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000
FXUS65 KRIW 120911
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
211 AM MST THU DEC 12 2013

.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT

A FEW CLOUDS NOTED ACROSS CENTRAL WYOMING THIS MORNING. TEMPERATURE
AND DEWPOINT SPREADS ACROSS THE WESTERN VALLEYS CONTINUES TO
SHRINK...WITH THE POTENTIAL FOR SOME PATCHY FOG THROUGH THE MORNING
HOURS. A DECENT TEMPERATURE GRADIENT IS DISPLAYED IN THE CURRENT
MODEL ANALYSIS BETWEEN CODY AND EASTERN YELLOWSTONE WITH AN
ANTICIPATED WESTERLY FLOW. THIS WILL KEEP GUSTY WINDS ACROSS THE
CLARK AREA THROUGH AT LEAST THE MORNING HOURS...WITH THE POTENTIAL
FOR CONTINUING INTO THE AFTERNOON HOURS AS WELL.

OTHERWISE...DRY CONDITIONS EXPECTED TODAY UNDER THE CONTINUED
INFLUENCE OF A PASSING RIDGE OF HIGH PRESSURE. A SURGE OF WARMER H7
AIR EXPECTED TODAY...ESPECIALLY EAST OF THE DIVIDE. EXPECT SOME
MORNING INVERSIONS WHICH MAY HELP TO TRAP SOME OF THE COLD AIR
ACROSS THE CENTRAL BASINS TODAY. WIND ACROSS THE CENTRAL BASINS ARE
EXPECTED TO BE TOO LIGHT TO ASSIST WITH MUCH WARMING TODAY. THE
EASTERN BASINS MAY SEE SOME BENEFIT FROM GUSTY SOUTHWEST WIND TO
HELP PROVIDE WARMER TEMPERATURES TODAY. DECREASED TEMPERATURES
ACROSS THE WIND RIVER BASIN FOR TODAY WITH ALL OF THIS IN
CONSIDERATION...ESPECIALLY WITH THE LACK OF WARMING EXPERIENCED
WEDNESDAY UNDER A SIMILAR PATTERN.

A WAVE OF LOW PRESSURE IS EXPECTED TO MOVE THROUGH THE STATE FRIDAY
AFTERNOON AND EVENING...PROVIDING A SHOT OF COLDER AIR AND ENOUGH
INSTABILITY ACROSS THE WEST TO GENERATE SOME SNOWFALL. MODELS SHOW
THIS SNOWFALL LINGERING ACROSS THE WESTERN MOUNTAINS AND VALLEYS
THROUGH SATURDAY...WITH ACTIVITY DECREASING THROUGH THE AFTERNOON
AND EVENING HOURS.

.LONG TERM...SUNDAY THROUGH THURSDAY

A RELATIVELY MOIST NORTHWEST FLOW WILL PREVAIL THROUGH WEDNESDAY.
THIS WILL KEEP AT LEAST SLIGHT CHANCES OF LIGHT SNOW ACROSS THE
NORTHWEST/NORTHERN MOUNTAINS...POSSIBLY GETTING INTO THE
ADJACENT LOWER ELEVATIONS AT TIMES. THE MAIN STORM TRACK WILL BE
ACROSS SOUTHERN CANADA INTO THE NORTHERN PLAINS AND UPPER
MIDWEST...WITH A COUPLE OF CLIPPER SYSTEMS. THE MAIN IMPACT FROM
THESE SYSTEMS WILL BE BREEZY TO WINDY CONDITIONS AT TIMES ACROSS THE
AREA. NOT OUT OF THE QUESTION THAT SOME AREAS...SUCH AS THE CODY
FOOTHILLS...COULD APPROACH HIGH WIND CRITERIA.

TEMPERATURES WILL BE SEASONAL TO WELL ABOVE AVERAGE THROUGH WEDNESDAY
...A FAR CRY FROM THE BITTER COLD THAT OCCURRED OVER THE FORECAST
AREA IN EARLY DECEMBER.

MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH A TROUGH IN THE
NORTHWEST FLOW PUSHING INTO THE PACIFIC NORTHWEST WEDNESDAY...THEN
INTO THE INTERMOUNTAIN WEST WEDNESDAY NIGHT...AND THEN ACROSS THE
NORTHERN/CENTRAL ROCKIES THURSDAY. IF THIS HOLDS UP...THIS SHOULD
RESULT IN SOME SNOWFALL BREAKING OUT ACROSS THE WEST LATE WEDNESDAY
AND THEN BECOMING MORE WIDESPREAD AND SPREADING EAST OF THE DIVIDE
WEDNESDAY NIGHT INTO THURSDAY AS A STRONG COLD FRONT PUSHES SOUTH
ACROSS THE FORECAST AREA.

&&

.AVIATION.../12Z ISSUANCE/

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

VFR CONDITIONS WILL PREVAIL VCNTY KJAC AND SOUTH THROUGH 12Z
FRIDAY.  HOWEVER...PATCHY IFR/LIFR FOG MAY PARTIALLY OBSCURE TERRAIN
THROUGH 19Z THURSDAY.  AREAS OF MVFR CIGS WILL BE ENCOUNTERED 30SM
NORTH OF KJAC ALONG WITH FRQT MTN OBSCURATIONS THROUGH 06Z FRIDAY.
AN UPPER LEVEL DISTURBANCE WILL SPREAD AREAS OF MVFR/IFR -SN INTO
THE NW...AGAIN PRIMARILY 30SM NORTH OF KJAC 06Z-12Z FRIDAY WITH
CONDITIONS EXPECTED TO DETERIORATE VCNTY KJAC AFTER 12Z FRIDAY.

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

SW WIND AT 20-30KT WITH GUSTS NEAR 40KT WILL CONTINUE VCNTY 50SM NE
KRKS-KCPR THROUGH 00Z FRIDAY WITH SOME TAPERING OFF OF THE WIND
THURSDAY NIGHT.  GUSTY WEST WIND WITH AREAS OF LLWS WILL ALSO BE
ENCOUNTERED VCNTY KCOD-KDUB THROUGH 06Z FRIDAY WITH A GRADUAL
TAPERING OFF OF WIND FRIDAY MORNING.  OTHERWISE VFR...CLR BLO
12KFT...CONDITIONS WILL PREVAIL THROUGH 12Z FRIDAY EXCEPT FOR SOME
PATCHY VALLEY FOG IN THE BIG HORN AND WIND RIVER BASINS PARTIALLY
OBSCURING TERRAIN THROUGH 19Z THURSDAY.

&&

.FIRE WEATHER...

A FAIRLY QUIET BEGINNING TO THE PERIOD WITH SOME MORNING INVERSIONS
POSSIBLE ACROSS THE WESTERN VALLEYS AND BASINS. THESE INVERSIONS MAY
RESULT IN SOME PATCHY MORNING FOG. A SURGE OF WARMER AIR WILL MOVE
OVER THE CENTRAL AND EASTERN BASINS THIS AFTERNOON...CREATING SOME
ADDITIONAL INVERSIONS OVER THE WIND RIVER BASIN. THESE DEVELOPING
INVERSIONS MAY DECREASE THE ABILITY TO WARM TODAY...ESPECIALLY WITH
A GENERAL LACK OF NORTHWEST WIND ACROSS THE AREA. OTHER LOCATIONS
EAST OF THE DIVIDE MAY SEE PERIODS OF GUSTY WIND...WHICH MAY ASSIST
IN THEIR ABILITY TO WARM. GENERALLY DRY CONDITIONS EXPECTED THROUGH
FRIDAY AFTERNOON. A PASSING WAVE OF LOW PRESSURE IS ANTICIPATED TO
PRODUCE LIGHT SNOWFALL ACROSS THE WESTERN MOUNTAINS AND VALLEYS
THROUGH SATURDAY NIGHT...WITH ACCUMULATIONS GENERALLY REMAINING LESS
THAN SIGNIFICANT.

&&

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

&&

$$

SHORT TERM...BRANHAM
LONG TERM...WM
AVIATION...AEM
FIRE WEATHER...BRANHAM