Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 282124
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
324 PM MDT TUE OCT 28 2014

.SHORT TERM...TONIGHT THROUGH MONDAY

GENERALLY DRY CONDITIONS EXPECTED THIS EVENING ACROSS THE
AREA...WITH HIGH PRESSURE REMAINING. A WEAK WAVE OF LOW PRESSURE
WILL SWEEP THROUGH MONTANA...WITH ITS EDGE IMPACTING THE NORTHERN
PORTION OF THE STATE. THIS MAY BE ENOUGH TO GENERATE SOME ISOLATED
TO WIDELY SCATTERED SHOWERS OVER THE NORTHERN QUARTER OF THE
STATE...WITH MOST ACTIVITY EXPECTED TO REMAIN CONFINED TO THE
MOUNTAIN AREAS. SOME STRONG DOWNSLOPE WIND ACROSS THE FAVORED
LOCATIONS OF THE ABSAROKAS AND WIND RIVERS. STRONG WIND TO 50 MPH
WILL BE POSSIBLE AT SOME LOCATIONS...BUT WIND OVERALL IS EXPECTED TO
REMAIN BELOW HIGH WIND CRITERIA.

THIS WAVE OF LOW PRESSURE WILL DIVE THROUGH THE EASTERN HALF OF THE
STATE WEDNESDAY AFTERNOON...BRINGING INCREASED CLOUD COVER BUT IS
NOT EXPECTED TO RESULT IN ANY SHOWER ACTIVITY. HOWEVER...COVERAGE
MAY INCREASE SLIGHTLY ACROSS THE NORTHERN MOUNTAINS AND THE BIG HORN
BASIN. EXPECT TEMPERATURES TO CONTINUE TO WARM WEDNESDAY...WITH A
RETURN OF GUSTY WIND DURING THE AFTERNOON HOURS...ESPECIALLY ACROSS
THE WIND CORRIDOR BETWEEN ROCK SPRINGS AND CASPER.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY

THE SYSTEM THAT BROUGHT THE SHOWERS ON WEDNESDAY ACROSS THE NORTH
LOOKS TO EXIT STAGE EAST ON WEDNESDAY NIGHT. WITH LINGERING UPSLOPE
FLOW THERE WILL STILL BE A FEW MOUNTAIN SHOWERS THROUGH THE EVENING
ALTHOUGH AMOUNTS LOOK TO BE INSIGNIFICANT. OTHER PERIOD OF QUIET
WEATHER WILL THEN MOVE IN FOR THURSDAY INTO FRIDAY AS RIDGING BUILDS
ACROSS THE AREA. A SYSTEM APPROACHING FROM THE WEST WILL TIGHTEN THE
PRESSURE GRADIENT A BIT FRIDAY AFTERNOON AND BRING A GUSTY WIND TO
THE FAVORED LOCATIONS IN SOUTHWESTERLY FLOW SUCH AS FROM ROCK
SPRINGS NORTHEASTWARD THROUGH NATRONA AND SOUTHERN JOHNSON COUNTIES.
MUCH OF THE REST OF THE COUNTRY WOULD CALL THIS WINDY...BUT IN
WYOMING WE CALL IT FRIDAY. THE NEXT DECENT WEATHER MAKER THEN LOOKS
TO BE MOVE IN FOR SATURDAY. BOTH THE GFS AND EUROPEAN HAVE SLOWED
THE PROGRESS OF THE STORM SO WE HAVE REMOVED PRECIPITATION FOR
SATURDAY MORNING. PRECIPITATION WILL SPREAD ACROSS AREAS WEST OF THE
DIVIDE THOUGH FOR SATURDAY AFTERNOON AS BETTER FORCING MOVES IN FROM
THE WEST. MEANWHILE...WITH THE PRESSURE GRADIENT CONTINUING TO
TIGHTEN EXPECT A WINDY DAY ACROSS AREAS EAST OF THE DIVIDE. THE
MODELS ARE SPLIT WITH THE EUROPEAN HAVING 50 KNOT WINDS AT 700
MILLIBARS WHILE THE GFS AS 40 TO 45 KNOTS. SO...THINGS WILL HAVE TO
BE WATCHED FOR HIGH WIND HIGHLIGHTS...ESPECIALLY IN AREAS FROM ROCK
SPRINGS TO CASPER. AT THE SAME TIME...THE STRONG DOWNSLOPING FLOW
WILL BRING WARM TEMPERATURES TO THE AREA WITH HIGH TEMPERATURES
POSSIBLY APPROACHING 70 IN SOME OF THE WARMER SPOTS IN THE EAST.
THIS DOWNSLOPING FLOW SHOULD KEEP AREAS EAST OF THE DIVIDE DRY
THROUGH MOST OF THE AFTERNOON. THE NEXT CONCERN IS POTENTIAL
SNOWFALL AMOUNTS...ESPECIALLY IN THE MOUNTAINS. BOTH THE GFS HAVE
SIMILAR TIMING WITH THE BEST DYNAMICS MOVING INTO NORTHERN WYOMING
FOR SATURDAY NIGHT BEFORE DEPARTING INTO MONTANA ON SUNDAY MORNING.
THE EUROPEAN REMAINS THE MORE MOIST MODEL ALTHOUGH IT HAS BACKED OFF
ON QPF JUST A BIT AS COMPARED TO THE 00Z RUN. THE PRECIPITATION AND
SNOWFALL AMOUNTS LOOKED REASONABLE AT THIS POINT SO WE MADE FEW
CHANGES. UNSETTLED WEATHER LOOKS TO BE THE RULE ACROSS THE AREA FOR
SUNDAY. MOST OF THE UPPER LEVEL FORCING WILL MOVE AWAY.
HOWEVER...WITH A TROUGH AXIS REMAINING OVER THE AREA AND
COOL...MOIST CYCLONIC CURVATURE AROUND SHOWS WILL PERSIST ON SUNDAY.
THE RESULT WILL BE THE 3C`S...CLOUDY...COOL AND CRUMMY. THE MODELS
THEN DIVERGE A BIT FOR MONDAY AND TUESDAY WITH DIFFERENT TIMING ON
SHORTWAVES. AS A RESULT...WE WENT WITH MAINLY SLIGHT CHANCE TO
CHANCE POPS ACROSS THE WESTERN MOUNTAINS WITH FAVORED OROGRAPHIC
FLOW AND MAINLY DRY EAST OF THE DIVIDE.

