799 FXUS65 KTFX 181223 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 520 AM MST WED JAN 18 2012 UPDATED AVIATION SECTION .DISCUSSION... TODAY THROUGH FRIDAY...A COLD AND SNOWY PERIOD IS IN STORE FOR THE AREA THE REMAINDER OF THE WEEK. THE SURFACE COLD FRONT CONTINUES TO PUSH SOUTH AND HAS GONE THROUGH HELENA. EXPECT THE FRONT TO REACH BOZEMAN LATER THIS MORNING. A WEST TO SOUTHWEST FLOW ALOFT CONTINUES TO BRING MOISTURE OVER THE COLD AIRMASS IN PLACE EAST OF THE CONTINENTAL DIVIDE. RESULTING SNOW BANDS HAVE BROUGHT LIGHT SNOW TO PORTIONS OF NORTH CENTRAL MONTANA THIS MORNING. SNOW SHOULD PICK UP IN INTENSITY LATER THIS AFTERNOON AND INTO TONIGHT. THE MANY HIGHLIGHTS IN PLACE WILL CONTINUE. WINDS HAVE DECREASED A LITTLE BUT VERY COLD WIND CHILL READINGS WILL CONTINUE THROUGH MIDMORNING. PERIODS OF SNOW ALONG WITH THE COLD TEMPERATURES WILL PERSIST THROUGH THURSDAY. BY FRIDAY THE SNOW WILL TAPER OFF AS THE COLD AIR BEGINS TO RETREAT TO THE NORTH AND EAST. TEMPERATURES WILL REMAIN WELL BELOW SEASONAL AVERAGES BUT READINGS WILL APPROACH SEASONAL AVERAGES FRIDAY ACROSS SOUTHWEST MONTANA. EMANUEL FRIDAY NIGHT THROUGH WEDNESDAY NIGHT...A PROGRESSIVE WESTERLY FLOW WITH A SERIES OF EMBEDDED DISTURBANCES WILL DOMINATE THIS PERIOD. THIS WILL KEEP A GOOD CHANCE OF SNOW IN THE MOUNTAINS THROUGH THE PERIOD...WITH LESS OF A CHANCE OF SHOWERS OVER THE PLAINS AND IN THE VALLEYS OF SOUTHWEST MONTANA. THE BEST CHANCE OF OVERALL PRECIPITATION DURING THIS PERIOD WILL BE DURING THE FRIDAY NIGHT THROUGH SATURDAY TIME FRAME. THE SURFACE BOUNDARY SEPARATING THE COLDER AND WARMER AIRMASSES WILL MOVE NORTHEAST THROUGH THE TFX CWA DURING THIS TIME. NOT ONLY WILL TEMPERATURES WARM BACK CLOSER TO NORMAL ACROSS NORTH CENTRAL MONTANA...THE BOUNDARY WILL PROVIDE A GOOD FOCUS FOR PRECIPITATION OVER THAT AREA AS WELL. FOR THE REMAINDER OF THE LONG TERM PERIOD...A SERIES OF COLD FRONTS/LEE SIDE SURFACE TROUGHS WILL MOVE ACROSS THE AREA. THIS WILL HELP KEEP SURFACE WINDS WESTERLY AND DOWNSLOPING...WHICH WILL MAINTAIN SLIGHTLY WARMER THAN NORMAL TEMPERATURES AND DRIER CONDITIONS AT LOWER ELEVATIONS. HOWEVER...HAVE GONE A BIT LOWER THAN MOST FORECAST MODELS FOR THE MAJORITY OF THE LONG TERM PERIOD...AS LINGERING SNOW COVER WILL LIKELY KEEP TEMPERATURES COOLER THAN MODELS CURRENTLY INDICATE. COULSTON && .AVIATION... UPDATED 1220Z. OVERRUNNING CONDITIONS WILL CONTINUE AS A MOIST SOUTHWEST FLOW ALOFT RIDES OVER A VERY COLD AIRMASS EAST OF THE CONTINENTAL DIVIDE. THE RESULTING SNOW WILL BE HEAVY OVER THE MOUNTAINS AND LIGHT TO MODERATE AT TIMES OVER THE PLAINS. THESE CONDITIONS WILL PERSIST BEYOND 00Z. MVFR/IFR CONDITIONS PREVAIL WITH WIDESPREAD MOUNTAIN OBSCURATION. && .PRELIMINARY POINT TEMPS/POPS... GTF -6 -15 4 -2 / 100 100 90 50 CTB -12 -23 -4 -11 / 100 100 90 50 HLN 12 5 28 12 / 100 90 90 50 BZN 18 16 32 17 / 100 90 90 50 WEY 16 15 29 15 / 100 100 100 100 DLN 20 20 36 21 / 80 80 80 50 HVR -10 -24 -4 -10 / 80 80 80 60 LWT -4 -13 8 -3 / 100 90 80 70 && .TFX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 4 AM MST FRIDAY FOR ELEVATIONS BELOW 5000 FEET FOR CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...JUDITH BASIN...MEAGHER. WINTER STORM WARNING UNTIL 4 AM MST FRIDAY FOR ELEVATIONS ABOVE 5000 FEET FOR CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK... JUDITH BASIN...MEAGHER. WINTER WEATHER ADVISORY FROM NOON TODAY TO 4 AM MST FRIDAY CHOUTEAU...EASTERN GLACIER...EASTERN PONDERA...EASTERN TETON... FERGUS...LIBERTY...TOOLE. WIND CHILL ADVISORY UNTIL 10 AM MST THIS MORNING BLAINE... CASCADE...CHOUTEAU...EASTERN PONDERA...EASTERN TETON...FERGUS... HILL...JUDITH BASIN...LIBERTY. WINTER WEATHER ADVISORY UNTIL 4 AM MST FRIDAY BEAVERHEAD... BROADWATER...GALLATIN...JEFFERSON...MADISON. WINTER STORM WARNING UNTIL 4 AM MST FRIDAY FOR ELEVATIONS ABOVE 7000 FEET FOR BEAVERHEAD...GALLATIN...MADISON. WIND CHILL WARNING UNTIL 10 AM MST THIS MORNING EASTERN GLACIER...NORTHERN ROCKY MOUNTAIN FRONT...TOOLE. WINTER STORM WARNING UNTIL 4 AM MST FRIDAY NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT. && $$ WEATHER.GOV/GREATFALLS