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000
FXUS65 KRIW 112146
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
246 PM MST WED DEC 11 2013

.SHORT TERM...TONIGHT THROUGH THURSDAY

PRECIPITATION FREE AND QUIET WEATHER WILL BE THE RULE FOR MOST OF
THE AREA THROUGH THE SHORT TERM PERIOD AS HIGH PRESSURE BUILDS TO
THE WEST AND THE REGION REMAINS UNDER A DRY WEST FLOW. BUT OF
COURSE...THIS IS WYOMING IN WINTER SO THERE HAS TO BE AT LEAST ONE
FLY IN THE OINTMENT. AND IN THIS CASE...IT IS THE EVER PRESENT
WYOMING WIND. IT WILL BE MAINLY A PROBLEM ACROSS THE USUAL AREAS
LIKE THE SOUTHWESTERN WIND CORRIDOR FROM ROCK SPRINGS THROUGH CASPER
AND NEAR THE CENTER OF THE UNIVERSE...CLARK IN THE CODY FOOTHILLS.
WITH STRONG HIGH PRESSURE OVER IDAHO THERE WILL BE A STRONG PRESSURE
GRADIENT DEVELOPING OVER THE STATE. HOWEVER...700 MILLIBAR WINDS ARE
NOT AS STRONG AS THE PREVIOUS EVENT EARLY IN THE WEEK WITH MAXIMUM
WINDS AROUND 40 KNOTS RATHER THAN THE FAVORED 50 KNOTS. AND THE
JET PASSING TO THE NORTH IS NOT THAT STRONG. SO AT THIS
POINT...WE WILL HOLD OFF FROM ANY HIGH WIND HIGHLIGHTS.
HOWEVER...GUSTS TO 40 MPH ARE LIKELY AND 50 MPH ARE POSSIBLE AS
WELL. WE CAN`T RULE OUT A 60 MPH GUST AT A SENSOR LIKE FALES
ROCK...BUT THIS IS NOT A PROBLEM SINCE NO ONE LIVES THERE BUT DEER
AND RATTLESNAKES. THERE COULD BE A GUST TO 60 MPH AROUND CLARK AS
WELL...BUT IT SHOULD NOT MAKE IT DOWN INTO MORE POPULATED AREAS
LIKE CODY. MOST AREAS SHOULD SEE TEMPERATURES FAIRLY CLOSE TO
NORMAL WITH THE WARMEST TEMPERATURES IN THE WINDIER
AREAS...ESPECIALLY EAST OF THE ABSAROKAS.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY

THE PATTERN DOES NOT CHANGE MUCH DURING THE MEDIUM AND LONG
TERM...WITH ONLY A FEW WEAK STORM SYSTEMS MOVING THROUGH THE COWBOY
STATE. OTHERWISE...A NORTHWEST FLOW PATTERN WILL DOMINATE BEFORE
ANOTHER ARCTIC SURGE BECOMES POSSIBLE BY THE MIDDLE OF NEXT
WEEK.

A TRANSITORY RIDGE WILL WEAK AND SHIFT EASTWARD...AS A PACIFIC STORM
SYSTEM MOVES INTO THE GREAT BASIN THURSDAY NIGHT INTO FRIDAY
MORNING. A WEAK COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL MOVE
THROUGH DURING THE DAY ON FRIDAY. A CHANCE FOR SNOW SHOWERS ACROSS
THE WESTERN MOUNTAINS AND THE BIGHORNS WILL OCCUR WITH THIS SYSTEM
AS WELL...CONTINUING INTO SATURDAY. TEMPERATURES WILL ONLY DROP A
FEW DEGREES COMPARED TO THURSDAYS READINGS.

THE PATTERN REESTABLISHES ITSELF BY SUNDAY...AS ANOTHER WEAK COLD
FRONT MOVES THROUGH THE NORTHERN ROCKIES SUNDAY. NO REAL EFFECTS
WITH THIS FRONT...OTHER THAN BREEZY CONDITIONS ACROSS THE WIND
CORRIDOR. BY MONDAY...STRONG WINDS COULD OCCUR ACROSS THE BIG HORN
BASIN AND JOHNSON AND NATRONA COUNTIES...CONTINUING INTO TUESDAY.
THIS WILL BE DUE TO A 120KT JET MAX EMBEDDED WITHIN THE POLAR FRONT
JET...MOVING OVER A STRENGTHENING SURFACE PRESSURE GRADIENT. THIS
WILL BE SIMILAR TO WHAT OCCURRED THIS PAST MONDAY. WILL HAVE TO
WATCH IF THE MODELS CONTINUE THIS TREND OVER THE NEXT SEVERAL RUNS.

TEMPERATURES WILL ALSO BEGIN TO MODERATE FROM SUNDAY
ONWARD...ESPECIALLY EAST OF THE DIVIDE. THE NORTHWEST FLOW PATTERN
IS FAVORABLE FOR THESE AREAS TO MIX WITH THE LAST VESTIGES OF ARCTIC
AIR THAT MAY BE IN PLACE. H7 TEMPERATURES WILL ALSO BE RELATIVELY
WARMER...RANGING FROM -2 TO -8.

OUTSIDE OF THE FORECAST PERIOD...THE GFS AND ECMWF ARE BEGINNING TO
HINT AT ANOTHER ARCTIC SYSTEM MOVING INTO THE AREA. THE 12Z EMCWF IS
THE FASTER SOLUTION...BRINGING THE ARCTIC FRONT THROUGH NORTHERN
PORTIONS BY THURSDAY MORNING. STAY TUNED FOR FURTHER DEVELOPMENTS.
&&

.AVIATION.../00Z ISSUANCE/

VFR CONDITIONS WILL PREDOMINATE AT ALL TAF SITES. A GUSTY SOUTHWEST
WIND OF 20 TO 30 KNOTS WITH GUSTS TO 40 KNOTS WILL BE FOUND AT KCPR
WITH GUSTY CONDITIONS AT KRKS AS WELL.
&&

.FIRE WEATHER...

HIGH PRESSURE WILL BRING DRY WEATHER OVER THE AREA THROUGH THURSDAY.
A TIGHT PRESSURE GRADIENT WILL BRING GUSTY WINDS ACROSS THE
SOUTHWESTERN WIND CORRIDOR FROM THE RED DESERT INTO NATRONA COUNTY
AS WELL AS EAST OF THE ABSAROKAS. THE NEXT CHANCE OF SNOW WILL MOVE
INTO WESTERN WYOMING ON FRIDAY.
&&

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

$$

SHORT TERM...HATTINGS
LONG TERM...LAVOIE
AVIATION...HATTINGS
FIRE WEATHER...HATTINGS