Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 201707
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1006 AM MST TUE JAN 20 2015

.SHORT TERM...TUESDAY THROUGH THURSDAY NIGHT

AT THIS TIME WE ARE UNDER THE INFLUENCE OF NORTHWEST FLOW WITH SOME
WEAK DISTURBANCES MOVING THROUGH THE FLOW. AND IN THE WINTER YOU
KNOW THAT THAT MEANS. THOSE ANNOYING SNOW SHOWERS AND SNOW BANDS
THAT THE MODELS DO SUCH A GOOD JOB WITH...NOTE SARCASM...AND ARE
ENOUGH TO MAKE A FORECASTER RIP THIS HAIR OUT. SINCE PINPOINTING
THEM IS DIFFICULT AT BEST...WE HAVE KEPT ISOLATED POPS ACROSS MUCH
OF THE NORTHERN HALF OF THE COUNTY WARNING AREA TODAY WITH HIGHER
POPS ACROSS THE HIGHER ELEVATION. SINCE THE WAVE IS MOISTURE
STARVED...WE DON`T EXPECT ANY BIG TOTALS AT THIS TIME. AS FOR
TEMPERATURES...LOOK FOR A COOLER DAY THAN YESTERDAY WITH THE COLD
ADVECTION. HOWEVER...STILL NOT BAD FOR THIS TIME OF YEAR. THE SNOW
SHOWERS SHOULD WANE LATE TONIGHT AS THE SHORTWAVE MOVES AWAY AND
RISING HEIGHTS BRING MORE SETTLED WEATHER. IF THERE IS ENOUGH
CLEARING...WE COULD SEE SOME FOG IN FAVORED AREAS SO WE KEPT
CONTINUITY IN THAT REGARD.

FAIRLY SETTLED WEATHER SHOULD THEN DOMINATE THROUGH THURSDAY AS HIGH
PRESSURE BUILDS ACROSS WYOMING. WITH LIGHT FLOW WE HAVE TO WATCH OUT
FOR INVERSIONS IN THE VALLEYS AND BASINS. HOWEVER...EAST OF THE
DIVIDE...THE RECENT WARMER WEATHER HAS MELTED A DECENT AMOUNT OF THE
SNOW AND THE LEFTOVER SNOW HAS A LOWER ALBEDO SO TEMPERATURES SHOULD
NOT BE FRIGID. HOWEVER...IT WILL BE COOLER THAN THE RECENT FEW DAYS.
THE COLDER SPOTS WOULD BE THE WESTERN VALLEYS WHERE THE RECENT FRESH
SNOW COVER SHOULD AID IN RADIATIONAL COOLING. THE NEXT TROUGH MAY
APPROACH BY LATE THURSDAY NIGHT. HOWEVER...THE MODELS ARE SPLIT ON
THE TIMING SO KEPT THINGS DRY THROUGH THE SHORT RANGE. MORE ON THIS
IN THE LONG RANGE PORTION OF THE DISCUSSION.

.LONG TERM...FRIDAY THROUGH TUESDAY

A WEAK WEATHER SYSTEM MOVES THROUGH THE AREA ON FRIDAY. MOISTURE IS
LIMITED AND SOME LIGHT MOUNTAIN SNOW SHOULD OCCUR. LOWER ELEVATIONS
SHOULD BE DRY FRIDAY. THE ECMWF MODEL HAS A MOIST NW FLOW FOR
SATURDAY THROUGH SUNDAY EVENING WITH PERIODS OF PRECIP FOR THE
MOUNTAINS AND POSSIBLY SOME PRECIP OVER THE LOWER ELEVATIONS OF THE
NORTH AND EAST ZONES. THE GFS CONTINUES TO COME AROUND TO THE ECMWF
SOLUTION WHICH ADDS TO THE FORECAST CONFIDENCE. HAVE MADE MINOR
ADJUSTMENTS TO THE FORECAST SATURDAY THROUGH SUNDAY EVENING. THE
REST OF THE REGION WILL BE DRY SATURDAY AND SUNDAY. THE WEATHER
PATTERN TURNS DRY FOR NEXT MONDAY AND TUESDAY PER BOTH LONG RANGE
MODELS. HIGH TEMPS FRIDAY THROUGH SUNDAY WILL BE AT OR SLIGHTLY
ABOVE SEASONAL NORMALS. NEXT MONDAY AND TUESDAY WILL BE QUITE MILD.
LOCATIONS THAT ARE SNOW FREE WILL LIKELY WARM UP THE MOST.

&&

.AVIATION.../18Z ISSUANCE/

EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL ROUTES

A COUPLE OF WEAK UPPER LEVEL DISTURBANCES WILL MOVE ACROSS THE
REGION TODAY AND TONIGHT. HOWEVER...VFR CONDITIONS WILL PREVAIL
TODAY BEFORE BETTER CHANCES FOR VFR/MVFR CONDITIONS START TO COME
INTO PLAY EARLY THIS EVENING. AFTER 06Z...MVFR CONDITIONS IN LOW
CIGS AND POSSIBLE REDUCED VIS IN BR/-SN WILL EXPAND ACROSS THE
FORECAST AREA...ESPECIALLY EAST/NORTHEAST OF A KCOD TO KLND LINE.
THE FINAL DISTURBANCE WILL MOVE THROUGH THE AREA BETWEEN 09Z AND 15Z
WEDNESDAY...SCOURING OUT THE SKIES AND IMPROVING CONDITIONS BY MID
TO LATE MORNING AT MOST LOCATIONS.

WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS ROUTES

VFR CONDITIONS MOST LOCATIONS EARLY...EXCEPT KJAC WHICH MAY FLIRT
WITH MVFR FOR THE NEXT HOUR OR TWO. THE POSSIBILITY OF LIGHT FOG
BECOMES AN ISSUE THIS EVENING...ESPECIALLY AFTER 06Z WEDNESDAY. EVEN
SO...CIGS/VIS LOOK TO REMAIN AT AT OR ABOVE MVFR FOR MOST TERMINAL
LOCATIONS THROUGH THE END OF THE FORECAST.

&&

.FIRE WEATHER...

WIDESPREAD SNOW COVER WILL CONTINUE WITH COOL TEMPERATURES AND
FAVORABLE RELATIVE HUMIDITY. LIMITED MOISTURE IN NORTHWEST FLOW WILL
BRING SOME VERY LIGHT SNOWFALL TO THE NORTHERN HALF OF WYOMING.
WINDS WILL BE LIGHT TO MODERATE ACROSS MOST AREAS.  MIXING HEIGHTS
WILL BE LOW WITH GENERALLY POOR SMOKE DISPERSAL. MAINLY DRY WEATHER
WITH POSSIBLE VALLEY AND BASIN INVERSIONS WILL BE THE RULE FOR
WEDNESDAY INTO THURSDAY.

&&

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

&&

$$

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






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