FXUS65 KTFX 251735
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1035 AM MST WED NOV 25 2009
...UPDATE TO AVIATION...
.AVIATION (18Z TAFS)...
MINOR AVIATION CONCERNS AT BEST WITH SOME GUSTY WINDS AT AIRPORTS
ALONG THE ROCKY MOUNTAIN FRONT...MAINLY CTB AND GTF. VFR
CONDITIONS SHOULD CONTINUE THROUGH THE ENTIRE PERIOD...WITH LITTLE
BUT SOME HIGH CLOUD COVER MAKING IT ACROSS THE ROCKIES. GUSTS AT
CTB AND GTF MAY REACH 30 TO 35 KTS ON THE HIGH END THIS AFTERNOON
AND EVENING BEFORE RELAXING SOME DURING THE OVERNIGHT PERIOD.
OUTSIDE OF CTB AND GTF...WINDS MAY BECOME LIGHT AND VARIABLE OR
LIGHT SOUTHERLIES OVERNIGHT. SCHOTT
&&
.UPDATE...
ONLY CHANGE MADE THIS MORNING WAS TO LOWER CLOUD COVER OVER NORTH-
CENTRAL MONTANA. KEPT PARTLY CLOUDY CONDITIONS OVER THE DIVIDE AS
SOME MOISTURE MOVES OVER THE UPPER-LEVEL RIDGE...HOWEVER RIDGE
AXIS WILL CONTINUE TO SHIFT EASTWARD TODAY. REMAINDER OF THE
FORECAST IS RIGHT ON TRACK WITH QUIET CONDITIONS AND ABOVE AVERAGE
TEMPERATURES. MLS
&&
.PREVIOUS DISCUSSION /ISSUED 518 AM MST WED NOV 25 2009/
TODAY THROUGH FRIDAY...A MOIST NORTHWESTERLY FLOW ALOFT AHEAD OF
AN UPPER LEVEL HIGH PRESSURE RIDGE WILL KEEP AREAS OF MID AND
HIGH CLOUDS OVER THE TFX CWA THIS MORNING. SKIES WILL BEGIN TO
CLEAR THIS AFTERNOON AS THE RIDGE AXIS MOVES INTO THE AREA.
BREEZY WESTERLY WINDS WILL ALSO PERSIST ALONG THE ROCKY MOUNTAIN
FRONT AS A SURFACE TROUGH DEEPENS OVER THE EAST SLOPES OF THE
ROCKIES. WINDS WILL INCREASE FURTHER OVERNIGHT INTO THANKSGIVING
DAY AS DISTURBANCES EJECTING FROM AN UPPER LEVEL LOW PRESSURE OFF
THE PACIFIC COAST FLATTEN THE UPPER RIDGE AND INCREASE THE FLOW
ALOFT. AM EXPECTING THE WINDS TO BECOME STRONG ALONG THE ROCKY
MOUNTAIN FRONT DURING THIS TIME...BUT THEY SHOULD REMAIN BELOW
HIGH WIND CRITERIA. THE BULK OF THE MOISTURE IN THIS INCREASING
WESTERLY FLOW ALOFT WILL REMAIN ALONG THE CANADIAN
BORDER...KEEPING MAINLY HIGH CLOUDINESS OVER THE AREA WITH A
CHANCE FOR A CHINOOK ARCH JUST TO THE LEE OF THE ROCKIES. WINDS
AND CLOUDS WILL DECREASE SOMEWHAT THURSDAY NIGHT AS THE UPPER
TROUGH MOVES ONSHORE AND AMPLIFIES THE UPPER RIDGE OVER THE AREA.
