235 FXUS65 KTFX 130538 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1040 PM MST MON NOV 12 2012 UPDATED AVIATION SECTION .DISCUSSION... WINDS ALONG THE ROCKY MOUNTAIN FRONT DECREASED BELOW WARNING CRITERIA BY 6 PM MST...SO ALLOWED REMAINING PORTION OF HIGH WIND WARNING THERE TO EXPIRE. WINDS IN GENERAL HAVE DECREASED ACROSS THE AREA THROUGH THE EVENING HOURS AS WELL...ESPECIALLY ACROSS LIBERTY COUNTY AND EASTERN PORTIONS OF HILL AND CHOUTEAU COUNTIES...WHERE WINDS WERE NO LONGER GUSTING. HAVE THEREFORE REMOVED THOSE AREAS FROM THE ADVISORY FOR BLOWING SNOW. AM GENERALLY THINKING THAT THE THREAT FOR BLOWING SNOW IS DECREASING...BUT WINDS REMAIN QUITE GUSTY WEST OF INTERSTATE 15 TO THE ROCKY MOUNTAIN FRONT...THROUGH THE GAP AREAS OF JUDITH BASIN COUNTY...AND IN THE FAVORED DOWNSLOPE AREAS OFF THE HIGHWOOD MOUNTAINS IN SOUTHERN CHOUTEAU COUNTY. WILL THEREFORE ALLOW ADVISORY TO CONTINUE THERE OVERNIGHT AS WINDS IN THOSE AREAS GRADUALLY DECREASE. OVERALL...THOUGH...TEMPERATURES ARE REMAINING FAIRLY MILD (ABOVE FREEZING) IN THE WINDY AREAS...WHICH MAY HELP DEVELOP A CRUST ON SNOWPACK AND HINDER BLOWING SNOW. REGARDLESS...AM EXPECTING TEMPERATURES TO CONTINUE TO WARM INTO TUESDAY...WHICH SHOULD FURTHER LIMIT THE THREAT FOR BLOWING SNOW. WITH THESE CONTINUED MILD TEMPERATURES...HAVE RAISED OVERNIGHT LOWS 3 TO 5 DEGREES IN THESE WINDY AREAS. IN SOUTHWEST MONTANA...SOME SNOW SHOWER ACTIVITY HAS MADE IT INTO SOME VALLEY LOCATIONS AS CLOUD COVER INCREASES FROM THE WEST...SO HAVE RAISED POPS THERE. MANY OF THOSE VALLEY LOCATIONS ARE ALREADY APPROACHING THEIR FORECAST LOWS...SO HAVE LOWERED LOWS A FEW DEGREES. THE INCREASING CLOUD COVER WILL KEEP TEMPERATURES THERE FROM FALLING TOO MUCH MORE...THOUGH. PATCHY FOG MAY STILL DEVELOP IN THE NORTHEAST PORTION OF THE AREA (NORTHERN BLAINE COUNTY) DUE TO LESS WIND AND CLOUD COVER. COULSTON && .AVIATION... UPDATED 0540Z. WEST TO NORTHWEST FLOW ALOFT CONTINUES. MID AND HIGH LEVEL CLOUDS ARE INCREASING OVER THE AREA AS A DISTURBANCE ALOFT APPROACHES FROM THE WEST. SCATTERED SNOW WILL DEVELOP OVER THE WESTERN AND SOUTHWEST MOUNTAINS WITH ISOLATED SNOW OVER THE PLAINS. GUSTY SURFACE WINDS ARE SLOWLY DECREASING ALONG THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS BUT WILL STILL CAUSE AREAS OF BLOWING SNOW. VFR CONDITIONS PREVAIL WITH AREAS OF MVFR DUE TO LOW CEILINGS AND BLOWING SNOW. MOUNTAINS WILL BE OBSCURED AT TIMES. && .PREV DISCUSSION... /ISSUED 450 PM MST MON NOV 12 2012/ TODAY THROUGH WEDNESDAY...SHORTWAVE ENERGY ALOFT CONTINUES TO MOVE TOWARD MONTANA AND WILL BRING WIDESPREAD SNOW ALONG THE CONTINENTAL DIVIDE WITH SCATTERED SHOWERS IN SOUTHWEST MONTANA AND THE CENTRAL MOUNTAINS. SNOW ACCUMULATIONS ARE EXPECTED TO BE LIGHT. OVER THE PLAINS CONDITIONS REMAIN WINDY WITH AREAS OF BLOWING SNOW CONTINUING TO CAUSE PROBLEMS