Area Forecast Discussion
Issued by NWS Riverton, WY

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000
FXUS65 KRIW 160944
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
344 AM MDT WED JUL 16 2014

.SHORT TERM...WEDNESDAY THROUGH FRIDAY NIGHT

ALL THE EXCITEMENT OF YESTERDAY HAS QUIETED CONSIDERABLY AS OF THIS
HOUR. HOWEVER...IT HAS NOT GONE AWAY COMPLETELY. THE BIG PINWHEEL OF
AN UPPER LEVEL LOW CONTINUES TO DRIFT SOUTHEASTWARD AND NOW MOVES
INTO NORTHERN WYOMING. SOME ADDITIONAL SHOWERS HAVE BEGUN TO DEVELOP
AHEAD OF IT AND SHOULD CONTINUE TO SPREAD THROUGH INTO THIS MORNING.
LIGHTNING HAS ALSO QUIETED CONSIDERABLY ALTHOUGH WE CANNOT RULE OUT
A BIT OF IT DURING THE LATE NIGHT AND EARLY MORNING HOURS. THE LOW
WILL CONTINUE DO DROP SOUTH AND WITH THE INSTABILITY WE WILL
CONTINUE TO SEE SOME SHOWERS AND THUNDERSTORMS ON AND OFF THROUGH
THE DAY. THE CHANCE OF SEVERE WEATHER SHOULD BE MUCH LESS TODAY
HOWEVER SINCE TEMPERATURES WILL BE COOLER...THERE WILL BE MORE CLOUD
COVER AND UPPER LEVEL SUPPORT WILL BE LESS.THE MAIN THREAT MAY BE
HAIL ALTHOUGH THE SMALLER VARIETY WITH COOLER TEMPERATURES AND LOWER
WET BULB ZERO TEMPERATURES. ONE CHANGE WE MADE WAS TO REMOVE
PRECIPITATION FROM THE FAR WEST WITH SATELLITE IMAGERY SHOWING DRIER
AIR MOVING IN FROM IDAHO AND MODELS SHOWING PRECIPITABLE WATER
VALUES DROPPING BELOW 0.50 INCHES. THESE SHOWERS AND STORMS SHOULD
END BY EVENING AS RIDGING BEGINS TO BUILD ACROSS THE AREA.

THE AFOREMENTIONED RIDGING WILL BRING A WARMER DAY TO THE AREA FOR
THURSDAY. HOWEVER...IT DOES NOT LOOK TO BE TOTALLY DRY AS A
SHORTWAVE WILL RIDGE OVER THE RIDGE IN THE AFTERNOON AND EVENING
WITH ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. AT THIS TIME...THE
BEST FORCING LOOKS TO REMAIN IN MONTANA. THEREFORE...WE HAVE
CONFINED THE PRECIPITATION TO NORTHERN AND WESTERN PORTIONS OF THE
STATE. AND...EVEN HERE ACTIVITY LOOKS TO REMAIN ON THE ISOLATED SIDE
SINCE MOISTURE WILL DEFINITELY NOT BE VERY RICH. WITH THE RIDGING
TEMPERATURES WILL BE ON THE REBOUND BUT STILL BE NEAR TO BELOW
NORMAL FOR MOST LOCATIONS.

WITH RISING HEIGHTS AND THICKNESSES OVER THE AREA FOR FRIDAY WE WILL
CONTINUE TO TURN THE THERMOSTAT UP A FEW MORE DEGREES SO
TEMPERATURES MAY BE PACK IN THE 90S FOR THE WARMER AREAS. ONCE
AGAIN...ANOTHER SHORTWAVE MOVING OVER THE TOP OF THE RIDGE MAY BRING
A FEW SHOWERS AND THUNDERSTORMS TO NORTHERN PORTIONS OF THE COUNTY
WARNING AREA. BOTH THE NAM AND GFS ARE NOT OVERWHELMING WITH THE
CHANCES. HOWEVER...SINCE THE MODELS CAN BE FICKLE THIS FAR OUT WE
MADE ONLY SMALL CHANGES AT THIS TIME.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

HIGH PRESSURE WILL EXPAND ACROSS THE SOUTHERN AND CENTRAL ROCKIES
DURING THIS PERIOD BRINGING ABOVE NORMAL TEMPERATURES ALONG
ISOLD/WDLY SCT THUNDERSTORMS BLOSSOMING AROUND THE PERIPHERY OF
THE UPPER HIGH. FORECAST CONTINUES TO GIVE LITTLE WEIGHT TO
DETERMINISTIC SOLUTIONS...ESPECIALLY ECMWF...OF CRASHING THE RIDGE
BY BRINGING TROUGH OFF THE NW COAST OVER THE TOP OF THE RIDGE.
ENSEMBLES TEND TO KEEP THE BULK OF THIS ENERGY ALONG THE COAST
THROUGH THE PERIOD.