&&

.AVIATION.../00Z DISCUSSION/

VFR CONDITIONS EXPECTED THROUGH THE MAJORITY OF THE FORECAST PERIOD.
A WEAK WAVE OF LOW PRESSURE WILL MOVE THROUGH NORTHERN WYOMING AFTER
03Z TONIGHT...POTENTIALLY GENERATING SOME WEAK SHOWER ACTIVITY. MOST
ACTIVITY WILL BE CONFINED TO THE HIGHER ELEVATIONS. THIS ACTIVITY
MAY HELP TO INCREASE TURBULENCE OR ICING OVER THE IMPACTED MOUNTAIN
PASSES.

STRONGER MOUNTAIN RELATED WIND IS EXPECTED OVERNIGHT NEAR THE
TERMINALS OF KCOD AND KLND. WHILE THE STRONGEST SURFACE WIND IS NOT
ANTICIPATED TO IMPACT EITHER OF THESE TERMINALS...SOME LLWS WILL BE
POSSIBLE BETWEEN 06Z AND 15Z WEDNESDAY. A RETURN OF GUSTY WIND AFTER
17Z WILL BE POSSIBLE AT MANY TERMINALS DUE TO THE PASSAGE OF THE
WEAK WAVE OF LOW PRESSURE.

&&

.FIRE WEATHER...

GENERALLY DRY CONDITIONS ARE ANTICIPATED DURING THE EARLY EVENING
HOURS TONIGHT. AN APPROACHING WEAK WAVE OF LOW PRESSURE MAY GENERATE
SOME SHOWER ACTIVITY OVER THE NORTHERN MOUNTAINS AFTER 0300
TONIGHT...WHICH MAY CONTINUE AND INCREASE IN COVERAGE THROUGH
THE AFTERNOON. TEMPERATURES OVERALL WILL CONTINUE TO WARM
ACROSS THE FORECAST AREA...WITH SOME INCREASED AFTERNOON WIND.

&&

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

$$

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





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