER AND
COOL MOIST CONDITIONS OVER WESTERN 3/4RDS OF FA WILL KEEP OVERALL
INSTABILITY ON THE LOW SIDE COMPARED WITH TODAY. JOHNSON COUNTY
HOWEVER WILL ONCE AGAIN HAVE THE BEST SHOT AT PRODUCING STRONGER
THUNDER SATURDAY. OTHERWISE...EXPECT SCATTERED SHOWERS AND ISOLATED
THUNDER OVER MOST AREAS...WITH LESS PRECIP AND AREAL COVERAGE OVER
THE SOUTH CENTRAL AND SOUTHWEST CWA.
.LONG TERM...XXX THROUGH XXX
THE MAIN DIGGING NEGATIVELY TILTED TROUGH SHOULD BE OVER OUR CWA BY
SATURDAY NIGHT BEFORE CLOSING OFF BY 18Z SUNDAY. ON SATURDAY NIGHT
MOST OF THE PRECIP WILL BE CONFINED TO CENTRAL AND NORTHERN WYOMING.
THEN AS THE LOW CLOSES OFF OVER THE EASTERN HALF OF
WYOMING...MOISTURE AND COLD AIR WILL WRAP AROUND THE CLOSED LOW
SPREADING PRECIP INTO SOUTHERN WYOMING. THE COOLING TREND WILL
CONTINUE ON SUNDAY. H7 TEMPS WILL COOL DOWN TO BETWEEN -3 AND -4C IN
NW WYOMING BY SUNDAY WITH SNOW LEVELS GETTING DOWN TO 6500 FEET
THERE. ELSEWHERE...SNOW LEVELS SHOULD BE AROUND 8K. ON SUNDAY NIGHT
CYCLOGENESIS WILL TAKE PLACE AT H7 AND ABOVE OVER SOUTH DAKOTA WHICH
WILL DEEPEN THE NORTHERLY UPSLOPE FLOW EAST OF THE DIVIDE. THE
UPSLOPE COMPONENT WILL LOWER THE SNOW LEVEL DOWN TO 7500 FEET DUE TO
ADIABATIC COOLING ALONG THE EAST SLOPE OF THE WIND RIVER...ABSAROKA
AND BIG HORN MOUNTAINS SUNDAY NIGHT. CONVERSELY...SNOW LEVELS SHOULD
BE UP AS HIGH AS 9K ALONG THE WEST SLOPE OF THE WIND RIVER MTNS
SUNDAY NIGHT DUE TO DOWNSLOPE FLOW THERE. THESE SNOW LEVELS SHOULD
PERSIST THROUGH MONDAY WITH THE PRECIP BECOMING MORE STRATIFORM EAST
OF THE DIVIDE AS THE UPSLOPE DEEPENS. THE MOST SNOWFALL SHOULD FALL
ALONG THE EAST SLOPE OF THE WIND RIVER MTNS WHERE THE ORIENTATION OF
THE MOUNTAIN RANGE WILL BE BETTER SUITED TO FORCING THE NORTHERLY
FLOW INTO AN UPSLOPE COMPONENT WHERE AT LEAST 4 TO 5 INCHES OF SNOW
IS EXPECTED SUNDAY NIGHT INTO MONDAY. THE BIG HORN AND ABSAROKA MTNS
SHOULD SEE 2 TO 3 INCHES. ON MONDAY NIGHT THE PRECIP SHOULD START TO
WIND DOWN. ON TUESDAY A SHORT LIVED RIDGE OF HIGH PRESSURE WILL
PROVIDE A PRECIP FREE DAY AND SLIGHTLY MILDER TEMPS. THEN BY
WEDNESDAY A STRONG CLOSED LOW MIGRATING DOWN ALONG THE CANADIAN
PACIFIC COAST WILL SET UP SHOP OVER THE PACIFIC NORTHWEST. THE FIRST
SHORTWAVE THAT THIS CIRCULATION WILL EJECT TOWARD THE NORTHEAST WILL
PROVIDE A SHOT OF THUNDERSTORMS TO NW WYOMING FOR WEDNESDAY. A
SURFACE BASED SOUTHEAST FLOW PROVIDING AMPLE LOW LEVEL MOISTURE
COMBINING WITH INSTABILITY WILL RESULT IN THUNDERSTORM DEVELOPMENT
IN JOHNSON COUNTY AND THE BIG HORN MTNS AS WELL WEDNESDAY. THE NEXT
SUCH EJECTED SHORTWAVE WILL PROVIDE ANOTHER SHOT OF T STORMS FOR NW
WYOMING NEXT FRIDAY WITH SOUTHEAST SURFACE WINDS FEEDING LOW LEVEL
MOISTURE INTO JOHNSON COUNTY AND THE BIG HORN MOUNTAINS FOR
THUNDERSTORMS THERE AS WELL. THE SOUTHWEST STEERING FLOW OUT AHEAD
OF THIS CLOSED LOW IN THE PACIFIC NW WILL PROVIDE A WARMING TREND
FOR THE CWA THROUGH NEXT WEEK. THE EURO AND THE GFS BOTH SUPPORT
THIS TREND.
&&
.AVIATION.../00Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA AS ANOTHER WAVE MOVES
OVERHEAD IN SOUTHWEST FLOW...KJAC HAS BEEN IN AND OUT OF MVFR TO IFR
CONDITIONS THROUGH THE MORNING WITH WIDESPREAD MOUNTAIN OBSCURATIONS
ONGOING. SOME CLEARING HAS TAKEN PLACE THIS MORNING AROUND KBPI AND
KPNA AS A RIDGE OF HIGH PRESSURE BATTLES THE TROF TO THE WEST.
TRICKY FORECAST AT KBPI AND KPNA AS THEY WILL LAY JUST ON THE
INFLECTION POINT BETWEEN THE TWO DIFFERING AIR MASSES.
HOWEVER...SHOWERS AND SOME STORMS WILL INCREASE IN COVERAGE AFTER
22Z...SO WILL KEEP VCTS AND VCSH IN FORECAST FOR THOSE TWO
TERMINALS. OTHERWISE...SHOWERS WILL CONTINUE ON AND OCCASIONALLY
OFF THROUGH THE TAF PERIOD AT KJAC AS A COLD FRONT PUSHES IN AND
STALLS IN ADDITION TO AN UPPER LEVEL SHORTWAVE MOVING OVERHEAD FOR MUCH OF
THE DAY.
AT ALL OTHER TERMINALS...SCATTERED CONVECTION IS EXPECTED TO RETURN
FROM NOW THROUGH THE EVENING TODAY EXCEPT KCPR AND KRKS WHERE MOSTLY
DRY SOUTHWEST WINDS COULD GUST AS HIGH AS 35 KTS IN THE AFTERNOON.
AN ISOLATED SHOWER OR TWO CANNOT BE RULED OUT NEAR KRKS IF THEY ARE
INITIATED OFF THE UNITAH MOUNTAINS. HOWEVER...OVERALL CONDITIONS ARE
NOT CONDUCIVE TO MAINTAINING THUNDERSTORMS FROM KRKS TO KCPR. STORMS
TODAY WILL FAVOR THE BIG HORN VALLEY AND ADJACENT MOUNTAINS...AND
THE WIND RIVER MOUNTAINS AND VALLEY SECONDLY. STORMS THAT DO FORM
WILL HAVE VERY GUSTY AND ERRATIC OUTFLOWS...ESPECIALLY FROM 18-00Z.
A COLD FRONT MOVES THROUGH FROM WEST TO EAST THROUGH THE FORECAST
PERIOD.
&&
.FIRE WEATHER...
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS CONTINUE TODAY AS ANOTHER
COUPLE UPPER LEVEL DISTURBANCES MOVE THROUGH THE REGION...ESPECIALLY
ACROSS THE WESTERN HALF OF THE CWA. THESE STORMS WILL PRESNT AT
TIMES...BRIEF STRONG ERRATIC WINDS...SMALL HAIL AND OCCASIONAL TO
FREQUENT LIGHTNING. AMBIENT WINDS WILL ALSO BECOME STRONG AND QUITE
GUSTY THIS AFTERNOON...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES...EAST OF A LINE FROM ROCK SPRINGS TO MUDDY GAP AND ONE TO
CASPER. AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
SATURDAY AND SUNDAY...HOWEVER COOLER HIGH TEMPERATURES...MORE
MOISTURE IN THE AREA AND EXITING INSTABILITY - LESS CHANCES FOR
LIGHTNING SATURDAY AND SUNDAY - WILL LIMIT FIRE DANGERS THIS WEEKEND
AND INTO THE BEGINNING OF NEXT WEEK.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...BRAUN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 171731
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 AM MDT FRI MAY 17 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
SHOWERS CONTINUE TO MOVE ACROSS PORTIONS OF THE FORECAST AREA THIS
MORNING. LINGERING SHOWER ACTIVITY IS EXPECTED THROUGH THE MORNING
HOURS.
AN APPROACHING TROUGH OF LOW PRESSURE WILL MOVE INTO THE
INTERMOUNTAIN WEST BY THE AFTERNOON HOURS. THIS WILL STRENGTHEN
SOUTHWEST FLOW OVER THE AREA...INCREASE INSTABILITY...AND INTRODUCE
ANOTHER ROUND OF MOISTURE TO THE AREA. THIS COMBINATION WILL RESULT
IN SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH OF WESTERN
WYOMING TODAY. COVERAGE OF THUNDERSTORMS WILL NOT BE AS MUCH AS WHAT
WAS EXPERIENCED ON THURSDAY...BUT MODELS DID PUSH MOISTURE A BIT
FURTHER EAST. MODIFICATIONS WERE MADE TO CENTRAL WYOMING INITIATE
SHOWER ACTIVITY A BIT EARLIER IN THE AFTERNOON THAN WAS PREVIOUSLY
FORECAST. THUNDERSTORMS MAY AGAIN CONTAIN GUSTY WIND...AND SOME
STORMS MAY HAVE PERIODS OF HEAVY RAINFALL. THUNDERSTORM ACTIVITY IS
EXPECTED TO WEAKEN WITH THE LOSS OF DAYLIGHT.
THE AFOREMENTIONED TROUGH WILL CONTINUE ITS EASTWARD PROGRESSION ON
SATURDAY...WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. COOLER
TEMPERATURES ASSOCIATED WITH THIS TROUGH WILL BEGIN TO IMPACT THE
AREA LATE SATURDAY MORNING...ESPECIALLY ACROSS THE WEST AND SOUTH.
EVEN WITH THESE COOLER TEMPERATURES...SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE FOUND ACROSS MUCH OF THE AREA.
MODELS VARY SLIGHTLY AT THE PROGRESSION OF THE TROUGH ONCE IT MOVES
FURTHER INTO WYOMING ON SUNDAY. THE NAM CREATES A CLOSED LOW OVER
NORTHEASTERN WYOMING BY SUNDAY AFTERNOON...WITH MOST OTHER MODELS
KEEPING THE SYSTEM AS AN OPEN WAVE. REGARDLESS...TEMPERATURES WILL
COOL FURTHER ON SUNDAY AS THE TROUGH AXIS MOVES THROUGH THE STATE.
