269 FPUS65 KBIL 032021 AFDBIL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 145 PM MDT WED JUN 3 1998 TOUGH FORECAST FOR JUNE. UPPER TROUGH FROM WESTERN MONTANA INTO NEVADA PROGGED TO SWING THROUGH THE AREA TONIGHT AND TOMORROW. ABUNDANT LOW TO MID LEVEL MOISTURE WILL BE LAYING AROUND TO WORK WITH. ONE SHORTWAVE MOVING INTO EASTERN IDAHO WILL GET THINGS GOING AGAIN TONIGHT. PROBLEM IS LOCATION OF PRECIPITATION BAND. ETA SHIFTS THE BAND FARTHER SOUTH AND I ACCEPT THIS SOLUTION AS WATER VAPOR AND VISIBLE IMAGERY SHOWING DRIER AIR WORKING SOUTH FROM NORTHERN MONTANA. 700MB LOW PROGGED OVER CENTRAL WYOMING WITH UPSLOPE CONTINUING TROUGH THURSDAY. ETA LAYS DOWN SIGNIFICANT QPF OVER SOUTHERN MONTANA AND NORTHERN WYOMING. CERTAINLY COLD ENOUGH FOR DECENT SNOW ACCUMULATIONS. HAVE COORDINATED WITH CYS AND GTF AND WILL ISSUE SNOW ADVISORY FOR ELEVATIONS ABOVE 4500 FEET OVER SOUTHERN MONTANA AND ALSO FOR LOWER ELEVATIONS OF SHERIDAN COUNTY. WILL KEEP THE BIG HORN MOUNTAINS BELOW WARNING CRITERIA. TROUGH MOVES EAST THURSDAY BUT STILL KEEP A WEAK NORTH FLOW SO WILL NOT HAVE MUCH OF AN AIRMASS CHANGE. WITH DRIER AIR...HOWEVER WILL GRADUALLY WARM THINGS UP. COOL UNSTABLE AIRMASS WILL ALLOW FOR LOW POPS SOUTH CENTRAL CONTINUING AND WILL LOOK FOR CLOUDS QUICKLY DEVELOPING AGAIN THURSDAY AFTERNOON. A SHORTWAVE WILL ROLL THROUGH EASTERN MONTANA FRIDAY...SO WILL INCLUDE LOW POPS THERE. A DIFFERENT SHORTWAVE WILL DIVE DOWN TOWARD SOUTHWEST MONTANA FRIDAY...SO WILL KEEP POPS GOING FOR SOUTH CENTRAL MONTANA. HUMPHREY BIL EB 038/054 036/062 041 556322 LVM .. 034/059 032/065 ... 556323 HDN .. 036/056 034/063 ... 556422 MLS .. 039/061 037/065 ... 552002 4BQ .. 040/059 037/065 ... 553202 BHK .. 035/059 033/064 ... 552002 SHR OB 036/045 033/057 037 557632