Area Forecast Discussion
Issued by NWS Riverton, WY

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671
FXUS65 KRIW 152026
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
226 PM MDT FRI MAY 15 2015

.SHORT TERM...TONIGHT THROUGH SATURDAY

SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE AREA WILL CONTINUE INTO
THE EVENING HOURS TONIGHT...ESPECIALLY ACROSS THE NORTHERN HALF OF
THE AREA. GUSTY WINDS AND SMALL HAIL MAY BE POSSIBLE WITH STORM
ACTIVITY. GENERALLY SOUTHERLY FLOW CONTINUES AS THE AREA OF LOW
PRESSURE APPROACHES SOUTHWESTERN WYOMING.

DRIER AIR WILL MOVE INTO SOUTHERN WYOMING THIS EVENING...HELPING TO
END SHOWER ACTIVITY. THIS DRIER AIR WILL INCREASE THROUGH THE
OVERNIGHT HOURS...WITH SHOWERS MAINLY LINGERING OVER NORTHWESTERN
WYOMING BY SATURDAY MORNING. SHOWERS AND THUNDERSTORMS WILL BE FOUND
OVER NORTHWESTERN WYOMING THROUGH MUCH OF THE FORECAST
PERIOD...WITH STORMS RETURNING TO PORTIONS OF SOUTHERN AND EASTERN
WYOMING SATURDAY AFTERNOON. GUSTY WIND AND HAIL MAY BE POSSIBLE WITH
ANY STORM ACTIVITY.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY

A LARGE COOL AND MOIST LOW PRESSURE SYSTEM WILL BE OVER WESTERN AND
CENTRAL WYOMING SATURDAY NIGHT WITH WIDESPREAD SHOWERS WITH ISOLATED
EVENING THUNDERSTORMS. THE NORTHERN MOUNTAINS CAN EXPECT SNOWFALL
ABOVE 9500 FEET LOWERING TO AROUND 8500 FEET THROUGH THE NIGHT.
AS THE LOW PRESSURE SYSTEM MOVES EAST...THE AREA WILL BE UNDER COOL
AND MOIST NORTH NORTHWEST FLOW WITH SOME LINGERING SHOWERS.  WITH
DAYTIME HEATING...SOME ISOLATED THUNDERSTORMS ARE EXPECTED...
ESPECIALLY OVER THE MOUNTAINS.  THE BIGHORN AND ABSAROKA MOUNTAINS
CAN EXPECT AREAS OF 5 TO 10 INCHES OF SNOW ABOVE 9000 FEET WITH
2 TO 5 INCHES BELOW 9000 FEET DOWN TO 7500 FEET.  LITTLE
ACCUMULATION IS EXPECTED BELOW 7500 FEET.  WEAK TEMPORARY RIDGING
WILL OCCUR SUNDAY NIGHT WITH SOME LINGERING MOUNTAIN SHOWERS.  AS
ANOTHER LARGE SCALE LOW PRESSURE SYSTEM MOVES INLAND FROM THE
EASTERN PACIFIC INTO THE CALIFORNIA COAST...MOIST SOUTHERLY FLOW WILL
BEGIN TO SPREAD WIDESPREAD CLOUDS AND SHOWERS INTO THE SOUTH AND
WEST ON MONDAY.  TEMPERATURES WILL BE WARMER ON THE OUTSET...BUT COOL
LATER IN THE AFTERNOON MONDAY AS SHOWERS SPREAD NORTH AND EAST
ACROSS THE AREA.  AGAIN AFTERNOON AND EVENING THUNDERSTORMS WILL BE
A THREAT...ESPECIALLY OVER THE SOUTH AND WEST.  THE LOW PRESSURE
SYSTEM WILL BEGIN TO MOVE EAST INTO THE GREAT BASIN MONDAY NIGHT AND
TUESDAY CONTINUING TO SPREAD PACIFIC MOISTURE INTO THE AREA KEEPING
WIDESPREAD MOUNTAIN SHOWERS WITH ISOLATED THUNDERSTORMS IN THE
AFTERNOON AND EVENING HOURS TUESDAY AFTERNOON AND TUESDAY EVENING.
OVERALL LITTLE CHANGE IN TEMPERATURES IS EXPECTED WITH LOCALLY
COOLER AIR OVER AREAS WITH HEAVY RAINFALL.  A PORTION OF THE GREAT
BASIN LOW WILL EJECT NORTHEAST OVER THE AREA WEDNESDAY KEEPING
SCATTERED SHOWERS AND A FEW AFTERNOON AND EVENING THUNDERSTORMS OVER
THE AREA. THE UPPER LEVEL FLOW PATTERN BECOMES VERY COMPLEX
WEDNESDAY NIGHT AND THURSDAY WITH A CONTINUAL THREAT OF SHOWERS...
MOST NUMEROUS OVER THE MOUNTAINS CONTINUING THROUGH FRIDAY. OVERALL
THIS WILL BE A VERY UNSETTLED PERIOD WITH MOST AREAS RECEIVING
PRECIPITATION DAILY.  OVERALL MODELS ARE IN FAIR AGREEMENT THROUGH
THE PERIOD.

