Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 170530
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1130 PM MDT WED JUL 16 2014

.SHORT TERM...TONIGHT THROUGH THURSDAY (ISSUED AT 150 PM MDT)

UPR LVL WAVE AXIS OVR THE FA TODAY...ALIGNED W TO E...WITH CONTINUE
TO MOVE S AND OUT OF THE CWA THIS EVENING...PUSHING A SFC
BOUNDARY/FRONT S TO SW INTO AND THRU THE SRN ZONES...WITH SHRA/ ISO
TSRA ENDING FROM N TO S THRU THE EVENING PERIOD. BEHIND ALL
THIS...MODEST HIGH PRESS RISES BOTH AT THE SFC AND ALOFT WILL OCCUR
THROUGH MOST OF THE DAY ON THURSDAY...RESULTING IN DRY STABLE
CONDITIONS FOR THE MOST PART. LATE IN THE AFTERNOON...MORE TOWARDS
THE EVENING PERIOD...A WEAK UPR LVL DISTURBANCE...NOW LOCATED IN WRN
WA...WILL MOVE THROUGH THE BUILDING RIDGE TOP...SETTING OFF A FEW
SHOWERS AND THUNDERSTORMS ACROSS THE NW ZONES....AND MAINLY OVER THE
HIGHER TERRAIN. A COUPLE OF STRONGER STORMS COULD PRODUCE SMALL
HAIL...BUT AGAIN MORE LIKELY IN THE EVENING WITH THE CURRENT TIMING
OF THE SW. HIGH TEMPS ACROSS THE FORECAST AREA WITH RISE SOME 5 TO
10 DEG OVR THOSE TODAY...WHILE RH VALUES WILL DROP SOME 10 TO 15
PERCENT...THE BEGINNING OF A WARMING AND DRYING TREND THAT WILL LAST
THROUGH MUCH OF THE NEXT WEEK.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

SHORTWAVE CURRENTLY NEAR THE WA COAST IS EXPECTED TO ARRIVE IN THE
NW LATE THURSDAY AND THEN TRACK SE ACROSS THE AREA THU NGT. NOT A LOT
OF MOISTURE AND INSTABILITY TO WORK WITH BUT I EXPECT THAT THE
CONVECTION THAT FORMS OVER THE NW WILL TRY AND WORK SE OFF THE
MOUNTAINS INTO THE EVENING HOURS. SLIM CHANCES BUT AT LEAST A SHOT
OF A FEW AREAS ALONG THE CODY FOOTHILLS AND NWRN HALF OF THE WIND
RIVER BASIN GETTING A MAINLY HIGHER BASED GUSTY THUNDERSTORM OR
SHOWER WITH STRONG OUTFLOWS. A FEW LIGHTER SHOWERS MAY LINGER
OVERNIGHT IN THE HIGH COUNTRY. 45-50KT JET STREAK WILL ALSO MOVE SE
WITH THIS DISTURBANCE POSSIBLY PROVIDING A LITTLE RIGHT ENTRANCE
REGION SUPPORT. ANOTHER WEAKER WAVE IS POSSIBLE LATE FRIDAY OR FRI
EVENING ACROSS THE NORTH WITH THE MONSOONAL HIGH BUILDING NWD
ALLOWING FOR SOME MID LEVEL MOISTURE TO SNEAK INTO THE SW. ISOLATED
MAINLY HIGHER BASED STORMS WILL RESULT ACROSS THE SOUTHWEST. A FEW
OF THESE STORMS WILL MOVE OFF THE MOUNTAINS LATE IN THE AFTERNOON OR
EARLY EVENING. AGAIN...NOT A LOT BUT WORTHY OF SLGHT CHANCES. MAINLY
MID LEVEL MONSOONAL MOISTURE WILL CONTINUE ACROSS THE SOUTH HALF ON
SATURDAY FOR ANOTHER ROUND OF MAINLY HIGH BASED GUSTY THUNDERSTORMS.
TEMPERATURES WILL BE QUITE WARM FRIDAY AND SATURDAY WITH HIGHS IN
THE UPPER 80S TO MID 90S EAST OF THE DIVIDE...MAINLY 80 TO 85 LOWEST
ELEVATIONS OF THE WEST WITH 60S AND 70S IN THE HIGH COUNTRY.

