Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 212001
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
201 PM MDT MON APR 21 2014

.SHORT TERM...TONIGHT AND TUESDAY

RIDGE AXIS MOVING INTO THE WEST WITH ONLY SOME HIGH CLOUDS FILTERING
THROUGH WITH IT. OTHERWISE...ANOTHER MILD DAY WITH MOST AREAS NOT
SEEING ANY SIGNIFICANT WINDS. WEATHER PATTERN STARTS TO CHANGE LATER
THIS EVENING AS THE FIRST SHORTWAVE MOVES OUT OF OUR APPROACHING
UPPER LOW. THIS SHORTWAVE MOVES ACROSS THE NORTHWEST LATER TONIGHT
WITH AN INCREASING CHANCE OF RAIN AND SNOW SHOWERS. NOTHING TOO
SIGNIFICANT BUT A DECENT CHANCE OF SHOWERS FROM ABOUT THE TETONS
NWD. THE TROUGH MOVES INTO THE GREAT BASIN DURING THE DAY TUESDAY
WITH INCREASING SLY FLOW ACROSS OUR AREA. TIMING IS A LITTLE SLOWER
THAN YESTERDAY SO EVEN THOUGH IT WILL STILL BE WINDY IN MOST AREAS
TOMORROW...IT SEEMS THE RISK OF HIGH WINDS HAS DIMINISHED DURING THE
AFTERNOON HOURS TUESDAY. SHOWERS AND HIGHER MOUNTAIN SNOW STILL
LOOKS GOOD OUT WEST WITH ISOLATED AT BEST FOR MOST OF THE AREA EAST
OF THE DIVIDE. A FEW THUNDERSTORMS ARE POSSIBLE IN THE FAR WEST
BASED ON ADJUSTED SOUNDINGS. NOT THAT EXCITING EAST OF THE DIVIDE
BUT COULD BE SOME LOCALIZED SMALL CAPE SO WON`T CHANGE IDEA OF
ISOLATED THUNDERSTORMS FOR THE ENTIRE CWFA TUESDAY AFTERNOON.
OTHERWISE...WARM WITH 70S TO 80 IN THE WARMEST LOCALES EAST OF THE
DIVIDE WITH 50S AND 60S WEST. CONTINUED SNOWMELT IN THE MOUNTAINS
WITH HIGHS IN THE 50S UP TO 9000 FEET EAST OF THE DIVIDE WITH MAINLY
40S WEST. SNOW LEVEL IN THE FAR WEST WILL LIKELY BE AROUND 10K FEET
DURING THE DAY.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY

THE FOREMENTIONED COLD FRONT WILL SWEEP ACROSS THE AREA TUE NIGHT
AND INTO WEDNESDAY. THE PERIOD OF STEADIEST PRECIPITATION OUT WEST
STILL LOOKS TO BE TUESDAY EVENING WITH THE FRONT. WITH COLD AIR
PUSHING IN BEHIND THE FRONT WE EXPECT SNOW LEVELS TO DROP TO THE
VALLEY FLOORS DURING THE NIGHT. WITH THE BEST ENERGY GONE BY
WEDNESDAY WE EXPECT THE PRECIPITATION TO BECOME MORE SHOWERY AT
THAT POINT. MEANWHILE...EAST OF THE DIVIDE WE EXPECT THE
PRECIPITATION TO BE A LOT MORE SCATTERED TUESDAY NIGHT DUE TO THE
STRONG WESTERLY DOWNSLOPING FLOW FOR MANY AREAS. WITH THE BEST
ENERGY ACROSS NORTHERN AREAS WE KEPT THE POPS HIGHER IN THIS
VICINITY. AS FOR WEDNESDAY EAST OF THE DIVIDE...IT WILL BE MUCH
COOLER...AROUND 20 DEGREES COOLER FOR MANY LOCATIONS. IT WILL ALSO
BE A TOUPEE ALERT DAY WITH A TIGHT PRESSURE GRADIENT REMAINING
OVER THE AREA WITH HIGH PRESSURE TO THE WEST AND DEVELOPING LOW
PRESSURE TO THE EAST. AS FOR POSSIBLE HIGH WIND HIGHLIGHTS...700
MILLIBAR WINDS DO NOT LOOK TO BE QUITE STRONG ENOUGH AT THIS
POINT. GFS MOS DOES SHOW 40 KNOTS AT THE ROCK SPRINGS AIRPORT BUT
THIS TENDS TO OVERDO THE WIND. HOWEVER...A BLUSTERY DAY FOR MANY
AREAS. AS FOR PRECIPITATION...BOTH MODELS SHOW LITTLE ACROSS THE
AREA. WITH SOME INSTABILITY THERE COULD BE A FEW SHOWERS HOWEVER
MOST AREAS OTHER THAN THE MOUNTAINS SHOULD BE PRECIPITATION FREE A
VAST MAJORITY OF THE TIME WITH DOWNSLOPING OFF OF THE MOUNTAINS.

THINGS SHOULD QUIET DOWN A BIT AS WE HEAD INTO WEDNESDAY NIGHT AND
THURSDAY AS SOME SHORT WAVE RIDGING MOVES ACROSS THE AREA. AS A
RESULT WE REDUCED POPS A BIT ACROSS THE AREA. WITH THE PRESSURE
GRADIENT RELAXING A BIT WINDS SHOULD BACK OFF A BIT ALTHOUGH IT WILL
STILL BE BREEZY TO WINDY IN MANY LOCATIONS.

