959 FXUS65 KTFX 271140 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 530 AM MDT SAT OCT 27 2012 ...UPDATE TO AVIATION... .DISCUSSION... TODAY THROUGH MONDAY...UNSTABLE NORTHWEST FLOW ALOFT CONTINUES SHORT WAVE ENERGY MOVING ACROSS THE AREA THIS MORNING IS PRODUCING LIGHT SNOW ACROSS PORTIONS OF NORTH CENTRAL MONTANA. SNOW ACCUMULATIONS OVER THE PLAINS ARE GENERALLY LIGHT WITH THIS FEATURE. HEAVIER AMOUNTS ARE POSSIBLE IN THE MOUNTAINS AND A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR ELEVATIONS ABOVE 6000 FEET OVER SOUTHWEST AND PORTIONS OF NORTH CENTRAL MONTANA. SNOW WILL TAPER OFF THIS AFTERNOON. 500 MB HEIGHTS BEGIN TO RISE TONIGHT BUT ADDITIONAL SHORT WAVE ENERGY WILL PUSH ACROSS THE AREA RESULTING IN ANOTHER ROUND OF LIGHT SNOW OVERNIGHT AND INTO EARLY SUNDAY. WITH THE BUILDING RIDGE TONIGHT...WARM AIR ADVECTION OVERNIGHT WILL LIFT OVER THE COLD AIRMASS ALREADY IN PLACE AND MAY CAUSE AREAS OF FREEZING RAIN. WITH ABUNDANT LOW LEVEL MOISTURE REMAINING IN PLACE OVER THE AREA AND TRANSIENT SHORT WAVE ENERGY MOVING THROUGH THE FLOW ALOFT...SCATTERED RAIN AND SNOW SHOWERS WILL CONTINUE ON MONDAY. A TIGHTENING SURFACE GRADIENT SUNDAY WILL ALLOW FOR GUSTY WINDS...MAINLY ALONG THE EAST SLOPES OF THE ROCKIES. AT THIS POINT IN TIME...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA. TEMPERATURES SHOULD REMAIN BELOW SEASONAL AVERAGES TODAY BUT WARM TO SEASONAL AVERAGES TO START THE WEEK. EMANUEL MONDAY NIGHT THROUGH SATURDAY...MODELS CONTINUE TO KEEP A WEAK UPPER LEVEL RIDGE OVER THE REGION FOR THE BULK OF THE LONG TERM PERIOD. IT SHOULD BE NOTED THAT ALTHOUGH THE RIDGE IS THE LARGE SCALE SYNOPTIC FEATURE SOME SHORTWAVE TROUGHS WILL MOVE THROUGH DURING THE TIME FRAME AND WILL BRING SOME MOISTURE AND INSTABILITY TO THE REGION. THE BEST EXAMPLE OF THE SHORTWAVES WILL OCCUR AS THE LONG TERM PERIOD BEGINS. MOISTURE WILL CONTINUE TO BE ADVECTED FROM THE PACIFIC AND WHILE THE BULK OF THE PRECIPITATION WILL FALL WEST OF THE DIVIDE SOME MOUNTAIN SHOWERS ARE POSSIBLE WITH A LESSER CHANCE OF PRECIPITATION OCCURRING OVER THE LOWER ELEVATIONS. TEMPERATURES WARM PAST SEASONAL AVERAGES BY TUESDAY AFTERNOON AND SOME LOCATIONS COULD SEE NEARLY 10 DEGREES ABOVE SEASONAL NORMALS THROUGH THURSDAY. BY FRIDAY A LOW PRESSURE TROUGH DOES SWING THROUGH THE AREA AND BRING THE NEXT SOLID CHANCE OF WIDESPREAD PRECIPITATION. THIS LOW IS CURRENTLY BEING FORECASTED BY THE MAJOR MODEL SUITES TO BE A PACIFIC SYSTEM WHICH WILL BRING THE POTENTIAL FOR PLENTY OF MOISTURE...AND A RELATIVELY MILD DROP IN TEMPERATURES FRIDAY THROUGH SATURDAY...WHERE CURRENT TEMPERATURES ARE EXPECTED TO DROP BACK DOWN TO SEASONAL AVERAGES. AFTER THIS SYSTEM EXITS...THE MODELS QUICKLY DIVERGE AND AND REMOVE ANY CONFIDENCE IN THE MODEL SOLUTIONS BY 228 HOURS OUT. SUK && .AVIATION... UPDATED 1130Z. SCATTERED LIGHT SNOW SHOWERS WILL CONTINUE TO MOVE ACROSS THE AREA THROUGH MID MORNING AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHEASTWARD THROUGH THE REGION. EXPECT MOUNTAINS TO BE OBSCURED THROUGH THE PERIOD WITH LOW CLOUDS AS WELL. MOST AREAS WILL HAVE VFR CONDITIONS WITH SOME BRIEF INTRUSIONS INTO IFR CONDITIONS IN/NEAR SNOW SHOWERS. ANOTHER DISTURBANCE WILL MOVE THROUGH THE REGION TOWARDS 6Z SUNDAY. INCREASING CLOUDS AND A NEW CHANCE FOR LIGHT SNOW STARTING TOWARDS THE END OF THE TAF PERIOD. SUK && .PRELIMINARY POINT TEMPS/POPS... GTF 40 31 54 38 / 70 30 30 30 CTB 34 25 49 30 / 40 40 20 40 HLN 42 31 53 37 / 60 40 30 50 BZN 42 29 55 36 / 50 40 30 50 WEY 36 21 43 27 / 60 50 60 50 DLN 43 30 55 36 / 20 30 30 30 HVR 33 22 49 28 / 20 20 20 20 LWT 35 26 51 35 / 60 20 30 40 && .TFX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR ELEVATIONS ABOVE 6000 FEET FOR BEAVERHEAD...BROADWATER...CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...GALLATIN...JEFFERSON...JUDITH BASIN...MADISON...MEAGHER. && $$ SHORT TERM...EMANUEL LONG TERM...SUK AVIATION...SUK WEATHER.GOV/GREATFALLS