Area Forecast Discussion
Issued by NWS Riverton, WY

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FXUS65 KRIW 151739 AAA
AFDRIW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RIVERTON WY
1139 AM MDT WED OCT 15 2014

.SHORT TERM...WEDNESDAY THROUGH FRIDAY NIGHT

YOU KNOW THAT YOU ARE TRANSITIONING INTO THE COOLER SEASONS WHEN WE
START TALKING ABOUT THE THING THAT MAKES WEARERS OF HATS...CAPS AND
TOUPEES DREAD...THE WYOMING WIND. A COLD FRONT MOVING TO THE
SOUTHEAST WILL APPROACH THE STATE TODAY AND PASS THROUGH THIS
AFTERNOON AND EVENING. THE QUESTION THAT HAS CAUSED MUCH
CONSTERNATION AT THE HUMBLE RIVERTON WEATHER ABODE IS THE QUESTION
OF THE POSSIBILITY OF HIGH WIND WARNINGS. THESE WOULD BE FOR THE
AFTERNOON IN THE FAVORED AREAS SUCH AS FROM THE RED DESERT THROUGH
CASPER. AND ALSO FOR THE MOST IMPORTANT CROSSROAD IN AMERICA...CLARK
IN THE CODY FOOTHILLS. THE FAVORS FOR IT INCLUDE A DECENT 700
MILLIBAR WIND THAT IS EXPECTED TO BE AROUND 50 KNOTS IN THE
AFTERNOON AND EVENING. ALSO...WE WILL HAVE A TIGHTENING PRESSURE
GRADIENT AHEAD OF THE COLD FRONT. HOWEVER...MOS NUMBERS DO NOT LOOK
IMPRESSIVE. EVEN THE GFS MOS...WHICH TRENDS TO OVERDO TO THE
WIND...HAS SUB WARNING WINDS AT CASPER. IN ADDITION...THE BEST UPPER
LEVEL SUPPORT WITH THE RIGHT FRONT QUAD OF THE JET DOES NOT ARRIVE
UNTIL THIS EVENING SO THE BEST MIXING WILL LIKELY BE GONE. AS FOR
CLARK...WHICH IS SUSCEPTIBLE TO MOUNTAIN WAVES...COLD ADVECTION
COMING IN THE EVENING SHOULD KILL IT. SO...WE WILL STICK WITH THE
STRONGLY WORDED SPS FOR NOW. THIS NOT TO SAY AREAS LIKE THE OUTER
DRIVE OF CASPER OR FALES ROCK MAY SEE A GUST TO 60 MPH...BUT MOST
AREAS SHOULD NOT SEE HIGHLIGHT WORTHY WIND. THE STRONGEST WIND IN
SOME AREAS MAY ACTUALLY BE THIS EVENING WITH THE FRONT AND COLD
ADVECTION BEHIND IT. THE OTHER EFFECT WILL BE FOR VERY WARM
TEMPERATURES WITH STRONG DOWNSLOPING FLOW AHEAD OF THE FRONT WITH
BASIN AREAS SEEING HIGH TEMPERATURES RISING WELL INTO THE 70S. AS
FOR ANY CHANCE OF PRECIPITATION...THE MODELS DO BRUSH THE
NORTHWESTERN MOUNTAINS WITH SOME LIGHT SHOWERS LATE TODAY AND THIS
EVENING BUT AREAS EAST OF THE DIVIDE SHOULD REMAIN DRY WITH THE
DOWNSLOPING. THE WIND SHOULD DECREASE LATER TONIGHT AS THE FRONT
PASSES...THE PRESSURE GRADIENT WEAKENS AND THE JET STREAK MOVES AWAY
TO THE EAST.

