Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 232058
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
158 PM MST FRI JAN 23 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY
MID LEVEL CIRCULATION AND ASSOCIATED TROUGH AXIS CONTINUES TO PUSH
SOUTH ACROSS THE AREA THIS AFTERNOON. THE BEST BAND OF LIGHT SNOW
HAS BEEN PUSHING SOUTH FROM THE UPPER GREEN INTO THE THE SW
CORNER. ANOTHER AREA OVER CENTRAL WYO BROUGHT SOME FLURRIES FROM
RIW TO WEST OF CPR EARLIER AND WHAT`S LEFT OF THAT AREA IS PUSHING
THROUGH FROM NEAR SOUTH PASS EAST TO PATHFINDER. CLOUDS STILL
LINGERING FOR SEVERAL HOURS BEHIND THIS AREAS OF PCPN. LOOKS LIKE
A LOT OF THE AREA WILL CLEAR OFF EARLY THIS EVENING AND THAT
COMBINED WITH SIGNIFICANT WARMING ALOFT MAY SET THE STAGE FOR SOME
BRIEF FOG OR LOW CLOUDS IN THE BASINS AND VALLEYS. THE BEST CHANCE
WILL PROBABLY BE IN THE WIND RIVER BASIN WITH A SECONDARY AREA OR
TWO IN THE UPPER GREEN AND WRL SWD. FURTHER NORTH...THE CLOUDS
START EDGING IN TOWARDS MORNING WHICH WILL LIMIT OR NOT ALLOW THE
FOG TO FORM. ONLY ADDED PATCHY FOG TO THOSE AREAS. LEADING EDGE OF
THE SHORTWAVE EDGES INTO THE NW BEFORE 12Z AND THEN ACROSS MOST OF
THE NORTH DURING THE MORNING. MODEST ISENTROPIC UPGLIDE OVERALL
BUT ENOUGH FOR SOME HIGH COUNTY SNOW AND PROBABLY A COUPLE INCHES
FOR SOME OF THE FAR NRN MOUNTAINS FROM THE ABSAROKAS OVER TO THE
BIGHORNS. ALSO LOOKS LIKE A SHOT IN THE MT BORDER AREAS OF THE
BIGHORN BASIN AND ESPECIALLY IN JOHNSON COUNTY SATURDAY MORNING...
POSSIBLY MAKING IT DOWN TO CASPER AND CASPER MTN. ADDED IN SOME
SLIGHT CHANCES THERE FROM MID MORNING TO EARLY AFTERNOON. WARM
ENOUGH THAT IT MAY BECOME SPRINKLES. ALSO LOOKS QUITE WINDY IN THE
BYG AREA AS THE DAY WEARS ON SO PREVIOUS FCST OF 50-55 MPH WINDS
STILL LOOKS GOOD. A FEW FLURRIES ARE POSSIBLE AGAIN ON THE EDGE OF
THIS SYSTEM A LITTLE FURTHER WEST. OTHERWISE...QUITE A BIT OF
CLOUDS ACROSS THE AREA LIKE TODAY. ANOTHER WEATHER INTEREST IS
SOME DECENT GAP FLOW AT TIMES IN THE CODY FOOTHILLS THROUGH
SATURDAY. NOTHING WARRANTING A HIGHLIGHT BUT WINDY NONETHELESS.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

THE LAST IN THE SERIES OF SHORTWAVES WILL SWING THROUGH THE AREA ON
SATURDAY NIGHT WITH ANOTHER BATCH OF MAINLY LIGHT SNOW ACROSS THE
MOUNTAINS AND PORTIONS OF THE LOWER ELEVATIONS. AGAIN...THE SYSTEM
IS MOISTURE STARVED SO ANY ACCUMULATIONS ONCE AGAIN WILL BE LIGHT.
ONE CONCERN IS SOME GUSTY WINDS IN THE FAVORED AREAS LIKE CLARK AND
EVEN PORTIONS OF THE NORTHERN BIG HORN BASIN AND NEAR BUFFALO THAT
ARE FAVORED IN NORTHWEST FLOW. AT THIS POINT...700 MILLIBAR WINDS DO
NOT LOOK STRONG ENOUGH TO SUPPORT ANY HIGH WIND HIGHLIGHTS BUT WE
WILL WATCH IT.

THEN STARTING ON SUNDAY...ANY SNOW SHOWERS WILL DECREASE AS THE WAVE
MOVES AWAY AND HEIGHTS START TO RISE . BY SUNDAY NIGHT...SNOW
SHOWERS SHOULD END AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE AREA
FROM MONDAY AND INTO TUESDAY. THE MAIN CONCERN HERE IS FOR POSSIBLE
INVERSIONS WITH THE WEAK FLOW. AT THIS POINT...THE WESTERN VALLEYS
WITH DEEPER SNOWPACK LOOK LIKE A BETTER BET FOR THAT. EAST OF THE
DIVIDE...EVEN IN THE BASINS MANY OF THE LOWER ELEVATIONS HAVE LOST
SNOWPACK AND THE SNOW THAT IS LEFT IS OLDER...HENCE LIMITING ALBEDO.
THEREFORE...IT LOOKS UNSEASONABLE MILD. SOME MODELS ARE HINTING AT
SOME AREAS MAKING A RUN AT HIGHS OF 60 MONDAY OR TUESDAY...MAINLY
EAST OF THE BIGHORN RANGE.  NOT READY TO BITE ON THAT YET...BUT IT
CERTAINLY WILL NOT FEEL LIKE JANUARY. THERE WILL BE THE CHANCE FOR
SOME LATE NIGHT FOG IN THE FAVORED VALLEYS AND BASIN AREAS WITH THE
CLEAR SKIES AND LIGHT WINDS.