THUNDERSTORMS WILL AGAIN BE POSSIBLE ON SUNDAY AFTERNOON...THOUGH
PERIODS OF RAINFALL ARE ANTICIPATED THROUGH MUCH OF THE WEEKEND.
.LONG TERM...MONDAY THROUGH FRIDAY
A NEARLY STATIONARY UPPER LOW ACROSS EASTERN SOUTH DAKOTA/NEBRASKA
AND A SHORTWAVE DIVING SOUTHEAST ACROSS UTAH INTO THE FOUR CORNERS
AREA WILL COMBINE FOR A COOL AND INCLEMENT DAY MONDAY INTO MONDAY
NIGHT. THIS WILL BE ESPECIALLY TRUE IN FAVORED UPSLOPE AREAS EAST OF
THE DIVIDE...WITH MODELS SHOWING NORTHERLY FLOW IN THE LOW AND MID
LEVELS OF THE ATMOSPHERE. HAVE COOLED TEMPERATURES DOWN
MONDAY...ESPECIALLY IN FAVORED UPSLOPE REGIONS WHERE PRECIPITATION
COULD OCCUR FOR MUCH OF THE DAY. 700MB TEMPERATURES ARE EXPECTED TO
BE -1C TO -3C EAST...AND -1C TO +1C WEST MONDAY. THESE TEMPERATURES
TRANSLATE ROUGHLY TO SNOW DOWN TO AROUND 7500 FT EAST...AND 8500
FT WEST. FAVORED UPSLOPE AREAS EAST OF THE DIVIDE COULD SEE SNOW
DOWN TO AROUND 6500 FEET. COULD BE CLOSE TO WINTER WEATHER
ADVISORY SNOW AMOUNTS FOR EASTERN WIND RIVER MTS AND/OR CASPER
MOUNTAIN.
GLOBAL MODELS THEN DIVERGE SIGNIFICANTLY ON HOW QUICKLY TO END THE
PRECIPITATION ACROSS THE REGION. THE 00Z GFS SHUTS OF THE PRECIP
EARLY MONDAY NIGHT...WHILE THE ECMWF CONTINUES TO KEEP PRECIPITATION
ONGOING ACROSS THE EXTREME EAST THROUGH THE DAY TUESDAY...WITH THE
GEM IN BETWEEN THE TWO...BUT LEANING MORE TOWARD THE ECMWF. WILL
HAVE SOME POPS TUESDAY...ESPECIALLY EAST TO RESPECT THE SLOWER ECMWF
SOLUTION.
UPSTREAM...A STRONG UPPER LOW WILL BE MOVING INTO THE PACIFIC
NORTHWEST TUESDAY. GLOBAL MODELS SHOW THIS STRONG UPPER LOW
REMAINING NEARLY STATIONARY ACROSS THE PACIFIC NORTHWEST THROUGH AT
THURSDAY. THIS WILL RESULT IN INCREASING SOUTH/SOUTHWESTERLY FLOW
AND WARMER TEMPERATURES WEDNESDAY AND THURSDAY. THE ECMWF AND GFS
SHOW A DISTINCT SHORTWAVE TROUGH PUSHING NORTHWARD ACROSS IDAHO AND
WESTERN MONTANA WEDNESDAY/WEDNESDAY NIGHT. THE ENERGY ASSOCIATED
WITH THIS SYSTEM COULD ALLOW FOR ISOLATED TO SCATTERED CONVECTION
ACROSS MUCH OF THE AREA...BUT ESPECIALLY OVER THE NORTHWEST. A COLD
FRONT ASSOCIATED WITH THIS STRONG SHORTWAVE IS EXPECTED TO PUSH INTO
THE WEST/NORTHWEST LATE WEDNESDAY/WEDNESDAY NIGHT...BUT QUICKLY
RETREAT BACK NORTHWEST DURING THE DAY THURSDAY.
THE MAIN UPPER LOW/TROUGH IS EXPECTED TO REMAIN WEST OF THE FORECAST
AREA THURSDAY AND FRIDAY WITH CONTINUED SOUTHERLY FLOW...AND A CHANCE
OF MAINLY AFTERNOON/EVENING CONVECTION...BUT WILL KEEP CONVECTION
MAINLY CONFINED TO THE MOUNTAINS FOR NOW.
&&
.AVIATION.../18Z ISSUANCE/
SHOWERS CONTINUE ACROSS THE WEST TERMINAL AREA AS ANOTHER WAVE MOVES
OVERHEAD IN SOUTHWEST FLOW...KJAC HAS BEEN IN AND OUT OF MVFR TO IFR
CONDITIONS THROUGH THE MORNING WITH WIDESPREAD MOUNTAIN OBSCURATIONS
ONGOING. SOME CLEARING HAS TAKEN PLACE THIS MORNING AROUND KBPI AND
KPNA AS A RIDGE OF HIGH PRESSURE BATTLES THE TROF TO THE WEST.
TRICKY FORECAST AT KBPI AND KPNA AS THEY WILL LAY JUST ON THE
INFLECTION POINT BETWEEN THE TWO DIFFERING AIR MASSES.
HOWEVER...SHOWERS AND SOME STORMS WILL INCREASE IN COVERAGE AFTER
22Z...SO WILL KEEP VCTS AND VCSH IN FORECAST FOR THOSE TWO
TERMINALS. OTHERWISE...SHOWERS WILL CONTINUE ON AND OCCASIONALLY
OFF THROUGH THE TAF PERIOD AT KJAC AS A COLD FRONT PUSHES IN AND
STALLS IN ADDITION TO AN UPPER LEVEL SHORTWAVE MOVING OVERHEAD FOR
MUCH OF THE DAY.
AT ALL OTHER TERMINALS...SCATTERED CONVECTION IS EXPECTED TO RETURN
FROM NOW THROUGH THE EVENING TODAY EXCEPT KCPR AND KRKS WHERE MOSTLY
DRY SOUTHWEST WINDS COULD GUST AS HIGH AS 35 KTS IN THE AFTERNOON.
AN ISOLATED SHOWER OR TWO CANNOT BE RULED OUT NEAR KRKS IF THEY ARE
INITIATED OFF THE UNITAH MOUNTAINS. HOWEVER...OVERALL CONDITIONS ARE
NOT CONDUCIVE TO MAINTAINING THUNDERSTORMS FROM KRKS TO KCPR. STORMS
TODAY WILL FAVOR THE BIG HORN VALLEY AND ADJACENT MOUNTAINS...AND
THE WIND RIVER MOUNTAINS AND VALLEY SECONDLY. STORMS THAT DO FORM
WILL HAVE VERY GUSTY AND ERRATIC OUTFLOWS...ESPECIALLY FROM 18-00Z.
A COLD FRONT MOVES THROUGH FROM WEST TO EAST THROUGH THE FORECAST
PERIOD.
&&
.FIRE WEATHER...
AN APPROACHING AREA OF LOW PRESSURE WILL MOVE INTO THE INTERMOUNTAIN
WEST TODAY. THIS SYSTEM WILL SPREAD SHOWER AND THUNDERSTORM ACTIVITY
ACROSS THE WESTERN HALF OF THE STATE BY THE AFTERNOON HOURS...WITH
COVERAGE INCREASING TO INCLUDE MUCH OF THE FORECAST AREA BY THIS
EVENING. AS THE AREA OF LOW PRESSURE APPROACHES...EXPECT INCREASES
IN DAYTIME HUMIDITY...AND COOLER TEMPERATURES ACROSS THE AREA.
PERIODS OF GUSTY WIND WILL ALSO BE POSSIBLE...ESPECIALLY THIS
AFTERNOON. ANY THUNDERSTORM ACTIVITY MAY RESULT IN GUSTY AND ERRATIC
WIND...ALONG WITH BRIEF PERIODS OF HEAVY RAIN. THE AREA OF LOW
PRESSURE WILL HAVE A FIRM GRIP ON THE FORECAST AREA BY SUNDAY
AFTERNOON...WITH WIDESPREAD SHOWER ACTIVITY AND CONTINUED COOLING
TEMPERATURES.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...ALLEN
AVIATION...BRAUN
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 170941
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
341 AM MDT FRI MAY 17 2013
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
SHOWERS CONTINUE TO MOVE ACROSS PORTIONS OF THE FORECAST AREA THIS
MORNING. LINGERING SHOWER ACTIVITY IS EXPECTED THROUGH THE MORNING
HOURS.
AN APPROACHING TROUGH OF LOW PRESSURE WILL MOVE INTO THE
INTERMOUNTAIN WEST BY THE AFTERNOON HOURS. THIS WILL STRENGTHEN
SOUTHWEST FLOW OVER THE AREA...INCREASE INSTABILITY...AND INTRODUCE
ANOTHER ROUND OF MOISTURE TO THE AREA. THIS COMBINATION WILL RESULT
IN SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH OF WESTERN
WYOMING TODAY. COVERAGE OF THUNDERSTORMS WILL NOT BE AS MUCH AS WHAT
WAS EXPERIENCED ON THURSDAY...BUT MODELS DID PUSH MOISTURE A BIT
FURTHER EAST. MODIFICATIONS WERE MADE TO CENTRAL WYOMING INITIATE
SHOWER ACTIVITY A BIT EARLIER IN THE AFTERNOON THAN WAS PREVIOUSLY
FORECAST. THUNDERSTORMS MAY AGAIN CONTAIN GUSTY WIND...AND SOME
STORMS MAY HAVE PERIODS OF HEAVY RAINFALL. THUNDERSTORM ACTIVITY IS
EXPECTED TO WEAKEN WITH THE LOSS OF DAYLIGHT.
THE AFOREMENTIONED TROUGH WILL CONTINUE ITS EASTWARD PROGRESSION ON
SATURDAY...WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. COOLER
TEMPERATURES ASSOCIATED WITH THIS TROUGH WILL BEGIN TO IMPACT THE
AREA LATE SATURDAY MORNING...ESPECIALLY ACROSS THE WEST AND SOUTH.
EVEN WITH THESE COOLER TEMPERATURES...SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE FOUND ACROSS MUCH OF THE AREA.
MODELS VARY SLIGHTLY AT THE PROGRESSION OF THE TROUGH ONCE IT MOVES
FURTHER INTO WYOMING ON SUNDAY. THE NAM CREATES A CLOSED LOW OVER
NORTHEASTERN WYOMING BY SUNDAY AFTERNOON...WITH MOST OTHER MODELS
KEEPING THE SYSTEM AS AN OPEN WAVE. REGARDLESS...TEMPERATURES WILL
COOL FURTHER ON SUNDAY AS THE TROUGH AXIS MOVES THROUGH THE STATE.
THUNDERSTORMS WILL AGAIN BE POSSIBLE ON SUNDAY AFTERNOON...THOUGH
PERIODS OF RAINFALL ARE ANTICIPATED THROUGH MUCH OF THE WEEKEND.
