Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 272128
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
228 PM MST TUE JAN 27 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...

SYNOPTIC SET UP... SHORT TERM BEGINS WITH A RIDGE OF WARM HIGH
PRESSURE EXTENDING UP THROUGH THE US PLAINS AND BENDING BACK INTO
MONTANA AND SOUTHERN ALBERTA. A TROUGH OF COOLER AIR RUNS DOWN THE
PACIFIC NORTHWEST AND TERMINATES OVER THE CENTRAL US ROCKIES OF
WYOMING AND COLORADO. THE COLDEST AIR OF THE NORTHERN HEMISPHERE
SETS IN TWO TWIRLING LOBES... WITH ONE OVER BAFFIN SEA AND THE
OTHER OVER THE NORTHWEST TERRITORIES. FARTHER WEST SPLIT FLOW SETS
OFF THE NORTH AMERICAN COAST WITH A WEAK TOUGH WEST OF THE
CALIFORNIA COAST AND A WEAK RIDGE OFF OF THE BRITISH COLUMBIAN COAST AND
GULF OF ALASKA.

THIS AFTERNOON THROUGH WEDNESDAY... MID TO UPPER LEVEL CHINOOK
ARCH CLOUDS THIS AFTERNOON ARE RUNNING AROUND THE THE TOP OF THE
RIDGE THAT IS EXITING THE AREA. MODELS HAVE DONE A VERY POOR
PERFORMANCE IN CATCHING ONTO THIS ACROSS THE SPECTRUM SO SKY COVER
HAS NEEDED TO BE GREATER THAN ANTICIPATED AND LOWERED THE DAYS
HIGHS MORE THAN PREDICTED. CONSEQUENTLY THIS IS ALSO FORCING HI
RESOLUTION MODELS TO BELIEVE THAT THE FRONTS TO THE NORTH ARE
MOVING FAR FASTER THAN ANTICIPATED THROUGH TONIGHT.

COOL CORE TROUGH OVER THE PACIFIC NORTHWEST WILL MOVE THROUGH THE
AREA DURING THE MORNING HOURS AND ALLOW THE COLD FRONT TO THE
NORTH TO FINALLY MOVE THROUGH THE CWA INTO MID-DAY WEDNESDAY. A
LITTLE IT OF OVERRUNNING WILL BE POSSIBLE WITH THIS PASSAGE BUT
MOST OF THE PRECIPITATION WILL STAY TO THE FAR NORTHEAST SECTIONS
OF THE CWA AND BE VERY LIMITED IN SCOPE.

WEDNESDAY NIGHT INTO THURSDAY... FLOW WILL TURN SOUTHWEST AND THE
COLD AIR SLIDES OFF INTO THE LOW PLAINS AND MISSISSIPPI VALLEY.
STABLE CONDITIONS SHOULD LEAD TO PARTLY CLOUDY SKIES AND DRY
CONDITIONS BUT TEMPERATURES SHOULD WARM SLOWLY.


.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
AS MUCH AS I DREAD DOING THIS...AFTER SEEING THE MODELS CONTINUING
TO TREND COLDER THIS WEEKEND INTO NEXT WEEK AND THE NEW GUIDANCE
COMING IN...THE ONLY REAL CHANGE TO THE EXTENDED IS TO DROP
TEMPERATURES DOWN A FEW MORE DEGREES. THE MODELS SOMETIMES HAVE A
HARD TIME CATCHING ONTO A BIG CHANGE LIKE THIS. FRANSEN

PREVIOUS DISCUSSION...NORTHEAST MONTANA WILL FIND ITSELF NEARLY
CONSTANTLY UNDER NORTHWESTERLY FLOW ALOFT THROUGH MOST OF THE
EXTENDED FORECAST PERIOD AND IN AN INCESSANT BATTLE BETWEEN COLDER
AIR TO THE NORTHEAST AND WARMER AIR TO THE SOUTHWEST.

THE SHORT WAVE DISTURBANCES THAT SLIDE THROUGH THIS FLOW WILL
BRING OCCASIONAL CHANCES OF LIGHT SNOW SHOWERS...PREDOMINANTLY ON
SATURDAY AND SUNDAY. THERE WAS JUST BARELY ENOUGH MODEL CONSENSUS
TO BRING SOME OF THOSE AREAS UP TO CHANCE POPS. OTHERWISE...A
TREND TO CLIMO POPS MAKES THE MOST SENSE GIVEN THE LACK OF MODEL
CONSISTENCY IN THE FLOW PATTERN AND SMALLER-SCALE MODEL QPF
OUTPUT.

TEMPERATURES ARE EXPECTED TO GRADUALLY DECREASE THROUGH THE
FORECAST PERIOD AS THE INFLUENCE FROM THE HIGH PRESSURE RIDGE
SHIFTS MORE WESTWARD TOWARD THE WEST COAST AND PLACES NORTHEAST
MONTANA MORE IN THE INFLUENCE OF THE COLDER CANADIAN AIR MASS.
BMICKELSON


&&

.AVIATION...
FLIGHT CATEGORY: VFR.

SYNOPSIS: AN UPPER-LEVEL RIDGE OF HIGH PRESSURE PERSISTS OVER THE
REGION TODAY AND WILL ALLOW FOR A FEW HIGH CHINOOK ARCH CLOUDS. THEN AN
UPPER-LEVEL SHORT WAVE SWINGS ACROSS NORTHERN MONTANA AFTER 00Z
FOR A WIND SHIFT AND FURTHER INCREASE IN LOW LEVEL CLOUDINESS.

FREEZING RAIN: A SLIGHT CHANCE FOR MIXED PRECIPITATION INCLUDING
FREEZING RAIN APPEARS AFTER 12Z TO THE NORTH AND EAST OF KOLF AND
KSDY BUT IS TOO LOW TO INCLUDE IN THE TAFS DIRECTLY. THIS THREAT
ENDS BY 00Z WEDNESDAY AFTERNOON.

VSBY: MULTIPLE MODELS ARE POINTING TOWARD IFR CLOUDS AND REDUCED
VISIBILITY THIS EVENING AND OVERNIGHT. HOWEVER... MULTIPLE MODELS
ARE ALSO NOT TAKING INTO ACCOUNT CURRENT SKY COVERAGE AND
THEREFORE COULD EASILY BE WRONG WITH THE PROPAGATION AND OF TIMING
OF THE MOISTURE AND FRONT INTO THE AREA. MORE THAN LIKELY THIS
WILL NOT IMPACT THE TAF SITES BUT A SMALL AMOUNT OF UNCERTAINTY
REMAINS.

AREA WINDS: SOUTHWEST UNDER 10 KTS THROUGH MIDNIGHT... VEERING TO
THE NORTHWEST AND INCREASING TO 10 TO 15 KTS DURING THE MORNING
HOURS.

GAH


&&

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

&&

$$

WEATHER.GOV/GLASGOW




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