000 FXUS65 KTFX 072105 AFDTFX SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 300 PM MDT SUN APR 7 2002 .SHORT TERM...CANADIAN COLD FRONT HAS PUSHED THROUGH THE GTF AREA THIS AFTERNOON...WITH TEMPERATURES DROPPING INTO THE 30S. EXPECT COLD ADVECTION TO CONTINUE INTO THE EVENING ALLOWING THE RAIN SHOWERS TO CHANGE OVER TO SNOW. UPPER LEVEL SHORTWAVE TROUGH MOVING OVER THE AREA TODAY IS SLIGHTLY DEEPER THAN PROGGED. MODELS ARE NOW KEEPING SLIGHTLY CYCLONIC NORTHWEST FLOW OVER THE AREA THROUGH MONDAY EVENING. AIRMASS IS SOMEWHAT DRYER ON MONDAY...AND MODELS INDICATE THAT A SURFACE LOW WILL FORM IN ALTA ALLOWING DOWNSLOPE WINDS TO RETURN TO THE AREA. SOUTHWEST FLOW ALOFT DEVELOPS OVER THE NRN ROCKIES ON TUESDAY...AHEAD OF A TROUGH THAT SWINGS INLAND ON WEDNESDAY. SURFACE HIGH PUSHES INTO THE CWA ON TUESDAY...ALLOWING UPSLOPE FLOW TO RE-DEVELOP. ETA/AVN MODELS MOVE A SHEARED VORTICITY LOBE IN A MOIST SOUTHWEST FLOW ALOFT OVER WRN AND CNTRL MT BY TUESDAY AFTERNOON. EXPECT THAT THIS SCENARIO WILL ALLOW A SHOWERY OVER-RUNNING REGIME TO DEVELOP AND HAVE BROAD-BRUSHED CHANCE POPS FOR MOST OF THE CWA. AS THE UPPER TROUGH SWINGS INLAND ON WEDNESDAY THE AVN DEVELOPS A CLOSED LOW OVER WY AND S CNTRL MT. MODEL ALSO PAINTS A BAND OF IMPRESSIVE QPF VALUES IN SW AND S CNTRL MT AS THIS SYSTEM EVOLVES. HAVE CONSULTED WITH BIL FORECASTER...AND AGREE THAT IT IS TOO SOON TO BE SURE IF THIS EVENT WILL PLAY OUT AS ADVERTISED. FOR NOW WILL CONTINUE BROAD-BRUSH FORECAST OF CHANCE POPS IN THE SOUTHWEST AND DROP TEMPERATURES DOWN FROM EARLIER FORECAST. MPJ .EXTENDED...MODELS SHOWING SOME CHANGES FOR THURSDAY. AVN DEVELOPS SURFACE LOW OVER NORTHEAST WYOMING WEDNESDAY NIGHT WITH AN AREA OF STRONG QPF BACK ACROSS SOUTH-CENTRAL MONTANA. MRF INDICATING SIMILAR PATTERN. WILL ADD A WEDNESDAY NIGHT GHOST PERIOD FOR SOUTHWEST MONTANA AND THE LEWISTOWN AREA TO AT LEAST GET A FOOT IN THE DOOR SHOULD THIS SOLUTION COME TO PASS. BY THURSDAY AFTERNOON DOWNSLOPE GRADIENT DEVELOPS AGAIN. INCREASING BACKING FLOW ALOFT SATURDAY WITH A LEE SIDE TROF PRODUCING DOWNSLOPE WINDS. UPPER TROF MOVES ACROSS AREA SATURDAY BUT MODELS WEAKER WITH THIS FEATURE FROM PREVIOUS RUNS. ASSOCIATED SURFACE LOW ACROSS SOUTHERN CANADA WILL HELP KEEP DOWNSLOPE GRADIENTS IN PLACE. WEAK RIDGING SUNDAY FOR GENERALLY DRY CONDITIONS. TEMPERATURES SHOW LITTLE VARIATION THROUGH THE PERIOD THOUGH SLIGHTLY COOLER BY THE WEEKEND. .CCF NUMBERS GTF BW 024/050 028/046 030 14611 ENNEE 050/030 058/030 061/028 054/028 055 32232222222 CTB BW 022/046 024/042 027 14311 ENNEE 048/026 055/026 057/026 052/026 052 32222222222 HLN BW 030/054 032/055 032 14212 WEEEE 050/030 056/030 058/030 053/030 053 43332222222 BZN BW 026/053 028/053 030 14212 WEEEE 052/020 057/024 057/024 052/024 052 43354223222 WEY BW 024/046 026/046 026 14213 WEEEE 040/015 046/015 045/015 042/015 042 54454224322 DLN BW 028/052 032/052 032 14213 WEEEE 048/025 056/028 057/028 053/028 053 53332222222 HVR BE 022/050 027/045 028 14211 ENNEE 049/030 057/032 058/032 054/032 054 22222221111 LWT BW 023/050 028/047 030 14611 WNEEE 051/026 056/027 058/027 054/027 054 33343223222 .TFX...NONE.