Winter Storm Watch 7, NWS Riverton, WY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1116 AM MST MON DEC 3 2012

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT

IT WILL BE MUCH CALMER TODAY AS HIGH PRESSURE BUILDS IN FROM THE
WEST. TEMPERATURES ARE MUCH COOLER BEHIND THE FRONT THAT SWEPT
THROUGH LAST NIGHT...WHICH MAY CREATE SLICK ROADS ACROSS THE WEST
AND OVER THE HIGHER ELEVATIONS AS AREAS OF RAIN AND VERY WET SNOW
FINALLY FREEZE. OTHERWISE...WINDS WILL REMAIN GUSTY IN A FEW AREAS
THIS MORNING...PREVENTING FOG FORMATION IN THE VALLEYS AND KEEPING
THE LOW ELEVATIONS WELL MIXED. THESE WINDS WILL DROP OFF
DRAMATICALLY BEFORE NOON WITH ONLY A FEW GUSTS OVER 35 MPH ACROSS
THE HIGHER ELEVATIONS OF THE ABSAROKAS AND WIND RIVER RANGE.

THE NEXT SYSTEM THEN APPROACHES FOR TUESDAY AND INTO WEDNESDAY.
ADVISORY LEVEL SNOW IS POSSIBLE ACROSS THE WESTERN MOUNTAINS WITH
THIS SYSTEM...BUT WITH ITS ORIGINS IN THE PACIFIC AND WARM
SOUTHWEST FLOW AHEAD OF THE MAIN TROUGH...THIS SYSTEM WILL ALSO BE
ON THE WARM SIDE AND WILL HAVE SNOW LEVELS ABOVE 7500 FEET AGAIN.
DETAILS ARE STILL MUDDY HOWEVER THIS FAR OUT. EAST OF THE
DIVIDE...EXPECT A RETURN OF DRY WEATHER WITH ABOVE NORMAL
TEMPERATURES ALONG WITH WINDY CONDITIONS WITH THE PRESSURE
GRADIENT TIGHTENING BETWEEN THE PACIFIC SYSTEM AND HIGH PRESSURE
TO THE EAST.

.LONG TERM...THURSDAY THROUGH MONDAY
A SHORTWAVE IN THE WEST NORTHWEST FLOW SHOULD PUSH QUICKLY ACROSS
THE NORTHERN ROCKIES IN THE LATE THURSDAY/FRIDAY TIME FRAME. THE
BEST SHOT AT PRECIPITATION SHOULD BE ACROSS THE WEST...AND OVER THE
NORTH NEAR A WEAK FRONTAL BOUNDARY ALREADY IN PLACE. PRECIPITATION
AMOUNTS ARE EXPECTED TO BE LIGHT WITH THIS SYSTEM...AND SHOULD BE
MAINLY SNOW EVEN IN THE LOWER ELEVATIONS.

MEDIUM RANGE MODELS ARE COMING INTO BETTER AGREEMENT WITH SOME
ARCTIC AIR PLUNGING INTO THE COWBOY STATE SATURDAY NIGHT AND
SUNDAY...AS A TROUGH DIGS INTO THE WEST/CENTRAL CONUS. THE ECMWF
REMAINS FARTHER EAST WITH INITIAL DIGGING OF THIS TROUGH AND REMAINS
MORE PROGRESSIVE WITH IT THAN THE 00Z GFS. HOWEVER...BOTH SOLUTIONS
BRING IN ARCTIC AIR IN THE SATURDAY NIGHT/SUNDAY TIME FRAME. THE
ECMWF IS DRIER THAN THE GFS WITH AN EMPHASIS ACROSS THE
NORTHWEST/NORTHERN MOUNTAINS IN A MOIST NORTHWEST FLOW...WHILE THE
GFS IS WETTER...ESPECIALLY EAST OF THE DIVIDE WHERE UPSLOPE AREAS
WOULD BE FAVORED SUNDAY/SUNDAY NIGHT. DUE TO THE CONTINUED LARGE
SPREAD IN SOLUTIONS...HAVE BROAD BRUSHED SLIGHT VALLEY/CHANCE
MOUNTAIN POPS FOR THE WEEKEND...AND HAVE CONTINUED THE TREND OF
COOLING TEMPERATURES.