&&

.AVIATION.../00Z ISSUANCE/

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

SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH AROUND 06Z THIS
EVENING BEFORE DISSIPATING. STORMS MAY CONTAIN ERRATIC AND GUSTY
WIND AND BRING INCREASED TURBULENCE OVER IMPACTED TERMINALS.
RELATIVELY BENIGN CONDITIONS ANTICIPATED WITH THE DEPARTURE OF STORM
ACTIVITY THIS EVENING AS DRIER AIR BUILDS OVER THE AREA. VFR
CONDITIONS EXPECTED THROUGH 18Z. A SLIGHT OPPORTUNITY EXISTS FOR A
RETURN OF SHOWERS AND THUNDERSTORMS AFTER 18Z SATURDAY....MAINLY
IMPACTING THE KCPR AND KLND AND KRIW TERMINALS.

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

THUNDERSTORM ACTIVITY WILL WEAKEN WITH LOSS OF DAYLIGHT...THOUGH
SHOWER ACTIVITY IS EXPECTED TO CONTINUE THROUGH THE OVERNIGHT HOURS.
THESE SHOWERS WILL MAINLY IMPACT THE HIGHER TERRAIN...THOUGH KJAC
COULD SEE PERIODS OF SHOWER ACTIVITY THROUGH THE OVERNIGHT HOURS.
ANOTHER PUSH OF INSTABILITY COULD BRING THUNDERSTORMS ACROSS THE
AREA AFTER 15Z SATURDAY...ESPECIALLY OVER THE HIGHER TERRAIN.
MOUNTAIN TOP OBSCURATION IS ALSO ANTICIPATED IN LOWERED CLOUD COVER.

&&

.FIRE WEATHER...

A MOIST SOUTH TO SOUTHEAST FLOW WILL CONTINUE THIS EVENING...WITH
SHOWERS AND THUNDERSTORMS REMAINING OVER MUCH OF THE NORTHERN HALF
OF THE STATE. GUSTY AND ERRATIC WIND...LIGHTNING...AND SMALL HAIL
MAY ACCOMPANY ANY STORM ACTIVITY THIS EVENING. SOME DRIER AIR WILL
MOVE INTO THE AREA OVERNIGHT...BUT THE REPRIEVE WILL BE SHORT LIVED
AS STORMS RETURN TO THE AREA ON SATURDAY AFTERNOON. ISOLATED TO
SCATTERED SHOWERS WILL LINGER OVER THE AREA ON SUNDAY...WITH A
TRANSITORY RIDGE BUILDING OVER THE AREA ON MONDAY WITH DRIER
CONDITIONS EXPECTED LATE SUNDAY AND INTO MONDAY MORNING. THE NEXT
SURGE OF MOISTURE WILL ALREADY BEGIN TO IMPACT WESTERN WYOMING BY
MONDAY AFTERNOON. ANY STORM ACTIVITY MAY PRODUCE GUSTY WIND...AND
SMALL HAIL.

&&

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

$$

SHORT TERM...BRANHAM
LONG TERM...C.BAKER
AVIATION...BRANHAM
FIRE WEATHER...BRANHAM






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