Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 260515
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1015 PM MST SUN JAN 25 2015

.SHORT TERM...TONIGHT THROUGH MONDAY (ISSUED AT 210 PM MST)

WARM ADVECTION CLOUDS CONTINUE TO STREAM DOWN FROM THE NORTH WITH
ONE THICK BATCH EXITING THE SOUTH ATTM AND A SMALLER NEW AREA
HITTING THE NWRN CORNER ATTM. LOW CLOUDS AND SLOPE FOG IN THE FAR
WESTERN VALLEYS AND YNP CONTINUE THIS AFTERNOON. SOME THINNING IN
THE SRN JACKSON VALLEY BUT STILL CONSIDERABLE LOW CLOUDS IN THE
NRN JACKSON VALLEY AND MOST OF THE STAR VALLEY. THIS IS THE TRICKY
AREA TONIGHT WITH CONSIDERABLE WARM ADVECTION THROUGH THE NIGHT.
STRATUS LAYER COULD STAY IN OR BRIEFLY BREAKUP YET AND THEN FOG
COULD FORM AS SPREADS ARE SMALL AND DEW POINTS ARE UP NEAR 30.
WILL LIKELY HAVE TO KEEP SOME LOW CLOUDS AND FOG IN THROUGH MONDAY
MORNING. OTHERWISE...THE TEMPERATURES ARE SOARING IN THE MIXED
AREAS LIKE THE CODY FOOTHILLS WHERE TEMPERATURES ARE BETWEEN 55
AND 60 IN MANY AREAS. THE UPPER WIND RIVER BASIN FOOTHILLS ARE
ALSO IN THE MID 50S TO AROUND 60 FROM OUR BULL LAKE SENSOR TO
CROWHEART. DUBOIS IS WINDY AND MID TO UPPER 40S. EVEN THE WIND
RIVER BASIN IS SLOWLY CLIMBING THROUGH THE 30S WITH A FEW 40S
STARTING TO SURFACE IN THE ELEVATED AREAS. SNOW COVER IN
THERMOPOLIS IS HOLDING THEM DOWN AND THIS WILL LIKELY CONTINUE
WITH ABOUT 10 INCHES OF SNOW STILL ON THE GROUND. WARM ADVECTION
CONTINUES THROUGH THE DAY MONDAY WITH H7 TEMPS FORECAST TO RISE TO
BETWEEN 5C AND 7C. EXTREMELY WARM FOR LATE JANUARY. THE MIXED
AREAS WILL BENEFIT MOST OF THESE WHILE THE INVERSION TRAPPED AREAS
STRUGGLE TO WARM MUCH IF ANY. THE TOUGHEST AREAS ARE THE AREAS
ADJACENT TO THE BALMY FOOTHILL AREAS LIKE LANDER. BASED ON WHAT`S
ALREADY GOING ON TODAY...I HAVE BUMPED UP TEMPERATURES FOR THE
MIXED AREAS FROM CROWHEART TO CODY WHILE OTHER AREAS WERE
GENERALLY JUST TWEAKED. IT IS LIKELY THAT A FEW AREAS WILL HAVE TO
BE ADJUSTED FURTHER BASED ON OVERNIGHT LOWS TONIGHT AND HOW THE
BREEZY AREAS ALIGN. CODY COULD BE QUITE BALMY TOMORROW IF AN
AFTERNOON NE WIND DOESN`T DEVELOP. BUFFALO IS ANOTHER AREA TO
WATCH. WE HAVE LOWER 60S THERE BUT IT`S GENERALLY RUNNING CLOSER
TO THE WARMEST GUIDANCE TODAY. DON`T REAL SEE THE 75 ON THE MET
BUT 62 ON THE MAV IS THE COOLEST. ECE IS 66. JUST AN AREA TO
WATCH. WE HAVE 64 IN THERE RIGHT NOW. VERY LITTLE IF ANY CLOUDS ON
MONDAY.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY

