FXUS65 KTFX 090538
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 PM MST TUE DEC 8 2009
.UPDATE...
STARTED THE WIND CHILL ADVISORY AT 00Z AND EXPANDED THE AREA TO
INCLUDE LIBERTY HILL AND BLAINE COUNTIES. SLIGHTLY INCREASED WINDS
AND DECREASED CLOUD COVER TO ACCOUNT FOR THE CURRENT CONDITIONS.
TEMPERATURES ARE ALREADY STARTING TO WARM UP DUE TO THE SOUTHWEST
CHINOOK WINDS. SHOULD SEE A RELATIVELY STEADY RISE IN
TEMPERATURES AFTER MIDNIGHT THROUGH THE EARLY MORNING HOURS ACROSS
MUCH OF THE HIGH PLAINS. HOWEVER WHILE THE TEMPERATURES WILL WARM
COMPARED TO THE LAST TWO DAYS THANKS TO THE CHINOOK WINDS...WE
WILL CONTINUE TO SEE WIND CHILLS BELOW NEGATIVE 30 DEGREES THROUGH
THE EARLY MORNING HOURS.
&&
.AVIATION...
UPDATED 0540Z.
MOISTURE AHEAD OF A WEATHER SYSTEM WILL BE INCREASING TONIGHT INTO
WEDNESDAY. CEILINGS ABOVE 15000 FT WILL SPREAD OVERNIGHT THEN LOWER
TO AROUND THE 5000 TO 8000 FT RANGE AT KCTB LATE TONIGHT THEN SPREAD
SOUTH WEDNESDAY MORNING. EXPECT SCATTERED SNOW SHOWERS WEDNESDAY AND
WEDNESDAY EVENING ESPECIALLY OVER THE MOUNTAINS. MOUNTAINS COULD
BECOME OBSCURED AT TIMES. OVER THE PLAINS AND VALLEYS CONDITIONS
SHOULD STAY VFR FOR THE MOST PART WEDNESDAY/WEDNESDAY EVENING THOUGH
THERE COULD BE BRIEF MVFR CONDITIONS IN SNOW SHOWERS. IT APPEARS THE
TAF MOST SUSCEPTIBLE TO MVFR CONDITIONS WILL BE KHVR. WEST WINDS
WILL INCREASE ALONG THE EAST SLOPES OF THE ROCKY MOUNTAINS NEAR AND
AFTER MIDNIGHT. EXPECT LOCAL MVFR/IFR VISIBILITIES IN BLOWING SNOW
OVER THIS AREA. BLANK
&&
.PREV DISCUSSION...
/ISSUED 455 PM MST TUE DEC 8 2009/
TONIGHT THROUGH THURSDAY...EXPECT COOL WEATHER TO CONTINUE OVER THE
REGION OVER THE NEXT FEW DAYS...EVEN THOUGH THERE WILL BE SOME
SLIGHT WARMING OF TEMPERATURES. EXPECT TEMPERATURES TO FALL QUICKLY
THIS EVENING...WITH TEMPERATURES WARMING AFTER MIDNIGHT. A WIND
CHILL ADVISORY WAS ISSUED FOR A PORTION OF NORTH CENTRAL MONTANA
LATER TONIGHT...AS WINDS INCREASE BEFORE THE WARMER AIR MOVES IN. AN
ALBERTA CLIPPER WILL MOVE THROUGH THE REGION ON WEDNESDAY. EXPECT
SCATTERED SNOW SHOWERS OVER THE REGION...BUT SNOW ACCUMULATIONS WILL
BE REALLY LIGHT. GENERALLY LESS THAN A HALF INCH OVER THE
PLAINS...AND MAYBE AN INCH IN THE MOUNTAINS. FOR WEDNESDAY NIGHT AND
THURSDAY...EXPECT ANOTHER COLD EVENING WEDNESDAY EVENING...WITH
TEMPERATURES WARMING UP AGAIN AFTER MIDNIGHT. ANOTHER WIND CHILL
ADVISORY MAY BE REQUIRED FOR THURSDAY MORNING...BUT LATER SHIFTS
WILL DECIDE THAT. ADDITIONALLY...AREAS OF BLOWING SNOW ARE ALSO
POSSIBLE. WITH THE BREEZY WEST WINDS...SLIGHTLY WARMER AIR WILL
CONTINUE TO MOVE INTO THE REGION...BUT WITH THE WINDS...IT WILL
STILL FEEL QUITE COLD. BRUSDA
THURSDAY NIGHT THROUGH TUESDAY...JUST WHEN THE FORECAST MODELS
SEEMED TO BE TRENDING TOWARD DISSIPATING THE ARCTIC CONDITIONS OVER
CENTRAL AND SOUTHWEST MT...LATEST GFS AND EUROPEAN MODEL RUNS NOW
PUSH THE RETURN OF MORE SEASONAL TEMPERATURES INTO EARLY NEXT WEEK.
WHILE MAIN PORTION OF THE LONGWAVE TROF THAT BROUGHT THE BITTER COLD
DOES INDEED DRIFT EASTWARD INTO THE MIDWEST AS DISCUSSED HERE THE
PAST FEW DAYS...IT APPEARS THAT THE WESTERN PORTION OF THE LONGWAVE
WILL BE REINFORCED BY A FAIRLY STRONG AND MOIST UPPER LEVEL
SHORTWAVE DROPPING OUT OF SOUTHWEST CANADA ON SAT. CURRENT MODEL
SOLUTIONS MERGE THIS SYSTEM WITH A WEAKER BUT EQUALLY MOIST
DISTURBANCE MOVING EAST OFF THE PACIFIC TO CREATE A MOISTURE PLUME
THAT COVERS ALL OF THE GREAT BASIN AND NORTHERN ROCKIES. THE
COMBINED IMPACT OF THE TWO SYSTEMS WILL BRING WIDESPREAD CLOUD COVER
AND AREAS OF LIGHT SNOW ACROSS THE CWA...ALONG WITH ANOTHER COLD
CANADIAN AIRMASS THAT WILL KEEP TEMPS 15 TO 20 DEG BELOW NORMAL THIS
WEEKEND. THE MOISTURE BEGINS TO THIN OUT ON MONDAY AS A TRANSIENT
UPPER LEVEL RIDGE APPROACHES FROM THE WEST. THE RESULTING GRADIENT
BETWEEN THE BACKSIDE OF THE LONGWAVE AND THE UPPER RIDGE MAY
GENERATE GUSTY WINDS...POSSIBLY STRONG ENOUGH FOR A WARNING...DURING
THE DAY ON MON. HOWEVER...THE BENEFIT IS THE QUICKER ARRIVAL OF A
MILDER PACIFIC AIRMASS THAT SHOULD BRING TEMPS BACK TO/ABOVE
FREEZING FOR MON AND TUES. WARANAUSKAS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF -23 6 -7 13 / 0 20 20 20
CTB -20 6 -7 11 / 0 20 20 20
HLN -20 5 -5 16 / 0 20 20 10
BZN -23 6 -11 16 / 0 30 20 20
WEY -25 5 -16 9 / 20 30 30 30
DLN -19 8 -9 15 / 0 20 20 10
HVR -28 8 -6 12 / 0 20 20 20
LWT -24 5 -9 11 / 0 30 20 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 9 AM MST WEDNESDAY FOR MTZ009>013-
044>051.
&&
$$
SHORT TERM...SUK
LONG TERM...ZELZER
AVIATION...BLANK
WEATHER.GOV/GREATFALLS
