205 FXUS65 KTFX 301519 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 920 AM MDT SUN SEP 30 2012 .UPDATE... CURRENT FORECAST IS ON TRACK FOR TODAY. NO UPDATES AT THIS TIME. BRUSDA && .AVIATION... UPDATED 1130Z. VFR CONDITIONS WILL CONTINUE ACROSS THE AREA FOR THE NEXT COUPLE DAYS. A WEAK DISTURBANCE IN THE FLOW WILL MOVE OVER THE AREA LATER TONIGHT AND THROUGH THE DAY HELPING GENERATE SOME SCATTERED MID LEVEL CLOUDS. SURFACE WINDS SHOULD BE LIGHT WEST-NORTHWEST AND MAY BE A LITTLE BREEZY IN THE AFTERNOON...ESPECIALLY NEAR KCTB. && .FIRE WEATHER... FIRE WEATHER WATCH IN EFFECT FOR MONDAY AFTERNOON/EVENING FOR PORTIONS OF CENTRAL AND NORTH CENTRAL MT. HIGH PRESSURE RIDGE OVER THE NRN ROCKIES WILL BREAK DOWN MON AFTN DUE TO APPROACHING STRONG CANADIAN LOW PRESSURE SYSTEM. GUSTY WINDS AND LOW AFTERNOON HUMIDITIES WILL SIGNIFICANTLY INCREASE POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS. MAIN IMPACT AREA WILL BE ALONG THE ROCKY MTN FRONT AND ADJACENT PLAINS GENERALLY ALONG/NORTH OF A LINE FROM LINCOLN TO GREAT FALLS TO HAVRE...THAT IS ALL OF FIRE ZONES 112/114 BUT JUST THE NORTHERN/WESTERN PORTIONS OF FIRE ZONES 113/115/117. WARANAUSKAS && .PREV DISCUSSION...(ISSUED AT 400 AM MDT SUN SEP 30 2012) TODAY THROUGH TUESDAY EVENING...QUIET CONDITIONS ON SUNDAY WILL TRANSITION TO PERIOD OF ACTIVE WEATHER...WITH HIGH WIND AND FIRE WEATHER WATCHES ALREADY POSTED...FOR MONDAY AND TUESDAY. FOR TODAY...HIGH PRESSURE RIDGING OVER THE ERN PACIFIC IS CURRENTLY BUILDING ACROSS CA/WA/OR AND WILL SPREAD INTO THE NRN ROCKIES THRU THE DAY. SATELLITE IMAGERY SHOWS A FEW MINOR WAVES IN THE WESTERLY FLOW AHEAD OF THE RIDGE CUTTING ACROSS SRN CANADA WITH THEIR ACCOMPANYING MOISTURE BANDS BRINGING SCATTERED CLOUDS OVER WESTERN/CENTRAL MT...BUT DO NOT EXPECT ANY RAINFALL IN OUR REGION FROM THESE WEAK DISTURBANCES. COOL NORTHWEST FLOW ALOFT WILL KEEP HIGH TEMPERATURES IN THE LOW TO MID 70S TODAY. THE RIDGE REMAINS OVER THE STATE ON MONDAY BUT BEGINS TO WEAKEN IN THE AFTERNOON IN RESPONSE TO A STRONG SHORTWAVE TROF MOVING FROM THE GULF OF ALASKA INTO SOUTHWEST CANADA. THE RESULTING TIGHT PRESSURE GRADIENT BETWEEN THE RIDGE AND TROF WILL PRODUCE WIDESPREAD GUSTY WINDS OVER CENTRAL AND NORTH CENTRAL MT...WHICH WILL COMBINE WITH AFTERNOON HUMIDITIES DROPPING INTO THE TEENS AND LOW 20 PERCENT RANGE TO INCREASE POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS. SO HAVE ISSUED A FIRE WEATHER WATCH FOR MON AFTN/EVE (SEE DETAILS IN FIRE WEATHER SECTION BELOW). LIKEWISE...THE WINDS WILL BE STRONGEST ALONG THE ROCKY MTN FRONT (GUSTS OF 55-65 MPH POSSIBLE)...SO THE HIGH WIND WATCH FOR MON AFTN THRU MIDDAY TUES REMAINS IN EFFECT WITH NO CHANGES. MARKED WARM AIR ADVECTION WITH THE WINDS WILL PUSH HIGH TEMPS INTO THE UPPER 70S TO LOW 80S ON MON...ABOUT 10-15 DEG ABOVE NORMAL. THE WARMUP WILL BE SHORT-LIVED THOUGH AS FORECAST MODELS CONTINUE TO BE IN GOOD AGREEMENT THAT A SHARP COLD FRONT FROM THE SHORTWAVE TROF WILL CROSS THE US/CAN BORDER EARLY TUES MORNING AND RACE SOUTHWARD DURING THE DAYTIME HOURS. INITIALLY WE WILL SEE JUST A QUICK WIND SHIFT TO THE NORTHWEST AND STEADY TEMPERATURES AS SEVERAL