.LONG TERM...MONDAY THROUGH FRIDAY
A NEARLY STATIONARY UPPER LOW ACROSS EASTERN SOUTH DAKOTA/NEBRASKA
AND A SHORTWAVE DIVING SOUTHEAST ACROSS UTAH INTO THE FOUR CORNERS
AREA WILL COMBINE FOR A COOL AND INCLEMENT DAY MONDAY INTO MONDAY
NIGHT. THIS WILL BE ESPECIALLY TRUE IN FAVORED UPSLOPE AREAS EAST OF
THE DIVIDE...WITH MODELS SHOWING NORTHERLY FLOW IN THE LOW AND MID
LEVELS OF THE ATMOSPHERE. HAVE COOLED TEMPERATURES DOWN
MONDAY...ESPECIALLY IN FAVORED UPSLOPE REGIONS WHERE PRECIPITATION
COULD OCCUR FOR MUCH OF THE DAY. 700MB TEMPERATURES ARE EXPECTED TO
BE -1C TO -3C EAST...AND -1C TO +1C WEST MONDAY. THESE TEMPERATURES
TRANSLATE ROUGHLY TO SNOW DOWN TO AROUND 7500 FT EAST...AND 8500
FT WEST. FAVORED UPSLOPE AREAS EAST OF THE DIVIDE COULD SEE SNOW
DOWN TO AROUND 6500 FEET. COULD BE CLOSE TO WINTER WEATHER
ADVISORY SNOW AMOUNTS FOR EASTERN WIND RIVER MTS AND/OR CASPER
MOUNTAIN.
GLOBAL MODELS THEN DIVERGE SIGNIFICANTLY ON HOW QUICKLY TO END THE
PRECIPITATION ACROSS THE REGION. THE 00Z GFS SHUTS OF THE PRECIP
EARLY MONDAY NIGHT...WHILE THE ECMWF CONTINUES TO KEEP PRECIPITATION
ONGOING ACROSS THE EXTREME EAST THROUGH THE DAY TUESDAY...WITH THE
GEM IN BETWEEN THE TWO...BUT LEANING MORE TOWARD THE ECMWF. WILL
HAVE SOME POPS TUESDAY...ESPECIALLY EAST TO RESPECT THE SLOWER ECMWF
SOLUTION.
UPSTREAM...A STRONG UPPER LOW WILL BE MOVING INTO THE PACIFIC
NORTHWEST TUESDAY. GLOBAL MODELS SHOW THIS STRONG UPPER LOW
REMAINING NEARLY STATIONARY ACROSS THE PACIFIC NORTHWEST THROUGH AT
THURSDAY. THIS WILL RESULT IN INCREASING SOUTH/SOUTHWESTERLY FLOW
AND WARMER TEMPERATURES WEDNESDAY AND THURSDAY. THE ECMWF AND GFS
SHOW A DISTINCT SHORTWAVE TROUGH PUSHING NORTHWARD ACROSS IDAHO AND
WESTERN MONTANA WEDNESDAY/WEDNESDAY NIGHT. THE ENERGY ASSOCIATED
WITH THIS SYSTEM COULD ALLOW FOR ISOLATED TO SCATTERED CONVECTION
ACROSS MUCH OF THE AREA...BUT ESPECIALLY OVER THE NORTHWEST. A COLD
FRONT ASSOCIATED WITH THIS STRONG SHORTWAVE IS EXPECTED TO PUSH INTO
THE WEST/NORTHWEST LATE WEDNESDAY/WEDNESDAY NIGHT...BUT QUICKLY
RETREAT BACK NORTHWEST DURING THE DAY THURSDAY.
THE MAIN UPPER LOW/TROUGH IS EXPECTED TO REMAIN WEST OF THE FORECAST
AREA THURSDAY AND FRIDAY WITH CONTINUED SOUTHERLY FLOW...AND A CHANCE
OF MAINLY AFTERNOON/EVENING CONVECTION...BUT WILL KEEP CONVECTION
MAINLY CONFINED TO THE MOUNTAINS FOR NOW.
&&
.AVIATION.../12Z ISSUANCE/
SHOWERS WILL CONTINUE ACROSS THE WEST AS ANOTHER WAVE APPROACHES IN
THE SOUTHWEST FLOW...OCCNL MVFR TO IFR CONDITIONS WITH WIDESPREAD
MOUNTAIN OBSCURATIONS POSSIBLE AROUND KJAC...KBPI AND KPNA THROUGH
15Z. SOME CLEARING IS POSSIBLE LATE MORNING AS A RIDGE TRIES TO
BUILD IN FROM THE SOUTH. SHOWERS AND STORMS INCREASE IN COVERAGE
AFTER 18Z. SHOWERS WILL CONTINUE THROUGH THE TAF PERIOD AS A COLD
FRONT FINALLY PUSHES EAST AFTER STALLING OUT VCNTY KJAC FOR MUCH OF
THE DAY.
ELSEWHERE...SCATTERED CONVECTION IS EXPECTED TO RETURN AFTER 18Z
TOMORROW AT ALL TERMINALS EXCEPT KCPR AND KRKS WHERE VERY DRY
SOUTHWEST WINDS COULD GUST AS HIGH AS 30 KTS IN THE AFTERNOON...BUT
AN ISOLATED SHOWER OR TWO CANNOT BE RULED OUT. THE MID LEVEL
MOISTURE ACROSS THE BIGHORN AND WIND RIVER BASINS SHOULD WORK TO
OVERCOME THE DRY LOWER LEVELS...BUT ANY STORMS THAT DO FORM WILL
HAVE VERY GUSTY AND ERRATIC OUTFLOWS...ESPECIALLY FROM 18-00Z. A
COLD FRONT MOVES THROUGH FROM WEST TO EAST FROM 00Z...EXITING KCPR
TOWARD THE END OF THE TAF PERIOD.
&&
.FIRE WEATHER...
AN APPROACHING AREA OF LOW PRESSURE WILL MOVE INTO THE INTERMOUNTAIN
WEST TODAY. THIS SYSTEM WILL SPREAD SHOWER AND THUNDERSTORM ACTIVITY
ACROSS THE WESTERN HALF OF THE STATE BY THE AFTERNOON HOURS...WITH
COVERAGE INCREASING TO INCLUDE MUCH OF THE FORECAST AREA BY THIS
EVENING. AS THE AREA OF LOW PRESSURE APPROACHES...EXPECT INCREASES
IN DAYTIME HUMIDITY...AND COOLER TEMPERATURES ACROSS THE AREA.
PERIODS OF GUSTY WIND WILL ALSO BE POSSIBLE...ESPECIALLY THIS
AFTERNOON. ANY THUNDERSTORM ACTIVITY MAY RESULT IN GUSTY AND ERRATIC
WIND...ALONG WITH BRIEF PERIODS OF HEAVY RAIN. THE AREA OF LOW
PRESSURE WILL HAVE A FIRM GRIP ON THE FORECAST AREA BY SUNDAY
AFTERNOON...WITH WIDESPREAD SHOWER ACTIVITY AND CONTINUED COOLING
TEMPERATURES.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...ALLEN
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 170526 AAA
AFDRIW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
1126 PM MDT THU MAY 16 2013
.SHORT TERM...TONIGHT THROUGH FRIDAY
WV IMAGERY SHOWING AMPLIFYING TROF NEAR THE EPAC COASTAL REGION. AS
TROF CONTINUES TO AMPLIFY THERE WILL BE SEVERAL CHANCES FOR SHORT
WAVE/JET STREAK ENHANCEMENT AHEAD OF THE SLOW MOVING TROF TO MAKE
THEIR WAY INTO AT LEAST THE WRN TO NWRN PORTION OF OUR CWA. MORNING
CONVECTION...ASSOCIATED WITH ONE OF THESE UPPER SPEED MAXES...MOVED
IN FROM SERN ID AFFECTING THE AFTON AREA...AND ALL AFTER THEY WERE
MILDLY ROCKED BY A 3.6 EARTHQUAKE LAST NIGHT. ANOTHER ONE OF THESE
VORT MAXES HAS BEGUN TO INFLUENCE OUR FORECAST AREA THIS AFTERNOON
WITH STRONG HIGH BASED THUNDERSTORMS THAT DEVELOPED IN THE LEE OF
THE WIND RIVER MOUNTAINS AND BLEW THROUGH LANDER AND RIVERTON
BETWEEN 0100 AND 0130 PM. LATER THIS EVENING AND
TONIGHT...ESPECIALLY THE NWRN QUAD INCLUDING THE TETON AND
YELLOWSTONE REGIONS...EXPECT SHOWERS TO CONTINUE THROUGH THE NIGHT.
OVERALL INSTABILITY IS IS FAIRLY LOW WITH MIXED LAYER CAPE AOBL 100
J/KG MOST PLACES EXCEPT HIGHER TERRAIN OF BIG HORNS...AND TO A
LESSER EXTENT ALONG THE WIND RIVER...OWL CREEK...GREEN
MOUNTAIN...AND ABSAROKA RANGES WHERE ML CAPE IS RIDING BETWEEN 100
AND 200...TO AROUND 500 J/KG BIG HORNS. EVEN THOUGH SFC DPTS ARE A
BIT HIGHER TODAY AND STRETCH FURTHER WEST THAN YESTERDAY... PWS ARE
ONLY A FEW HUNDREDTHS HIGHER THAN YESTERDAY...SO MODE OF CONVECTION
WILL BE SIMILAR...RELATIVELY DRY...OUTFLOW DOMINATED...OCCASIONAL
BRIEF SMALL HAIL AND BRIEF HEAVY RAIN. BEST CHANCE FOR SCATTERED
THUNDERSTORMS WILL OCCUR ALONG AND NEAR THESE ELEVATED POINTS AND IN
THE ADJACENT VALLEY/BASINS. MAX TEMPS TODAY WILL BE CLOSE TO
YESTERDAY`S HIGHS...SO NO REAL CHANGES HERE.
FIRST SVR WARNING AND STATEMENT THIS AFTERNOON WITH 60MPH GUSTS
HERE AT THE STATION.
