970 FXUS65 KBYZ 120821 AFDBIL SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 219 AM MDT FRI OCT 12 2001 .SHORT TERM...VALID FOR TDY AND SAT... FAST NORTHWEST FLOW TO BE OVER AREA IN THE SHORT TERM. TODAY...A BIT OF A TRANSITION BETWEEN EXITING SYSTEM AND NEXT SYSTEM TO DROP IN FROM THE NORTHWEST TONIGHT. SOME INSTABILITY EARLY TODAY WITH SOME SHOWERS POSSIBLE. DOWNSLOPE WILL BE STRONG IN WESTERN ZONES WITH PROBABLY A BETTER CHANCE FOR ISOLATED SHOWERS IN EASTERN ZONES. WILL LEAVE LOW POPS IN. WILL BE RAISING TEMPERATURES WITH SLIGHTLY WARMER LOW LEVEL TEMPS AND LESS CLOUDS THAN YESTERDAY. TONIGHT...WAVE DROPS DOWN INTO EASTERN MONTANA BRINGING A VERY FAST UPPER FLOW TO AREA. AVN AND ETA BOTH VERY MOIST WITH THE FLOW HITTING WESTERN MOUNTAINS THE HARDEST. POTENTIAL INSTABILITY INCREASES LATE BUT COMBINED WITH DOWNSLOPE AGAIN AT LOW LEVELS SHOULD RESULT IN A FEW SHOWERS PLAINS AT MOST...PER CURRENT FORECAST. BIGGEST PROBLEM WILL BE WESTERN MOUNTAINS AND LIVINGSTON WHERE THERE IS BETTER INSTABILITY AND WET NORTHWEST FLOW WILL LIKELY HIT MOUNTAINS PRETTY GOOD. ANOTHER PROBLEM WILL BE WINDS AS STRONG GRADIENT BUILDS INTO AREA...AS WELL AS 50-55 KNOTS WINDS AT 700 MB. THIS LOOKS TO BE COVERED VERY WELL IN CURRENT FORECAST. FAIRLY HIGH THICKNESSES AND THE WIND SHOULD KEEP TEMPERATURES UP OVERNIGHT. THIS SHOULD KEEP PRECP TO MAINLY RAIN IN LVM AS WELL...WITH SNOW IN THE MOUNTAINS. NEXT STRONG UPPER SYSTEM DIVES INTO NORTHEAST MT/NORTHWEST ND SATURDAY. STRONG COLD FRONT WILL MOVE ACROSS AREA MIDDAY WITH THIS SYSTEM. AGAIN...MAIN PROBLEM WITH THIS SYSTEM WILL BE HIGH TEMPERATURE FORECAST AND WINDS...WITH BEST COLD PUSH IN EASTERN ZONES. DOWNSLOPE WILL BE STRONG AGAIN...BUT WITH STRENGTH OF SYSTEM THINK ISOLATED POPS LOOK GOOD. BEST UPPER DYNAMICS WILL BE IN EASTERN ZONES AS FAR AS WINDS GO. BEST PRESSURE RISES MOVE ACROSS NORTHEAST MONTANA AND SOUTHERN CANADA DURING THE DAY. BEST SUBSIDENCE ALSO GOES NORTH OF BILLINGS COUNTY WARNING AREA AS WELL AS 850 WINDS STAYING AROUND 30-35 KNOTS. WILL BE WINDY BUT NO HIGHLIGHTS LOOK NECESSARY...PER CURRENT FORECAST. WILL RAISE TEMPERATURES A BIT...BUT NOT GO AS HIGH AS GUIDANCE SUGGESTS. RASCH .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... THE NEW AVN RUN WHEN COMPARED WITH THE EUROPEAN IS MORE PROGRESSIVE AND SEEMS TO BE STRONGER WITH THE SHORT WAVE TO AFFECT AREA SATURDAY NIGHT AND SUNDAY. WITH MORE CLOUDS AND POSSIBLY STRONGER WINDS...AM QUESTIONING THE TEMPERATURES FOR THE INITIAL PERIOD. THESE MAY BE COOLER THAN WHAT COULD OCCUR. WITH THAT IN MIND...WILL BE MODIFYING THESE TO REFLECT WARMER CONDITIONS. THERE SHOULD BE SOME PRECIPITATION AS WELL ON SUNDAY AS THE SHORT WAVE MOVES THROUGH. THE NEW AVN RUN KEEPS A MORE PROGRESSIVE PATTERN THAN DOES THE ECMWF. AM RELUCTANT TO CHANGE MUCH BEYOND THE FIRST DAY. THE DAY SHIFT SHOULD HAVE MORE DATA TO LOOK AT IN THIS REGARD. CHB TDY SAT SUN MON TUE WED THU ------------------------------------------------------- BIL 057 040/052 033/053 032/055 032/062 040/065 036/053 2/W 22/N 13/W 11/B 11/B 22/E 22/E LVM 053 037/052 031/049 029/053 030/058 035/061 031/047 3/W 63/N 33/W 11/B 11/B 22/E 22/E HDN 058 038/053 030/055 030/057 030/063 038/066 034/054 2/W 22/N 13/W 11/B 11/B 22/E 22/E MLS 055 038/050 027/051 029/054 030/057 033/064 029/052 2/W 22/N 13/N 11/B 11/B 22/E 22/E 4BQ 054 037/049 026/050 029/053 029/056 032/062 028/051 2/W 22/N 13/N 11/B 11/B 22/E 22/E BHK 053 036/048 025/048 028/052 028/055 030/060 026/050 2/W 22/N 13/N 11/B 11/B 22/E 22/E SHR 057 035/053 028/053 028/054 028/060 034/064 029/055 2/W 22/N 13/W 11/B 11/B 22/E 22/E .BYZ...NONE.