THE REST OF THE FORECAST LOOKS RELATIVELY TRANQUIL. A RIDGE OF HIGH
PRESSURE WILL THEN BUILD ACROSS THE ROCKIES THROUGH FRIDAY AND BRING
SETTLED WEATHER. A WEAK SHORTWAVE WILL PASS THROUGH THURSDAY NIGHT
OR FRIDAY BUT SHOULD BRING NOTHING MORE THAN SOME CLOUDS.
TEMPERATURES WILL BE ABOUT 15 DEGREES COLDER THURSDAY THAN TODAY BUT
THIS IS ONLY BACK TO SEASONAL NORMS. A SLOW WARMING TREND SHOULD
THEN COMMENCE FRIDAY AND CONTINUE INTO THE WEEKEND. BUT MAY ESTEEMED
COLLEAGUE WILL HAVE MORE ON THAT IN THE LONG TERM DISCUSSION BELOW.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

A WEAK SHORTWAVE SHOULD PUSH EAST ACROSS MONTANA SATURDAY/SATURDAY
NIGHT. MOISTURE AND DYNAMICS WITH THIS SYSTEM IS QUITE LIMITED...BUT
WILL CONTINUE TO RESPECT IT...AND WILL KEEP SOME SLIGHT POPS FOR THE
NORTHERN MOUNTAINS.

UPPER LEVEL RIDGING WILL DOMINATE THE WEATHER SUNDAY AND MONDAY.
ABOVE AVERAGE TEMPERATURES AND DRY CONDITIONS CAN BE EXPECTED BOTH
DAYS.

A PACIFIC TROUGH WILL APPROACH THE AREA TUESDAY WITH INCREASING
SOUTHWEST FLOW ALOFT AND POSSIBLY SOME CONVECTION PUSHING INTO THE
WEST. EAST OF THE DIVIDE...DOWNSLOPING SHOULD KEEP IT DRY AND VERY
WARM FOR LATE OCTOBER.

THERE IS THE TYPICAL MODEL VARIABILITY THIS FAR OUT WITH PROGRESSION
OF THIS TROUGH...BUT CURRENTLY THE MAIN IMPACT LOOKS TO BE TUESDAY
NIGHT AND WEDNESDAY. THUS WILL BROAD BRUSH SLIGHT VALLEY/CHANCE
MOUNTAIN POPS TUESDAY NIGHT AND WEDNESDAY...WITH A PACIFIC COLD
FRONT AROUND TUESDAY NIGHT. PRECIPITATION WILL BE VALLEY
RAIN/MOUNTAIN SNOW...BUT SYSTEM DOES NOT LOOK TO BE THAT IMPRESSIVE
SO PRECIP AMOUNTS SHOULD BE ON THE LIGHT SIDE.

&&

.AVIATION.../18Z ISSUANCE/

AREAS OF LLWS BE ENCOUNTERED ACROSS THE AREA UNTIL FULL MIXING
OCCURS EARLY THIS AFTERNOON AS SW WINDS 7-8KFT INCREASING TO BTWN
35-45 KTS. STRONGER WINDS WILL MIX DOWN TO THE SFC ACROSS MOST OF
THE AREA 16Z-20Z TODAY. ELEVATED MOUNTAIN WAVES EXPECTED OVER THE
WIND RIVER MOUNTAINS THIS AFTERNOON AND EVENING SHIFTING TO THE
ABSAROKAS AND BIGHORNS LATER TONIGHT. A SFC COLD FRONT WILL PUSH
WEST TO EAST ACROSS WYOMING THIS EVENING WITH ISOLATED TO SCT
-SHSN/-SHRA PARTIALLY OBSCURING THE NW MTNS...VCNTY AND NORTH OF A
KJAC-KCOD LINE. GUSTY WEST SFC WINDS WILL FOLLOW THE
FRONT...BEFORE GRADUALLY DIMINISHING THURSDAY MORNING.

&&

.FIRE WEATHER...

A MAINLY DRY COLD FRONT WILL APPROACH THE AREA TODAY AND BRING GUSTY
WINDS TO PARTS OF THE AREA...ESPECIALLY ON THE LEE SIDE OF THE
ABSAROKAS AND WIND RIVER RANGE AND FROM THE RED DESERT THROUGH
NATRONA COUNTY. THE WIND SHOULD SUBSIDE AFTER MIDNIGHT TONIGHT. A
RIDGE OF HIGH PRESSURE WILL THEN BUILD INTO THE AREA FROM THURSDAY
INTO THE WEEKEND AND BRING TRANQUIL WEATHER. TEMPERATURES WILL COOL
ON THURSDAY BEFORE SLOWLY WARMING FRIDAY AND INTO THE WEEKEND.

&&

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

$$

SHORT TERM...HATTINGS
LONG TERM...WM
AVIATION...ALLEN
FIRE WEATHER...HATTINGS





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