FXUS65 KTFX 291133
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
430 AM MST SUN NOV 29 2009
UPDATED AVIATION DISCUSSION
.DISCUSSION...
SUNDAY THROUGH TUESDAY...THE MAIN INTEREST THIS PERIOD IS THE
SHORTWAVE TROF APPROACHING THE ZONES LATE MONDAY AFTERNOON AND THE
RESULTING STRONG WINDS AND ASSOCIATED COLDFRONT PASSAGE. AN UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE ROCKIES WILL KEEP THE AIRMASS
WARM AND DRY TODAY AND MONDAY. A SURFACE TROF IS IN PLACE ALONG THE
LEE OF THE ROCKIES. STRONG WINDS ALOFT STAY WELL TO THE NORTH OF THE
ZONES SO SURFACE WINDS WILL BE BRISK BUT NOT NEAR WARNING CRITERIA.
BY MONDAY AFTERNOON...THE UPPER LEVEL JET WILL HAVE MOVED SOUTH OVER
THE NORTHERN ROCKIES. MODELS INDICATE STRONG WINDS NEAR WARNING
CRITERIA...WILL ISSUE A HIGH WIND WATCH...HOWEVER THE STRONGEST
WINDS SHOULD PASS THROUGH THE AREA QUICKLY. A LOW PRESSURE SHORT
WAVE WILL BE MOVING OVER THE WEST COAST MONDAY AND CROSSING THE
ROCKIES BY LATE AFTERNOON. THIS SYSTEM WILL HAVE STRONG DYNAMICS
BUT WILL BE FAST MOVING AND QPF WILL BE SKIMPY. AN ASSOCIATED COLD
FRONT WILL CROSS THE CANADIAN BORDER MONDAY NIGHT. PRECIP WILL
DEVELOP ACROSS THE NORTHERN ZONES BY MORNING AND INTO CENTRAL
MONTANA BY MID DAY. TEMPS WILL NOT RISE MUCH FROM OVERNIGHT LOWS.
ZELZER
TUESDAY NIGHT THROUGH FRIDAY NIGHT...A RATHER QUIET PERIOD OF
WEATHER EXPECTED TO BEGIN THE PERIOD...AS THE MAIN COLD FRONT FROM
TUESDAY MORNING SHOULD HAVE EXITED THE REGION BY TUESDAY EVENING. A
FEW EVENING SNOW SHOWERS WILL BE POSSIBLE TUESDAY EVENING...MAINLY
OVER SOUTHWEST MONTANA...OTHERWISE JUST EXPECT COLD AND DRY
CONDITIONS. SEASONABLE CONDITIONS ARE EXPECTED WEDNESDAY AND
THURSDAY...WITH ANY PRECIPITATION OCCURRING WILL BE VERY LIGHT AND
MAINLY OVER THE MOUNTAINS. FOR FRIDAY...THE GFS/ECMWF HAVE VERY
DRASTIC DIFFERENCES...AS THE GFS PROGS A FAIRLY GOOD SNOWSTORM OVER
THE AREA ALONG WITH COLD CONDITIONS...WHILE THE ECMWF PROGS A FAIRLY
STRONG RIDGE OF HIGH PRESSURE AND MOSTLY DRY CONDITIONS. SINCE THE
EC HAS BEEN DOING FAIRLY WELL AS OF LATE...WENT WITH THAT
SOLUTION...BUT THINGS COULD CHANGE SIGNIFICANTLY SHOULD THE GFS
MODEL START TO PAN OUT. BRUSDA
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 1145Z.
WITH AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDING OVER THE PACIFIC
NORTHWEST...EXPECT FAIRLY QUIET WEATHER WITH MAINLY VFR CONDITIONS
OVER THE REGION THROUGH THE PERIOD. EXPECT INCREASING SURFACE WINDS
ALONG THE FRONT RANGE OF THE ROCKIES THIS MORNING...AND THESE BREEZY
CONDITIONS WILL CONTINUE THROUGH TONIGHT. BRUSDA
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 50 35 54 30 / 10 0 0 50
CTB 49 34 52 28 / 10 0 0 60
HLN 45 28 48 29 / 10 10 0 30
BZN 36 17 42 22 / 10 0 0 20
WEY 31 11 34 15 / 10 0 0 10
DLN 38 22 43 22 / 10 0 0 20
HVR 50 29 53 26 / 0 0 0 40
LWT 48 29 55 25 / 0 0 0 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM NOON MONDAY TO 5 AM MST TUESDAY FOR
MTZ009-010-044-046-048-049.
&&
$$
WEATHER.GOV/GREATFALLS
