000 FXUS65 KTFX 301736 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1035 AM MST SUN OCT 30 2005 .UPDATE... WILL MAKE MINOR UPDATES TO ZONE AND STATE FORECASTS BY 945 AM. A WEAK DISTURBANCE MOVING THROUGH WEST CENTRAL INTO CENTRAL MONTANA THIS MORNING WILL CONTINUE TO BRING ISOLATED SHOWERS TO THAT AREA THROUGH EARLY AFTERNOON...THEREFORE WILL UPDATE FORECAST TO INCREASE MAINLY MOUNTAIN POPS AND CLOUDINESS ACROSS CENTRAL TFX ZONES. WINDS HAVE ALSO BEGUN SHIFTING MORE TO THE NORTHWEST ACROSS THE NORTHWEST TFX ZONES AS A WEAK SURFACE BOUNDARY MOVES SOUTH OUT OF CANADA. LATEST MODEL RUNS ALSO INCREASE WINDS ACROSS THE NORTHERN AND CENTRAL TFX ZONES. THEREFORE...WILL INCREASE WINDS AND SHIFT THEM MORE NORTHWEST DURING THE AFTERNOON. TEMPERATURES ARE IN GOOD SHAPE AT THIS TIME...AND WILL EVALUATE HIGH WIND WATCHES/WARNINGS FOR THE AFTERNOON PACKAGE. COULSTON && .AVIATION... UPDATED 1735Z. ANOTHER WEAK DISTURBANCE WILL MOVE THROUGH SW MT THIS AFTERNOON. THERE WILL ONLY BE AN OUTSIDE CHANCE OF A FEW SHOWERS ASSOCIATED WITH THE DISTURBANCE. OTHERWISE EXPECT ONLY FEW TO SCATTERED CUMULUS CLOUDS. HIGH CLOUDS WILL SPREAD EAST OVER THE ROUTES LATE THIS EVENING AND AFTER MIDNIGHT. THE HIGH CLOUD DECK WILL THEN LOWER WITH CEILINGS 8000 TO 12000 FT AGL EXPECTED BY MONDAY MORNING. HOOKUP WEST TO NORTHWEST WINDS WILL WEAKEN BY DARK THEN EXPECT SOUTHWEST WINDS TO DEVELOP AND INCREASE IN SPEED TO 15 TO 25 KNOTS OVER THE PLAINS DURING THE MORNING ON HALLOWEEN. STRONG WEST WINDS NEAR 50 KNOTS ARE LIKELY THROUGH THE HIGHER MOUNTAIN PASSES OF THE ROCKY MOUNTAIN FRONT BY LATE MORNING. BLANK && .PREV DISCUSSION... (ISSUED 411 AM MST SUN OCT 30 2005) SUNDAY THROUGH TUESDAY...AN AUTUMN PATTERN IS SET UP ACROSS THE ZONES...ZONAL FLOW ALOFT...SURFACE HIGH PRESSURE WEST OF THE DIVIDE AND LOW PRESSURE OVER SASKATCHEWAN. WEAK DISTURBANCES CONTINUE TO MOVE THRU THE FLOW...ONE SHORTWAVE WILL LEAVE THE ZONES THIS MORNING WHILE A SECOND IS APPROACHING THE ROCKIES BY LATE AFTERNOON AND EVENING. AN UPPER LEVEL HIGH PRESSURE RIDGE WILL BUILD OVER THE PACIFIC NORTHWEST AND GRADUALLY MOVE EAST. BY MONDAY...A STRONG VORT MAX MOVING INTO ALBERTA WILL HELP DEVELOP A LEE TROF OVER THE EASTERN SLOPES AND PLAINS. THE STRONGEST MID-LEVEL WINDS WILL MOVE THROUGH THE ZONES BETWEEN 18Z MONDAY AND 06Z TUESDAY. THE HIGH WIND WARNING AND WATCH WILL REMAIN AS IS...THE CURRENT WATCH IS STILL MARGINAL AND WILL NOT MAKE ANY DECISIONS AT THIS POINT. THE DEVELOPMENT OF THE UPPER LEVEL HIGH PRESSURE RIDGE WILL KEEP A WARMING TREND OVER THE CWA MONDAY THRU TUESDAY. TUESDAY WILL SEE STRONG MID-LEVEL WINDS AGAIN. THE RIDGE PATTERN CURRENTLY DOES NOT SUPPORT A WIDESPREAD WIND EVENT WITH VERY LITTLE FLATTENING OF THE RIDGE. ZELZER TUESDAY NIGHT THROUGH SUNDAY NIGHT...PERIOD BEGINS WITH A BROAD UPPER LEVEL RIDGE OVER THE NORTHERN PLAINS STATES WHICH THEN IS REPLACED BY A BROAD TROUGH OVER THE WESTERN U.S THROUGH THE REMAINDER OF THE EXTENDED FORECAST PERIOD. THIS OVERALL PICTURE IS SUPPORTED BY MOST MODELS...HOWEVER MODELS STILL HAVE SIGNIFICANT DIFFERENCES WITH DETAILS...INCLUDING AMPLITUDE OF THE UPPER LEVEL RIDGE AT THE BEGINNING OF THE PERIOD. STRONG GRADIENT ALOFT AND SURFACE LOW PRESSURE MOVING ACROSS NORTHERN MT AND SOUTHERN ALBERTA WITH BRING WINDY CONDITIONS WEDNESDAY NIGHT WITH PRECIPITATION MAINLY OVER THE MTNS AND ALONG THE CONTINENTAL DIVIDE. A STRONGER SHORTWAVE WITH MORE SIGNIFICANT COOLING WILL MOVE TO THE NORTHERN ROCKIES WEDNESDAY NIGHT. THIS MAY PROVIDE SOME SIGNIFICANT PRECIPITATION TO SOUTHERN ZONES...BUT ENOUGH MODEL DIFFERENCES CONTINUE TO KEEP POPS IN THE CHANCE RANGE AT THIS TIME. SNOW LEVELS WILL LOWER TO AROUND 5000 FT IN MOST AREAS BY THURSDAY MORNING. MOIST WESTERLY FLOW WILL KEEP OROGRAPHIC PRECIPITATION CONTINUING ALONG THE DIVIDE THROUGH NEXT WEEKEND...WITH EMBEDDED DISTURBANCES BRINGING PRECIPITATION CHANCES TO CENTRAL AND SW MT AT TIMES. WESTERLY DOWNSLOPE SURFACE WINDS WILL GENERALLY KEEP THE PLAINS DRY. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY BELOW SEASONAL AVERAGES THROUGH THE PERIOD. HOENISCH && .PRELIMINARY POINT TEMPS/POPS... GTF 49 30 60 34 / 0 0 10 10 CTB 46 30 59 35 / 0 0 10 10 HLN 49 27 57 33 / 10 0 10 10 BZN 47 20 50 29 / 10 0 10 10 WEY 43 20 46 23 / 20 30 20 20 DLN 43 24 52 32 / 10 0 10 10 HVR 54 27 60 33 / 0 0 0 10 LWT 47 27 56 34 / 0 0 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING FOR MTZ012-MTZ044-MTZ046-MTZ049. HIGH WIND WARNING FROM 12 PM MONDAY TO MIDNIGHT MST MONDAY NIGHT FOR MTZ009-MTZ010-MTZ048. && $$ SHORT TERM...COULSTON/ZELZER LONG TERM...BLANK AVIATION...BLANK WEATHER.GOV/GREATFALLS