WITH TRAVEL SO HAVE OPTED TO EXTEND THE WINTER WEATHER ADVISORY FOR BLOWING SNOW OVERNIGHT. BY MORNING I ANTICIPATE THE DECREASING WIND SPEEDS COUPLED WITH WARMER TEMPERATURES SHOULD CAUSE THE BLOWING SNOW TO DIMINISH. FOR TUESDAY AND WEDNESDAY THE FOCUS FOR THE WEATHER SHIFTS BACK TO ANTICIPATING HOW MUCH OR LITTLE TEMPERATURES WILL WARM AS THE ADVECTION OF WARMER AIR COUPLED WITH GUSTY DOWNSLOPE WINDS WARS WITH SNOW COVER AND VALLEY INVERSIONS. HAVE CONTINUED TO KEEP FORECASTED HIGH TEMPERATURES BELOW GUIDANCE THROUGH THE SHORT TERM BUT ANTICIPATE THAT ANY BREAKS IN THE CLOUD COVER COULD ALLOW TEMPERATURES TO CLIMB MORE THAN ANTICIPATED. BREEZY CONDITIONS WILL ALSO CONTINUE BUT SHOULD NOT BE AS STRONG AS THOSE OF TODAY. FINALLY... WITH A MOIST WESTERLY FLOW ALOFT CONTINUING HAVE KEPT LIKELY TO CATEGORICAL POP OVER THE ROCKY MOUNTAIN FRONT THROUGH THE ENTIRE PERIOD WITH GENERALLY LIGHT ACCUMULATIONS EXPECTED. ANOTHER SHORTWAVE WILL APPROACH MONTANA LATE ON WEDNESDAY WITH SCATTERED POPS SPREADING INTO SOUTHWEST MONTANA. MPJ WEDNESDAY NIGHT THROUGH MONDAY...EXTENDED FORECAST PERIOD CURRENTLY SHAPING UP TO RATHER QUIET WITH NO SIGNIFICANT WEATHER SYSTEMS CURRENTLY PROJECTED TO MOVE THROUGH CENTRAL/SOUTHWEST MT. PERIOD BEGINS WITH A WEAK UPPER LEVEL TROF SLIDING THROUGH OUR REGION AND PRODUCING A FEW LIGHT SNOW SHOWERS OVER THE SOUTHWEST MTNS THROUGH EARLY THURS MORNING. AS THE TROF EXITS TO THE EAST...THE FLOW ALOFT BECOMES MORE WESTERLY ON FRI WITH A SLIGHT POSSIBILITY FOR STRONG WINDS ALONG THE ROCKY MTN FRONT AS A SMALL SECTION OF THE JET STREAM TRACKS ALONG THE US/CAN BORDER. MOSTLY DRY CONDITIONS CONTINUE INTO THIS WEEKEND AS HIGH PRESSURE RIDGING GRADUALLY BUILDS INTO THE NRN ROCKIES LARGELY IN RESPONSE TO THE DEVELOPMENT OF A LONGWAVE TROF OVER THE NORTHEAST PACIFIC. FORECAST MODELS ARE IN GOOD AGREEMENT THAT THE LONGWAVE WILL EXPAND SOUTHWARD OFF THE PACIFIC COAST BUT MAKE LITTLE EASTWARD MOVEMENT UNTIL LATE MONDAY. AS A RESULT...WE WILL STAY UNDER PERSISTENT SOUTHWEST FLOW ALOFT...KEEPING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR FRI THROUGH MON WITH LITTLE/NO PRECIPITATION EXPECTED EXCEPT FOR A FEW OCCASIONAL SHOWERS OVER THE ROCKY MTN FRONT AND SOUTHWEST MTNS ON SAT AND MON. WARANAUSKAS && .PRELIMINARY POINT TEMPS/POPS... GTF 30 39 30 41 / 10 0 0 10 CTB 29 40 27 40 / 10 10 0 10 HLN 21 36 26 39 / 50 10 10 20 BZN 18 35 22 39 / 50 10 10 20 WEY 11 30 15 33 / 60 40 30 30 DLN 19 34 23 37 / 50 10 10 20 HVR 20 36 22 36 / 10 0 0 10 LWT 26 37 23 39 / 20 0 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY CASCADE... CHOUTEAU...EASTERN GLACIER...EASTERN PONDERA...EASTERN TETON... JUDITH BASIN...NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT...TOOLE. && $$ SHORT TERM...MPJ/COULSTON LONG TERM...WARANAUSKAS AVIATION...EMANUEL WEATHER.GOV/GREATFALLS