323 
FXUS65 KTFX 052348
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
445 PM MST WED DEC 5 2012

UPDATED AVIATION SECTION

.DISCUSSION...

TONIGHT THROUGH FRIDAY...STRONG WESTERLY WINDS WILL CONTINUE TO
MIX DOWN TO THE SURFACE ALONG AND BEHIND THE PACIFIC COLD FRONT AS
IT MOVES EAST THROUGH NORTH CENTRAL AND SOUTHWEST MONTANA THIS
AFTERNOON. SURFACE WINDS WILL DECREASE EARLY THIS EVENING AS THE
SURFACE GRADIENT RELAXES AND WINDS ALOFT DECREASE. WILL THEREFORE
CONTINUE WITH THE HIGH WIND WARNINGS FOR THE ROCKY MOUNTAIN
FRONT AND ADJACENT PLAINS AND NORRIS HILL...AND WILL KEEP AN EYE
ON THE EASTERN TFX PLAINS AS THE FRONT PASSES.
OVERALL...PRECIPITATION HAS BEEN DECREASING AS WELL...WITH ONLY
LINGERING CONVECTIVE SHOWERS IN THE MOUNTAINS. TEMPERATURES ARE
LIKELY TO STAY ABOVE FREEZING FOR THE REMAINDER OF THE AFTERNOON
IN THE WEST YELLOWSTONE/RAYNOLDS PASS/TARGHEE PASS AREAS OF FAR
SOUTHWEST MONTANA...AS LINGERING SHOWERS CONTINUE TO DIMINISH.
THEREFORE...WILL CANCEL THE WINTER WEATHER ADVISORY FOR
THERE...AS TRAVEL CONDITIONS SHOULD NOT BE QUITE AS HAZARDOUS NOW.
LINGERING CLOUDS IN THE MOUNTAIN AREAS AND BREEZY PLAINS WINDS
SHOULD KEEP TEMPERATURES FROM DROPPING SIGNIFICANTLY BELOW
SEASONAL AVERAGES...BUT SOME HIGHER VALLEYS MAY STILL NEED TO BE
MONITORED. A MOIST CYCLONIC WESTERLY FLOW ALOFT WILL THEN DEVELOP
OVER THE AREA THURSDAY THROUGH FRIDAY...LIKELY BRINGING LIGHT
MEASURABLE SNOWFALL TO THE MOUNTAINS. WEAK DISTURBANCES MOVING
THROUGH THE AREA WILL ALSO KEEP THE AIRMASS SLIGHTLY UNSTABLE
DURING THE AFTERNOON HOURS...WHICH WILL KEEP A GOOD CHANCE OF
SHOWERS IN THE SOUTHWEST VALLEYS. OVER THE PLAINS...THE CHANCE FOR
SHOWERS WILL BE LOWER...AS BREEZY WESTERLY DOWNSLOPE WINDS PERSIST
THROUGH THE PERIOD. AM NOT EXPECTING SNOW AMOUNTS TO BE HEAVY
ENOUGH TO WARRANT WINTER WEATHER HIGHLIGHTS AT THIS TIME. DAYTIME
HIGHS WILL REMAIN NEAR SEASONAL AVERAGES...BUT CLOUD COVER WILL
KEEP OVERNIGHT LOWS SLIGHTLY ABOVE NORMAL.  COULSTON