FRIDAY...LOOKS A BIT SPLIT AS FAR AS HIGH TEMPS GO...FEW DEGREES
WARMER OVER THE EASTERN HALF OF THE CWA...SOMEWHAT COOLER WEST AND
NORTHWEST. SHORTWAVE MOVING QUICKLY THROUGH BOTTOM OF DEVELOPING
TROF NEAR CNTRL CA THAT WILL BEGIN TO AFFECT OUR WRN AND NWRN CWA
LATE THIS AFTERNOON WILL BE FOLLOWED CLOSELY BY ANOTHER WHICH WILL
KEEP CHANCES OF SHOWERS AND THUNDER GOING OVERNIGHT TONIGHT AND
THROUGH THE MORNING HOURS...ALL BEFORE YET ANOTHER DISTURBANCE
MOVES OVER WRN WY AS TROF BEGINS TO DEFORM AND BECOME NEGATIVELY
TILTED. AGAIN...THIS WILL KEEP MOST OF THE ACTION OVER THE WRN AND
NWRN CWA. ALSO...DYNAMICS ASSOCIATED WITH THESE DISTURBANCES LOOK
TO BE MORE VIGOROUS IN PROVIDING UPWARD VERTICAL AND IMPROVED
SHEAR VALUES WOULD ALSO KEEP STORMS GOING LONGER. STORM MOTION
WILL TEND TOWARDS A MORE SSW TO NNE TRACK. WRN
MOUNTAINS...ESPECIALLY WEST OF A LYMAN TO LOVELL LINE...LOOKS TO
MAKE OUT BEST...WITH A SECONDARY WIDELY SCATTERED ARE ACROSS THE
BIGHORNS.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
THE LEAD SHORTWAVE THAT WILL EJECT OFF THE MAIN TROUGH THAT IS
CURRENTLY DIGGING JUST OFF THE PACIFIC COAST WILL DRIVE A COLD FRONT
SOUTH ACROSS THE CWA FRIDAY NIGHT. NORTH WINDS WILL PICK UP SOMEWHAT
WITH THIS FRONT EAST OF THE DIVIDE ALONG AND BEHIND THE FRONT WITH 3
HOURLY 5MB SURFACE PRESSURE RISES. H7 TEMPS WILL DROP TO -1C IN
WESTERN WYOMING BY 12Z SATURDAY AND TO 6C OVER EASTERN NATRONA
COUNTY. THUS WE WILL SEE A DOWNWARD SLIDE IN TEMPERATURES THROUGH
SUNDAY. MOST OF THE SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
THIS SHORTWAVE WILL BE OVER WESTERN AND NORTHWESTERN WYOMING FRIDAY
NIGHT. AS THE MAIN TROUGH ITSELF APPROACHES THE CWA...PRECIP WILL
SPILL OVER THE DIVIDE WITH ALONG WITH LIKELY POPS IN THE WEST. BY
SUNDAY HIGHS WILL ONLY BE IN THE 60S AT THE LOWER ELEVATIONS EAST OF
THE DIVIDE WITH 50S WEST. THE BROAD MAIN TROUGH AXIS SHOULD BE
OVERHEAD BY SUNDAY. THEN BY SUNDAY NIGHT AND MONDAY...COOL AIR WILL
ADVECT AROUND THE BACKSIDE OF THE CLOSING LOW OVER THE PLAINS THAT
WILL BE ORGANIZING AND DEEPENING. THE COLD AIR AND MOISTURE WRAPPING
AROUND THE BACKSIDE OF THIS STRENGTHENING LOW MAY BE ENOUGH TO
PRODUCE UP TO 6 INCHES OF SNOWFALL IN THE BIG HORN MOUNTAINS SUNDAY
NIGHT INTO MONDAY...4 INCHES IN THE ABSAROKAS AND 3 INCHES IN THE
WIND RIVER MOUNTAINS. SNOW ACCUMULATION LEVELS SHOULD BE AT AROUND
8K. MONDAY WILL BE THE SECOND OF TWO COOL WET DAYS IN A ROW. THEN A
SHORT LIVED RIDGE OF HIGH PRESSURE WILL ALLOW TEMPS TO WARM TO THE
60S AND 70S TUESDAY BEFORE THE NEXT DEEPENING TROUGH INCREASES A
WARMING SOUTHWEST FLOW FOR THE REST OF THE WEEK. THE PRECIP FROM
THIS NEXT TROUGH WILL MAINLY AFFECT THE WESTERN CWA TOWARD THE END
OF NEXT WEEK IN THE FORM OF CONVECTION. HIGHS SHOULD RECOVER TO THE
70S AND 80S BY WEDNESDAY.
.AVIATION.../06Z ISSUANCE/
SCATTERED SHOWERS WITH OCCNL THUNDER WILL CONTINUE OVER WESTERN
MOUNTAINS BETWEEN KJAC AND KBPI THROUGH THE NIGHT AS ANOTHER WAVE
APPROACHES IN THE SOUTHWEST FLOW...OCCNL MVFR CONDITIONS WITH
WIDESPREAD MOUNTAIN OBSCURATIONS EXPECTED THROUGH THE NIGHT AT
KJAC...KBPI AND KPNA.
ELSEWHERE...ISOLATED SHOWERS AND PERHAPS A STRIKE OR TWO OF
LIGHTNING POSSIBLE THROUGH THE NIGHT AS THIS NEXT WAVE MOVES THROUGH
WITH ACTIVITY DIMINISHING ACROSS CENTRAL AND SOUTHERN TERMINALS
TOWARD MORNING. ISOLATED TO SCATTERED CONVECTION IS EXPECTED TO
RETURN AFTER 18Z TOMORROW AT ALL TERMINALS EXCEPT KCPR AND KRKS
WHERE VERY DRY SOUTHWEST WINDS COULD GUST AS HIGH AS 30 KTS IN THE
AFTERNOON...THE MID LEVEL MOISTURE ACROSS THE BIGHORN AND WIND RIVER
BASINS SHOULD WORK TO OVERCOME THE DRY LOWER LEVELS...BUT ANY STORMS
THAT DO FORM WILL HAVE VERY GUSTY AND ERRATIC OUTFLOWS...ESPECIALLY
FROM 18-00Z.
.FIRE WEATHER...
SHOWERS AND THUNDERSTORMS CONTINUE TODAY AS A FEW UPPER LEVEL
DISTURBANCES MOVE THROUGH THE REGION. THESE STORMS WILL PRESENT AT
TIMES...BRIEF STRONG ERRATIC WINDS...SMALL HAIL AND OCCASIONAL
LIGHTNING. AMBIENT WINDS WILL BECOME QUITE GUSTY IN THE AFTERNOON
HOURS THE NEXT FEW DAYS...ESPECIALLY ON FRIDAY AND SATURDAY AND OVER
SWEETWATER AND NATRONA COUNTIES AND THE HIGHER ELEVATIONS OF THE
WIND RIVERS. AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
THE NEXT COUPLE OF DAYS BEFORE A MUCH STRONGER TROUGH OF LOW
PRESSURE MOVES ACROSS THE FORECAST AREA ON SATURDAY...BRINGING
COOLER TEMPERATURES AND A MUCH BETTER CHANCE TO SHOWERS AND THUNDERSTORMS.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...ALLEN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 162208
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
408 PM MDT THU MAY 16 2013
.SHORT TERM...TONIGHT THROUGH FRIDAY
WV IMAGERY SHOWING AMPLIFYING TROF NEAR THE EPAC COASTAL REGION. AS
TROF CONTINUES TO AMPLIFY THERE WILL BE SEVERAL CHANCES FOR SHORT
WAVE/JET STREAK ENHANCEMENT AHEAD OF THE SLOW MOVING TROF TO MAKE
THEIR WAY INTO AT LEAST THE WRN TO NWRN PORTION OF OUR CWA. MORNING
CONVECTION...ASSOCIATED WITH ONE OF THESE UPPER SPEED MAXES...MOVED
IN FROM SERN ID AFFECTING THE AFTON AREA...AND ALL AFTER THEY WERE
MILDLY ROCKED BY A 3.6 EARTHQUAKE LAST NIGHT. ANOTHER ONE OF THESE
VORT MAXES HAS BEGUN TO INFLUENCE OUR FORECAST AREA THIS AFTERNOON
WITH STRONG HIGH BASED THUNDERSTORMS THAT DEVELOPED IN THE LEE OF
THE WIND RIVER MOUNTAINS AND BLEW THROUGH LANDER AND RIVERTON
BETWEEN 0100 AND 0130 PM. LATER THIS EVENING AND
TONIGHT...ESPECIALLY THE NWRN QUAD INCLUDING THE TETON AND
YELLOWSTONE REGIONS...EXPECT SHOWERS TO CONTINUE THROUGH THE NIGHT.
OVERALL INSTABILITY IS IS FAIRLY LOW WITH MIXED LAYER CAPE AOBL 100
J/KG MOST PLACES EXCEPT HIGHER TERRAIN OF BIG HORNS...AND TO A
LESSER EXTENT ALONG THE WIND RIVER...OWL CREEK...GREEN
MOUNTAIN...AND ABSOROKA RANGES WHERE ML CAPE IS RIDING BETWEEN 100
AND 200...TO AROUND 500 J/KG BIG HORNS. EVEN THOUGH SFC DPTS ARE A
BIT HIGHER TODAY AND STRETCH FURTHER WEST THAN YESTERDAY... PWS ARE
ONLY A FEW HUNDREDTHS HIGHER THAN YESTERDAY...SO MODE OF CONVECTION
WILL BE SIMILAR...RELATIVELY DRY...OUTFLOW DOMINATED...OCCASIONAL
BRIEF SMALL HAIL AND BRIEF HEAVY RAIN. BEST CHANCE FOR SCATTERED
THUNDERSTORMS WILL OCCUR ALONG AND NEAR THESE ELEVATED POINTS AND IN
THE ADJACENT VALLEY/BASINS. MAX TEMPS TODAY WILL BE CLOSE TO
YESTERDAY`S HIGHS...SO NO REAL CHANGES HERE.
FIRST SVR WARNING AND STATEMENT THIS AFTERNOON WITH 60MPH GUSTS HERE AT THE
STATION.
FRIDAY...LOOKS A BIT SPLIT AS FAR AS HIGH TEMPS GO...FEW DEGREES
WARMER OVER THE EASTERN HALF OF THE CWA...SOMEWHAT COOLER WEST AND
NORTHWEST. SHORTWAVE MOVING QUICKLY THROUGH BOTTOM OF DEVELOPING
TROF NEAR CNTRL CA THAT WILL BEGIN TO AFFECT OUR WRN AND NWRN CWA
LATE THIS AFTERNOON WILL BE FOLLOWED CLOSELY BY ANOTHER WHICH WILL
KEEP CHANCES OF SHOWERS AND THUNDER GOING OVERNIGHT TONIGHT AND
THROUGH THE MORNING HOURS...ALL BEFORE YET ANOTHER DISTURBANCE MOVES
OVER WRN WY AS TROF BEGINS TO DEFORM AND BECOME NEGATIVELY TILTED.
AGAIN...THIS WILL KEEP MOST OF THE ACTION OVER THE WRN AND NWRN CWA.
ALSO...DYNAMICS ASSOCIATED WITH THESE DISTURBANCES LOOK TO BE MORE
VIGOROUS IN PROVIDING UPWARD VERTICAL AND IMPROVED SHEAR VALUES
WOULD ALSO KEEP STORMS GOING LONGER. STORM MOTION WILL TEND TOWARDS
A MORE SSW TO NNE TRACK. WRN MOUNTAINS...ESPECIALLY WEST OF A LYMAN
TO LOVELL LINE...LOOKS TO MAKE OUT BEST...WITH A SECONDARY WIDELY
SCATTERED ARE ACROSS THE BIGHORNS.
.FRIDAY NIGHT THROUGH THURSDAY...
