Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 041030
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
330 AM MST THU FEB 4 2016

.DISCUSSION...
TODAY THROUGH SATURDAY EVENING...CURRENT WATER VAPOR SATELLITE
IMAGERY SHOWS SHORTWAVE TROF IN CENTRAL WA/OR MAKING STEADY EASTWARD
PROGRESS TOWARD MONTANA. NORTH-TO-SOUTH ELONGATED MOISTURE AREA
AHEAD OF THE TROF AXIS HAS ALREADY REACHED WESTERN PARTS OF THE
STATE BUT LOCAL RADARS ONLY SHOWING SCATTERED AREAS OF LIGHT SNOW
FROM MISSOULA TO KALISPELL AS OF 3:00 AM.  SHORT-TERM FORECAST
MODELS CONTINUE TO SHOW GOOD RUN-TO-RUN CONTINUITY AND AGREEMENT
THAT THE TROF AXIS SHOULD REACH THE ROCKY MTN FRONT BY LATE THIS
MORNING/MIDDAY. ISOLATED TO SCATTERED SNOW SHOWERS WILL DEVELOP
MAINLY ALONG THE ROCKY MTN FRONT AND SPREAD INTO SOUTHWEST MT AND
AS FAR NORTH AS THE BIG/LITTLE BELT MTNS THIS AFTN. A SMALL
SECONDARY SWATH OF LIGHT SNOW IS ALSO POSSIBLE FOR EASTERN PARTS
OF THE HILINE THIS AFTN. SNOWFALL AMOUNTS IN ALL THOSE AREAS WILL
BE LESS THAN AN INCH AT LOWER ELEVATIONS, WITH 1-2 INCHES IN THE
MTNS. WINDS WILL BECOME GUSTY ALONG THE ROCKY MTN FRONT AND
THROUGH THE CENTRAL AND HILINE COUNTIES WITH PASSAGE OF THE TROF
AXIS, BUT THEN DECREASE THIS EVE AS THE SHORTWAVE EXITS INTO ERN
MT/NRN WY. PRECIP COVERAGE DECREASES AS WELL TONIGHT. HIGH
PRESSURE RIDGING RETURNS ON FRI WITH DRY CONDITIONS ACROSS OUR
REGION AND TEMPS WARMING INTO THE UPPER 30S TO LOW 40S.

THE RIDGE WILL BARELY BE OVER OUR AREA FOR 24 HRS AS A MODERATELY
STRONG, QUICK-MOVING LOW PRESSURE SYSTEM RACES THROUGH WA/OR AND
INTO WESTERN MT BY EARLY SAT MORNING. A SHARP COLD FRONT FROM THIS
SYSTEM IS EXPECTED TO MOVE EAST OF THE CONTINENTAL DIVIDE AROUND
SUNRISE AND SWEEP THROUGH CENTRAL/SOUTHWEST MT DURING THE MORNING/
EARLY AFTN HOURS. ALTHOUGH AREAS OF LIGHT SNOW WILL OCCUR ALONG THE
DIVIDE AND OVER THE SOUTHWEST COUNTIES, THE PRIMARY CONCERN WITH
THIS SYSTEM WILL BE THE STRONG WINDS OVER THE CENTRAL PLAINS AND
THE FOOTHILLS FROM BROWNING TO NEAR LINCOLN. FORECAST MODELS
CONTINUE TO INDICATE IMPRESSIVE SURFACE PRESSURE GRADIENTS OF
12-15 MILLIBARS BETWEEN BUTTE AND HAVRE AND 3-HR PRESSURE RISES ON
THE ORDER OF 5-8 MILLIBARS BEHIND THE COLD FRONT THROUGH SAT
MORNING. BUT WINDS ALOFT ARE ONLY AROUND 60-70 MPH, WHICH IS THE
LOW END OF TYPICAL HIGH WIND WARNING EVENTS. ALSO ACTING AGAINST
WARNING CRITERIA WINDS IS THE QUICK PROGRESSION OF THE
SHORTWAVE/COLD FRONT ACROSS OUR AREA, AS THE TIGHT PRESSURE
GRADIENTS BEGIN TO DECREASE BY EARLY-MID AFTN. THUS, WE WILL
CONTINUE TO HOLD OFF ON ISSUING ANY HIGH WIND HIGHLIGHTS AT THIS
TIME. HOWEVER, RESIDENTS/TRAVELERS SHOULD STILL EXPECT TO SEE A
PERIOD OF WIND GUSTS IN THE 40 TO 50 MPH RANGE ALONG AND EAST OF
THE INTERSTATE 15 CORRIDOR FROM CASCADE COUNTY NORTH TO THE US/CAN
BORDER AND 50 TO 65 MPH ALONG THE ROCKY MTN FRONT. WARANAUSKAS

