FXUS65 KTFX 281139
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
445 AM MST SAT NOV 28 2009
UPDATED AVIATION DISCUSSION
.DISCUSSION...
TODAY THROUGH MONDAY...UPPER LEVEL SHORTWAVE OVER THE REGION MOVES
EAST TODAY AS RIDGING OVER THE PACIFIC NORTHWEST EDGES INTO
WESTERN MONTANA. SURFACE COLD FRONT THAT ACCOMPANIED THE SHORTWAVE
WILL LEAVE A COOLER AIRMASS IN PLACE TODAY WITH SCATTERED SNOW
SHOWERS LINGERING OVER THE MOUNTAINS OF CENTRAL AND SOUTHWEST
MONTANA THIS MORNING. AREAS OF FOG AND PATCHY DENSE FOG WILL
DISSIPATE BY MID TO LATE MORNING AS SKIES CLEAR ACROSS THE
FORECAST AREA. HOWEVER...MID AND HIGH LEVEL MOISTURE FROM THE NEXT
UPSTREAM SYSTEM WILL STREAM INTO WESTERN PORTIONS OF THE FORECAST
AREA BY AFTERNOON SO ANY CLEARING WILL BE SHORT-LIVED. WESTERLY
FLOW AT THE SURFACE WILL KEEP THE PLAINS GENERALLY DRY AND BREEZY
BUT EXPECT A CHANCE OF SNOW OVER THE WESTERN MOUNTAINS LATE THIS
AFTERNOON AND OVERNIGHT. AS THE UPPER RIDGE CONTINUES TO BUILD
OVER THE PACIFIC NORTHWEST AND NORTHERN ROCKY MOUNTAIN REGION
TEMPERATURES WILL WARM SUNDAY THROUGH MONDAY WITH MOSTLY DRY
CONDITIONS PREVAILING. SURFACE PRESSURE GRADIENTS ARE EXPECTED TO
GRADUALLY INCREASE AS A LOW PRESSURE TROUGH DEVELOPS IN ALBERTA
FOR GUSTY WESTERLY WINDS ALONG THE EAST SLOPES OF THE ROCKY
MOUNTAINS AND OVER THE ADJACENT PLAINS. MPJ
MONDAY NIGHT THROUGH THURSDAY NIGHT...A CANADIAN COLD FRONT WILL
MOVE SOUTHWARD THROUGH THE REGION ON TUESDAY. EXPECT A RETURN TO
MORE WINTER/SEASONAL TEMPERATURES OVER THE REGION BEGINNING ON
TUESDAY AND THEN CONTINUING THROUGH THE REST OF THE WEEK. THERE WILL
BE A GOOD CHANCE FOR SNOW WITH THE FRONTAL PASSAGE...BUT TOTAL SNOW
ACCUMULATIONS ON TUESDAY STILL LOOK TO BE ON THE MINOR SIDE...WITH
AROUND OF INCH OF SNOWFALL EXPECTED AT LOWER ELEVATIONS AND 2 TO 4
INCHES IN THE MOUNTAINS. FAIRLY QUIET WEATHER IS EXPECTED FOR
WEDNESDAY AND THURSDAY...WITH ANY PRECIPITATION THAT FALLS CONFINED
MAINLY TO MOUNTAINS...AND TEMPERATURES RETURNING TO SLIGHTLY BELOW
NORMAL READINGS. BRUSDA
FRIDAY THROUGH SATURDAY...MODEL DIFFERENCES AND RUN TO RUN
INCONSISTENCIES DETRACT FROM FORECAST CONFIDENCE DURING THIS PERIOD.
THIS FORECAST LEANS TOWARD THE ECMWF WHICH HAS SHOWN A LITTLE BETTER
RUN TO RUN CONTINUITY. A RIDGE OVER THE WEST COAST RESULTS IN A COLD
BUT GENERALLY DRY NORTHERLY FLOW ALOFT. A WEAK FRONT SLIDES SOUTH
EARLY FRIDAY...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. A WEAK UPPER LEVEL
SHORTWAVE MOVES QUICKLY SOUTHEAST ACROSS THE REGION FRIDAY NIGHT
WITH INCREASING CLOUDS...A CHANCE OF SNOW CONTINUES OVER THE
MOUNTAINS WITH A SLIGHT CHANCE OVER THE VALLEYS AND UPSLOPE AREAS OF
THE PLAINS. DRIER AIR ALOFT SATURDAY SHOULD BRING DECREASING CLOUDS
AND PRECIPITATION. TEMPERATURES WILL BE A LITTLE BELOW SEASONAL
AVERAGES. EK
&&
.AVIATION...
UPDATED 1145Z.
A WEAK UPPER LEVEL DISTURBANCE IS EXITING THE REGION THIS
MORNING...WHILE ANOTHER FAST MOVING UPPER LEVEL DISTURBANCE WILL
MOVE THROUGH THE REGION TONIGHT. EXPECT LOW CLOUDS AND ISOLATED
SHOWERS OVER SOUTHWEST MONTANA UNTIL 15Z...(GENERALLY IFR
CONDITIONS)...WHILE WIDESPREAD LOW CLOUDS AND DENSE FOG...WITH VLIFR
CONDITIONS...IS LIKELY TO AFFECT AREAS BETWEEN CUT BANK AND HAVRE
THROUGH 16Z. MOUNTAINS WILL BE OBSCURED THROUGH THE MORNING OVER
MUCH OF THE REGION. SOME CLEARING WILL TAKE PLACE THIS
AFTERNOON...BUT EXPECT INCREASING MID/HIGH LEVEL CLOUDS BY
21Z...WITH A GENERAL OVERCAST CONDITIONS EXPECTED TONIGHT ACROSS THE
REGION. ANY PRECIP AFTER 21Z SATURDAY SHOULD BE CONFINED MAINLY TO
THE ROCKY MOUNTAIN FRONT. BRUSDA
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 27 46 33 / 0 10 0 0
CTB 40 25 46 31 / 0 0 0 0
HLN 41 24 44 27 / 10 10 0 0
BZN 36 15 37 16 / 30 10 0 0
WEY 30 6 30 9 / 30 20 0 0
DLN 34 17 36 20 / 10 0 0 0
HVR 43 20 48 28 / 10 10 0 0
LWT 40 21 44 27 / 20 10 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/EK
AVIATION...BRUSDA
WEATHER.GOV/GREATFALLS
