980 
FXUS65 KTFX 301158
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
600 AM MDT MON APR 30 2012

.DISCUSSION...

TODAY THROUGH WEDNESDAY...A SERIES OF DISTURBANCES WILL MOVE
THROUGH THE MOIST WESTERLY FLOW ALOFT THROUGH WEDNESDAY FOR AN
UNSETTLED WEATHER PATTERN WITH BREEZY WESTERLY WINDS. A PACIFIC
COLD FRONT WILL APPROACH THE AREA FROM THE WEST AHEAD OF THE FIRST
DISTURBANCE TODAY...CAUSING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS TO SPREAD ACROSS THE AREA BY LATE THIS AFTERNOON AND
CONTINUE INTO THIS EVENING UNTIL THE PASSAGE OF THE COLD FRONT.
THE PASSAGE OF THE DISTURBANCE...COMBINED WITH THE SURFACE LOW
PRESSURE AREA ASSOCIATED WITH THE FRONT LINGERING OVER SOUTHERN
ALBERTA/SASKATCHEWAN THROUGH WEDNESDAY...WILL KEEP LOW/MID LEVEL
WESTERLY WINDS FAIRLY BREEZY AND GUSTY ACROSS NORTH CENTRAL
MONTANA...ESPECIALLY ALONG THE CANADIAN BORDER. FORECAST MODELS
INDICATE THAT WINDS MAY BE IN THE 45-50 KT RANGE BEGINNING AROUND
MIDNIGHT TONIGHT AND CONTINUING THROUGH THE DAY ON TUESDAY ALONG
THE NORTHERN ROCKY MOUNTAIN FRONT...SO HAVE ISSUED A HIGH WIND
WATCH FOR THAT AREA. IMMEDIATELY ADJACENT AREAS HAVE THE POTENTIAL
TO APPROACH THIS HIGH WIND CRITERIA...BUT AM NOT CONVINCED THAT
THIS WILL HAPPEN...SO WILL JUST CONTINUE TO MONITOR FORECAST MODEL
DEVELOPMENT REGARDING THESE WINDS. THE DOWNSLOPE WINDS WILL HINDER
PRECIPITATION DEVELOPMENT TUESDAY THROUGH WEDNESDAY OVER THE
PLAINS...BUT THE SURFACE LOW NORTH OF THE BORDER...ALONG WITH A
LINGERING SURFACE LOW OVER WYOMING...WILL ALLOW FOR A SLIGHT
CHANCE OF THUNDERSTORMS ALONG THE CANADIAN BORDER AND ACROSS
SOUTHWEST MONTANA...RESPECTIVELY. TEMPERATURES WILL BE A FEW
DEGREES WARMER THAN NORMAL TODAY AND TONIGHT...BUT THE COOLER
AIRMASS IN THE WAKE OF THE COLD FRONT WILL CAUSE TEMPERATURES TO
COOL ABOUT 5 TO 10 DEGREES FOR TUESDAY THROUGH WEDNESDAY. COULSTON

WEDNESDAY NIGHT THROUGH MONDAY...MODELS ARE IN DECENT AGREEMENT
EARLY IN THE MEDIUM RANGE PERIOD. AN UNSETTLED SOUTHWESTERLY FLOW
ALOFT WILL PREVAIL THROUGH FRIDAY WITH OCCASIONAL DISTURBANCES
PASSING THROUGH THE REGION FOR SCATTERED SHOWERS AND
THUNDERSTORMS MAINLY OVER THE WESTERN AND SOUTHWEST MOUNTAINS.
DURING THIS TIME TEMPERATURES WILL REMAIN NEAR SEASONAL AVERAGES.
FORECAST BECOMES A BIT MORE INTERESTING OVER THE WEEKEND AS AN
UPPER LEVEL TROUGH MOVES INLAND OVER THE PACIFIC NORTHWEST.
MODELS ARE SHOWING DIFFERENCES WITH REGARD TO MODEL STRENGTH AND
POSITION AS THIS SYSTEM IMPACTS THE NORTHERN ROCKY MOUNTAIN
REGION BUT THEY ARE EACH INCREASING THE CHANCE FOR PRECIPITATION
BY SUNDAY. HAVE LEANED A BIT TOWARD THE WETTER ECMWF SOLUTION AND
INCREASED POPS FOR SATURDAY NIGHT AND SUNDAY. UNSETTLED WEATHER
IS LIKELY TO PERSIST ACROSS THE REGION THROUGH MONDAY SO HAVE
KEPT MENTION OF SHOWERS FOR THIS TIME FRAME. MPJ

