000
FXUS65 KGGW 060406
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
906 PM MST SUN FEB 5 2012

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT...
WEAK COOL ADVECTION STARTING FROM THE N TONIGHT. THE LEADING EDGE
OF THIS IS A WEAK COLD FRONT THAT IS HARD TO PICK OUT BY SURFACE
TEMPS AND THERE ARE NO CLOUDS WITH IT...BUT THERE IS A WIND SHIFT.

A LOWER OVERCAST IS PUSHING S ACROSS E SK...BUT MODELS DON`T GET
CLOSE TO OUR AREA WITH THIS UNTIL MORNING. ANOTHER OVERCAST AREA
OVER AB IS EXPANDING SE...BUT AGAIN NOT TO ARRIVE UNTIL AFTER
TONIGHT...SO UPDATED TO LOWER CLOUDCOVER. SIMONSEN

PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH
TUESDAY...WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWING A
SOMEWHAT BLOCKED AND STAGNANT UPPER LEVEL PATTERN. THE DUAL LOBED
CLOSED UPPER LOW OVER OUR NATIONS MID- SECTION CONTINUES TO
SEPARATE. THE EASTERN LOBE IS BEING RE- ABSORBED INTO THE NORTHERN
STREAM UPPER LEVEL TROUGH OVER THE GREAT LAKES AND THE
NORTHEASTERN STATES. THE WESTERN LOBE REMAINS STATIONARY OVER THE
INTER-MOUNTAIN WEST.

THIS BLOCKING PATTERN HAS ISOLATED AN AREA OF HIGH PRESSURE OVER
THE NORTHERN ROCKIES AND ADJACENT NORTHERN HIGH PLAINS. AN UPPER
LOW IS BUTTING UP AGAINST THIS...RIDING NORTHWARD OVER THE EASTERN
PACIFIC OCEAN. AN UPPER LEVEL SHORT WAVE TROUGH IS QUICKLY
DESCENDING SOUTHWARD ALONG AND ON THE LEE SIDE OF THE CANADIAN ROCKIES.

EXPECT A WIND SHIFT TONIGHT FROM THE NORTH AND COLDER TEMPERATURES
SETTLING INTO NORTHEAST MONTANA BY MONDAY NIGHT...CLOSER TO NORMAL
LEVELS FOR THIS TIME OF YEAR.

IT IS THIS WAVE WHICH WILL PUSH COLDER TEMPERATURES THROUGH
NORTHEAST MONTANA BEGINNING MONDAY AFTERNOON. IT WILL ALSO
REPRESENT THE ONLY CHANCE FOR PRECIPITATION FOR OUR AREA IN THE
FORECAST PERIOD. MODEL RUNS CONTINUE TO ISOLATE THESE SNOW SHOWERS
AS LIGHT AND FLEETING AND SKIRTING BOTH THE NORTHEASTERN CORNER OF
OUR CWA WITH FLURRIES...AND THE SOUTHWESTERN CORNER OF OUR CWA
WITH SMALL SLIGHT CHANCES OF SNOW SHOWERS AT BEST. LOWERED POPS A
BIT FROM THE PREVIOUS FORECAST FOLLOWING RECENT RETREATING MODEL
TRENDS. THIS SHORT WAVE TROUGH WILL ALSO BE RESPONSIBLE FOR
RE-ABSORBING THE STALLED WESTERN LOBE OF THE BLOCKED UPPER LOW
BACK INTO THE NORTHERN STREAM.

TUESDAY...HIGH PRESSURE RETURNS AND A STAGNANT UPPER LEVEL FLOW
REGIME BETWEEN WEATHER SYSTEM TAKES OVER AGAIN FOR NORTHEAST
MONTANA. BMICKELSON


.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
NORTHWEST FLOW ALOFT WILL DOMINATE OVER NORTHEAST MONTANA
IN BETWEEN A LONGWAVE UPPER RIDGE TO THE WEST AND THE HUDSON BAY
LOW TO THE NORTHEAST THROUGH NEXT SATURDAY. MODELS HAVE FLIP-FLOPPED
FOR WEDNESDAY NIGHT INTO FRIDAYS ARCTIC PUSH AND NOW ARE TRENDING
TOWARD A BIT WARMER SOLUTION. HELD OFF ON MAKING ANY CHANGES FOR
NOW...WAITING FOR FUTURE HOPEFULLY BETTER RUN TO RUN CONSISTENCY
IN THE MODELS. GILCHRIST

PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE RE-BUILDS STRONGLY AND
SHARPLY N OVER THE PACIFIC COAST STATES AND BC. MEANWHILE...THERE
IS A STRONG HUDSON BAY LOW. THIS PUTS NE MT INTO A FAST NNW FLOW
ALOFT WITH SOMEWHAT COLDER AIR HEADING OUR WAY. THE LEADING COLD
FRONT ARRIVES WEDNESDAY. UPPER SUPPORT WEAKENS A LOT THOUGH AS THE
ACCOMPANYING TROUGH IS SWALLOWED BY THE LARGE HUDSON BAY LOW
CIRCULATION...THUS MAINLY DRY FOR OUR AREA.

A SURFACE HIGH PRESSURE MOVES SSE FROM THE ARCTIC OCEAN INTO NE MT
FOR THU AND FRI. MODELS IN GOOD AGREEMENT WITH THIS...EXCEPT THE
LATEST ECMWF WHICH APPEARS AN OUTLIER...WEAKER...WARMER...AND
FARTHER E WITH THIS HIGH. OTHER MODELS HAVE THICKNESSES AS LOW AS
510 DM INTO OUR NE...AND 850 MB TEMPS DOWN TO -18C...00Z GFS -22C.
ALTHOUGH NOT TERRIBLY STRONG OR COLD...THE HIGH DOES HOLD UP
WELL ON ITS WAY S...AS STRONG AS 1040 MB INTO OUR AREA. CURRENT
FORECAST APPEARS TOO WARM FOR THE PATTERN...WARMER THAN MOST
GUIDANCE...BUT THERE IS ALSO ZERO SNOW COVER...THUS WILL ONLY
MODESTLY LOWER TEMPS FOR THU THRU SAT.

MOST MODELS WEAKEN THE RIDGE AS IT MOVES E INTO THE ROCKIES OVER
THE WEEKEND...SHOWING QUITE A BIT OF VARIATION ON THE DETAILS
THOUGH AND ALSO A POSSIBLE SHORTWAVE SYSTEM FROM THE W. CMC GEM
TENDS TO KEEP US IN THE COLDER NNW FLOW. SOME GFS ENSEMBLE MEMBERS
ALSO SHOWING THIS IS POSSIBLE. PREFER TO GO WITH THE IDEA OF THIS
BRINGING SOME WARMING...BUT TOO MUCH MODEL VARIETY ON THE POSSIBLE
SHORTWAVE FOR ANY SIGNIFICANT POPS YET. SIMONSEN

&&

.AVIATION...
VFR. A COLD FRONTAL PASSAGE OVERNIGHT WILL INCREASE NORTHERLY WINDS
A BIT. SCATTERED CLOUDS AT MULTIPLE LEVELS CAN BE EXPECTED AT
TIMES MONDAY. JAMBA

&&

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

&&

$$

WEATHER.GOV/GLASGOW

NWS GGW Office Area Forecast Discussion