THE NEXT SYSTEM WITH ORIGINS IN THE BAJA WILL MOVE INTO THE STATE
TUESDAY NIGHT. AT THIS POINT...WE LIKE THE GFS BETTER SINCE IT HAS
BEEN MORE CONSISTENT WITH TIMING THAN THE EUROPEAN WHICH HAS JUMPED
AROUND THE PAST FEW RUNS. AT THIS POINT...IT DOES NOT LOOK LIKE A
MAJOR STORM WITH THE BEST CHANCES FOR PRECIPITATION TUESDAY NIGHT
AND WEDNESDAY OUT WEST. THE SMALLEST CHANCES WOULD BE NEAR CASPER
WERE SOUTHWESTERLY FLOW COULD PREVENT PRECIPITATION FROM REACHING
THE GROUND. WE ALSO AGREE THAT THE SYSTEM WILL BE FAIRLY WARM WITH
MANY EASTERN VALLEY AND BASINS LOCATIONS POSSIBLY SEEING MOSTLY RAIN
WITH SNOW LEVELS AROUND 6000 FEET OR SO. THIS SYSTEM SHOULD EXIT
EAST WEDNESDAY NIGHT. FOR THE END OF THE WORKWEEK...OR AT LEAST THE
WORKWEEK FOR PEOPLE WHO DO NOT DO SHIFT WORK...WE WILL RETURN TO A
NORTHWEST FLOW PATTERN WITH SOME WEAK DISTURBANCES MOVING THROUGH
THE FLOW. BOTH THE EUROPEAN AND GFS SHOW AN ALBERTA CLIPPER DROPPING
DOWN FOR FRIDAY. THE BEST ENERGY REMAINS WELL TO THE EAST OF
WYOMING...ALTHOUGH IT COULD GET CLOSE ENOUGH TO BRUSH THE AREA WITH
A FEW SHOWERS.

&&

.AVIATION.../00Z ISSUANCE/
VFR CONDS ARE EXPECTED OVERNIGHT EXCEPT FOR PATCHY FOG IN THE
BASINS AND VALLEYS OVERNIGHT WITH LCL IFR CONDS POSSIBLY AFFECTING
KJAC...KBPI...KPNA ...KRIW AND KWRL. IT WILL BE SHORT LIVED AS
ANOTHER SYSTEM WILL MOVE QUICKLY IN FROM THE NW WITH MORE
CLOUDS...AND VERY LIGHT SNOW OR FLURRIES ACROSS THE NORTH HALF OF
THE AREA SATURDAY. THE HIGHEST PROBABILITY OF LIGHT SNOW WILL BE
IN THE NORTHERN MOUNTAINS WHICH WILL BE OBSCURED AT TIMES
SATURDAY. STRONG NORTH TO NORTHWEST WIND WILL BLOW IN THE
MOUNTAINS AND NORTHERN JOHNSON COUNTY. SCATTERED SNOW SHOWERS OR
FLURRIES ACROSS THE FAR NORTHERN BIGHORN BASIN AND JOHNSON COUNTY
COULD BECOME A MIXTURE OF RAIN OR SNOW BY EARLY AFTERNOON BEFORE
ENDING LATE IN THE DAY. WIND GUSTS OVER 50 MPH ARE POSSIBLE AROUND
KBYG SATURDAY.

&&

.FIRE WEATHER...
HIGH PRESSURE LOOMS TO THE WEST WHILE A FEW WEAK SYSTEMS RIPPLE
AROUND THE HIGH AGAIN ON SATURDAY. THEY WILL HAVE MINOR IMPACT ON
THE AREA WITH SOME INCREASING CLOUDS AND SOME BREEZES IN MOST
AREAS. THE MOUNTAINS MAY SEE SOME SNOW WITH A VERY SMALL CHANCE OF
A RAIN OR SNOW SHOWER IN THE LOW ELEVATIONS OF NORTHERN CODY
DISPATCH AND CASPER DISPATCH. TEMPERATURES WILL BE MILD THROUGH
THE PERIOD WITH A WARMING TREND EXPECTED TO LAST INTO NEXT WEEK.
WE STILL CAN NOT GET MIXING HEIGHTS UP TOO MUCH...ESPECIALLY IN
LESS WIND PRONE AREAS. HOWEVER THERE WILL BE SOME HIGH END POOR TO
FAIR SMOKE DISPERSAL POSSIBLE WITH EACH WAVE...EVEN IN THE LESS
WINDY AREAS.

&&

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

&&

$$

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









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