000 FXUS65 KBYZ 121604 AFDBYZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BILLINGS MT 1004 AM MDT SUN OCT 12 2008 .SHORT TERM...VALID FOR TDY AND MON... UPDATE TO ZFP BUT NOT WRKAFP. UPPER LOW CENTER WAS SHIFTING NE INTO SW ID/W WY THIS MORNING PER SATELLITE IMAGERY TRENDS. SATELLITE ALSO SHOWED A PRONOUNCED DRY SLOT LIFTING NE INTO THE SE PART OF THE AREA. ENHANCED AREA OF SNOWFALL ON RADAR E AND N OF KBIL...WAS ROTATING NE AND WAS ASSOCIATED WITH STRONG JET DIVERGENCE DEPICTED WELL ON THE 06Z GFS. RADAR ALSO INDICATED BAND OF SNOW SHOWERS MOVING N FROM E WY TOWARD FAR SE ZONES. 12Z UPPER AIR DATA SHOWED STRONG DIFLUENCE ALOFT OVER THE AREA. SPOTTER REPORT FROM KMLS HAD 4 INCHES OF SNOW IN KMLS SINCE 14Z AND INDICATED HEAVY SNOW AT 1530Z. GFS AND NEW WRF SHOWED THE STRONG UPPER SUPPORT WILL MOVE N OF THE REGION BY 18Z. MODELS DISAGREED ON EXACTLY WHERE THE NEW UPPER LOW WILL REFORM THIS AFTERNOON WITH WRF SHOWING IT S OF KBIL AND GFS KEEPING IT OVER SE MT. REALITY WILL LIKELY BE SOMEWHERE IN BETWEEN THE TWO SOLUTIONS. EXPECT FLOW TO BECOME NW OVER CENTRAL AND W ZONES WITH GOOD MOISTURE BUT LIMITED LIFT. MEANWHILE...BAND LIFTING N FROM E WY WILL SHIFT OFF TO THE E AND DRY SLOT WILL WORK IT/S WAY INTO THE SE. HAVE CUT BACK ON POPS A BIT THIS AFTERNOON ESPECIALLY SE. EXPECT AROUND 3 INCHES OF NEW SNOW ACCUMULATION CENTRAL AND W WITH LESSER AMOUNTS SE THRU 00Z TONIGHT. WILL LIKELY BE CANCELLING WINTER STORM HIGHLIGHTS LATER TODAY. NEW LSR HAS BEEN SENT OUT TO COVER CRITERIA AMOUNTS RECEIVED SINCE YESTERDAY AND PNS WILL BE OUT LATER THIS MORNING. ARTHUR .LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT... PATTERN FOR EXTENDED APPEARS ABOUT THE SAME AS HAS OVER THE LAST SEVERAL DAYS. ONLY MINOR TWEAKING OF FORECAST FOR NEIGHBORS. A SHALLOW UPPER TROF MOVING ACROSS CANADA BRINGS MILDLY CYCLONIC...SOMEWHAT ZONAL FLOW INTO THE REGION IN ADVANCE OF A WEAK RIDGE BUILDING INTO THE PACIFIC NORTHWEST. A WEAK SHORTWAVE MOVES ACROSS THE AREA BEGINNING TUESDAY NIGHT INTO THURSDAY...WHICH WILL BRING A SLIGHT CHANCE OF SHOWERS TO THE REGION. MORE PRONOUNCED DOWNSLOPE FLOW COMES INTO PLAY LATE THURSDAY AS FLOW BECOMES MORE NORTHWESTERLY...FURTHER IMPROVING AS RIDGE MOVES INTO THE AREA FRIDAY. THE RIDGE REMAINS IN CONTROL OVER THE REGION THROUGH SATURDAY EVENING WHEN A SHORTWAVE RIDING UP THE BACKSIDE OF THE RIDGE BRINGS ANOTHER CHANCE FOR PRECIP THROUGH THE END OF THE EXTENDED. CONTINUED TREND OF GRADUAL WARMUP THROUGH THE EXTENDED...AS A RESULT OF EXTENSIVE SNOW COVER. THE RIDGE WILL HELP TO CLEAR OUT MORE OF THE SNOW...BRINGING TEMPS NEAR NORMAL ON FRIDAY. A SLIGHT COOLOFF WILL FOLLOW AS THE RIDGE MOVES OFF AND SHORTWAVE MOVES CREATING INCREASED CLOUD COVER WITH PRECIP POTENTIAL. GILSTAD && .AVIATION... IFR/LIFR CONDITIONS WILL PERSIST ACROSS THE AREA THROUGH LATE MORNING...THEN WILL IMPROVE SLIGHTLY TO MVFR WITH LOCAL IFR THIS AFTERNOON. MOUNTAINS WILL REMAIN OBSCURED THROUGH THE DAY. ARTHUR && .PRELIMINARY POINT TEMP/POPS... TDY MON TUE WED THU FRI SAT ------------------------------------------------------- BIL 032 022/037 026/038 024/049 033/054 032/060 040/058 +/S 53/S 00/B 22/O 21/B 11/B 11/B LVM 031 018/041 025/043 027/051 033/054 033/061 040/056 9/S 52/S 01/B 22/R 22/W 11/B 11/B HDN 034 018/039 026/040 026/052 032/055 031/063 039/062 +/S 53/S 00/B 21/B 21/B 11/B 11/B MLS 034 023/038 026/044 029/053 033/056 032/062 040/059 +/S 64/S 01/B 22/R 22/W 11/U 11/U 4BQ 033 018/036 022/043 027/053 031/056 030/062 038/063 +/S 43/S 00/U 21/B 22/W 11/U 11/U BHK 034 019/036 022/046 026/051 031/054 030/059 039/060 +/S 64/S 01/B 22/R 22/W 11/B 11/B SHR 032 016/037 023/041 026/051 031/054 029/061 038/060 +/S 42/S 00/U 21/B 22/W 21/B 12/R && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR ZONES 28>42-56>58-63>68. WY...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR ZONES 98-99. && $$ WEATHER.GOV/BILLINGS