Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 220502
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1102 PM MDT SAT MAR 21 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY (ISSUED AT 214 PM MDT)

A PACIFIC TROUGH AND COLD FRONT WILL MOVE EAST ACROSS THE AREA
TONIGHT AND SUNDAY. SHOWER ACTIVITY IS EXPECTED ACROSS THE NORTHWEST
AND NORTH MOUNTAINS...WHILE THE LOWER ELEVATIONS WILL SEE MAINLY
INCREASING CLOUD COVER AND A WIND SHIFT TO THE NORTH. THE COLD FRONT
BESIDES BRINGING A WIND SHIFT...WILL BRING COOLER TEMPERATURES
ESPECIALLY TO THE NORTH. SOME LIGHT SNOW WILL FALL IN THE HIGHEST
MOUNTAINS...OTHERWISE VERY LIGHT PRECIPITATION IS EXPECTED.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY

WITH THE AREA IN BETWEEN SYSTEMS ON SUNDAY NIGHT EXCEPT MAINLY DRY
WEATHER FOR THAT PERIOD. AFTER THAN...WE WILL ENTER A PERIOD OF
UNSETTLED WEATHER. NO REAL DEEP OR ORGANIZED SYSTEMS...MAINLY A
PERIOD OF SHORTWAVES MOVING THROUGH THE AREA BRINGING A CHANCE OF
SHOWERS EACH DAY. THE PROBLEM...MUCH THE SAME AS YESTERDAY IS THAT
THE MODELS CONTINUE TO AGREE TO DISAGREE ON THE STRENGTH AND TIMING
OF MANY OF THEM.

THERE IS DECENT AGREEMENT ON THE FIRST WAVE WHICH WILL ENTER WESTERN
WYOMING ON MONDAY MORNING AND THEN SPREAD EASTWARD THROUGH THE DAY.
WITH MAINLY WESTERLY FLOW EXPECTED...MOST OF THE PRECIPITATION
SHOULD FALL IN THE WESTERN MOUNTAINS. EAST OF THE MOUNTAINS...WITH
DOWNSLOPING FLOW MANY SHOWERS ARE EXPECTED TO BE LIGHT. AND...WITH
THE SHOWERY NATURE OF THE PRECIPITATION PINPOINTING A MORE
CONCENTRATED AREAS OF SHOWERS IS DIFFICULT AT BEST. IN
ADDITION...STRONG WINDS SHOULD DEVELOP ACROSS SOUTHERN WYOMING SO
THIS WILL HAVE TO BE WATCHED AS WELL. AT THIS POINT...CONTINUITY
LOOKED DECENT SO WE MADE FEW CHANGES.

ANOTHER WAVE THEN ROLLS ACROSS FOR TUESDAY. THIS ONE APPEARS COLDER
SO TEMPERATURES WILL DROP DOWN INTO THE 40S. A GOOD POINT WAS MADE
BY THE PREVIOUS SHIFT THAT WITH LOW WET BULB ZERO LEVELS THAT SOME
SNOW PELLETS OR GRAUPEL COULD FALL EVEN IF HIGH TEMPERATURES ARE INTO
THE 40S. HOWEVER...WITH THE RECENT WARM WEATHER ACCUMULATION IS
UNLIKELY. ANOTHER WAVE THEN MOVES THROUGH FOR WEDNESDAY BUT THE
MODELS CONTINUE TO FLIP FLOP ON THIS ONE AS WELL WITH THE EUROPEAN
MORE IMPRESSIVE WITH IT WHICH IS DIAMETRICALLY OPPOSED TO YESTERDAY
AT THIS TIME WHEN THE GFS WAS MORE BULLISH. SO...RATHER THAN FLIP
FLOP OURSELVES WE LEFT CONTINUITY ALONE.

THINGS STILL LOOK TO SETTLE DOWN ON THURSDAY AS RIDGING BUILDS
ACROSS THE STATE BUT ONE LAST SHORTWAVE MAY BRING A FEW SHOWERS FOR
THURSDAY...MAINLY ACROSS THE EAST AND HIGHER ELEVATIONS. THINGS THEN
LOOK DRY AND MILD FOR FRIDAY WITH RIDGING BACK OVER THE AREA. THE
NEXT SYSTEM MAY DROP IN FROM THE NORTH AND WEST FOR SATURDAY BUT
STILL PLENTY OF TIME TO WATCH THAT.

&&

.AVIATION.../06Z ISSUANCE/

ISOLATED RAIN SHOWERS WITH MOUNTAIN SNOW SHOWERS WILL OCCUR OVER THE
NORTH THROUGH 14Z. LOCAL MVFR CONDITIONS WILL BE POSSIBLE IN AND
NEAR THE NORTHERN MOUNTAINS.

OTHERWISE...VFR CONDITIONS WILL OCCUR OVERNIGHT THROUGH SUNDAY
EVENING. ISOLATED SHOWERS WILL BE POSSIBLE IN FAR SOUTHERN WY AFTER
21Z SUNDAY THROUGH 06Z MONDAY. THE SHOWERS ARE EXPECTED TO BE SOUTH
OR SOUTHEAST OF THE KRKS AIRPORT.

&&

.FIRE WEATHER...

A PACIFIC TROUGH AND COLD FRONT WILL MOVE EAST ACROSS THE AREA
TONIGHT AND SUNDAY. SHOWER ACTIVITY IS EXPECTED ACROSS THE NORTHWEST
AND NORTH MOUNTAINS...WHILE THE LOWER ELEVATIONS WILL SEE MAINLY
INCREASING CLOUD COVER AND A WIND SHIFT TO THE NORTH. THE COLD FRONT
BESIDES BRINGING A WIND SHIFT...WILL BRING COOLER TEMPERATURES
ESPECIALLY TO THE NORTH AND A RELIEF TO RELATIVE HUMIDITY. MIXING
HEIGHTS WILL ALSO LOWER ABOUT 2500 FEET WITH A FRONTAL INVERSION
OVER THE AREA SUNDAY AND GENERALLY FAIR SMOKE DISPERSAL. SOME
WINDIER AREAS WILL HAVE GOOD SMOKE DISPERSAL.

&&

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

&&

$$

SHORT TERM...C.BAKER
LONG TERM...HATTINGS
AVIATION...AR
FIRE WEATHER...C.BAKER











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