Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 100538
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1037 PM MST TUE FEB 9 2016

.SHORT TERM...TONIGHT THROUGH WEDNESDAY

WIND WILL BE THE MAIN STORY IN THE SHORT TERM AS A LEE TROUGH DIGS
AT THE SURFACE AND A SHARP TEMPERATURE GRADIENT DEVELOPS ALONG THE
ABSAROKAS. THERE IS A WEAK MOUNTAIN WAVE SIGNATURE THAT DEVELOPS
ALONG THE CODY FOOTHILLS. FLOW ACROSS THE BARRIER IS MARGINAL AND
THE DIRECTION OF THE FLOW IS HOLDING TO MUCH OF A NORTHERLY
COMPONENT FOR A CLASSIC CLARK BREAKING MOUNTAIN WAVE...BUT THERE
WILL BE SOME GUSTY CROSS WINDS ALONG HIGHWAY 120 AND FOR AREAS
WEST OF CODY AND AROUND CLARK TONIGHT INTO WEDNESDAY MORNING.
THERE COULD BE SOME 30 TO 40 MPH WINDS COMING OUT OF THE CANYONS
WITH OCCASIONAL GUSTS TO 60 MPH POSSIBLE IN FAVORED AREAS.
OTHERWISE...FLOW WILL INCREASE FROM THE RED DESERT TO CASPER AS
THE LEE TROUGH CONTINUES TO SET UP WITH 20 TO 35 MPH WINDS COMMON
IN THAT AREA.

THE GOOD NEWS WITH ALL OF THE WIND IS THAT THERE WILL BE WARM AIR
ALOFT MIXING DOWN. THERE COULD EVEN BE SOME RECORD HIGHS IN
FOOTHILL LOCATIONS EAST OF THE DIVIDE. THE WESTERN VALLEYS ARE
EXPECTED TO REMAIN UNDER RATHER STEEP INVERSIONS WITH MORNING FOG
OBSCURING THE SKIES AGAIN ON WEDNESDAY. THERE IS A BETTER CHANCE
FOR MIXING IN THE BASINS EAST OF THE DIVIDE...BUT EVEN IF WE DO
NOT FULLY MIX THERE WILL STILL BE A NICE SUNNY AND MILD DAY FOR
WEDNESDAY.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

MAINLY QUIET WEATHER WILL CONTINUE TO BE THE RULE INTO MUCH OF THE
LONG TERM PERIOD. THERE WILL STILL BE SOME GUSTY WINDS WEDNESDAY
NIGHT ACROSS THE USUAL LOCATIONS LIKE NEAR CLARK AND ALSO ACROSS THE
SOUTHWESTERN WIND CORRIDOR HOWEVER HIGH WINDS ARE NOT EXPECTED AT
THIS TIME. A WEAK COLD FRONT AND ASSOCIATED SHORT WAVE WILL THEN
SLIDE ACROSS THE AREA ON THURSDAY AND THURSDAY NIGHT. THE NAM IS
SHOWING A FEW SHOWERS WITH THE PASSAGE BUT EVEN THESE LOOK TO BE
FAIRLY INCONSEQUENTIAL. THE FRONT COULD MIX OUT THE BASINS A BIT
MORE FOR THURSDAY AS WELL. TEMPERATURES SHOULD CONTINUE ACROSS SLOW
CLIMB ACROSS THE BASINS AS THE ABOVE FREEZING TEMPERATURES MELT THE
SNOW PACK AND THE ALBEDO DECREASES THROUGH FRIDAY. ALL IN ALL THE
RESULTS OF RIDGING ACROSS THE AREA.

BY SATURDAY ANOTHER WAVE WILL APPROACH THE WEST. THERE ARE SOME
DIFFERENCES WITH THE MODELS WITH THE EUROPEAN SHOWING A BOUNDARY
SETTING UP ACROSS NORTHERN WYOMING. MEANWHILE...THE GFS IS FURTHER
NORTH AND KEEPS PRECIPITATION ACROSS MONTANA. WITH THE UNCERTAINTY
WE MADE FEW CHANGES. ANOTHER PIECE OF ENERGY MAY BRING A FEW MORE
SHOWERS FOR SUNDAY ACROSS THE WESTERN AND NORTHERN MOUNTAINS BUT
AGAIN THE BEST MOISTURE LOOKS TO REMAIN TO THE NORTH OF THE AREA.
ALMOST ALL THE LOWER ELEVATIONS EAST OF THE DIVIDE SHOULD REMAIN DRY
THROUGH THE WEEKEND.

THE MODELS REALLY DIVERGE FOR EARLY NEXT WEEK. THE GFS REBUILDS THE
RIDGE THROUGH TUESDAY WITH DRY WEATHER ACROSS MUCH OF THE COWBOY
STATE. MEANWHILE...THE EUROPEAN HAS A FLATTER RIDGE WITH SOME
DISTURBANCES RIDING OVER THE TOP OF IT. BUT AGAIN...MOST OF THE
ENERGY AT THIS POINT LOOKS TO STAY ACROSS MONTANA AND THE MODEL IS
FURTHER NORTH THAN THE 00Z RUN. FOR NOW...FEW CHANGES WERE MADE TO
CONTINUITY UNTIL THE MODELS COME INTO BETTER AGREEMENT.

&&

.AVIATION.../06Z ISSUANCE/

FOG AND LOW CLOUDS WILL ONCE AGAIN IMPACT THE FAR WESTERN VALLEYS
WEDNESDAY MORNING. THE FOG/LOW CLOUDS ONCE THEY FORM WILL PROBABLY
NOT SCATTER OUT/LIFT UNTIL EARLY WEDNESDAY AFTERNOON.
OTHERWISE...VFR CONDITIONS ARE EXPECTED WITH ONLY INCREASING HIGH
CLOUDS WEDNESDAY. THE BASINS AND VALLEYS WILL SEE FAIRLY LIGHT WINDS
THROUGH THE PERIOD WHILE MOUNTAINS...FOOTHILLS AND WIND CORRIDOR
FROM KRKS TO KCPR WILL BE BREEZY TO WINDY AT TIMES.

&&

.FIRE WEATHER...

STEEP TEMPERATURE INVERSIONS...ESPECIALLY IN THE WESTERN VALLEYS
WILL LEAD TO VERY POOR SMOKE DISPERSION. WINDS...HOWEVER...WILL
BE ON THE BREEZY SIDE ACROSS THE USUAL WIND PRONE AREA OF CENTRAL
WYOMING. WEDNESDAY...AREAS IN AND ADJACENT TO THE ABSAROKA
MOUNTAINS COULD SEE A FEW GUSTS OVER 50 MPH NEAR THE CANYONS. IT
WILL BE FAIRLY WINDY FROM THE RED DESERT TO CASPER WEDNESDAY AS
WELL...WHICH WILL IMPROVE SMOKE DISPERSION IN THESE AREAS. NO
MAJOR SNOW STORMS OR WIDESPREAD STRONG WIND EVENTS ARE ON THE
HORIZON...

&&

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

&&

$$

SHORT TERM...ALLEN
LONG TERM...HATTINGS
AVIATION...WM
FIRE WEATHER...ALLEN


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