000 FXUS65 KTFX 010508 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1105 PM MDT TUE MAR 31 2009 ...UPDATE TO AVIATION... .UPDATE... MOISTURE SUPPORT ASSOCIATED WITH THE UPPER LEVEL SHORTWAVE DOES NOT LOOK AS PRONOUNCED AS PREVIOUS MODELS SUGGESTED. LATEST RUNS FROM THE RUC AND NAM ARE ALREADY STARTING TO HINT. LOWERED POPS ESPECIALLY IN THE HIGH PLAINS OF CENTRAL AND NORTH CENTRAL MONTANA. ANY PRECIPITATION ASSOCIATED WITH THE SHORTWAVE AND ASSOCIATED SURFACE COLD FRONT WILL LIKELY BE IN THE FORM OF DISCRETE SHOWERS AND NOT A LARGE MASS OF INSTABILITY. THEREFORE QPF AND SNOW TOTALS WERE NOT LOWERED AS MUCH AS POPS. NO SIGNIFICANT CHANGES TO WINDS...TEMPERATURES...OR OTHER GRID FIELDS. SUK && .AVIATION... UPDATED 0505Z. AN UPPER LEVEL SHORTWAVE TROUGH WITH AN ASSOCIATED WEAK COLD FRONT WILL MOVE SOUTHEAST THROUGH NORTH CENTRAL...CENTRAL...AND SOUTHWEST MONTANA TONIGHT AND WEDNESDAY. SCATTERED SNOW SHOWERS WILL AFFECT THE AREA EARLY WITH MOUNTAIN OBSCURATION AND OCCASIONAL MVFR CONDITIONS. SNOW SHOWERS WITH MVFR CONDITIONS AND BREEZY NORTHWEST WINDS WILL BECOME MORE WIDESPREAD AS THE SYSTEM MOVES INTO THE AREA AFTER 08Z...WITH IFR CONDITIONS AT TIMES MAINLY BETWEEN 09Z AND 15Z. CONDITIONS WILL GRADUALLY IMPROVE FROM THE NORTHWEST AFTER 15Z...BUT SCATTERED SNOW SHOWERS MAY REDEVELOP AFTER 18Z. COULSTON && .PREV DISCUSSION... /ISSUED 650 PM MDT TUE MAR 31 2009/ TONIGHT...AN UPPER LEVEL DISTURBANCE WILL MOVE THROUGH THE REGION TONIGHT...PRODUCING PERIODS OF SNOW. A BRIEF PERIOD OF MODERATE SNOWFALL IS POSSIBLE IN HEAVIER SNOW SHOWERS...BUT GENERALLY MOST OF THE SNOWFALL SHOULD BE LIGHT. TOTAL SNOW ACCUMULATIONS STILL LOOK TO BE ON THE LOW SIDE...WITH LOWER ELEVATIONS GENERALLY IN THE 1 TO 3 INCH RANGE...AND FROM 4 TO 7 INCHES IN THE MOUNTAINS. WE WILL CONTINUE TO HOLD OFF ON AN ADVISORY...AND WE WILL CONTINUE TO MONITOR THE SITUATION CLOSELY THROUGH THE EVENING HOURS TO SEE IF AN ADVISORY IS NECESSARY. EXPECT SCATTERED SNOW SHOWERS OVER THE REGION ON WEDNESDAY MORNING...AS THE MAIN STORM SYSTEM CONTINUES TO MOVE TO THE SOUTHEAST TOWARDS COLORADO. WITH SURFACE WINDS MAINLY OUT OF THE NORTH ON WEDNESDAY...EXPECT ANOTHER COOL DAY OVER THE AREA...WITH TEMPERATURES ABOUT 9 TO 12 DEGREES BELOW NORMAL. FOR WEDNESDAY NIGHT AND THURSDAY...ANOTHER UPPER LEVEL DISTURBANCE WILL BEGIN TO APPROACH THE REGION BY THURSDAY. EXPECT INCREASING CLOUDS BY LATE WEDNESDAY NIGHT...WITH ANOTHER ROUND OF PRECIP MOVING INTO THE REGION BY THURSDAY AFTERNOON. THE BEST CHANCE FOR PRECIP WILL BE OVER WESTERN MOUNTAINS AND SOUTHWEST MONTANA...WITH ACCUMULATING SNOWS POSSIBLE IN THE MOUNTAINS. SINCE THIS STORM IS COMING UP FROM THE SOUTH...WARM AIR WILL MOVE INTO THE REGION AND THE PRECIP SHOULD FALL MAINLY IN THE FORM OF RAIN AT LOWER ELEVATIONS DURING THE DAY. BRUSDA THURSDAY NIGHT THROUGH SUNDAY NIGHT...MEDIUM RANGE PATTERN REMAINS A PROGRESSIVE ONE. AN UPPER TROF MOVES ACROSS THE AREA THURSDAY NIGHT AND FRIDAY BRINGING SCATTERED SHOWERS AND KEEPING TEMPERATURES COOL. LATEST MODEL RUNS HAVE MODIFIED THEIR EARLIER SOLUTIONS BY SLOWING EASTWARD DEPARTURE OF THE UPPER TROF...KEEPING A CHANCE OF RAIN/SNOW SHOWERS OVER CENTRAL AND SOUTHWEST ZONES THRU SATURDAY. THE MODELS CONTINUE TO DISAGREE ON THE SOLUTION FOR SUNDAY. THE GFS PERSISTS IN MOVING THE RIDGE OVER THE AREA THEREBY ENSURING A DRY FORECAST WHILE THE ECMWF FOLDS THE UPPER RIDGE OVER SOUTHERN CANADA LEAVING THE AREA UNDER THE INFLUENCE OF A WEAK UPPER TROF AND SCATTERED PRECIPITATION. WILL CONTINUE TO LEAN TOWARD THE GFS SOLUTION AND HAVE DRIED OUT THE FORECAST FOR LATE IN THE WEEKEND. TEMPERATURES WILL SLOWLY WARM THROUGH THE PERIOD BUT REMAIN SLIGHTLY BELOW SEASONAL AVERAGES. WARANAUSKAS MONDAY AND TUESDAY...A BROAD AND COLD UPPER LEVEL LOW WILL REMAIN OVER THE WESTERN U.S WITH MOST ENERGY DIGGING INTO THE DESERT SOUTHWEST. THUS...WILL GO WITH CONTINUED UNSEASONABLY COOL WITH SCATTERED LIGHT RAIN AND SNOW SHOWERS. PRECIPITATION WILL BE MORE NUMEROUS OVER THE MOUNTAINS...ESPECIALLY ALONG THE CONTINENTAL DIVIDE. WILLIAMSON DC && .PRELIMINARY POINT TEMPS/POPS... GTF 26 38 22 43 / 50 40 20 30 CTB 22 34 19 36 / 40 30 20 30 HLN 27 40 23 43 / 70 50 20 60 BZN 25 41 20 44 / 70 40 20 60 WEY 16 34 17 39 / 90 60 40 60 DLN 20 37 20 42 / 70 20 20 70 HVR 24 38 20 40 / 50 50 20 20 LWT 22 37 20 39 / 50 60 20 20 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SUK LONG TERM...WARANAUSKAS AVIATION...COULSTON WEATHER.GOV/GREATFALLS