Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 262125
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
225 PM MST THU FEB 26 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY

SURFACE HIGH BUILDS INTO CENTRAL HIGH PLAINS TONIGHT. CHALLENGE
FOR CENTRAL WYOMING WILL BE TIMING OF DECREASING CLOUD COVER. WEAK
LOW LEVEL UPSLOPE FLOW PERSISTS...BUT SURFACE FLOW TO TURN MORE
SOUTHERLY TONIGHT. BEST CONFIDENCE FOR CLEARING WILL BE OVER
NATRONA AND JOHNSON COUNTIES...TO NORTHERN SECTIONS OF FORECAST
AREA. REGARDLESS...IT WILL BE QUITE COLD TONIGHT INTO EARLY FRIDAY.

WEAK FLOW ALOFT SETS UP ON FRIDAY WITH UPPER LEVEL LOW DROPPING INTO
CALIFORNIA. AS A RESULT...LITTLE OR NO ENERGY OVER WYOMING WELL AHEAD
OF THIS TROUGH. COULD STILL SEE A FEW MOUNTAIN SNOW SHOWERS WITH
HEATING OF THE DAY. OTHERWISE...ANOTHER COLD DAY ACROSS WEST
CENTRAL WYOMING WITH MORE SUNSHINE EXPECTED. WITH A VERY LIGHT
SURFACE WIND...IT SHOULD FEEL DECENT OUTDOORS ON FRIDAY.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

AT THIS TIME...FRIDAY NIGHT LOOKS LIKE A MAINLY QUIET PERIOD WITH
JUST A FEW OROGRAPHIC SNOW SHOWERS ACROSS THE WESTERN MOUNTAINS. THE
REST OF THE REGION LOOKS MAINLY DRY WITH BELOW NORMAL TEMPERATURES
FOR THE START OF THE WEEKEND.

THE FIRST OF TWO SYSTEMS OF CONCERN IN THE LONG RANGE WILL START TO
EFFECT THE WEATHER FOR SATURDAY. A PIECE OF ENERGY WILL MOVE OFF A
CUT OFF LOW OVER CALIFORNIA AND MOVE INTO THE ROCKIES. HOWEVER...IT
APPEARS THAT THE BEST UPPER LEVEL SUPPORT WILL REMAIN OVER UTAH AND
COLORADO. AT AS RESULT...RIGHT NOW THIS LOOKS TO MAINLY A NUISANCE
EVENT AND ONLY EFFECT SOUTHERN PORTIONS OF THE COUNTY WARNING AREA
AND MAINLY WEST OF THE DIVIDE. BOTH THE GFS...EUROPEAN AND NAM ARE
IN GOOD AGREEMENT OF THIS. AS A RESULT...WE TRIMMED POPS ACROSS
AREAS NORTH AND EAST OF THE WIND RIVER RANGE FOR SATURDAY AND
SATURDAY NIGHT. EVEN IN AREAS THAT GET SNOW...THIS DOES NOT LOOK
WORTHY OF ANY SORT OF WARNINGS OR ADVISORIES RIGHT NOW. ON
SUNDAY...THERE IS SOME SLIGHT DISAGREEMENT WITH THE GFS KEEPING A
FEW SHOWERS ALONG THE SOUTHERN BORDER AND THE EUROPEAN MAINLY DRY.
WITH THE DIFFERENCES WE MADE FEW CHANGES TO CONTINUITY. MAINLY DRY
BUT CONTINUED CHILLY WEATHER WILL BE THE RULE FOR MONDAY WITH WEAK
SURFACE HIGH PRESSURE IN CONTROL.

THE NEXT AND PROBABLY MORE IMPACTFUL SYSTEM THEN APPROACHES FOR
MONDAY NIGHT AND ESPECIALLY FOR TUESDAY. THIS ONE HAS CHILLY ORIGINS
COMING IN FROM ALASKA.  THE MODELS AGAIN ARE IN FAIRLY GOOD
AGREEMENT WITH SNOW BEGINNING IN THE WEST ON MONDAY NIGHT AND THEN
SPREADING ACROSS ALL AREAS FOR TUESDAY. THE PREVIOUS FORECAST HAD
CHANCE POPS ACROSS MOST AREAS AND THESE LOOK PRETTY GOOD AT THIS
POINT SO FEW CHANGES WERE MADE. SNOWFALL AMOUNTS ARE STILL UNCERTAIN
RIGHT NOW...AS A LOT WILL DEPEND ON THE JET DYNAMICS AND OF COURSE
THE MODELS ARE PERFECT WITH THIS FIVE DAYS OUT...NOTE SARCASM. THERE
IS ALSO MORE AGREEMENT WITH THE END TIME. THE EUROPEAN HAS COME
AROUND TO THE MORE PROGRESSIVE GFS SOLUTION IN KICKING THE SYSTEM TO
THE SOUTH AND EAST DURING WEDNESDAY WITH ALL AREAS DRY AT THAT
POINT. TUESDAY NIGHT AND WEDNESDAY HAVE THE POTENTIAL TO QUITE COLD.
LOWS TUESDAY NIGHT MAY DEPEND ON HOW QUICKLY THE SKY CLEARS THOUGH.
MAINLY DRY BUT COOL WEATHER WILL BE THE RULE FOR WEDNESDAY INTO
THURSDAY WITH DRY NORTHWEST FLOW PREDOMINATING.

&&

.AVIATION.../00Z ISSUANCE/

CONDITIONS TO BECOME VFR TONIGHT AT ALL AIRPORT LOCATIONS. THIS IS
DUE TO DECREASING CLOUDS EAST OF THE CONTINENTAL DIVIDE. KBYG TO KCPR
EXPECTED TO CLEAR OUT BY LATE EVENING...THEN CENTRAL AND SOUTHWEST
WYOMING TO FOLLOW. HIGH PRESSURE IN CONTROL MOST AREAS ON FRIDAY.

SOME MOUNTAIN FLURRIES OR SNOW SHOWERS ARE STILL POSSIBLE FRIDAY
AFTERNOON AND EVENING. WESTERN MOUNTAIN PEAKS COULD BE OBSCURED
FRIDAY NIGHT INTO EARLY SATURDAY. OTHERWISE...LIGHT SURFACE WIND
AND VFR CONDITIONS CAN BE EXPECTED TO BEGIN THE WEEKEND ON BOTH
SIDES OF THE DIVIDE.

&&

.FIRE WEATHER...

NO FIRE WEATHER CONCERNS IN THE SHORT TERM...AS A COLD WEATHER
PATTERN CONTINUES FOR THE ENTIRE DISTRICT. LITTLE OR NO
PRECIPITATON THROUGH THE UPCOMING WEEKEND EAST OF THE DIVIDE...
BUT RELATIVE HUMIDITIES TO REMAIN HIGH.

WEST OF THE DIVIDE...INCREASING CLOUDS CAN BE EXPECTED ON FRIDAY.
A WEAK UPPER LEVEL TROUGH WILL MOVE OVER THE WESTERN MOUNTAINS LATE
FRIDAY TO HELP INITIATE SNOW SHOWERS. AREAS OF LIGHT SNOW WILL
PERSIST FRIDAY NIGHT...POSSIBLY REACHING THE WESTERN VALLEYS OF
WYOMING.

&&


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

$$

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




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