&&

.AVIATION.../18Z ISSUANCE/

THERE WILL BE SOME MOUNTAIN OBSCURATIONS IN THE FAR WEST MOUNTAINS
TODAY AND TONIGHT ALONG WITH A FEW HIGHER ELEVATION FLURRIES...
OTHERWISE EXPECT VFR CONDITIONS THROUGH TONIGHT. A NEW STORM
SYSTEM WILL BRING SNOW BACK INTO THE FAR WEST BY TUESDAY AFTERNOON
WITH IFR CONDITIONS RETURNING TO THE MOUNTAINS ALONG WITH
WIDESPREAD MOUNTAIN OBSCURATION AND MVFR TO LOCALIZED IFR
CONDITIONS IN THE FAR WEST VALLEYS. WINDY AREAS WILL CONTINUE FROM
JEFFREY CITY TO CASPER AND ALONG THE EAST SLOPE OF THE ABSAROKAS
AND CODY FOOTHILLS TODAY THROUGH TUESDAY.

&&

.FIRE WEATHER...

TODAY WILL BE MUCH COOLER AND CALMER WITH JUST A FEW LIGHTER
BREEZES EXPECTED FROM ROCK SPRINGS TO CASPER AND OVER THE HIGHER
ELEVATIONS. BASIN INVERSIONS WILL BE FORMING TONIGHT WITH POOR
SMOKE DISPERSAL. MORE SNOW WILL BE POSSIBLE IN THE WESTERN
MOUNTAINS BEGINNING ON TUESDAY AFTERNOON AND LASTING THROUGH
THURSDAY. THIS NEXT SYSTEM WILL NOT HAVE AS MUCH MOISTURE WITH IT
AND IT WILL ALSO BE ON THE WARM SIDE WITH GUSTY WINDS AND HUMIDITY
DROPPING BELOW 30 PERCENT EAST OF THE DIVIDE.

&&

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

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RIVERTON WY
400 AM MST MON DEC 3 2012

WYZ001>020-022>030-041300-
ABSAROKA MOUNTAINS-BIGHORN MOUNTAINS SOUTHEAST-
BIGHORN MOUNTAINS WEST-CASPER MOUNTAIN-CODY FOOTHILLS-
EAST SWEETWATER COUNTY-FLAMING GORGE-
GREEN MOUNTAINS AND RATTLESNAKE RANGE-JACKSON HOLE-LANDER FOOTHILLS-
NATRONA COUNTY LOWER ELEVATIONS-NORTH BIG HORN BASIN-
NORTHEAST JOHNSON COUNTY-OWL CREEK AND BRIDGER MOUNTAINS-
ROCK SPRINGS AND GREEN RIVER-SALT RIVER AND WYOMING RANGES-
SOUTH LINCOLN COUNTY-SOUTHEAST BIG HORN BASIN-
SOUTHEAST JOHNSON COUNTY-SOUTHWEST BIG HORN BASIN-STAR VALLEY-
TETON AND GROS VENTRE MOUNTAINS-UPPER GREEN RIVER BASIN-
UPPER GREEN RIVER BASIN FOOTHILLS-UPPER WIND RIVER BASIN-
WIND RIVER BASIN-WIND RIVER MOUNTAINS EAST-WIND RIVER MOUNTAINS WEST-
YELLOWSTONE NATIONAL PARK-
400 AM MST MON DEC 3 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND CENTRAL WYOMING.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

TUESDAY AND WEDNESDAY...SIGNIFICANT SNOWFALL POSSIBLE ACROSS THE FAR
WESTERN MOUNTAINS WITH PERIODS OF GUSTY WINDS EXPECTED EAST OF THE
DIVIDE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

TEAM RIVERTON