000 FXUS65 KBYZ 010901 CCA AFDBIL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 158 AM MST THU APR 1 2004 .SHORT TERM...VALID FOR TDY AND FRI... RADARS AND MORNING SATELLITE IMAGERY SHOW MOISTURE STREAMING INTO THE WESTERN HALF OF MONTANA WITH AN UPPER LEVEL LOW SPINNING OVER OREGON. THIS LOW IS PROGGED TO DIG TODAY TRACKING SOUTH AND WEST OF THE TRACK WHICH HAD BEEN HEADED FOR CENTRAL MONTANA. AIRMASS IS UNSTABLE OVER WESTERN MONTANA AND EXPECT SHOWER ACTIVITY TO ADVANCE INTO THE CENTRAL ZONES BY MID DAY. BY 00Z THE UPPER LOW IS OVER SOUTHWEST IDAHO/NORTHERN NEVADA WITH AN AREA OF DIFFLUENT FLOW DEVELOPING OVER SOUTHERN MONTANA. THIS WILL AID THE SHOWER ACTIVITY SPREADING EASTWARD AND WILL BE SUPPORTED BY SURFACE UPSLOPE FLOW AND MID LEVEL WARM AIR ADVECTION. AS THE UPPER LOW CONTINUES TO DIG FURTHER SOUTHWARD INTO NEVADA ON TONIGHT IT KEEPS ADVECTING MOISTURE INTO THE AREA AND THE DIFFLUENT ZONE REMAINS OVER THE SOUTHERN PART OF MONTANA UNTIL 12Z. FOR FRIDAY...PATTERN STILL SUPPORTS PRECIPITATION WITH UPSLOPE AND WEAKER WARM AIR ADVECTION BUT BETTER PRECIPITATION SHOULD FALL TONIGHT. BIGGEST QUESTION IS SNOW FALL AMOUNTS AND WHERE. THINK THAT VERY WARM GROUND WILL HAVE A ROLE IN MELTING THE SNOW AS IT FALLS AND THIS SHOULD KEEP MOST OF THE AREA FROM REACHING ADVISORY CRITERIA. BORSUM .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... EXTENDED MODELS CONTINUE THEIR PATTERN OF RESOLVING THE DEVELOPING AREA OF LOW PRESSURE DIFFERENTLY EARLY ON IN THE EXTENDED PERIOD. GFS HAS A CUT OFF LOW DEVELOPING OVER THE SW PORTION OF UT WHILE THE ECMWF AND UKMET BOTH DEVELOP THIS LOW OVER THE SW PORTION OF CA...ALTHOUGH THESE 2 MODELS DIFFER ON PLACEMENT THEY BOTH SUGGEST AN AREA OF HIGH PRESSURE OVER THE MT REGION WHILE THE GFS SUGGESTS MORE OF A SPLIT FLOW REGIME. RESULTING 500MB HEIGHTS ARE DRASTICALLY DIFFERENT BASED ON THE SOLUTION EACH MODEL SUGGESTS AND RANGE FROM 570-576DM BY 00Z SUN OVER MT. SHORT TERM TRENDS HAVE SHOWN THAT THE SYSTEMS ARE SLOWING DOWN AND RETROGRADE AS THEY MOVE ON SHORE AND THAT THE ECMWF HAS ACTUALLY SHOWN BETTER OF THE REMAINING EXTENDED MODELS. SINCE CONFIDENCE IS RATHER LOW WITH THE EXTENDED PERIOD WILL TREND MORE IN LINE WITH THE ABOVE MENTIONED IDEAS AS EXTENDED PACKAGE COMES TOGETHER AND WILL TWEAK TO AGREE WITH OFFICES SURROUNDING MT. MAIN EMPHASIS WILL BE PLACED ON DAYS 3-5 WHILE DAYS 6 AND 7 WILL LIKELY REMAIN UNCHANGED OR GO ALONG WITH CLIMATE. SPRINGER && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 049 028/045 033/056 033/061 035/060 036/064 036/058 6/W 76/W 20/B 00/E 00/B 00/B 00/B LVM 046 026/044 029/054 031/059 033/058 034/061 034/060 7/W 76/W 10/B 00/E 00/B 00/B 00/B HDN 054 029/046 030/057 031/062 033/061 034/064 034/062 2/W 76/W 20/B 00/B 00/B 00/B 00/B MLS 056 030/044 029/055 032/064 034/060 035/060 035/062 0/E 66/W 00/B 00/B 00/B 00/B 00/B 4BQ 060 030/043 029/052 032/065 036/060 037/058 035/061 0/N 76/W 30/B 00/B 32/W 00/B 00/B BHK 057 028/040 027/052 030/062 032/058 033/059 033/057 0/B 66/W 20/B 00/B 01/B 00/B 00/B SHR 057 028/039 028/051 030/057 032/056 033/064 033/060 2/W 67/W 30/B 00/B 31/B 00/B 00/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$