FXUS65 KTFX 300450
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
945 PM MST SUN NOV 29 2009
UPDATE...MAIN ITEM OF NOTE THIS EVENING IS DECISION TO UPGRADE THE
HIGH WIND WATCH TO A WARNING FOR TOMORROW AFTN/EVE OVER THE ROCKY
MTN FRONT AND ADJACENT PLAINS. LATEST MODELS MAINTAINED CONTINUITY
ON BROAD AREA OF 60 TO 70 MPH WINDS OVER NORTHWEST PORTIONS OF THE
CWA IN RESPONSE TO INCREASED PRESSURE GRADIENT AND UPPER LEVEL JET
STREAK ACCOMPANYING QUICK-MOVING SHORTWAVE TROF DIGGING ACROSS SW
CANADA TOMORROW. HAVE INCREASED WIND GRIDS FOR MONDAY ACCORDINGLY.
ONLY OTHER CHANGES TO FORECAST WERE TO INCREASE CLOUD COVERAGE OVER
MUCH OF THE REGION FOR TONIGHT TO BETTER MATCH CURRENT SATELLITE
IMAGERY SHOWING WIDESPREAD CIRRUS SHIELD FROM THE CONTINENTAL DIVIDE
ALL THE WAY INTO EASTERN MT. WARANAUSKAS
.DISCUSSION...
TONIGHT THROUGH TUESDAY...UPPER LEVEL HIGH PRESSURE OVER THE
ROCKIES WILL KEEP WARM AND DRY CONDITIONS FOR THE REST OF TODAY
AND INTO MONDAY. STRONG WINDS WILL MIX DOWN SOME CAUSING SURFACE
WINDS TO BE BRISK BUT NOT NEAR WARNING CRITERIA. AN APPROACHING
SHORTWAVE WILL BEGIN TO IMPACT THE REGION LATE MONDAY AFTERNOON
WITH DEVELOPING STRONG WINDS ASSOCIATED WITH A COLD FRONT PASSAGE.
MODELS INDICATE STRONG WINDS THAT COULD EXCEED WARNING CRITERIA IN
SOME LOCATIONS. AS A RESULT...THE HIGH WIND WATCH HAS BEEN
CONTINUED AND COULD BE UPGRADED TO A HIGH WIND WARNING THIS
EVENING. THE STRONGEST WINDS DO APPEAR TO PASS THROUGH THE AREA
RATHER QUICKLY SO IT MAY BE MORE OF A ONE SHOT DEAL AT WARNING
LEVEL WINDS. A LOW PRESSURE TROF WILL MOVE INLAND OVER THE WEST COAST
MONDAY AND CROSS THE ROCKIES BY THE EVENING. THIS SYSTEM WILL
HAVE STRONG DYNAMICS BUT WILL ALSO BE FAST MOVING AND THUS
PRECIPITATION SHOULD NOT BE VERY MUCH. AN ASSOCIATED COLD FRONT WILL
CROSS THE CANADIAN BORDER MONDAY NIGHT WITH PRECIP DEVELOPING ACROSS
THE NORTHERN ZONES BY MORNING AND INTO CENTRAL MONTANA BY MID DAY.
TEMPS TOMORROW WILL REMAIN WARM BUT WILL THEN COOL QUITE A BIT AS
THE REGION IS INFLUENCED BY THE ABOVE MENTIONED SYSTEMS.
TUESDAY NIGHT THROUGH FRIDAY NIGHT...COLD FRONT THAT MOVES IN
TUESDAY AFTERNOON SHOULD BE EXITING THE REGION BY TUESDAY NIGHT.
A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE TUESDAY
EVENING...MAINLY OVER SOUTHWEST MONTANA. OTHERWISE...EXPECT COLD AND
DRY CONDITIONS. SEASONAL CONDITIONS ARE THEN EXPECTED TO RETURN
WEDNESDAY AND THURSDAY. ANY PRECIPITATION WILL BE LIGHT AND MAINLY
OVER THE MOUNTAINS. ANOTHER COLD SYSTEM FORECASTED FOR THE FRIDAY
AND SATURDAY PERIOD...AND WHILE ECMWF AND GFS BOTH ON BOARD BRINGING
IT IN...THEY DO HAVE SOME TIMING DIFFERENCES WITH THE GFS BEING
FASTER MOVING IN AS EARLY AS FRIDAY...ECMWF HAS A SIMILAR SOLUTION
OF COLD AIR AND PRECIPITATION...BUT HOLDS OFF BRINGING IT IN UNTIL
SATURDAY NIGHT OR SUNDAY.
SATURDAY THROUGH SUNDAY...MODEL DIFFERENCES AND RUN TO RUN
INCONSISTENCY CONTINUE TO DETRACT FROM FORECAST CONFIDENCE DURING
THIS PERIOD. THIS FORECAST WENT WITH A BLENDED COMPROMISE OF AN
UPPER LEVEL TROUGH DROPPING SOUTHEAST FROM BRITISH COLUMBIA. A WEAK
MODIFIED ARCTIC FRONT MOVES SOUTH OF THE BORDER SATURDAY MORNING...
WITH WINDS SHIFTING NORTHERLY BEHIND THE FRONT AND TEMPERATURES
FALLING. NOT MUCH MOISTURE WITH THE FRONT SO ONLY A CHANCE OF SNOW
OVER THE MOUNTAINS IS EXPECTED. PRECIP LAGS THE FRONT SEVERAL HOURS
WITH A SLIGHT CHANCE OF SNOW OVER THE PLAINS BY EARLY EVENING.
TEMPERATURES WILL FALL TO A LITTLE BELOW SEASONAL AVERAGES BY
SUNDAY. EK
&&
.AVIATION...
UPDATED 0000Z.
AN UPPER LEVEL RIDGE WILL REMAIN IN PLACE OVER THE NORTHERN ROCKIES
THROUGH TONIGHT WITH A SHORTWAVE TROUGH DROPPING INTO BRITISH
COLUMBIA AND FLATTENING THE UPPER LEVEL RIDGE BY MONDAY AFTERNOON.
WINDS ALOFT WILL GRADUALLY BACK FROM THE WEST-NORTHWEST TO THE WEST
AND INCREASE AS THE RIDGE BREAKS DOWN ON MONDAY. THIS WILL BRING
STRONG AND GUSTY SURFACE WINDS TO WESTERN PORTIONS OF NORTH-CENTRAL
MT WITH GUSTS IN EXCESS OF 50KTS POSSIBLE ALONG THE EAST SLOPES OF
THE ROCKIES. VFR CONDITIONS WILL PREVAIL UNDER BROKEN HIGH CLOUDS
THROUGH THE NEXT 24 HRS. HOENISCH
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 34 54 28 32 / 0 0 40 60
CTB 32 51 25 31 / 0 0 40 60
HLN 27 48 27 33 / 10 0 30 60
BZN 16 40 20 32 / 0 0 20 60
WEY 12 32 15 31 / 0 0 10 40
DLN 21 41 21 37 / 0 0 10 40
HVR 27 53 25 34 / 0 0 40 40
LWT 27 55 23 31 / 0 0 30 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM MONDAY AFTERNOON THROUGH LATE MONDAY NIGHT
FOR MTZ009-010-044-046-048-049.
&&
$$
SHORT TERM...GUSTAFSON
LONG TERM...LOSS
AVIATION...HOENISCH
WEATHER.GOV/GREATFALLS