ELEVATED FIRE WEATHER CONDITIONS WILL BE THE PRIMARY CONCERN OVER
THE WEEKEND INTO MONDAY ACROSS THE SOUTHERN HALF THE AREA...OR FROM
THE SOUTHERN HALF OF THE WIND RIVER MTNS AND SOUTH.  AFTERNOON WEST
WINDS WILL KICK UP ALONG WITH VERY LOW RH VALUES.  A SUB-TROPICAL
DISTURBANCE MOVING AROUND THE PERIPHERY OF THE RIDGE WILL MOVE ENE
ACROSS WY SAT/SAT NT BRINGING MAINLY DRY THUNDERSTORMS INTO SW/CEN
WY THAT MAY ACT AS AN IGNITION SOURCE.

UPPER RIDGE BUILDS INTO CENTRAL ROCKIES MON/TUE WILL BRING WARMER
MORE STABLE AIRMASS INTO SOUTHERN WYOMING WITH THE ARC OF CONVECTION
OR "RING OF FIRE" GRADUALLY PUSHED FURTHER NORTH...INTO MAINLY THE
NORTHERN THIRD OF WY TUE/WED.

HIGHS WILL BE MOSTLY IN THE UPPER 80S TO MID 90S ACROSS THE CENTRAL
BASINS THROUGH THE PERIODS WITH 80S IN THE WESTERN VALLEYS.

&&

.AVIATION.../12Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. AN AREA OF -SHRA
AND ISOLD TS WILL CONTINUE TO MOVE SE VCNTY AND SOUTH OF A KLND-
KCPR LINE INTO SE WY EARLY THIS MORNING LEAVING ISOLD -SHRA
THROUGH THE REST OF THE MORNING. SCT SHOWERS AND ISOLATED STORMS
WILL BLOSSOM IN THE AFTERNOON AND CONTINUE THROUGH 00Z. AREAS OF
MVFR WILL OCCUR DUE TO LOW CLOUD CEILINGS. AFTER 02Z SHOWERS AND
STORMS WILL DECREASE AND END BY 06Z THURSDAY.

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. ISOLATED SHOWERS
WILL OCCUR THROUGH 18Z IN THE MOUNTAINS. THEN AFTER 18Z ISOLATED
SHOWERS AND STORMS WILL OCCUR IN THE NW MOUNTAINS AND ALONG THE
WEST SLOPES OF THE WIND RIVER MOUNTAINS UNTIL 02Z. SOME OF THIS
ACTIVITY WILL MOVE ACROSS EASTERN SWEETWATER COUNTY FROM 20Z UNTIL
02Z. THE SHOWERS AND STORMS WILL DECREASE AFTER 02Z AND END BY 06Z
THURSDAY.

&&

.FIRE WEATHER...

AN UPPER LEVEL DISTURBANCE WILL CONTINUE TO DROP SOUTHWARD ACROSS
WYOMING TODAY AND KEEP THE CHANCE OF SHOWERS AND
THUNDERSTORMS...MOST OF THEM WET ACROSS MOST OF THE AREA. THE
EXCEPTION WILL BE THE FAR WEST WHERE DRIER AIR MOVING IN FROM IDAHO
SHOULD BRING A PRECIPITATION FREE DAY FOR MOST AREAS. A RIDGE WILL
BUILD ACROSS THE AREA FOR THURSDAY INTO THE WEEKEND AND BRING A
WARMING TREND ALONG WITH LOWERING RELATIVE HUMIDITY. UPPER LEVEL
DISTURBANCES MOVING OVER THE TOP OF THE RIDGE COULD BRING SHOWERS
AND THUNDERSTORMS TO PORTIONS OF NORTHERN WYOMING ON BOTH THURSDAY
AND FRIDAY AFTERNOONS.
&&

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

$$

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







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