426 FXUS65 KTFX 131651 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 951 AM MST TUE NOV 13 2012 .UPDATE...RELATIVELY QUIET WEATHER IS EXPECTED ACROSS THE FORECAST AREA TODAY. MAIN FORECAST CONCERN IS TEMPERATURES AND HAVE UPDATED TO TWEAK TEMPERATURES AND WIND SPEEDS DOWNWARD A BIT IN THE SOUTHWEST MONTANA VALLEYS WHERE COLD AIR WILL LIKELY REMAIN TRAPPED. HAVE ALSO TWEAKED HIGHS UP A TAD IN NORTH CENTRAL MONTANA BUT WILL STILL KEEP THEM BELOW GUIDANCE DUE TO ABUNDANT SNOW ON THE GROUND AND LIGHTER WINDS TODAY. FINALLY HAVE INCREASED CLOUD COVER IMMEDIATELY EAST OF THE CONTINENTAL DIVIDE TO DEPICT THE PERSISTENT CHINOOK ARCH. POPS AND WEATHER FORECAST APPEARS ON TRACK WITH MOST PRECIPITATION EXPECTED ALONG THE CONTINENTAL DIVIDE DUE TO THE MOIST NEARLY ZONAL FLOW ALOFT. MPJ && .AVIATION... UPDATED 1130Z. VFR CONDITIONS EXPECTED TODAY AS A WEAK DISTURBANCE AND ASSOCIATED MOISTURE EMBEDDED IN WESTERLY FLOW ALOFT CONTINUES TO SPREAD BROAD LAYERS OF MID- AND HIGH CLOUD COVER. CURRENT RADAR IMAGERY NOT INDICATING ANY PRECIPITATION OVER CENTRAL/SOUTHWEST MT SO HAVE REMOVED MENTION OF VCSH FOR THIS MORNING AT KBZN/KHLN. WINDS WILL BECOME BREEZY AGAIN AROUND MIDDAY WITH GUSTS OF 25 TO 30 KTS BETWEEN KGTF AND KCTB UNTIL AROUND 02Z. WARANAUSKAS && .PREV DISCUSSION... /ISSUED 430 AM MST TUE NOV 13 2012/ TODAY THROUGH THURSDAY...A ZONAL FLOW WILL BE IN PLACE OVER MUCH OF THE CENTRAL AND WESTERN UNITED STATES THROUGH WEDNESDAY BRINGING MID LEVEL MOISTURE INTO THE REGION FROM THE PACIFIC. MOISTURE WILL DECREASE ON THURSDAY AS A RIDGE OF HIGH PRESSURE DEVELOPS OVER THE NORTHERN ROCKIES. SNOW SHOWERS NEAR THE CONTINENTAL DIVIDE ARE EXPECTED TO CONTINUE THROUGH WEDNESDAY AS A RESULT OF THE STEADY STREAM OF PACIFIC MOISTURE PUSHING INTO THE AREA. A SHORTWAVE TROUGH MOVING THROUGH THE REGION ON WEDNESDAY WILL SPREAD SNOW SHOWERS FURTHER SOUTH AND EAST INTO THE MOUNTAINS OF CENTRAL AND SOUTHWEST MONTANA. STRONGER MID AND UPPER LEVEL WINDS ACCOMPANYING THE SHORTWAVE WILL BRING BREEZY WINDS TO THE PLAINS HOWEVER WINDS SHOULD REMAIN WELL BELOW WARNING CRITERIA. INSTABILITY WILL INCREASE ACROSS PORTIONS OF THE PLAINS AND THE SOUTHWEST VALLEYS ON WEDNESDAY. DOWNSLOPE FLOW SHOULD KEEP LOCATIONS IN THE PLAINS NEAR THE ROCKY MOUNTAIN FRONT DRY BUT INSTABILITY SHOULD BE SUFFICIENT TO GENERATE AT LEAST A FEW SHOWERS IN THE PLAINS ALONG AND EAST OF INTERSTATE 15 AND OVER THE SOUTHWEST VALLEYS WEDNESDAY AFTERNOON. SNOW ACCUMULATIONS THROUGH THE WEDNESDAY WILL REMAIN LIGHT. A SLOW WARMING TREND IS EXPECTED WITH MOST LOCATIONS WARMING TO NEAR OR SLIGHTLY ABOVE SEASONAL AVERAGES BY THURSDAY. LANGLIEB THURSDAY NIGHT THROUGH TUESDAY...LATEST FORECAST MODELS CONTINUE TO SHOW NO MAJOR WEATHER SYSTEMS IMPACTING CENTRAL AND SOUTHWEST MT THROUGH THIS WEEKEND. FLOW ALOFT WILL GRADUALLY SHIFT FROM WESTERLY ON THURS/FRI TO MORE SOUTHWESTERLY IN RESPONSE TO LONGWAVE TROF DIGGING SOUTH ALONG THE PACIFIC COAST ON SAT/SUN. WEAK MOISTURE PLUMES AHEAD OF THE MAIN TROF WILL PUSH INTO WESTERN MT ON FRI AND SUN BUT MODELS ARE IN GOOD AGREEMENT THAT MOST OF THE RESULTING LIGHT PRECIPITATION WILL REMAIN WEST OF THE DIVIDE. SOME ISOLATED SHOWERS WILL BE POSSIBLE ALONG THE ROCKY MTN FRONT AND THE MTNS OF FAR SOUTHWEST MT WHILE REST OF FORECAST AREA REMAINS DRY. THE SOUTHWEST FLOW AND MILD PACIFIC AIRMASS WILL KEEP HIGH TEMPERATURES AT OR A FEW DEG ABOVE NORMAL EACH DAY. THERE IS STILL A CHANCE OF GUSTY WINDS DEVELOPING ALONG THE ROCKY MTN FRONT AND WESTERN PORTIONS OF THE HILINE ON FRI AS A SMALL JET STREAK TRACKS ALONG THE US/CAN BORDER...BUT NOT ANTICIPATING ANY HIGH WIND HIGHLIGHTS AT THIS TIME. MODEL CONTINUITY BEGINS TO BREAK DOWN ON MON AS THE EUROPEAN SOLUTION BRINGS A SHORTWAVE TROF ACROSS THE NRN ROCKIES WITH LIGHT SHOWERS DEVELOPING OVER MUCH OF OUR FORECAST AREA ON MON AFTN AND CONTINUING THROUGH TUES. MEANWHILE THE GFS MODEL TAKES THE MAIN ENERGY OF THE LONGWAVE ALL THE WAY INTO SRN NEVADA AND ONLY GENERATES SHOWERS OVER SOUTHWEST MT ON TUES AFTN/EVE. CURRENT FORECAST LEANS MORE TOWARD THE GFS SOLUTION WITH JUST SLIGHT CHANCE TO CHANCE PROBABILITIES OF PRECIP FROM HELENA SOUTHWARD. WARANAUSKAS && .PRELIMINARY POINT TEMPS/POPS... GTF 41 32 43 26 / 0 0 20 0 CTB 43 27 41 22 / 10 0 10 0 HLN 40 26 42 23 / 10 10 30 10 BZN 33 23 42 20 / 10 10 40 10 WEY 29 14 34 12 / 40 30 60 20 DLN 34 24 39 21 / 10 10 20 10 HVR 38 23 39 20 / 0 0 10 0 LWT 41 25 42 22 / 0 10 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ WEATHER.GOV/GREATFALLS