FXUS65 KGGW 281655
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
955 AM MST SAT NOV 28 2009

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY...
MOIST SW FLOW ALOFT...ASSOCIATED WITH SPLIT UPPER TROUGH
CURRENTLY MOVING ACROSS OUR AREA...IS MOVING E AND SHOULD EXIT OUR
SE BY EARLY AFTERNOON. A FEW VERY LIGHT RAIN AND SNOW SHOWERS
ASSOCIATED. OTHERWISE...WATER VAPOR SATELLITE CHANNEL SHOWS MUCH
DRIER AIR HAVING INVADED THE TROUGH. PARTIAL CLEARING OVER NW HALF
OF CWA...BUT STILL AREAS OF STRATUS UPSTREAM. HIGH CLOUDS
APPROACHING OUR AREA FROM THE NW BY AFTERNOON TOO.

12Z KGGW SOUNDING SHOWED 5-10C COOLING OVER THE PAST 24 HOURS OFF
THE SURFACE...AND NOT MUCH ROOM FOR WARMING TODAY DESPITE SOME
SUNSHINE. COLD ADVECTION HAS ABOUT ENDED. FORECAST HIGHS LOOK
GOOD. MADE SOME ADJUSTMENT TO POPS/SKY COVER IN UPDATE. SIMONSEN

TODAY THROUGH TONIGHT... A SHORTWAVE THAT PASSED OVER THE REGION
DURING THE MORNING HOURS SHOULD EXIT THE REGION WITH ITS GENERATED
PRECIPITATION AROUND NOON. A DRY SLOT WILL MOVE IN WITH LESSENING
MOISTURE BY THE AFTERNOON HOURS CLEARING SKIES ARE ALSO
ANTICIPATED WITH THIS EVENT INTO THE EVENING HOURS.

SUNDAY THROUGH MONDAY... SYNOPTIC SCALE FRIGID COLD AIR WILL BE
IN PLACE ACROSS THE NORTHWEST TERRITORIES AND NORTHERN HUDSON BAY.
A STRONG TROUGH IS ANTICIPATED TO SET UP OVER THE GULF OF ALASKA
AND SLOWLY MOVE ACROSS BRITISH COLUMBIA INTO SOUTHERN
SASKATCHEWAN. OUT AHEAD OF THIS SYSTEM... A HIGH PRESSURE RIDGE IS
ANTICIPATED TO MOVE INTO MONTANA GENERATING A WARMING TRENDS WITH
POSITIVE SINGLE DIGIT 850 MB TEMPERATURES. THE RIDGE IS ALSO
ANTICIPATED TO GENERATE A CHINNOK ARCH EVENT WHICH WILL HELP TO
RAISE SURFACE TEMPERATURES THROUGH MONDAY. BY MONDAY THE RIDGE
SHOULD BE STEADILY EXITING THE REGION WITH THE TROUGH STRONG ON
ITS HEELS AND OVER CENTRAL ALBERTA. AT WHICH POINT THE TROUGH IS
ANTICIPATED TO TAP INTO THE FRIGID COLD AIR UP NORTH AND RAPIDLY
MOVE IT INTO SOUTHERN SASKATCHEWAN AND ON THE DOORSTEP OF MONTANA.
THIS RAPID MOVEMENT OF AIR SHOULD GENERATE ENOUGH COMPRESSION TO ADD TO
WARMING OUT AHEAD OF THE FRONT ON MONDAY... ON THE OTHER HAND THE
RELATIVE SPEED OF THE INCOMING COLD FRONT MAY ALSO BORE THROUGH
THE LOWER LEVELS BEFORE MUCH COMPRESSION CAN SET UP. ANY WAY YOU
LOOK AT IT MONDAY PROMISES TO BE RELATIVELY WARMER IN THE 40S AND
POSSIBLY LOWER 50S FOR HIGHS AND DRAMATICALLY DIFFERENT FROM THE
DAYS TO FOLLOW. GAH

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
THE EXTENDED FORECAST PERIOD BEGINS TUESDAY NIGHT WITH A SPLIT
FLOW LONG WAVE PATTERN. THE NORTHERN STREAM APPEARS TO BE MORE
AMPLIFIED WITH A SHORTWAVE DIVING SOUTH OUT OF CANADA. THE FRONTAL
PASSAGE AT THIS POINT APPEARS TO BE TUESDAY MORNING.

THE GFS HAS HAD THE MOST CONSISTENCY WITH THE FRONT KEEPING THE
HEART OF THE ARCTIC EAST OF NEMONT AND DRIER...WHEREAS THE EC IS
MORE MOIST BUT NOT MUCH AND PLACED FURTHER WEST BRINGING THE BRUNT
OF THE AIR MASS OVER THE CWA. GOING WITH TRENDS AND
CONSISTENCY...WOULD HAVE MORE CONFIDENCE IN THE GFS.
THEREFORE...CONTINUED TO LEAVE SLIGHT CHANCE POPS IN FOR TUESDAY.
ALSO WITH A STRONG GRADIENT AND QUITE A COLDER AIR MASS MOVING
SOUTH...TUESDAY PRESENTS A PROBLEM WITH STRONG WINDS AS 850MB
WINDS APPROACH 50 KNOTS. A HWO WILL ADDRESS THIS FOR NOW AS WINDS
APPEAR TO BE THE MAIN IMPACT. TUESDAY TEMPS WILL MOST LIKELY FALL
THROUGHOUT THE DAY AND THE SETTLING OF THE COLDER AIR MASS WILL
LIKELY ONLY BRING TEMPS BACK TO NORMAL IF NOT A LITTLE BIT BELOW
FOR TUE AND WED.

AFTER WED...THE MODELS DIVERGE GREATLY IN SOLUTIONS AS THE EC
BRINGS ANOTHER SHORTWAVE SOUTH JUST EAST OF THE FRONT RANGE AND
THE GFS TRIES TO SNEAK A WEAK RIDGE INTO THE AREA AND PROVIDE A
LITTLE WARMING. THE ENSEMBLES ALSO SHOW A WEAK RIDGE SO WILL LEAN
TO A SLIGHT WARM UP BASICALLY LEAVING TEMPS NORMAL FOR THIS TIME
OF YEAR. THE OVERALL TREND FOR THE NEXT WEEK IS DRY WEATHER AND
NEAR NORMAL TEMPS. SHALLENBERGER

&&

.AVIATION...
VFR CONDITIONS WITH CLEARING SKIES ARE MOVING IN FROM THE WEST
THIS MORNING SENDING THE MVFR CONDITIONS OF LOW CLOUDS AND
SCATTERED LIGHT SNOW SHOWERS TO THE EAST. THE KGDV TERMINAL
REMAINS UNDER IFR AT MID MORNING BUT THIS WILL CLEAR BY AFTERNOON 
WITH HIGH PRESSURE BRINGING CLEARING SKIES. HIGH CLOUDS WILL
SPREAD BACK INTO THE REGION TONIGHT. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

WEATHER.GOV/GLASGOW