FRIDAY NIGHT THROUGH WEDNESDAY...INDIVIDUAL EXTENDED RANGE
FORECAST MODELS AND MODEL ENSEMBLES IN GOOD AGREEMENT THAT A COOL
AND UNSETTLED NORTHWEST FLOW PATTERN WILL BE IN PLACE FOR MOST OF
THIS PERIOD. SHORTWAVE TROFS EMBEDDED IN THE FLOW WILL PASS
THROUGH OUR REGION ABOUT EVERY OTHER DAY BEGINNING ON
SATURDAY...WITH EACH SYSTEM BRINGING A CHANCE OF LIGHT SNOW TO
THE MOUNTAINS AND PLAINS. THE FIRST SYSTEM THIS WEEKEND WILL ALSO
USHER IN THE COLDEST TEMPERATURES OF THE PERIOD AS A CANADIAN
COLD FRONT SWEEPS SOUTHWARD. HIGHS SATURDAY SHOULD ONLY REACH THE
TEENS OVER THE HILINE AND THE SOUTHWEST VALLEYS AND LOW 20S OVER
THE CENTRAL COUNTIES. WITH ABOUT AN INCH OF FRESH SNOW EXPECTED
IN THE LOWER ELEVATIONS AND GRADUALLY CLEARING SKIES SAT
NIGHT...OVERNIGHT LOWS WILL DROP TO THE SINGLE DIGITS FOR MUCH OF
THE REGION WITH SOME HILINE LOCATIONS REACHING A FEW DEGREES
BELOW ZERO. AS THE FIRST SHORTWAVE EXITS...THE STRONG UPPER LEVEL
RIDGE OVER THE ERN PACIFIC WILL AMPLIFY SLIGHTLY OVER THE NRN
ROCKIES AND BRING A BRIEF PERIOD OF WARMER DOWNSLOPE CONDITIONS
SUN EVE BUT THE NEXT SYSTEM FOLLOWS QUICKLY ON MON. RIGHT NOW ITS
ACCOMPANYING AIRMASS DOES NOT APPEAR TO BE A COLD AS THE WEEKEND
SYSTEM THOUGH HIGH TEMPS WILL ONLY MAKE IT TO THE MID 30S...WHICH
IS RIGHT AT THE SEASONAL AVERAGE FOR EARLY DEC. GFS AND EUROPEAN
MODELS DIVERGE SOMEWHAT ON TUES WITH THE GFS EXPANDING THE UPPER
RIDGE EASTWARD AND KEEPING US DRY...WHILE THE EUROPEAN DROPS
ANOTHER SHORTWAVE TROF ACROSS THE STATE WITH SCATTERED LIGHT
SNOW. MODELS COME BACK TO SIMILAR SOLUTIONS ON WED WITH A
SLIGHTLY SHARPER AND COOLER TROF MOVING ACROSS THE PACIFIC NW AND
NRN ROCKIES AND MORE LIGHT SNOW. TEMPERATURES SHOULD REACH THE
MID- UPPER 30S AROUND MIDDAY BEFORE ANOTHER COLD FRONT ARRIVES
WED AFTN/EVE. WARANAUSKAS

&&

.AVIATION...
UPDATED 2345Z.
STRONG AND GUSTY SURFACE WINDS WILL SLOWLY DECREASE THROUGH 06Z AS 
AN UPPER LEVEL DISTURBANCE AND ASSOCIATED COLD FRONT CONTINUE TO 
MOVE AWAY FROM THE AREA. A FEW ISOLATED RAIN/SNOW SHOWERS WILL 
CONTINUE IN THE WAKE OF THE COLD FRONT PASSAGE BUT SHOULD END BY 
04Z. VFR CONDITIONS PREVAIL WITH MVFR CONDITIONS POSSIBLE IN THE 
VICINITY OF SHOWERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27  37  26  36 /   0  20  20  20 
CTB  24  33  20  31 /   0  20  10  20 
HLN  25  35  22  35 /  10  40  30  30 
BZN  25  35  20  34 /  20  40  40  30 
WEY  25  31  17  26 /  50  50  60  50 
DLN  26  34  20  33 /  20  40  40  30 
HVR  23  32  21  29 /  10  10  20  30 
LWT  24  34  20  33 /  10  20  20  30 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 6 PM MST THIS EVENING CASCADE...EASTERN 
GLACIER...EASTERN PONDERA...EASTERN TETON...JUDITH BASIN...
NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT...
TOOLE.

HIGH WIND WARNING UNTIL 6 PM MST THIS EVENING FOR ROUTE 287 OVER 
NORRIS HILL IN MADISON COUNTY.

&&

$$

SHORT TERM...COULSTON
LONG TERM...WARANAUSKAS
AVIATION...ZELZER

WEATHER.GOV/GREATFALLS