TODAY THROUGH WEDNESDAY...THE UPPER LEVEL LOW PRESSURE TROUGH OVER
THE WESTERN UNITED STATES WILL DICTATE OUR WEATHER THROUGH TUESDAY.
THE COOL AIR ALOFT WILL CONTINUE THE WEAK INSTABILITY IN THE
AIRMASS. SCATTERED SNOW SHOWERS ARE SLOW TO DIMINISH THIS MORNING
ALONG A SURFACE BOUNDARY FROM FORT BENTON TO JUST WEST OF LEWISTOWN.
THIS BOUNDARY WILL LINGER THROUGH THIS AFTERNOON, ALLOWING SCATTERED
SNOW SHOWER ACTIVITY TO REDEVELOP ACROSS MUCH OF NORTH CENTRAL AND
SOUTHWEST MONTANA, WITH THE MAIN FOCUS FOR SHOWERS IN A SIMILAR AREA
AS THIS MORNING. ALTHOUGH THERE WILL LIKELY BE SOME TRAVEL
DIFFICULTIES, ACCUMULATIONS SHOULD BE MINOR, SO AM NOT ANTICIPATING
A NEED FOR ANY WINTER HIGHLIGHTS AT THIS TIME. SHOWERS SHOULD
DECREASE OVERNIGHT AS THE UPPER TROUGH BEGINS MOVING EAST. A WEAKLY
UNSTABLE NORTHWEST FLOW ALOFT WILL BRING A CHANCE OF MAINLY MOUNTAIN
SNOW SHOWERS TO THE AREA ONCE AGAIN ON TUESDAY, BUT COVERAGE OVER
THE PLAINS SHOULD BE MORE ISOLATED. AN UPPER LEVEL RIDGE OF HIGH
PRESSURE WILL THEN START TO MOVE INTO THE AREA FROM THE WEST INTO
WEDNESDAY, KEEPING THE ONLY CHANCE FOR SHOWERS IN THE MOUNTAINS.
WINDS ALOFT WILL INCREASE DURING THIS TIME, BRINGING BREEZY WESTERLY
DOWNSLOPE WINDS TO THE PLAINS OF NORTH CENTRAL MONTANA, ESPECIALLY
ALONG THE ROCKY MOUNTAIN FRONT. WINDSPEEDS WILL LIKELY REMAIN WELL
BELOW HIGH WIND CRITERIA. UNDER THE TROUGH, TEMPERATURES WILL BE 5
TO 10 DEGREES BELOW NORMAL THROUGH TUESDAY. THE BREEZY DOWNSLOPE
WINDS OVER THE PLAINS WILL THEN WARM TEMPERATURES BACK ABOVE NORMAL
FOR WEDNESDAY, BUT THE MOUNTAINS AND PROTECTED VALLEYS WILL CONTINUE
TO BE COOL.
COULSTON

&&

.AVIATION...UPDATED 0520Z.

AN UPPER LEVEL HIGH PRESSURE RIDGE WILL KEEP THE AIRMASS DRY THIS
EVENING. HOWEVER, A LOW PRESSURE SHORTWAVE WILL MOVE THROUGH THE
PACIFIC NORTHWEST TONIGHT AND MOISTURE AHEAD OF THIS WILL SPREAD
EAST ACROSS THE ROCKIES EARLY THURSDAY MORNING. THIS WILL BRING SNOW
OVER THE ROCKIES AND A CHANCE OF SNOW ACROSS MAINLY SOUTHWEST
MONTANA. LOCAL MVFR/IFR CONDITIONS ARE POSSIBLE NEAR SHOWERS ALONG
WITH MOUNTAIN OBSCURATION. WINDS ALOFT WILL ALSO STRENGTHEN AS THE
SHORTWAVE APPROACHES AND SURFACE WINDS WILL STRENGTHEN DURING THE
NIGHT AND REMAIN STRONG AND GUSTY THROUGH THURSDAY. STRONGEST WINDS
WILL BE OVER THE LEE SLOPES OF THE ROCKIES AND ADJACENT PLAINS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  27  46  37 /  10  10  10   0
CTB  40  27  45  36 /  10   0  10   0
HLN  36  24  39  28 /  20  10  10  10
BZN  31  14  32  20 /  30  20  10  10
WEY  21   7  24  17 /  50  40  20  10
DLN  28  14  32  22 /  30  10  10  10
HVR  40  22  44  33 /  20  10  10   0
LWT  36  22  40  30 /  20  10  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

WEATHER.GOV/GREATFALLS



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