THE WEATHER THEN LOOKS TO TAKE ANOTHER UNSETTLED TURN AS A TROUGH
CARVES OUT ACROSS THE WESTERN UNITED STATES. AREAS EAST OF THE
DIVIDE SHOULD SQUEEZE OUT ONE MORE DRY DAY ON FRIDAY THOUGH. SHOWERS
WILL SPREAD BACK INTO WESTERN WYOMING HOWEVER. THERE ARE DIFFERENCES
THAT SHOW UP STARTING SATURDAY. THE GFS DEVELOPS A CLOSED UPPER LOW
ACROSS THE SOUTHERN GREAT BASIN AND SLOWLY DRIFTS IT EAST ACROSS
COLORADO THROUGH MONDAY. THE EUROPEAN HAS MORE OF A TROUGH.
HOWEVER...BOTH MODELS HAVE IT UNSETTLED WITH CHANCES OF SHOWERS EACH
DAY FROM SATURDAY THROUGH MONDAY. CLOSED UPPER LEVEL LOWS ARE VERY
HARD TO PREDICT MOVEMENT ON THOUGH WITH THE MODELS CHANGING THEIR
OPINIONS MORE THAN A POLITICIAN. AS A RESULT...PINPOINTING A WETTER
DAY IS NEARLY IMPOSSIBLE AT THIS POINT. SO THE SOLUTION WAS TO KEEP
A CHANCE OF SHOWERS THROUGH THE PERIOD. AS FOR THUNDERSTORMS...THE
BEST CHANCE WOULD BE SATURDAY AS A COLD FRONT MOVES THROUGH THE
STATE. TEMPERATURES LOOK TO BE NEAR TO BELOW NORMAL FROM SATURDAY
THROUGH MONDAY WITH CLOUD COVER AND GENERAL TROUGHINESS OVER THE
AREA.

&&

.AVIATION.../00Z ISSUANCE/

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

VFR CONDITIONS WILL OCCUR THROUGH TONIGHT AND IN MOST AREAS
THROUGH TUESDAY AFTERNOON. STRONG SOUTHERLY WINDS WILL DEVELOP
TUESDAY AFTERNOON WITH ISOLATED THUNDERSTORMS POSSIBLE THAT MAY
PRODUCE VERY STRONG...ERRATIC WIND GUSTS OVER 50 MPH.

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

VFR CONDITIONS WILL OCCUR TODAY THROUGH 06Z TUESDAY. ISOLATED RAIN
SHOWERS WILL DEVELOP OVER THE FAR WEST MOUNTAINS AFTER 03Z TUESDAY.
SCATTERED RAIN OR SHOWERS WILL OCCUR OVER THE WESTERN WY MOUNTAINS
AFTER 06Z TUESDAY WITH LOCAL MVFR CONDITIONS POSSIBLE. TUESDAY WILL
BE VERY SHOWERY IN THE WEST WITH MOUNTAIN OBSCURATION PREVALENT WITH
RAIN SHOWERS AND ISOLATED THUNDERSTORMS. THE SNOW LEVEL WILL BE
ABOVE 10K FEET. STRONG SOUTHERLY WINDS WILL BLOW IN MANY AREAS WITH
GUSTS OVER 40 MPH. ISOLATED THUNDERSTORMS COULD PRODUCE VERY STRONG
AND ERRATIC WIND GUSTS OVER 50 MPH.

&&

.FIRE WEATHER...

...HAZARDOUS BURNING CONDITIONS ON TUESDAY AND WEDNESDAY...

DRY WITH BREEZY AREAS...MAINLY IN THE MOUNTAINS AND FOOTHILLS
THROUGH TONIGHT. A WEAK WEATHER DISTURBANCE AHEAD OF A MAJOR WEATHER
SYSTEM WILL MOVE INTO THE NORTHWEST TONIGHT WITH A CHANCE OF SHOWERS
WITH HIGH SNOW LEVELS. SOUTHERLY WINDS WILL BE ON THE INCREASE
TONIGHT AND ESPECIALLY TUESDAY INTO WEDNESDAY. THE COMBINATION OF
STRONG TO VERY STRONG SOUTHERLY WINDS ON TUESDAY COMBINED WITH WARM
TEMPERATURES AND LOW RH`S WILL INCREASE THE FIRE DANGER. OUT
WEST...RAIN SHOWERS WITH BE LIKELY ON TUESDAY WITH THE SNOW LEVEL
NEAR 10K FEET. A STRONG COLD FRONT WILL SWEEP EAST ACROSS THE AREA
TUESDAY NIGHT WITH A BAND OF SHOWERS AND ISOLATED THUNDERSTORMS. IT
WILL CONTINUE VERY WINDY THROUGH WEDNESDAY. WEDNESDAY WILL ALSO BE
CONSIDERABLY COOLER THAN TUESDAY BUT STILL RATHER DRY EAST OF THE
DIVIDE WITH MIN RH`S IN THE TEENS AND 20S.

&&

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

&&

$$

SHORT TERM...SKRBAC
LONG TERM...HATTINGS
AVIATION...SKRBAC
FIRE WEATHER...SKRBAC






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