FXUS65 KGGW 050350
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
850 PM MST SAT FEB 4 2012

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
UPDATED TONIGHT TO LOWER TEMPS IN THE EAST AND ALSO ADDED PATCHY FOG.

SATELLITE IMAGERY SHOWING PATCHY FOG OVER NORTH DAKOTA TRYING TO
CREEP WEST TOWARD EASTERN MONTANA THIS EVENING. IT SHOULDN/T MAKE
TOO MUCH HEADWAY AS A SURFACE HIGH OVER THE AREA IS EXPECTED TO SINK
SOUTH. THIS WILL ALLOW SOUTHWEST WINDS TO KEEP THE FOG FROM
FORMING/BACKING INTO THE AREA. FOG MAY NOT EVEN GET INTO AREA...BUT
WILLISTON IS ALREADY REPORTING FOG WITH 5SM VISIBILITY. REST OF
FORECAST IN GOOD SHAPE. JAMBA

PREVIOUS DISCUSSION...
HIGH PRESSURE AT THE SURFACE REMAINS ANCHORED OVER EASTERN
MONTANA. FOG THAT WAS PRESENT ACROSS MUCH OF THE AREA THIS MORNING
HAS DISSIPATED AND WITH LIGHT SOUTHERLY WINDS USHERING IN DRIER AIR...
IS NOT EXPECTED TO REDEVELOP. A DEVELOPING LEE SIDE TROUGH ALONG
THE FRONT RANGE OF THE ROCKIES WILL HELP KEEP LIGHT SOUTHERLY
WINDS UP TONIGHT AS WELL. TEMPS WILL FALL OFF INTO THE TEENS TO
20S...WHICH IS AROUND 15 DEGREES ABOVE NORMALS.

SUNDAY WILL BRING ONE LAST WELL ABOVE NORMAL DAY UNDER SUNNY SKIES AS
THE HIGH OVER LOW BLOCK CONTINUES TO DOMINATE. SUNDAY NIGHT INTO
MONDAY THE BLOCK WILL BE BROKEN DOWN BY A SHORTWAVE FEATURE
DROPPING SOUTHWARD OUT OF CANADA. THE ASSOCIATED COLD FRONT WILL
PUSH THROUGH SUNDAY NIGHT...USHERING MUCH COLDER...I.E.NORMAL...TEMPS
FOR MONDAY. SOME LIGHT SNOW SHOWERS CONTINUE TO BE POSSIBLE WITH
THIS SYSTEM ON MONDAY ACROSS SOUTHERN PHILLIPS...PETROLEUM...AND
GARFIELD COUNTIES. NORTHERLY WINDS WILL ALSO DEVELOP AT AROUND 20
MPH AS THE MODIFIED ARCTIC SURFACE HIGH BUILDS IN OUT OF CANADA.
GILCHRIST

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...

LONG TERM FORECAST PERIOD BEGINS AS THE CLOSE UPPER LOW OVER THE
CENTRAL STATES FINALLY BEGINS TO BECOMES ABSORBED BY A LOBE SHORT
WAVE TROUGH OF THE LARGER AND STRONG UPPER LOW CENTER OVER HUDSON
BAY. THIS WILL DROP A COLD FRONT AND WIND SHIFT THROUGH OUT CWA
MONDAY NIGHT THROUGH TUESDAY MORNING WITH A SLIGHT CHANCE TO A
CHANCE OF SNOW FOR OUR FAR SOUTHWESTERN ZONES.

ANOTHER REX BLOCK UPPER LOW CLOSES OFF OVER SOUTHERN CALIFORNIA ON
WEDNESDAY AND SLIDES ALONG THE BAJA PENINSULA THROUGH THE WEEK.
MEANWHILE...MONTANA WILL BE A SOMEWHAT DIFFUSE UPPER LEVEL FLOW AS
THE NORTHERN STREAM BEGINS TO ASSERT ITS WEATHER PATTERN OVER OUR
REGION.

