000
FXUS65 KRIW 271017
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
317 AM MST MON DEC 27 2010
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
SPLIT TROUGH MOVING ACROSS THE ROCKIES THIS MORNING WITH WYOMING IN
BETWEEN THE NORTH AND SOUTHERN PORTIONS OF THE TROUGH. THIS BROUGHT
SOME LIGHT SNOW WITH UP TO 3 INCHES OF SNOW OVER THE WESTERN
MOUNTAINS. A WEST NORTHWEST FLOW IS BUILDING IN BEHIND THE TROUGH
WITH MOISTURE INCREASING ONCE AGAIN OVER THE WEST. SOME OROGRAPHIC
SNOWS WILL FALL TODAY AND TONIGHT OVER THE WEST WITH ONLY LIGHT
ACCUMULATIONS EXPECTED. COLD POOL WILL MOVE ACROSS WYOMING TODAY
WITH MAX TEMPERATURES MUCH COLDER OVER THOSE AREAS THAT WERE IN THE
40S TO LOWER 50S SUNDAY. SOME SOUTHWEST TO WEST WINDS ARE EXPECTED
TODAY OVER THE WESTERN MOUNTAINS AND CENTRAL WIND
CORRIDOR...ESPECIALLY THE EAST SLOPES OF THE WIND RIVERS AND
ABSAROKAS. MOISTURE WILL GRADUALLY BE ON THE INCREASE TUESDAY AND
TUESDAY NIGHT OVER THE WEST AS A TROUGH DROPS OUT OF THE GULF OF
ALASKA AND ACROSS BRITISH COLUMBIA AND SPINS UP OVER THE NORTHERN
ROCKIES TUESDAY NIGHT INTO WEDNESDAY. WEAK ISENTROPIC LIFT WILL
BRING SOME LIGHT SNOW TO THE WEST TUESDAY AND TUESDAY NIGHT
INCREASING SIGNIFICANTLY OVER THE WEST FOR WEDNESDAY INTO WEDNESDAY
EVENING. COULD GET SOME BAROCLINIC LEAF DYNAMICS WEDNESDAY OVER THE
WEST WITH SOME BETTER SNOWFALL RATES. WARNING AMOUNTS IN THE
MOUNTAINS AND FAR WEST VALLEYS IS CERTAINLY POSSIBLE. STRONG COLD
FRONT THEN MOVES INTO THE NORTH AN CENTRAL WEDNESDAY NIGHT AND
THURSDAY MORNING WITH A PERIOD OF UPSLOPE SNOW DEVELOPING OVER THE
WESTERN AND SOUTHERN BIG HORN BASIN AND LATER IN THE WIND RIVER
BASIN AND ALONG THE EASTERN WIND RIVER MOUNTAINS. VERY COLD AIR
MOVES IN BEHIND THE FRONT AS H7 TEMPS ALONG THE MONTANA BORDER
FALLING TO -20C.
LONG TERM...THURSDAY THROUGH MONDAY
THE GFS/ECMWF MODELS POINT TO THE STORM RAGING ON THURSDAY INTO
THURSDAY NIGHT OVER THE AREA. THE TRACK IS STILL LOOKING GOOD FOR
THE SOUTH HALF OF THE REGION BUT MOST EVERYONE SHOULD GET SNOW
FROM THIS STORM. THE CANADIAN IS MORE NORTH AND SEEMS THE ODD
MODEL OUT TONIGHT. MINOR CHANGES TO THE FORECAST THURS/THURS NIGHT.
THE STORM LIFTS INTO THE PLAINS ON FRIDAY WITH SNOW TAPERING OFF
FROM NW TO SE AS THE DEFORMATION AXIS PASSES THROUGH THE AREA
FRIDAY EVENING. DRYING TREND FRI NIGHT...SATURDAY AND MOST OF
SUNDAY. THERE MAY BE SCATTERED LIGHT SNOW IN THE NW MTS SATURDAY
AND WILL KEEP LOW POPS THERE. ANOTHER SHORTWAVE MAY MOVE THROUGH
THE REGION SUNDAY NIGHT INTO MONDAY BRINGING SOME LIGHT SNOW TO
THE MOUNTAINS. LOW PRECIP CHANCE IS FINE FOR NOW. WILL KEEP LOWER
ELEVATIONS DRY MONDAY. AS FOR TEMPS...FALLING TEMPS THURSDAY WITH
MOST PLACES IN THE SINGLE DIGITS OR LOW TEENS BY DARK. VERY COLD
FRIDAY AND FRIDAY NIGHT TO USHER IN THE NEW YEAR WITH BELOW ZERO
LOWS NEARLY ALL LOCATIONS. TEMPS WILL BEGIN TO WARM SATURDAY AND
THIS TREND WILL CONTINUE SUNDAY AND NEXT MONDAY. HOWEVER...SOME
BASINS WILL LIKELY NOT WARM UP AS FAST AS THE PLACES THAT WILL
MIX. THUS HAVE ADJUSTED HIGHS/LOWS TO ACCOUNT FOR THIS IN THE
SATURDAY TO MONDAY TIMEFRAME.
&&
.AVIATION...
JET STREAK-ENHANCED LIGHT SNOW ACROSS THE WEST SHOULD WANE EARLY
THIS MORNING. PROGRESSIVE WESTERLY FLOW TO KEEP MID AND HIGH CLOUD
DECKS AROUND THROUGH TODAY ALONG WITH LIGHT SNOW IN THE WESTERN
MOUNTAINS. VFR CONDITIONS TO PREVAIL AT ALL TERMINALS. ONLY
EXCEPTION WOULD BE MVFR VISIBILITY/CEILINGS AT KJAC IN ASSOCIATION
WITH WEAK IMPULSES GENERATING QUICK SHOT OF LIGHT SNOW. SURFACE
SOUTHWEST WIND TO BE 20-30KTS IN THE CORRIDOR FROM KRKS TO KCPR
WHILE KJAC WILL BE SOUTH 10-20KTS THROUGH THE DAY. OTHER TERMINALS
TO BE LESS THAN 12KTS WITH SNOW-COVERED INTERIOR BASINS LIGHT AND
VARIABLE. MOUNTAIN TOPS WILL BE FREQUENTLY OBSCURED ALONG AND WEST
OF THE CONTINENTAL DIVIDE. ALONG THE FAR WESTERN MOUNTAIN RANGES...
AREAS BELOW ABOUT 10K FT MSL TO BE MOST LIKELY LOCATIONS FOR ANY
ICING HAZARD TODAY.
&&
.FIRE WEATHER...
GUSTY WINDS WILL CONTINUE OVER THE EASTERN WIND RIVER AND ABSAROKAS
TODAY AS WELL AS THE CENTRAL WIND CORRIDOR...UPPER WIND RIVER BASIN
AND CODY FOOTHILLS. LIGHT SNOW/FLURRIES EXPECTED OVER THE WEST
TODAY...MOSTLY IN THE MOUNTAINS WITH LITTLE ACCUMULATIONS EXPECTED.
MOISTURE WILL INCREASE OVER THE WEST WITH A BIT MORE SNOW TUESDAY
AND TUESDAY NIGHT. A STRONG STORM WILL BRING SIGNIFICANT SNOWFALL TO
THE WEST WEDNESDAY AND WEDNESDAY NIGHT...THEN EAST OF THE DIVIDE AND
SOUTH WEDNESDAY NIGHT INTO THURSDAY. ALSO MUCH COLDER AIR WILL MOVE
IN.
&&
RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...TWB
LONG TERM...AR
AVIATION...CNJ
FIRE WEATHER...TWB