HOWEVER...THE RESULTING SOUTHWESTERLY FLOW ALOFT WILL BECOME MORE
MOIST ON FRIDAY AS THE UPPER TROUGH FURTHER APPROACHES THE
AREA...WHICH WILL LIKELY BRING SHOWERS TO THE WESTERN MONTANA
MOUNTAINS AND A CHANCE OF SHOWERS IN SOUTHWEST MONTANA. INCREASING
SOUTHWEST DOWNSLOPE WINDS ON FRIDAY WILL GENERALLY KEEP THE PLAINS
OF NORTH CENTRAL AND CENTRAL MONTANA DRY BUT WITH INCREASING
CLOUDS. TEMPERATURES WILL WARM FROM ABOUT 10 TO 15 DEGREES ABOVE
SEASONAL AVERAGES TODAY TO 15 TO 25 DEGREES ABOVE NORMAL ON
THANKSGIVING DAY. THE INCREASING CLOUDS AND APPROACHING TROUGH
WILL COOL TEMPERATURES ABOUT 5 TO 10 DEGREES ON FRIDAY. COULSTON
FRIDAY NIGHT THROUGH MONDAY NIGHT...PROGRESSIVE PATTERN WILL
CONTINUE THROUGH THE PERIOD. UPPER LEVEL RIDGE WILL PUSH EASTWARD
AS A BROAD UPPER TROUGH MOVES OVER THE AREA. MODELS ARE BETTER
ALIGNED THAN IN PREVIOUS RUNS AND WILL BRING THE TROUGH OVER THE
FORECAST AREA FRIDAY NIGHT. THIS FEATURE MOVES THROUGH FAIRLY
QUICKLY AND IS NOT ALL THAT STRONG. BEST THREAT FOR PRECIPITATION
WITH THIS SYSTEM WILL BE OVER THE MOUNTAINS OF THE ROCKY MOUNTAIN
FRONT AND SW MT. THERE IS ONLY A SLIGHT CHANCE OF PRECIPITATION
OVER THE LOWER ELEVATIONS. A RIDGE WILL MOVE OVER THE AREA
STARTING SUNDAY MORNING AND REMAIN IN PLACE THROUGH LATE MONDAY
NIGHT BRINGING DRIER CONDITIONS AND ABOVE AVERAGE TEMPERATURES. ON
SATURDAY TEMPERATURES WILL BE NEAR...TO SLIGHTLY ABOVE...NORMAL.
ON SUNDAY AND MONDAY TEMPERATURES WILL INCREASE DUE TO A SW FLOW
AND BE 10 TO 15 DEGREES ABOVE NORMAL. MERCER
TUESDAY THROUGH WEDNESDAY...MODELS PRESENT A SIMILAR SOLUTION
DURING THIS PERIOD. AN UPPER LEVEL TROUGH AND ASSOCIATED CANADIAN
COLD FRONT MOVE ACROSS THE FORECAST AREA TUESDAY. BEHIND THE FRONT
WINDS WILL SHIFT NORTHERLY WITH STEADY OR FALLING TEMPERATURES.
MODELS HAD HAD SOME RUN TO RUN INCONSISTENCIES IN THE STRENGTH AND
TIMING OF THESE SYSTEMS. FOR NOW THIS FORECAST WILL INTRODUCE A
TEN TO 15 DEGREE DROP IN TEMPERATURES WITH A CHANCE OR SLIGHT
CHANCE OF SNOW FOR MOST AREAS. BY THE NEXT RUN...THE FORECAST MAY
REFLECT COLDER TEMPERATURES WITH A GREATER LIKELIHOOD OF SNOW. EK
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 55 39 61 35 / 0 0 0 0
CTB 53 37 59 33 / 0 0 0 0
HLN 50 30 54 26 / 0 0 0 0
BZN 44 21 47 18 / 0 0 0 0
WEY 35 13 40 13 / 0 0 0 0
DLN 45 23 48 21 / 0 0 0 0
HVR 55 31 61 29 / 0 0 0 0
LWT 53 32 60 30 / 0 0 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COULSTON
LONG TERM...MERCER
AVIATION...SCHOTT
WEATHER.GOV/GREATFALLS