THE LEAD SHORTWAVE THAT WILL EJECT OFF THE MAIN TROUGH THAT IS
CURRENTLY DIGGING JUST OFF THE PACIFIC COAST WILL DRIVE A COLD FRONT
SOUTH ACROSS THE CWA FRIDAY NIGHT. NORTH WINDS WILL PICK UP SOMEWHAT
WITH THIS FRONT EAST OF THE DIVIDE ALONG AND BEHIND THE FRONT WITH 3
HOURLY 5MB SURFACE PRESSURE RISES. H7 TEMPS WILL DROP TO -1C IN
WESTERN WYOMING BY 12Z SATURDAY AND TO 6C OVER EASTERN NATRONA
COUNTY. THUS WE WILL SEE A DOWNWARD SLIDE IN TEMPERATURES THROUGH
SUNDAY. MOST OF THE SHOWERS AND THUNDERSTORMS ASSOCIATED WITH
THIS SHORTWAVE WILL BE OVER WESTERN AND NORTHWESTERN WYOMING FRIDAY
NIGHT. AS THE MAIN TROUGH ITSELF APPROACHES THE CWA...PRECIP WILL
SPILL OVER THE DIVIDE WITH ALONG WITH LIKELY POPS IN THE WEST. BY
SUNDAY HIGHS WILL ONLY BE IN THE 60S AT THE LOWER ELEVATIONS EAST OF
THE DIVIDE WITH 50S WEST. THE BROAD MAIN TROUGH AXIS SHOULD BE
OVERHEAD BY SUNDAY. THEN BY SUNDAY NIGHT AND MONDAY...COOL AIR WILL
ADVECT AROUND THE BACKSIDE OF THE CLOSING LOW OVER THE PLAINS THAT
WILL BE ORGANIZING AND DEEPENING. THE COLD AIR AND MOISTURE WRAPPING
AROUND THE BACKSIDE OF THIS STRENGTHENING LOW MAY BE ENOUGH TO
PRODUCE UP TO 6 INCHES OF SNOWFALL IN THE BIG HORN MOUNTAINS SUNDAY
NIGHT INTO MONDAY...4 INCHES IN THE ABSAROKAS AND 3 INCHES IN THE
WIND RIVER MOUNTAINS. SNOW ACCUMULATION LEVELS SHOULD BE AT AROUND
8K. MONDAY WILL BE THE SECOND OF TWO COOL WET DAYS IN A ROW. THEN A
SHORT LIVED RIDGE OF HIGH PRESSURE WILL ALLOW TEMPS TO WARM TO THE
60S AND 70S TUESDAY BEFORE THE NEXT DEEPENING TROUGH INCREASES A
WARMING SOUTHWEST FLOW FOR THE REST OF THE WEEK. THE PRECIP FROM
THIS NEXT TROUGH WILL MAINLY AFFECT THE WESTERN CWA TOWARD THE END
OF NEXT WEEK IN THE FORM OF CONVECTION. HIGHS SHOULD RECOVER TO THE
70S AND 80S BY WEDNESDAY.
&&
.AVIATION.../00Z ISSUANCE/
ISOLATED THUNDER OVER WESTERN MOUNTAINS BETWEEN KJAC AND KBPI THIS
MORNING ASSOCIATED WITH AN UPPER LEVEL DISTURBANCE. ISOLATED TO
SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON INTO THE EVENING.
OUTFLOW DOMINATED STORMS THIS AFTERNOON IN THE LEE OF THE WIND
RIVERS. THE BEST CONCENTRATION SHOULD BE ACROSS THE NORTHWEST...BUT
ALL TAF SITES EXCEPT WILL HAVE THE POSSIBILITY OF THUNDERSTORM
ACTIVITY THIS AFTERNOON. MOST OF THIS ACTIVITY WILL WANE AN HOUR OR
TWO AFTER SUNSET...EXCEPT ACROSS THE WEST AND NORTHWEST. KJAC WILL
HOWEVER HAVE CONVECTION AROUND THROUGH THE ENTIRE NIGHT WITH DECENT
UPPER LEVEL SUPPORT. VFR CONDITIONS ARE EXPECTED AT MOST TAF
SITES...EXCEPT FOR BRIEF PERIODS OF MVFR/IFR CONDITIONS ASSOCIATED
WITH ANY SHOWER/THUNDERSTORM ACTIVITY. KJAC COULD BE AFFECTED AFTER
03Z FRIDAY WHERE A SIGNIFICANT MVFR AREA COULD DEVELOP AS MORE
STRATIFORM TYPE OF CLOUDS AND PRECIP DEVELOPS. WILL KEEP VFR
CONDITIONS FOR NOW AND JUST MONITOR AS CIGS COULD BECOME MVFR OR
EVEN IFR FOR A FEW HOURS AROUND SUNRISE. ALSO TOMORROW...KCPR AND
KRKS COULD GUST AS HIGH AS 30 KTS IN THE AFTERNOON WITHOUT THUNDER
AROUND.
&&
.FIRE WEATHER...
SHOWERS AND THUNDERSTORMS CONTINUE TODAY AS A FEW UPPER LEVEL
DISTURBANCES MOVE THROUGH THE REGION. THESE STORMS WILL PRESENT AT
TIMES...BRIEF STRONG ERRATIC WINDS...SMALL HAIL AND OCCASIONAL
LIGHTNING. AMBIENT WINDS WILL BECOME QUITE GUSTY IN THE AFTERNOON
HOURS THE NEXT FEW DAYS...ESPECIALLY ON FRIDAY AND SATURDAY AND OVER
SWEETWATER AND NATRONA COUNTIES AND THE HIGHER ELEVATIONS OF THE
WIND RIVERS. AFTERNOON SHOWERS AND THUNDERSTORMS WILL CONTINUE FOR
THE NEXT COUPLE OF DAYS BEFORE A MUCH STRONGER TROUGH OF LOW
PRESSURE MOVES ACROSS THE FORECAST AREA ON SATURDAY...BRINGING
COOLER TEMPERATURES AND A MUCH BETTER CHANCE TO SHOWERS AND THUNDERSTORMS.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...LIPSON
AVIATION...BRAUN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 161723
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1122 AM MDT THU MAY 16 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
A FEW SHOWERS CONTINUE ACROSS PORTIONS OF NORTHERN AND WESTERN
WYOMING THIS MORNING. SHOWER ACTIVITY WILL WEAKEN...BUT SOME SHOWER
ACTIVITY WILL REMAIN OVER THE AREA THROUGH THE MORNING.
A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE STATE TODAY. THIS
SYSTEM WILL BRING ANOTHER ROUND OF INSTABILITY ACROSS THE STATE.
THUNDERSTORMS WILL BE POSSIBLE...WITH SOME THUNDERSTORM ACTIVITY
POSSIBLE DURING THE LATE MORNING HOURS. THUNDERSTORM COVERAGE AND
LIKELIHOOD WILL INCREASE THROUGH THE AFTERNOON. GUSTY WIND WILL BE
THE PRIMARY THREAT WITH ANY ACTIVITY...THOUGH SMALL HAIL WILL NOT BE
OUT OF THE QUESTION...ALONG WITH INSTANCES OF HEAVY RAIN. PAST
WILDFIRE BURN SCARS WILL BE MONITORED CLOSELY FOR ANY POTENTIAL
FOR FLOODING. ANOTHER DAY OF MILD TO WARM TEMPERATURES MAY ALSO
CONTINUE TO MELT SNOW PACK ACROSS THE HIGHER TERRAINS. RIVER
MONITORING EQUIPMENT WILL CONTINUE TO BE WATCHED FOR ANY
SIGNIFICANT RISES TODAY.
A STRONGER TROUGH OF LOW PRESSURE WILL MOVE TOWARDS THE AREA FRIDAY
MORNING AND AFTERNOON. WITH AN INCREASING SOUTHWEST FLOW...AND A
SLIGHT NEGATIVE TILT TO THE SYSTEM...SHOWERS AND THUNDERSTORMS WILL
AGAIN DEVELOP. SHOWER ACTIVITY WILL BE FOUND ESPECIALLY ACROSS THE
WESTERN MOUNTAINS AND VALLEYS FRIDAY MORNING...WITH COVERAGE
SPREADING TO INCLUDE MUCH OF NORTHWESTERN WYOMING BY FRIDAY
AFTERNOON. CONFIDENCE IS FAIR WITH THE DEVELOPMENT OF THIS PATTERN
AS THERE IS A FAIR AMOUNT OF CONSISTENCY BETWEEN THE VARIOUS MODELS.
THE TROUGH WILL MOVE THROUGH THE AREA ON SATURDAY BRINGING COOLER
TEMPERATURES ACROSS THE FORECAST AREA. ADDITIONALLY...THE PRESENCE
OF THIS SYSTEM WILL BRING WIDESPREAD SHOWERS AND THUNDERSTORMS BY
LATE SATURDAY MORNING. SHOWERS WILL CONTINUE THROUGH THE EARLY
EVENING HOURS...WITH COVERAGE DECREASING WITH THE LOSS OF DAYLIGHT.
.LONG TERM...SUNDAY THROUGH THURSDAY
AN UPPER LOW/TROUGH ASSOCIATED WITH A REX BLOCK ACROSS NORTH
AMERICA WILL AFFECT THE FORECAST AREA SUNDAY AND MONDAY. THIS WILL
RESULT IN COOL AND INCLEMENT WEATHER BOTH DAYS. A SECONDARY COLD
FRONT ASSOCIATED WITH THIS TROUGH IS EXPECTED TO PUSH SOUTH ACROSS
THE FORECAST AREA SUNDAY INTO SUNDAY NIGHT. GLOBAL MODELS ARE
SHOWING THE POTENTIAL FOR UPSLOPE POTENTIAL EAST OF THE DIVIDE IN
WAKE OF THIS FRONT. THE FLOW IS EXPECTED TO BACK MONDAY
NIGHT/TUESDAY AS THE UPPER LOW/TROUGH SHIFTS INTO THE PLAINS
SHUTTING OFF THE UPSLOPE FLOW. ALTHOUGH THERE WILL BE CHANCES FOR
PRECIPITATION ACROSS THE ENTIRE AREA SUNDAY AND MONDAY...THE BEST
CHANCE WILL BE EAST OF THE DIVIDE. PRECIPITATION TYPE WILL BE VALLEY
RAIN AND MOUNTAIN SNOW...WITH A SNOW/RAIN ELEVATION RANGING
ROUGHLY BETWEEN 7500 AND 9000 FEET SUNDAY AND MONDAY.
WEAK RIDGING IS EXPECTED ACROSS THE FORECAST AREA TUESDAY...IN
BETWEEN AN UPPER LOW ACROSS THE MIDWEST AND A STRONGER UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST. THIS WILL RESULT IN WARMER AND
DRIER CONDITIONS TUESDAY. HOWEVER STILL CANNOT RULE OUT SOME
CONVECTION ESPECIALLY EAST OF THE DIVIDE.
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE STRONG UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST LATE TUESDAY INTO TUESDAY NIGHT
WILL REMAIN ACROSS PACIFIC NORTHWEST AREA WEDNESDAY AND THURSDAY.
THE MAIN RESULT FOR THE FORECAST AREA WILL BE WARMING TEMPERATURES
AND INCREASING SOUTHWEST FLOW. MOISTURE APPEARS TO BE SOMEWHAT
LIMITED IN THE SOUTHWEST FLOW AHEAD OF THIS UPPER LOW...BUT ENOUGH
TO WARRANT SLIGHT CHANCE POPS...MAINLY ACROSS THE WEST AND
NORTHWEST.
