515 
FXUS65 KTFX 022121
AFDTFX
 
SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
230 PM MST THU DEC 2 1999
 
PAC TROF CONTS TO MOVE INLAND WITH MAIN DYNAMICS CONTG TO SHIFT TO BASE
OF TROF PER WATER VAPOR IMAGERY. ASSOC PAC CDFNT OVER ERN WA AT 19Z
EXPECTED TO MOVE ACROSS CWA LATER TONIGHT. WITH SFC LOW REMAINING NORTH
OF BORDER...COLDEST AIR DELAYED REACHING NRN CWA TIL UPR TROF PASSES ON
FRI. ENCOURAGING POINT FOR PRECIP IS THAT NGM/AVN MODELS DEVELOP VORT
CENTER NEAR GTF BY 12Z FRI. WITH ETA FRH DATA SHOWING LIGHT PRECIP
TONIGHT THRU FRI PROSPECTS FOR SIGNIFICANT PRECIP NOT TOO ENCOURAGING.
FOR NOW WILL HIT HARDEST THOSE AREAS AFFECTED BY OROGRAPHIC LIFT AND NW
FLOW ALOFT. CONSIDERING AMOUNT OF MOISTURE STREAMING IN ADVANCE OF
APPROACHING UPR TROF WILL KEEP ISSUE SNOW AND BLOWING SNOW ADVISORY FOR
ZONE 9 AND EXTEND TO ZONES 14 AND 15 WITH MENTION OF LOCALLY HEAVY SNOW
IN THE MOUNTAINS. WILL ALSO ISSUE ADVISORY LATER TONIGHT AND FRIDAY FOR
FOOTHILLS OF ZONE 13. FRI NIGHT AND SAT POS TILTED UPR RDG SHIFTING OVER
AREA LOOKS DIRTY WITH WAA THRU TOP OF RDG LOWERING SFC PRES OVER ALTA
EARLY SAT. THIS MAY PUT A FLOOR ON OTHERWISE FALLING MIN TEMPS FRI
NIGHT. DOWNSLOPE WINDS WILL ALSO AID WARMUP ON SAT. SW VALLEYS HOWEVER
MAY HAVE TO OVERCOME INVERSION LAYER BEFORE SEEING SUBSTANTIAL WARMING.
EYSSAUTIER
GTF 6600 HLN 8600 HVR 6620