&&

.AVIATION...
UPDATED 1200Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS THE AREA THROUGH 
TONIGHT...UNLESS OTHERWISE SPECIFIED BELOW. A PACIFIC COLD FRONT 
WILL MOVE INTO THE AREA FROM THE WEST LATER TODAY. SCATTERED SHOWERS 
AND THUNDERSTORMS WILL DEVELOP AHEAD OF THIS FRONT BEGINNING LATER 
THIS MORNING AND SPREAD EAST ACROSS THE AREA THROUGH THIS AFTERNOON. 
THESE STORMS MAY PRODUCE STRONG WIND GUSTS...SMALL HAIL...AND BRIEF 
HEAVY RAINFALL...CAUSING LOCALIZED MVFR CONDITIONS. THESE STORMS 
WILL DECREASE FROM THE WEST LATER THIS AFTERNOON WITH THIS TREND 
CONTINUING THROUGH THE EVENING. WESTERLY WINDS WILL ALSO BECOME 
QUITE GUSTY ALONG AND BEHIND THE FRONT THIS AFTERNOON...WITH MANY 
AREAS RECEIVING GUSTS OF 30 TO 35 KT. WINDS WILL DECREASE SOMEWHAT 
BUT REMAIN QUITE BREEZY OVERNIGHT IN THE WAKE OF THE COLD FRONT. 
HOWEVER...GUSTS ALONG THE ROCKY MOUNTAIN FRONT AND IN THE CUT BANK 
AREA COULD BECOME QUITE GUSTY AGAIN AFTER MIDNIGHT.  COULSTON

&&

.HYDROLOGY...
THOUGH AM NOT EXPECTING ANY SIGNIFICANT FLOODING ISSUES FOR THE
NEAR FUTURE...THE EVENTUAL MELTING OF THE SUBSTANTIAL ADDITIONAL
RECENT SNOWPACK MAY CAUSE MANY RIVERS AND STREAMS TO RISE
SOMEWHAT FOR THE NEXT SEVERAL DAYS. MOUNTAIN TEMPERATURES ARE NOT
EXPECTED TO BECOME SIGNIFICANTLY WARM...BUT THEY MAY BECOME WARM
ENOUGH DURING THE DAY TO INCREASE SNOWMELT TEMPORARILY. OVERNIGHT
TEMPERATURES WILL THEN COOL TO NEAR OR BELOW FREEZING TO SLOW OR
STOP THE SNOWMELT. WILL THEREFORE MENTION POTENTIALLY HIGH RIVER
AND STREAM LEVELS IN THE HAZARDOUS WEATHER OUTLOOK THIS MORNING.
COULSTON

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  63  40  56  34 /  50  20  10  10 
CTB  59  36  54  33 /  40  20  10  10 
HLN  63  38  55  34 /  60  40  20  10 
BZN  63  33  55  28 /  60  60  40  10 
WEY  51  28  46  24 /  60  50  40  20 
DLN  60  34  53  31 /  60  40  30  10 
HVR  65  39  60  36 /  50  30  20  10 
LWT  61  37  53  32 /  50  40  20  10 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM LATE TONIGHT THROUGH TUESDAY EVENING 
NORTHERN ROCKY MOUNTAIN FRONT.

&&

$$

SHORT TERM...COULSTON
LONG TERM...MPJ
AVIATION...COULSTON

WEATHER.GOV/GREATFALLS