&&
.AVIATION.../18Z ISSUANCE/
ISOLATED THUNDER OVER WESTERN MOUNTAINS BETWEEN KJAC AND KBPI THIS
MORNING ASSOCIATED WITH AN UPPER LEVEL DISTURBANCE. ISOLATED TO
SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON INTO THE EVENING.
THE BEST CONCENTRATION SHOULD BE ACROSS THE NORTHWEST...BUT ALL TAF
SITES EXCEPT WILL HAVE THE POSSIBILITY OF THUNDERSTORM ACTIVITY THIS
AFTERNOON. MOST OF THIS ACTIVITY WILL WANE AN HOUR OR TWO AFTER
SUNSET...EXCEPT ACROSS THE WEST AND NORTHWEST. KJAC WILL HOWEVER
HAVE CONVECTION AROUND THROUGH THE ENTIRE NIGHT WITH DECENT UPPER
LEVEL SUPPORT. VFR CONDITIONS ARE EXPECTED AT MOST TAF
SITES...EXCEPT FOR BRIEF PERIODS OF MVFR/IFR CONDITIONS ASSOCIATED
WITH ANY SHOWER/THUNDERSTORM ACTIVITY. KJAC COULD BE AFFECTED AFTER
03Z FRIDAY WHERE A SIGNIFICANT MVFR AREA COULD DEVELOP AS MORE
STRATIFORM PRECIP DEVELOPS. WILL KEEP VFR CONDITIONS FOR NOW...AND
TACKLE THIS QUESTION MORE WITH THE EVENING TAF RELEASE.
&&
.FIRE WEATHER...
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY.
WITH INCREASED CLOUD COVER TODAY...HUMIDITY WILL BE SLIGHTLY HIGHER
TODAY THAN WAS EXPERIENCED ON WEDNESDAY. HOWEVER...SOME AREAS WILL
STILL BE IN THE LOW TO MID TEENS...ESPECIALLY ACROSS THE CENTRAL AND
EASTERN BASINS. WIND WILL BECOME GUSTY IN THE AFTERNOON HOURS THE
NEXT COUPLE OF DAYS...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES. ERRATIC AND STRONGER WIND WILL BE POSSIBLE WITH
THUNDERSTORM ACTIVITY. AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE FOR THE NEXT COUPLE OF DAYS. A STRONGER TROUGH OF LOW
PRESSURE WILL MOVE ACROSS THE AREA ON SATURDAY...BRINGING COOLER
TEMPERATURES AND WIDESPREAD SHOWER ACTIVITY.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...BRAUN
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 161009
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
409 AM MDT THU MAY 16 2013
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
A FEW SHOWERS CONTINUE ACROSS PORTIONS OF NORTHERN AND WESTERN
WYOMING THIS MORNING. SHOWER ACTIVITY WILL WEAKEN...BUT SOME SHOWER
ACTIVITY WILL REMAIN OVER THE AREA THROUGH THE MORNING.
A WAVE OF LOW PRESSURE WILL MOVE THROUGH THE STATE TODAY. THIS
SYSTEM WILL BRING ANOTHER ROUND OF INSTABILITY ACROSS THE STATE.
THUNDERSTORMS WILL BE POSSIBLE...WITH SOME THUNDERSTORM ACTIVITY
POSSIBLE DURING THE LATE MORNING HOURS. THUNDERSTORM COVERAGE AND
LIKELIHOOD WILL INCREASE THROUGH THE AFTERNOON. GUSTY WIND WILL BE
THE PRIMARY THREAT WITH ANY ACTIVITY...THOUGH SMALL HAIL WILL NOT BE
OUT OF THE QUESTION...ALONG WITH INSTANCES OF HEAVY RAIN. PAST
WILDFIRE BURN SCARS WILL BE MONITORED CLOSELY FOR ANY POTENTIAL
FOR FLOODING. ANOTHER DAY OF MILD TO WARM TEMPERATURES MAY ALSO
CONTINUE TO MELT SNOW PACK ACROSS THE HIGHER TERRAINS. RIVER
MONITORING EQUIPMENT WILL CONTINUE TO BE WATCHED FOR ANY
SIGNIFICANT RISES TODAY.
A STRONGER TROUGH OF LOW PRESSURE WILL MOVE TOWARDS THE AREA FRIDAY
MORNING AND AFTERNOON. WITH AN INCREASING SOUTHWEST FLOW...AND A
SLIGHT NEGATIVE TILT TO THE SYSTEM...SHOWERS AND THUNDERSTORMS WILL
AGAIN DEVELOP. SHOWER ACTIVITY WILL BE FOUND ESPECIALLY ACROSS THE
WESTERN MOUNTAINS AND VALLEYS FRIDAY MORNING...WITH COVERAGE
SPREADING TO INCLUDE MUCH OF NORTHWESTERN WYOMING BY FRIDAY
AFTERNOON. CONFIDENCE IS FAIR WITH THE DEVELOPMENT OF THIS PATTERN
AS THERE IS A FAIR AMOUNT OF CONSISTENCY BETWEEN THE VARIOUS MODELS.
THE TROUGH WILL MOVE THROUGH THE AREA ON SATURDAY BRINGING COOLER
TEMPERATURES ACROSS THE FORECAST AREA. ADDITIONALLY...THE PRESENCE
OF THIS SYSTEM WILL BRING WIDESPREAD SHOWERS AND THUNDERSTORMS BY
LATE SATURDAY MORNING. SHOWERS WILL CONTINUE THROUGH THE EARLY
EVENING HOURS...WITH COVERAGE DECREASING WITH THE LOSS OF DAYLIGHT.
.LONG TERM...SUNDAY THROUGH THURSDAY
AN UPPER LOW/TROUGH ASSOCIATED WITH A REX BLOCK ACROSS NORTH
AMERICA WILL AFFECT THE FORECAST AREA SUNDAY AND MONDAY. THIS WILL
RESULT IN COOL AND INCLEMENT WEATHER BOTH DAYS. A SECONDARY COLD
FRONT ASSOCIATED WITH THIS TROUGH IS EXPECTED TO PUSH SOUTH ACROSS
THE FORECAST AREA SUNDAY INTO SUNDAY NIGHT. GLOBAL MODELS ARE
SHOWING THE POTENTIAL FOR UPSLOPE POTENTIAL EAST OF THE DIVIDE IN
WAKE OF THIS FRONT. THE FLOW IS EXPECTED TO BACK MONDAY
NIGHT/TUESDAY AS THE UPPER LOW/TROUGH SHIFTS INTO THE PLAINS
SHUTTING OFF THE UPSLOPE FLOW. ALTHOUGH THERE WILL BE CHANCES FOR
PRECIPITATION ACROSS THE ENTIRE AREA SUNDAY AND MONDAY...THE BEST
CHANCE WILL BE EAST OF THE DIVIDE. PRECIPITATION TYPE WILL BE VALLEY
RAIN AND MOUNTAIN SNOW...WITH A SNOW/RAIN ELEVATION RANGING
ROUGHLY BETWEEN 7500 AND 9000 FEET SUNDAY AND MONDAY.
WEAK RIDGING IS EXPECTED ACROSS THE FORECAST AREA TUESDAY...IN
BETWEEN AN UPPER LOW ACROSS THE MIDWEST AND A STRONGER UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST. THIS WILL RESULT IN WARMER AND
DRIER CONDITIONS TUESDAY. HOWEVER STILL CANNOT RULE OUT SOME
CONVECTION ESPECIALLY EAST OF THE DIVIDE.
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE STRONG UPPER LOW
PUSHING INTO THE PACIFIC NORTHWEST LATE TUESDAY INTO TUESDAY NIGHT
WILL REMAIN ACROSS PACIFIC NORTHWEST AREA WEDNESDAY AND THURSDAY.
THE MAIN RESULT FOR THE FORECAST AREA WILL BE WARMING TEMPERATURES
AND INCREASING SOUTHWEST FLOW. MOISTURE APPEARS TO BE SOMEWHAT
LIMITED IN THE SOUTHWEST FLOW AHEAD OF THIS UPPER LOW...BUT ENOUGH
TO WARRANT SLIGHT CHANCE POPS...MAINLY ACROSS THE WEST AND
NORTHWEST.
&&
.AVIATION.../12Z ISSUANCE/
VERY ISOLATED SHOWERS WILL REMAIN POSSIBLE OVER A GOOD CHUNK OF THE
REGION THROUGH THE MORNING. WILL WAIT UNTIL CLOSER TO 12Z TAF
ISSUANCE TO DECIDE IF THERE IS A NEED TO MENTION MORNING SHOWER
ACTIVITY AT ANY TAF SITE. ISOLATED TO SCATTERED CONVECTION IS
EXPECTED THIS AFTERNOON INTO THE EVENING. THE BEST CONCENTRATION
SHOULD BE ACROSS THE NORTHWEST...BUT ALL TAF SITES WILL HAVE THE
POSSIBILITY OF BEING IMPACTED BY THUNDERSTORM ACTIVITY THIS
AFTERNOON. MOST OF THIS ACTIVITY WILL WANE AN HOUR OR TWO AFTER
SUNSET...EXCEPT ACROSS THE NORTHWEST...INCLUDING KJAC...WHERE
CONVECTION WILL LINGER THROUGH THE NIGHT...ALONG AN UPPER LEVEL
FRONT. VFR CONDITIONS ARE EXPECTED AT TAF SITES...EXCEPT FOR BRIEF
PERIODS OF MVFR/IFR CONDITIONS ASSOCIATED WITH ANY
SHOWER/THUNDERSTORM ACTIVITY. THE EXCEPTION COULD BE AFTER 06Z
FRIDAY ACROSS THE NORTHWEST WHERE A SIGNIFICANT MVFR AREA COULD
DEVELOP AS STEADIER PRECIP DEVELOPS. THIS COULD IMPACT KJAC
TERMINAL...BUT WILL KEEP VFR CONDITIONS FOR NOW.
&&
.FIRE WEATHER...
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TODAY.
WITH INCREASED CLOUD COVER TODAY...HUMIDITY WILL BE SLIGHTLY HIGHER
TODAY THAN WAS EXPERIENCED ON WEDNESDAY. HOWEVER...SOME AREAS WILL
STILL BE IN THE LOW TO MID TEENS...ESPECIALLY ACROSS THE CENTRAL AND
EASTERN BASINS. WIND WILL BECOME GUSTY IN THE AFTERNOON HOURS THE
NEXT COUPLE OF DAYS...ESPECIALLY ACROSS SWEETWATER AND NATRONA
COUNTIES. ERRATIC AND STRONGER WIND WILL BE POSSIBLE WITH
THUNDERSTORM ACTIVITY. AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE FOR THE NEXT COUPLE OF DAYS. A STRONGER TROUGH OF LOW
PRESSURE WILL MOVE ACROSS THE AREA ON SATURDAY...BRINGING COOLER
TEMPERATURES AND WIDESPREAD SHOWER ACTIVITY.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...WM
FIRE WEATHER...BRANHAM
000
FXUS65 KRIW 160537 AAA
AFDRIW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
1137 PM MDT WED MAY 15 2013
.UPDATE...