BY THURSDAY...A SOLID NORTHWEST FLOW ALOFT SETS UP OVER MONTANA
AND BY FRIDAY...MODEL DISCREPANCIES BEGIN TO APPEAR. INTO NEXT
WEEKEND...GFS SUSTAINS A HEALTHY UPPER RIDGE MOVING SLOWLY THROUGH
OUR REGION WHILE THE EC DRAGS THROUGH A WEAK UPPER LEVEL TROUGH.
THUS FORECAST CONFIDENCE IS SOMEWHAT DIMINISHED BEYOND DAY 6 OF
THIS FORECAST. BMICKELSON

PREVIOUS LONG TERM DISCUSSION...ARCTIC AIR BEGINS TO MOVE SOUTH
INTO EASTERN CANADA NEXT WEEK. THIS UPPER LOW DEVELOPS INTO A
VORTEX OVER HUDSON BAY...THEN CONTINUES TO DESCEND INTO THE GREAT
LAKES REGION LATE IN THE WEEK. BY VARYING DEGREES...NORTHEAST
MONTANA WILL BE ON THE WESTERN EDGE OF THIS COLD AIR MASS...NEVER
RECEIVING A DIRECT BLOW. THE COLD BOUNDARY OF MODIFIED AIR WILL
MEANDER A BIT WITH THE NORTHEAST ZONES BEING AFFECTED BY THE
COLDEST AIR. 500MB FLOW ALOFT WILL GENERALLY BE NORTHERLY TO
NORTHWESTERLY THROUGH THE PERIOD. THE FLOW WILL BE DISTURBED BY A
COUPLE OF SHORTWAVES MONDAY NIGHT AND WEDNESDAY. THE LACK OF
MOISTURE WILL KEEP CONDITIONS MOSTLY DRY. HOWEVER LATE IN THE
PERIOD THE STATIONARY COLD BOUNDARY WILL BEGIN TO DRIFT EAST UNTIL
IT IS ACROSS NEMONT. OVERRUNNING MOISTURE ALONG THE BOUNDARY COULD
GENERATE OVERCAST AND SNOW. CURRENTLY THE GFS AND THE EC SUGGEST
THIS COULD OCCUR BEGINNING AROUND THURSDAY NIGHT AND INTO THE
WEEKEND.

WITH 850MB TEMPERATURES DROPPING TO -10*C TO -15*C...SURFACE
TEMPERATURES SHOULD TREND CLOSE TO NORMAL THROUGH THURSDAY OR
FRIDAY. AS THE STATIONARY BOUNDARY DRIFTS EAST IT WILL ACT AS A
WARM FRONT...WARMING 850MB TEMPERATURES TO ABOVE 0*C. HOWEVER
OVERCAST WILL NOT ALLOW HIGHS TO RISE MUCH MORE THAN A FEW DEGREES
ABOVE NORMAL.

WHILE CONDITIONS WILL BE MOSTLY DRY...A SHORTWAVE CLIPPER WILL
SWING PAST THE AREA ON ITS WAY FROM ALBERTA TO NORTH DAKOTA. THIS
WAVE SENDS A COLD FRONT THROUGH NEMONT THAT WILL DEVELOP GUSTY
NORTHWEST WINDS OF 15 TO 25 KTS THAT SHOULD DIMINISH WEDNESDAY
NIGHT. OTHERWISE WINDS WILL NOT BE MUCH OF AN ISSUE IN THE
EXTENDED PERIOD. SCT


&&

.AVIATION...
PATCHY VALLEY FOG POSSIBLE LATE TONIGHT AND SUNDAY MORNING MAY
REDUCE VISIBILITIES TO BELOW 1 MILE AT TIMES. OTHERWISE VFR
CONDITIONS. SIMONSEN


&&

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

&&

$$

WEATHER.GOV/GLASGOW


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