FXUS65 KTFX 030542
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 PM MST WED DEC 2 2009
...UPDATE TO AVIATION...
.UPDATE...
UPDATE FORTHCOMING. ANOTHER COLD NIGHT IS IN STORE FOR THE AREA.
WEAK SHORT WAVE ENERGY EMBEDDED WITHIN THE NORTHERLY FLOW ALOFT
CONTINUES TO INITIATE ISOLATED SNOW SHOWERS ACROSS THE EASTERN
PORTION OF THE COUNTY WARNING AREA. HAVE ADJUSTED POPS TO BETTER
ALIGN WITH NEIGHBORING OFFICES. HAVE ALSO ADDED PATCHY FOG TO THE
VALLEYS OF SOUTHWEST MONTANA. REMAINDER OF FORECAST LOOKS ON TRACK.
EMANUEL
&&
.AVIATION...
UPDATED 0540Z.
VFR CONDITIONS ARE EXPECTED ACROSS NORTH CENTRAL...CENTRAL...AND
SOUTHWEST MONTANA THROUGH AT LEAST 06Z THURSDAY...UNLESS NOTED
BELOW. LOW LEVEL MOISTURE IN A NORTHERLY FLOW WILL KEEP LOW VFR/HIGH
MVFR CEILINGS OVER PORTIONS OF NORTH CENTRAL (KHVR) AND CENTRAL
(KLWT AND KGTF) MONTANA THROUGH 12Z THURSDAY. LOCAL UPSLOPE
CONDITIONS IN THE KLWT AREA WILL KEEP THE BEST CHANCE FOR MVFR
CONDITIONS IN LIGHT SNOW THERE. SKIES WILL THEN CLEAR LATE TONIGHT
INTO THURSDAY MORNING. WINDS WILL BE LIGHT UNDER SURFACE HIGH
PRESSURE TONIGHT...BUT A DEEPENING SURFACE TROUGH OVER NORTH CENTRAL
AND CENTRAL MONTANA ON THURSDAY WILL INCREASE SOUTHERLY WINDS
THERE. COULSTON
&&
.PREV DISCUSSION...ISSUED 239 PM MST WED DEC 2 2009
TONIGHT THROUGH FRIDAY...NORTHERLY FLOW ALOFT WILL BE OVER THE
AREA THROUGH THURSDAY NIGHT. EMBEDDED IN THIS FLOW THERE WILL BE
SOME CLOUDINESS OVER THE PLAINS AND CENTRAL MOUNTAINS TONIGHT AND
COULD AGAIN SEE SOME FLURRIES IN UPSLOPE AREAS OF THE CENTRAL
MOUNTAINS THROUGH THIS EVENING. THIS CLOUDINESS IS EXPECTED TO
GRADUALLY DISSIPATE LATER THIS EVENING THROUGH THURSDAY MORNING.
ON FRIDAY AN UPPER RIDGE WILL MOVE OVER THE AREA WHICH SHOULD
RESULT IN WARMER TEMPERATURES. A STRONG UPPER LOW WILL MOVE TO THE
NORTHWEST OF THE FORECAST AREA FRIDAY AFTERNOON. MODELS DIFFER ON
ITS EXACT PLACEMENT BUT WITH THE FASTER MODELS THERE IS THE
POTENTIAL FOR SOME SNOW OVER THE MOUNTAINS OF THE ROCKY MOUNTAIN
FRONT AND NEARBY PLAINS BY LATE FRIDAY AFTERNOON. BLANK
FRIDAY NIGHT THROUGH MONDAY NIGHT...A VERY COLD AND WINTRY
WEATHER PATTERN IS SETTING UP OVER THE WEEKEND AND INTO EARLY NEXT
WEEK. BOTH THE EC/GFS MODELS CONTINUE TO INDICATE SOME FAIRLY COLD
AIR TO MOVE INTO THE REGION OVER THE WEEKEND...AND THEN CONTINUE
TO RESIDE OVER THE REGION FOR SEVERAL DAYS. AS THE COLD FRONT
MOVES THROUGH LATE FRIDAY NIGHT AND THROUGH THE DAY ON
SATURDAY...EXPECT ANOTHER ROUND OF LIGHT SNOW TO ACCOMPANY THE
FRONTAL PASSAGE. THE BULK OF THE PRECIPITATION IS EXPECTED ON
SATURDAY...WITH LINGERING LIGHT SNOW AND SNOW SHOWERS ON SATURDAY
NIGHT AND SUNDAY AS WEAK EASTERLY FLOW DEVELOPS AND A WEAK UPPER-
LEVEL SHORTWAVE ROTATES THROUGH THE MAIN TROUGH OF LOW PRESSURE.
SNOW AMOUNTS FOR SATURDAY SHOULD BE GENERALLY 1 TO 3 INCHES IN THE
VALLEYS AND 3 TO 6 INCHES IN THE MOUNTAINS...HOWEVER THIS WILL
DEPEND ON THE AMOUNT OF PACIFIC MOISTURE AVAILABLE SO HIGHER
AMOUNTS CANNOT BE RULED OUT. AFTER THIS COLD FRONT MOVES
THROUGH...MODIFIED ARCTIC AIR WILL MOVE INTO THE REGION...HOWEVER
CLOUD COVER MAY PREVENT MORNING LOW TEMPERATURES FROM DROPPING
NEAR 20 BELOW. WE WILL CONTINUE TO CLOSELY MONITOR THE PROGRESSION
OF THIS SYSTEM. COLD AIR AND ISOLATED SHOWERS ARE EXPECTED TO
PERSIST THROUGH THE EARLY PART OF NEXT WEEK. MLS/BRUSDA
TUESDAY AND WEDNESDAY...MODELS CONTINUE TO SHOW A COLD UPPER LEVEL
LOW OVER CENTRAL CANADA...BRINGING COLD ARCTIC AIR INTO THE REGION
UNDER A NORTHERLY FLOW ALOFT. TEMPERATURES WILL CONTINUE TO BE WELL
BELOW AVERAGE WITH ISOLATED SNOW SHOWERS. WILLIAMSON DC
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 0 22 11 32 / 0 0 0 10
CTB -2 18 8 32 / 0 0 0 20
HLN -3 21 3 31 / 0 0 0 10
BZN -13 14 -10 20 / 10 0 0 0
WEY -31 12 -17 17 / 10 0 0 0
DLN -8 16 2 27 / 0 0 0 10
HVR 1 24 1 29 / 0 0 0 0
LWT 2 20 -1 27 / 10 0 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...EMANUEL/BLANK
LONG TERM...MLS/BRUSDA/WILLIAMSON DC
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