MONSOONAL PLUME...NEWD MOVING DISTURBANCE AND FRONTAL BOUNDARY MAY
RESULT IN AN INCREASE IN STORMS ACROSS THE NW SUNDAY WITH A FEW
STORMS POSSIBLE ACROSS THE NORTH AND ERN SECTIONS. 12Z ECMWF IS A
LITTLE SLOWER WITH THIS SYSTEM. RIDGE CONTINUES TO EXPAND NWD ON
MONDAY SO ISOLATED STORMS LIMITED TO THE WEST AND FAR NORTH. ON
TUESDAY...WITH FURTHER RIDGE EXPANSION WILL LEAVE THE CURRENT
FORECAST OF ISOLATED THUNDERSTORMS ONLY IN THE FAR NORTH...MAINLY
MTNS...DURING THE AFTERNOON AND EVENING. LITTLE CHANGE ON WEDNESDAY
WITH THE GFS TAKING A SHORTWAVE ACROSS THE NRN ROCKIES. THE GEM AND
ECMWF LOOK HOT AND DRY. OTHERWISE...A VERY WARM TO HOT PERIOD WITH
UPPER 80S AND 90S EAST OF THE DIVIDE...UPPER 70S TO MID 80S WEST AND
MAINLY 60S AND 70S IN THE HIGH COUNTRY. WARMED UP TEMPERATURES EARLY
NEXT WEEK BUT NOT AS MUCH AS THEY COULD BE IF THE HIGH TRULY EXPANDS
THIS FAR NORTH. THE ECMWF H7 TEMPERATURES ARE ABOVE 20C BY
WEDNESDAY. EVEN THE `COOLER` GFS IS 18-19C IN THE SOUTH HALF. WE
STILL HAVE TIME TO GO MUCH HOTTER IF WE TRULY SEE THESE H5 HEIGHTS
CLIMBING WELL INTO THE 90S.

&&

.AVIATION.../06Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. ISOLATED SHOWERS AND
STORMS WILL OCCUR FROM 20Z THURSDAY UNTIL 04Z FRIDAY IN THE ABSAROKA
AND WIND RIVER MOUNTAINS. A FEW OF THESE WILL DRIFT EAST INTO THE
NEARBY FOOTHILLS AND COULD IMPACT THE KLND AND KCOD AIRPORTS WITH A
GUSTY WIND AND BRIEF RAINFALL. ISOLATED SHOWERS AND STORMS WILL ALSO
OCCUR IN THE NORTHERN BIGHORN MOUNTAINS FROM 22Z UNTIL 06Z FRIDAY.


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

VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. ISOLATED SHOWERS AND
STORMS WILL OCCUR OVER THE WESTERN MOUNTAINS AFTER 20Z THURSDAY AND
CONTINUE THROUGH 04Z FRIDAY. THE KJAC AIRPORT MAY BE IMPACTED BY
THIS ACTIVITY WITH A GUSTY WIND AND BRIEF RAINFALL.

&&

.FIRE WEATHER...

THE UPPER LEVEL DISTURBANCE THAT SET STRONG STORMS OFF ON TUESDAY
WILL CONTINUE TO DROP SOUTHWARD ACROSS EASTERN WYOMING TODAY...WITH
SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE THROUGH THIS EVENING
EAST OF THE DIVIDE...ALONG WITH RELATIVELY COOL TEMPERATURES. COOL
AND DRY WEST OF THE DIVIDE. OVERNIGHT AND THROUGH THURSDAY...MODEST
UPPER LEVEL RIDGING WILL BEGIN...BRINGING A WARMING AND DRYING TREND
TO THE FORECAST AREA. ANOTHER CHANCE FOR ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS WILL COME TO THE MOUNTAINS AND VALLEYS
MAINLY WEST OF THE DIVIDE THURSDAY EVENING AS A WEAK UPPER LEVEL
DISTURBANCE MOVES OVERHEAD. FROM FRIDAY ONWARD...WARMING AND DRYING
ALONG WITH ISOLATED CHANCES FOR RELATIVELY HIGH BASED SHOWERS AND
THUNDERSTORMS WILL COME TO PORTIONS OF WESTERN AND NORTHERN WYOMING
THROUGH THE WEEKEND. WINDS WILL ALSO TEND OUT OF THE WEST AND BREEZY
IN THE AFTERNOONS...SLOWLY INCREASING FIRE WEATHER CONCERNS AS FUELS
CONTINUE TO DRY OUT TOO.

&&

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

&&

$$

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










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