DRY AND SETTLED WEATHER WILL CONTINUE INTO TUESDAY MORNING AS HIGH
PRESSURE CONTINUES TO DOMINATE THE WEATHER. THE NEXT WEATHER MAKER
IN THE FORM OF A SHORTWAVE AND THE REMNANTS OF THE BAJA LOW WILL
MOVE TOWARD THE AREA FROM THE SOUTH AND WEST AND BEGIN TO SPREAD
SOME LIGHT SHOWERS TOWARD WESTERN WYOMING TUESDAY AFTERNOON.
HOWEVER...MOST AREAS SHOULD END UP WITH A MAINLY DRY AFTERNOON EVEN
IN SOUTHWESTERN WYOMING. MOISTURE WILL SPREAD NORTHWARD ACROSS
WESTERN WYOMING ON TUESDAY NIGHT. THE STEADIEST AND HEAVIEST
PRECIPITATION LOOKS TO BE LATER TUESDAY NIGHT AS THE MOISTURE
INTERACTS WITH SOME LEFT FRONT QUADRANT JET DYNAMICS THAT WILL
ENHANCE LIFT SOMEWHAT AND A COLD FRONT DROPS TOWARDS THE AREA FROM
THE NORTH. THE MODELS ARE ZEROING IN ON THE TETONS WITH THE HEAVIEST
PRECIPITATION. THERE IS SOME DISAGREEMENT WITH AMOUNTS WITH THE NAM
THE DRIEST AND THE GFS AND EUROPEAN A LITTLE WETTER.
NEVERTHELESS...ANY SNOW AMOUNTS SHOULD BE UNDER ADVISORY CRITERIA.
PRECIPITATION WILL SPREAD EAST OF THE DIVIDE FOR WEDNESDAY BUT
AMOUNTS ARE EXPECTED TO BE LIGHT AND SPOTTY. WITH THE UNSTABLE
NORTHWEST FLOW THERE IS THE POTENTIAL FOR THOSE ANNOYING SNOW BANDS
EAST OF THE DIVIDE THAT ARE UNPREDICTABLE AND THE MODELS DO A
TERRIBLE JOB IN PINPOINTING. CONTINUITY LOOKED REASONABLE SO WE MADE
FEW CHANGES. ANY SHOWERS SHOULD END AS THE WAVE MOVES AWAY TO THE
EAST. MAINLY DRY CONDITIONS SHOULD RETURN FOR THURSDAY AS RIDGING
MOVES ACROSS WYOMING. AS FOR TEMPERATURES...WITH NO REAL COLD AIR
AROUND...TEMPERATURES SHOULD CONTINUE TO BE NEAR TO ABOVE NORMAL.

A SOUTHERN STREAM SYSTEM THEN APPROACHES SOUTHERN WYOMING FOR FRIDAY
AND COULD BRING SOME SHOWERS. THERE ARE SOME SLIGHT DIFFERENCES WITH
THE MODELS...SO WE KEPT MAINLY SLIGHT POPS FROM AROUND INTERSTATE 80
AND SOUTHWARD. AS OPPOSED TO 24 HOURS AGO...THE MODELS HAVE COME
INTO AGREEMENT IN KEEPING AN ALBERTA CLIPPER DROPPING SOUTHWARD OUT
OF CANADA WELL EAST OF WYOMING AND THEREFORE ANY ARCTIC INTRUSIONS
EAST OF THE AREA. NEXT WEEKEND FEATURES A BROAD RIDGE ACROSS THE
WYOMING WHICH SHOULD LEAD TO DRY AND MAINLY MILD WEATHER INTO
SUPERBOWL SUNDAY.

&&

.AVIATION.../06Z ISSUANCE/

VFR CONDITIONS WILL PREVAIL OVER THE REGION THROUGH MONDAY NIGHT.
AREAS OF LOW CLOUDS OR FOG MAY AGAIN DEVELOP OVERNIGHT INTO MONDAY
MORNING IN THE FAR WEST VALLEYS. LOCAL MVFR OR IFR CONDITIONS WILL
OCCUR UNTIL 17Z. THE JACKSON AIRPORT MAY BE IMPACTED BY LOW CLOUDS
OR FOG BUT WILL ONLY HAVE VCFG IN THE TERMINAL FOR NOW.

&&

.FIRE WEATHER...

A LARGE RIDGE OF HIGH PRESSURE WILL MOVE IN FOR THE EARLY PART OF
THE WEEK WITH UNUSUALLY WARM TEMPERATURES IN THE
MOUNTAINS...FOOTHILLS AND BREEZY AREAS FROM JEFFREY CITY TO
CASPER. THE BASINS AND VALLEYS WILL SEE TEMPERATURE INVERSIONS
CONTINUING WITH LESS WIND AND HIGHER RH`S. MIXING WILL BE POOR IN
THE INVERSION AREAS WITH FAIR OR BETTER IN THE FOOTHILLS. THE NEXT
CHANCE FOR PRECIPITATION WILL TUESDAY NIGHT AS A SYSTEM MOVES UP
FROM THE SOUTHWEST.

&&

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

&&

$$

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






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