THE FLASH FLOOD WATCH FOR THE SHEEPHERDER HILL BURN SCAR AREA NEAR
CASPER WILL BE ALLOWED TO EXPIRE AT MIDNIGHT. LIGHT TO MODERATE
SHOWERS MOVING THROUGH THE AREA THIS EVENING ARE NOT EXPECTED TO
BE HEAVY ENOUGH TO CAUSE CONCERN.
.SHORT TERM...TONIGHT THROUGH THURSDAY
WV ANALYSIS SHOWING SSW TROF OVER SWRN UT THIS AFTERNOON WITH
DEVELOPING DIFFUSE SFC LOW OUT IN FRONT NEAR SWRN WY. SMALL
DISTURBANCE EXITING NERN WY. MOISTURE FEED FROM HIGH PLAINS INTO
EASTERN PORTIONS OF WY...TRYING TO GET INTO EASTERN PORTIONS OF THE
CWA. HOWEVER...MOISTURE STILL QUITE LIMITED WITH MIXED OUT DPTS
RANGING MOSTLY FROM THE MID 20S TO MID 30S. BETTER BL MOISTURE IS
SPOTTY AND LOCATED OVER THE SWRN CWA NEAR THE SALT AND WYOMING
RANGES...AND AGAIN NEAR THE SRN BIG HORNS AND MEDICINE BOW MOUNTAINS
SE OF CASPER. CONVECTION IS PROCEEDING...OVER THE SOUTHERN CWA
STARTING AT THE UINTAH MOUNTAINS...FOLLOWED BY THE WIND RIVER AND
CONFLUENCE WITH THE ABSOROKAS. LATER THIS EVENING...ANOTHER IN A
SERIES OF WEAK IMPULSES WILL ENHANCE SHOWERS ACROSS THE WRN AND NWRN
CWA.
THURSDAY...SLOW UPPER LVL HEIGHT FALLS AS APPROACHING EPAC SW TROF
AMPLIFIES AS IT IMPINGES ON COAST AND BEGINS TO AFFECT WEAK RIDGING
ATOP OUR REGION. ONLY VERY SLIGHT TEMPERATURE DIFFERENCES
TOMORROW...WITH HIGHS PERHAPS A DEGREE OR TWO LESS THAN TODAY. SW
IMPULSE OVER WRN ID AND NV THIS AFTERNOON WILL AFFECT THE N CNTRL AND
NWRN CWA IN THE MORNING...WEST OF A KBPI TO KCOD LINE...BEFORE A
SLIGHTLY BROADER IMPULSE...JUST STARTING TO SHOW UP OVER WEST CNTRL
CA SAT IMAGERY...WILL SWING AROUND AMPLIFYING TROF AND ARRIVE NEAR
OUR NWRN CWA LATE TOMORROW AFTERNOON AND EVENING...PROVIDING PERHAPS
ENOUGH EXTRA LIFT IN AND AROUND THE ELEVATED TERRAIN TO GET
MEASURABLE PRECIP WEST OF AN EVANSTON TO LANDER TO CODY LINE. MID
LVL MOISTURE WILL ALSO BE MORE AVAILABLE FOR PRECIP IN WRN AND NWRN
WY DURING THE DAY AND POPS... REFLECT THIS TREND.
ELSEWHERE...MEASURABLE PRECIPITATION WILL BE HARD TO COME BY WITH
ONLY VERY ISOLATED CHANCES AROUND THE REST OF THE CWA WITH A
SLIGHTLY BETTER CHANCE NEAR THE SRN BIG HORNS. APPROACH OF RATHER
WEAK JET ASSOCIATED WITH LEADING EDGE OF TROF WILL BE ENOUGH TO
ENHANCE UPWARD VERTICAL SHEAR THROUGH THE DAY AND INTO THE EVENING
WHICH MAY AID IN KEEPING SHOWER/THUNDER CHANCES GOING A BIT LATER
INTO THE EVENING.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY NIGHT
AS A PACIFIC LOW PRESSURE TROUGH MOVES INTO THE WEST COAST
AND DEEPENS...SOUTH SOUTHWEST FLOW ALOFT WILL INCREASE OVER
WESTERN AND CENTRAL WYOMING THURSDAY NIGHT. PACIFIC MOISTURE
WILL BE LIMITED TO THE WEST WITH A DRY SLOT OVER SOUTHERN AND
CENTRAL WYOMING LIMITING CONVECTION TO THE WESTERN MOUNTAINS.
WARMING ILL ACCOMPANY THE SOUTH SOUTHWEST FLOW. THE PACIFIC TROUGH
IS EXPECTED TO MOVE SLOWLY EAST AS IT MOVES INTO THE WESTERN GREAT
BASIN WITH THE SOUTH SOUTHWEST FLOW ALOFT INCREASING. SHOWERS AND
ISOLATED THUNDERSTORMS WILL BE LIMITED TO THE WEST AND NORTH WITH A
DRY SLOT CONTINUING IN THE SOUTH AND CENTRAL AREAS. TEMPERATURES
WILL CONTINUE TO WARM. FRIDAY NIGHT THE PACIFIC TROUGH WILL BE OVER
IDAHO AND UTAH WITH MOISTURE AND CONVECTION SPREADING EAST IN THE
STRONG SOUTH SOUTHWEST FLOW ALOFT BRINGING ISOLATED SHOWERS EASY
WITH SCATTERED SHOWERS IN THE WEST...ALONG WITH ISOLATED EVENING
THUNDERSTORMS. TEMPERATURES WILL CONTINUE THE WARMING TREND IN THE
EAST WITH COOLING IN THE WEST. SATURDAY THE PACIFIC TROUGH WILL
BEGIN TO MOVE ACROSS WESTERN WYOMING WITH SHOWERS AND ISOLATED
AFTERNOON THUNDERSTORMS CONTINUING TO SPREAD EAST WITH AN INCREASE
IN COVERAGE OVER THE WEST AND NORTH. TEMPERATURES WILL COOL WITH
CLOUD COVER AND INCREASED PRECIPITATION. A SURFACE FRONT WILL MOVE
INTO THE NORTH THROUGH SATURDAY ADDING TO THE COOLING IN THE NORTH.
SATURDAY NIGHT THE FIRST PACIFIC TROUGH WILL MOVE EAST INTO THE
NORTHERN AND CENTRAL PLAINS WHILE A SECOND PACIFIC TROUGH DEVELOPS
OVER THE NORTHERN ROCKIES AND NORTHERN GREAT BASIN. THIS WILL
CONTINUE TO BRING PACIFIC MOISTURE AND COLDER TEMPERATURES WITH
SCATTERED SHOWERS...MOST NUMEROUS IN THE WESTERN AND NORTHERN
MOUNTAINS...AND ISOLATED AFTERNOON THUNDERSTORMS SUNDAY. THIS
SECOND TROUGH WILL BRING THE COLD FRONT THROUGH THE STATE FROM THE
NORTH WITH A SECONDARY COLD PUSH BEHIND THE INITIAL COLD FRONT
SUNDAY NIGHT. THE SECOND PACIFIC TROUGH WILL MOVE SLOWLY ACROSS
WESTERN AND CENTRAL WYOMING KEEPING THE THREAT OF SHOWERS ELEVATED
OVER THE AREA AND CONTINUE THE COOLING TREND THROUGH MONDAY AND
MONDAY NIGHT WITH A GRADUAL DECREASE IN SHOWERS THROUGH THE NIGHT. A
HIGH PRESSURE RIDGE WILL BUILD IN AS THE SECOND TROUGH MOVES EAST OF
THE AREA INTO THE NORTHERN AND CENTRAL PLAINS. THE HIGH PRESSURE
WILL BRING AND END TO THE SHOWERS AND BRING SOME WARMING WITH MORE
SUNSHINE ON TUESDAY. TUESDAY NIGHT WILL REMAIN ON THE COOL SIDE WITH
CLEARING AND GREATER RADIATIONAL COOLING.
.AVIATION.../06Z ISSUANCE/
SCATTERED SNOWHERS AND ISOLATED THUNDERSTORMS REMAIN POSSIBLE
THROUGH THE NIGHT...BECOMING MORE ISOLATED WITH TIME...ONE BATCH
OF SHOWERS NEAR KCPR EXPECTED TO PUSH OUT OF THE AREA BY OFFICIAL
ISSUANCE TIME...BUT THEY COULD LEAVE BEHIND SOME MVFR CIGS VERY
EARLY IN THE PERIOD. KJAC WILL LIKELY REMAIN UNSETTLED AS ANOTHER
DISTURBANCE APPRACHES THE WESTERN MOUNTAINS...EXPECT WIDESPREAD
MOUNTAIN OBSCURATIONS IN THE WEST THROUGH THE NIGHT AND OCCNL MVFR
CONDITIONS IN -RA AND CIGS AOA 3KFT.
OTHERWISE...VFR CONDITIONS WILL PREVAIL TONIGHT AT ALL OTHER
TERMINALS. MORE SHOWERS AND SOME THUNDER CAN BE EXPECTED THURSDAY
NEAR MOST TERMINALS...BUT AFFECTING WESTERN TERMINALS THE MOST.
KRKS WILL ALSO FIND IN A BIT HARDER THAN OTHERS TO GET THUNDER OR
PRECIPITATION DUE TO THE DRIER AIR MOVING IN DURING THE
AFTERNOON...BUT VCSH WAS INCLUDED IN THE TAF AFTER 18Z TO ACCOUNT
FOR THE POSSIBLITY OF -SHRA...NOT MUCH PRECIP BUT A GOOD CHANCE OF
STRONG AND ERRATIC OUTFLOW WIND CAN BE EXPECTED WITH ANY SHOWERS
OR STORMS THAT FORM ACROSS THE SOUTH TOMORROW.
.FIRE WEATHER...
SOMEWHAT COOLER TEMPERATURES TODAY...DOWN 5 TO 7 DEG...UPPER LEVEL
HEIGHT FALLS BEGIN A SLOW PROGRESSION INTO THE FORECAST AREA FROM
THE SOUTHWEST. AHEAD OF THE AMPLIFYING TROF OUT WEST...SEVERAL
UPPER LEVEL DISTURBANCES WILL CONTINUE TO IMPACT THE STATE OVER
THE NEXT SEVERAL DAYS. CURRENTLY CONVECTION IS
PROCEEDING...STARTING OVER THE UINTAH MOUNTAINS AND MOVING INTO
THE SOUTHERN PORTIONS OF WY. THIS WAS FOLLOWED BY THE WIND RIVER
REGION AND AND CONFLUENCE WITH THE ABSOROKAS. THIS
EVENING...ANOTHER IN A SERIES OF WEAK IMPULSES WILL ENHANCE
SHOWERS ACROSS THE WRN AND NWRN TERMINALS INCLUDING KJAC.
