FXUS65 KGGW 012206
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
306 PM MST TUE DEC 1 2009

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
LARGE SCALE PATTERN HAS UPPER RIDGE BUILDING N OFF PACIFIC
COAST...WHILE THERE IS A STRONG DOUBLE CLOSED UPPER LOW COMPLEX
OVER S CANADA. NE MT IN A COLDER NNW FLOW BETWEEN THESE 2
FEATURES. THICKNESSES ARE ONLY IN THE 510S DM THRU THE
PERIOD...BUT REFLECTIVE OF THE DEEPLY COLD AIR ALOFT RATHER THAN
ARCTIC LOW LEVEL COLD. THIS COMBINED WITH MOSTLY CLOUDY SKIES AND
WIND WILL PREVENT ANY SUBZERO TEMPS...AT LEAST FOR THE NEXT
COUPLE OF NIGHTS ANYWAY.

TONIGHT THRU WED NIGHT WE WILL BE UNDER THE UPPER CYCLONIC
CIRCULATION. THIS WILL KEEP SKIES MOSTLY CLOUDY...ESPECIALLY IN
OUR E. INDIVIDUAL SHORTWAVES ARE WEAK THOUGH. SATELLITE CHANNELS
NOT LOOKING TOO IMPRESSIVE WITH MAINLY JUST LOW OVERCAST OVER S SK.
A PIECE OF THE UPPER LOW CIRCULATION MOVES SSE INTO ND TONIGHT.
THIS WILL GIVE THE BEST CHANCE OF ANY PRECIP...BUT THAT WON'T
AMOUNT TO MUCH...JUST ISOLATED LIGHT SNOW SHOWERS OR FLURRIES. THE
THREAT OF A FEW SNOW SHOWERS THOUGH WILL CONTINUE THRU WED NIGHT
ALONG WITH MOSTLY CLOUDY SKIES.

THERE HAS BEEN VERY LITTLE RISE IN TEMPS SINCE EARLY THIS MORN.
NOT MUCH CLEARING EXPECTED TONIGHT THOUGH...WITH NW WINDS
CONTINUING...AND JUST A LITTLE BIT MORE COLD ADVECTION. THE
FORECAST LOWS OF GENERALLY TEENS TONIGHT LOOK GOOD. SURFACE HIGH
OVER BC WILL GRADUALLY MOVE E INTO AB/SK WED...KEEPING A CHILLY
N-NW FLOW GOING IN THE LOWER LEVELS FOR NE MT. WINDS WILL BE LESS
THAN TODAY THOUGH.

FOR THU...INFLUENCE OF MAIN PART OF UPPER TROUGH STARTS TO MOVE
SSE OUT OF THE AREA...WITH UPPER RIDGING FROM THE WNW. SURFACE
HIGH IS ALSO DIRECTLY OVER NE MT. WOULD EXPECT CLEARING SKIES
THU...WHICH MODELS INDICATE WITH DRYING AIRMASS...BUT MODELS INDICATE
LITTLE OR NO WARMING OVER WED. SIMONSEN

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
A WEAK/NARROW UPPER RIDGE BEHIND THE DEPARTING LONG-WAVE TROUGH TO
THE EAST AND THE INCOMING VIGOROUS UPPER TROUGH IN THE WEST WILL
BRING A BRIEF WINDOW OF INCREASING 1000MB-500MB THICKNESS HEIGHTS.
THE RESULT WILL BE ONLY A SLIGHT WARMING OF TEMPERATURES FRIDAY.
HOWEVER...TMAX WILL REMAIN AROUND 5 TO 10 DEGREES BELOW NORMAL.

FRIDAY NIGHT THROUGH SATURDAY NIGHT...THE UPPER TROUGH ESSENTIALLY
ABSORBS THE WEAK RIDGE AND SENDS A COLD FRONT OVER ALL OF MONTANA.
850MB TEMPERATURES BEGIN TO DROP TO AROUND -12*C BY 12Z SAT. THE
MAIN STORM ENERGY SLIDES SOUTH ALONG THE DIVIDE AND SPREADS OUT
OVER THE PRAIRIE OF CENTRAL MONTANA. HOWEVER THE LOCAL CWA WILL
REMAIN MOSTLY DRY. ANY SNOW THAT DOES FALL WILL BE LIGHT WITH NOT
MUCH ACCUMULATION. TEMPERATURES SATURDAY WILL COOL TO AROUND 15
DEGREES BELOW NORMAL. 

SUNDAY AND BEYOND...THE GFS AND ECMWF DIFFER ON THE DEVELOPMENT OF
THE STORM SYSTEM AS IT AFFECTS THE FAR WESTERN STATES. BUT BOTH
MODELS KEEP NORTHEASTERN MONTANA MOSTLY DRY THROUGH THE REST OF
THE PERIOD WITH CONTINUED COLD...WITH MINIMUMS FALLING TO NEAR
ZERO. SCT

PREVIOUS DISCUSSION... 
NORTH TO NORTHWEST FLOW ALOFT WILL BRING WINTER LIKE TEMPERATURES
TO THE AREA FOR THE ENTIRE PERIOD. MODELS HAVE BACKED OFF ON THE
BRIEF WARM UP LATE IN THE WEEK AS THEY ALL HAVE WEAKENED THE
SHORTWAVE RIDGE THAT IS FORECASTED TO PASS THROUGH THE AREA ON
FRIDAY. HAVE LOWERED TEMPERATURES IN MOST PERIODS.

COLD FRONT DROPS SOUTH ON SATURDAY WITH A SHORTWAVE THAT HAS
LIMITED MOISTURE. WILL KEEP FORECAST DRY AT THIS POINT. COLD HIGH
PRESSURE BUILDS INTO THE AREA FOR SUNDAY AND MONDAY THAT COULD
LINGER INTO TUESDAY. MODELS ARE NOT IN PERFECT AGREEMENT ON THIS.
FORRESTER 

&&

.AVIATION...
LOW CLOUDS WILL CONTINUE TO ROTATE AROUND THE BACKSIDE OF THE
STORM CENTERED OVER SOUTHERN SASKATCHEWAN/MANITOBA TONIGHT AND
WEDNESDAY. EXPECT MOSTLY VFR AND SOME MVFR WITH BKN TO OVC LOW
CEILINGS OF 2500 TO 6000 FT AGL. OCCASIONAL LIGHT SNOW OR FLURRIES
COULD DIMINISH VISIBILITIES BRIEFLY AT TIMES. NORTHWEST WINDS WILL
SLOWLY DIMINISH TONIGHT AND WEDNESDAY FROM THE WEST. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR FORT PECK 
LAKE.

&&

$$

WEATHER.GOV/GLASGOW