MODELS INDICATE THAT A PRONOUNCED DRY SLOT WILL OCCUR BEHIND THE FRONT AND LAST THRU THE AFTERNOON/EARLY EVENING. PRECIPITATION FINALLY BEGINS TO DEVELOP AROUND 6PM ALONG THE HILINE AND NRN ROCKY MTN FRONT AS THE CORE OF THE COLD AIR SURGES SOUTH...WITH MTN SNOW AND VALLEY RAIN OR RAIN/SNOW MIX BECOMING WIDESPREAD ACROSS THE REST OF THE FORECAST AREA ON TUES NIGHT. GIVEN THE RELATIVELY EARLY ARRIVAL OF THE FRONT...HAVE KEPT HIGH TEMPS ONLY IN THE UPPER 50S TO LOW 60S NORTH OF A HELENA-TO-LEWISTOWN LINE. AREAS OF SOUTHWEST MT SHOULD REACH THE LOW-MID 70S BEFORE THE FRONT SWEEPS THROUGH AROUND MIDDAY. WARANAUSKAS TUESDAY NIGHT THROUGH SUNDAY...MODELS CONTINUE TO AGREE ON A SEASON SHIFTING SYSTEM COMING IN TO THE AREA MID TUESDAY. A SURFACE COLD FRONT LOOKS TO MOVE SOUTHEAST THROUGH NORTH-CENTRAL MONTANA THROUGH TUESDAY NIGHT. WIDESPREAD CHANCES FOR LIGHT PRECIPITATION LOOK POSSIBLE WITH THIS FRONT AND ALL MODELS AGREE FAIRLY WELL ON TIMING AND PLACEMENT. BEHIND THE FRONT TEMPERATURES WILL QUICKLY DROP BY AS MUCH AS 20 DEGREES WITH THE POTENTIAL FOR PRECIPITATION SPREADING ACROSS NORTH CENTRAL AND CENTRAL MONTANA TUESDAY NIGHT. PRECIPITATION WILL LIKELY START OFF AS RAIN BEFORE SHIFTING TO A MIX OF RAIN AND SNOW. SOME LOCATIONS MAY SEE STRAIGHT SNOW AS OVERNIGHT LOWS DROP BELOW FREEZING. EXPECT MOSTLY SNOW IN HIGHER TERRAIN. WITH ALL MODELS AGREEING HAVE BUMPED POPS UP ACROSS MUCH OF THE AREA FOR THE LATE TUESDAY TO EARLY THURSDAY TIME FRAME. POPS ARE GENERALLY CHANCE TO LIKELY OVER THE PLAINS WITH LIKELY OVER THE ROCKIES AND HIGHER TERRAIN. FAR SOUTHWEST MONTANA MAY NOT GET QUITE THE SHOT AT PRECIPITATION AS THE MAJORITY OF MOISTURE LOOKS TO WANT TO SHY AWAY FROM THE AREA. MODELS HAVE ONCE AGAIN CHANGED THE LONGER TERM AND NOW BRING BACK A SEPARATE SECONDARY TROUGH PASSING OVER NORTH-CENTRAL MONTANA SOMETIME FRIDAY. SCATTERED LIGHT PRECIPITATION WILL ACCOMPANY THIS TROUGH AS WELL AS PERSISTING COLD TEMPERATURES. THE REGION SHOULD STAY UNDER A SOMEWHAT UNSTABLE NORTH NORTHWEST FLOW THROUGH THE REST OF THE LONG TERM AND THUS GENERALLY PARTLY CLOUDY SKIES AND SLIGHT CHANCES FOR PRECIPITATION MAY MOVE IN AND OUT OF THE FORECAST AS THE MODEL RUNS SHIFT. THE ONE VERY HIGH CONFIDENCE PHENOMENA CONTINUES TO BE COLDER TEMPERATURES THROUGH THE PERIOD WITH HIGHS OVER THE PLAINS GENERALLY IN THE 50S WITH LOW 40S OVER HIGHER TERRAIN. LOW TEMPERATURES WILL BE IN THE MID TO LOW 30S AT MOST LOCATIONS WITH A HIGH LIKELIHOOD OF MOST PLACES AT LEAST TOUCHING THE FREEZING MARK. && .PRELIMINARY POINT TEMPS/POPS... GTF 71 43 80 46 / 0 0 0 0 CTB 67 37 76 40 / 0 0 0 10 HLN 74 42 78 46 / 0 0 0 0 BZN 73 35 78 41 / 0 0 0 0 WEY 67 25 67 27 / 0 0 0 0 DLN 73 38 77 42 / 0 0 0 0 HVR 70 37 80 41 / 0 0 0 10 LWT 70 38 77 44 / 0 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING BLAINE...CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK... CHOUTEAU...EASTERN GLACIER...EASTERN PONDERA...EASTERN TETON... FERGUS...HILL...JUDITH BASIN...LIBERTY...MEAGHER...NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT...TOOLE. HIGH WIND WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT. && $$ WEATHER.GOV/GREATFALLS