TEMPERATURES WILL CONTINUE TO COOL THROUGH THURSDAY WITH A SLIGHT
REBOUND ANTICIPATED FRIDAY AFTERNOON AHEAD OF THE STRONGER WAVE OF
LOW PRESSURE DUE TO ARRIVE THIS WEEKEND.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT WYZ020-022.
&&
$$
SHORT TERM...BRAUN
LONG TERM...C.BAKER
AVIATION...ALLEN
FIRE WEATHER...BRAUN
000
FXUS65 KRIW 152128
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
328 PM MDT WED MAY 15 2013
.SHORT TERM...TONIGHT THROUGH THURSDAY
WV ANALYSIS SHOWING SSW TROF OVER SWRN UT THIS AFTERNOON WITH
DEVELOPING DIFFUSE SFC LOW OUT IN FRONT NEAR SWRN WY. SMALL
DISTURBANCE EXITING NERN WY. MOISTURE FEED FROM HIGH PLAINS INTO
EASTERN PORTIONS OF WY...TRYING TO GET INTO EASTERN PORTIONS OF THE
CWA. HOWEVER...MOISTURE STILL QUITE LIMITED WITH MIXED OUT DPTS
RANGING MOSTLY FROM THE MID 20S TO MID 30S. BETTER BL MOISTURE IS
SPOTTY AND LOCATED OVER THE SWRN CWA NEAR THE SALT AND WYOMING
RANGES...AND AGAIN NEAR THE SRN BIG HORNS AND MEDICINE BOW MOUNTAINS
SE OF CASPER. CONVECTION IS PROCEEDING...OVER THE SOUTHERN CWA
STARTING AT THE UINTAH MOUNTAINS...FOLLOWED BY THE WIND RIVER AND
CONFLUENCE WITH THE ABSOROKAS. LATER THIS EVENING...ANOTHER IN A
SERIES OF WEAK IMPULSES WILL ENHANCE SHOWERS ACROSS THE WRN AND NWRN
CWA.
THURSDAY...SLOW UPPER LVL HEIGHT FALLS AS APPROACHING EPAC SW TROF
AMPLIFIES AS IT IMPINGES ON COAST AND BEGINS TO AFFECT WEAK RIDGING
ATOP OUR REGION. ONLY VERY SLIGHT TEMPERATURE DIFFERENCES
TOMORROW...WITH HIGHS PERHAPS A DEGREE OR TWO LESS THAN TODAY. SW
IMPULSE OVER WRN ID AND NV THIS AFTERNOON WILL AFFECT THE N CNTRL AND
NWRN CWA IN THE MORNING...WEST OF A KBPI TO KCOD LINE...BEFORE A
SLIGHTLY BROADER IMPULSE...JUST STARTING TO SHOW UP OVER WEST CNTRL
CA SAT IMAGERY...WILL SWING AROUND AMPLIFYING TROF AND ARRIVE NEAR
OUR NWRN CWA LATE TOMORROW AFTERNOON AND EVENING...PROVIDING PERHAPS
ENOUGH EXTRA LIFT IN AND AROUND THE ELEVATED TERRAIN TO GET
MEASURABLE PRECIP WEST OF AN EVANSTON TO LANDER TO CODY LINE. MID
LVL MOISTURE WILL ALSO BE MORE AVAILABLE FOR PRECIP IN WRN AND NWRN
WY DURING THE DAY AND POPS... REFLECT THIS TREND.
ELSEWHERE...MEASURABLE PRECIPITATION WILL BE HARD TO COME BY WITH
ONLY VERY ISOLATED CHANCES AROUND THE REST OF THE CWA WITH A
SLIGHTLY BETTER CHANCE NEAR THE SRN BIG HORNS. APPROACH OF RATHER
WEAK JET ASSOCIATED WITH LEADING EDGE OF TROF WILL BE ENOUGH TO
ENHANCE UPWARD VERTICAL SHEAR THROUGH THE DAY AND INTO THE EVENING
WHICH MAY AID IN KEEPING SHOWER/THUNDER CHANCES GOING A BIT LATER
INTO THE EVENING.
.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY NIGHT
AS A PACIFIC LOW PRESSURE TROUGH MOVES INTO THE WEST COAST
AND DEEPENS...SOUTH SOUTHWEST FLOW ALOFT WILL INCREASE OVER
WESTERN AND CENTRAL WYOMING THURSDAY NIGHT. PACIFIC MOISTURE
WILL BE LIMITED TO THE WEST WITH A DRY SLOT OVER SOUTHERN AND
CENTRAL WYOMING LIMITING CONVECTION TO THE WESTERN MOUNTAINS.
WARMING ILL ACCOMPANY THE SOUTH SOUTHWEST FLOW. THE PACIFIC TROUGH
IS EXPECTED TO MOVE SLOWLY EAST AS IT MOVES INTO THE WESTERN GREAT
BASIN WITH THE SOUTH SOUTHWEST FLOW ALOFT INCREASING. SHOWERS AND
ISOLATED THUNDERSTORMS WILL BE LIMITED TO THE WEST AND NORTH WITH A
DRY SLOT CONTINUING IN THE SOUTH AND CENTRAL AREAS. TEMPERATURES
WILL CONTINUE TO WARM. FRIDAY NIGHT THE PACIFIC TROUGH WILL BE OVER
IDAHO AND UTAH WITH MOISTURE AND CONVECTION SPREADING EAST IN THE
STRONG SOUTH SOUTHWEST FLOW ALOFT BRINGING ISOLATED SHOWERS EASY
WITH SCATTERED SHOWERS IN THE WEST...ALONG WITH ISOLATED EVENING
THUNDERSTORMS. TEMPERATURES WILL CONTINUE THE WARMING TREND IN THE
EAST WITH COOLING IN THE WEST. SATURDAY THE PACIFIC TROUGH WILL
BEGIN TO MOVE ACROSS WESTERN WYOMING WITH SHOWERS AND ISOLATED
AFTERNOON THUNDERSTORMS CONTINUING TO SPREAD EAST WITH AN INCREASE
IN COVERAGE OVER THE WEST AND NORTH. TEMPERATURES WILL COOL WITH
CLOUD COVER AND INCREASED PRECIPITATION. A SURFACE FRONT WILL MOVE
INTO THE NORTH THROUGH SATURDAY ADDING TO THE COOLING IN THE NORTH.
SATURDAY NIGHT THE FIRST PACIFIC TROUGH WILL MOVE EAST INTO THE
NORTHERN AND CENTRAL PLAINS WHILE A SECOND PACIFIC TROUGH DEVELOPS
OVER THE NORTHERN ROCKIES AND NORTHERN GREAT BASIN. THIS WILL
CONTINUE TO BRING PACIFIC MOISTURE AND COLDER TEMPERATURES WITH
SCATTERED SHOWERS...MOST NUMEROUS IN THE WESTERN AND NORTHERN
MOUNTAINS...AND ISOLATED AFTERNOON THUNDERSTORMS SUNDAY. THIS
SECOND TROUGH WILL BRING THE COLD FRONT THROUGH THE STATE FROM THE
NORTH WITH A SECONDARY COLD PUSH BEHIND THE INITIAL COLD FRONT
SUNDAY NIGHT. THE SECOND PACIFIC TROUGH WILL MOVE SLOWLY ACROSS
WESTERN AND CENTRAL WYOMING KEEPING THE THREAT OF SHOWERS ELEVATED
OVER THE AREA AND CONTINUE THE COOLING TREND THROUGH MONDAY AND
MONDAY NIGHT WITH A GRADUAL DECREASE IN SHOWERS THROUGH THE NIGHT. A
HIGH PRESSURE RIDGE WILL BUILD IN AS THE SECOND TROUGH MOVES EAST OF
THE AREA INTO THE NORTHERN AND CENTRAL PLAINS. THE HIGH PRESSURE
WILL BRING AND END TO THE SHOWERS AND BRING SOME WARMING WITH MORE
SUNSHINE ON TUESDAY. TUESDAY NIGHT WILL REMAIN ON THE COOL SIDE WITH
CLEARING AND GREATER RADIATIONAL COOLING.
&&
.AVIATION.../00Z ISSUANCE/
VFR CONDITIONS WILL PREVAIL TONIGHT AT KCOD AND KWRL...WITH SHOWERS
AND A FEW THUNDERSTORMS PERSISTING THROUGH 04Z MOST OTHER TERMINALS
EXCEPT FOR KJAC WHICH MAY REMAIN UNSETTLED THROUGH 09Z. STORM MOTION
WILL BE LARGELY FROM WSW TO ENE. LOCAL MVFR CONDITIONS MAY OCCUR IN
VCNTY STORMS. CLOUD BASES WILL LARGELY BE ABOVE 5K FT AGL WITH
SHOWERS AND STORMS ON THE DRY SIDE AND OUTFLOW DOMINATED WITH WIND
GUSTS NEAR SOME STORMS AT 30 TO 35 KTS. MOST TERMINAL SITES WILL
HAVE VCTS IN THEM BETWEEN TIL 02-03Z...EXCEPT KWRL. LINGERING SHOWERS
ARE EXPECTED THROUGH 06-09Z...AND THEN AGAIN AT KJAC AFTER 15Z
TOMORROW. MORE SHOWERS AND SOME THUNDER CAN BE EXPECTED THURSDAY
NEAR MOST TERMINALS...BUT AFFECTING WESTERN TERMINALS THE MOST. THE
LONE EXCEPTION WILL BE KWRL...WHERE SHRA OR TSRA SHOULD STAY OUT OF
THEIR REGIONAL FORECAST AREA. ROCK SPRINGS WILL ALSO FIND IN A BIT
HARDER THAN OTHERS TO GET THUNDER OR PRECIPITATION.
&&
.FIRE WEATHER...
SOMEWHAT COOLER TEMPERATURES TODAY...DOWN 5 TO 7 DEG...UPPER LEVEL
HEIGHT FALLS BEGIN A SLOW PROGRESSION INTO THE FORECAST AREA FROM
THE SOUTHWEST. AHEAD OF THE AMPLIFYING TROF OUT WEST...SEVERAL
UPPER LEVEL DISTURBANCES WILL CONTINUE TO IMPACT THE STATE OVER THE
NEXT SEVERAL DAYS. CURRENTLY CONVECTION IS PROCEEDING...STARTING
OVER THE UINTAH MOUNTAINS AND MOVING INTO THE SOUTHERN PORTIONS OF
WY. THIS WAS FOLLOWED BY THE WIND RIVER REGION AND AND CONFLUENCE
WITH THE ABSOROKAS. THIS EVENING...ANOTHER IN A SERIES OF WEAK
IMPULSES WILL ENHANCE SHOWERS ACROSS THE WRN AND NWRN TERMINALS
INCLUDING KJAC. TEMPERATURES WILL CONTINUE TO COOL THROUGH THURSDAY
WITH A SLIGHT REBOUND ANTICIPATED FRIDAY AFTERNOON AHEAD OF THE
STRONGER WAVE OF LOW PRESSURE DUE TO ARRIVE THIS WEEKEND.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BRAUN
LONG TERM...C.BAKER
AVIATION...BRAUN
FIRE WEATHER...BRAUN
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