Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 281047
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
347 AM MST SUN DEC 28 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
LIGHT SNOW CONTINUES TO SPREAD ACROSS SOUTHWESTERN PORTIONS OF THE
CWA...NAMELY SW PHILLIPS/PETROLEUM/GARFIELD COUNTIES. TO THE NORTH
AND EAST...FLURRIES AND LOW STRATUS ARE THE MAIN EXPECTATIONS
THROUGH THE DAY. 00Z GUIDANCE STILL IN FAIRLY EXCELLENT AGREEMENT
ON TIMING/PLACEMENT OF QPF. HIGH RESOLUTION GUIDANCE SHOWS
STEADIEST SNOWFALL NOW THROUGH LATE AFTERNOON AS WELL. DAY SHIFT
WILL NEED TO CLOSELY WATCH PRAIRIE COUNTY AS THEY WILL LIKELY
FLIRT WITH THE NORTHERN EDGE OF THE STEADIEST SNOW. THIS IS
PARTICULARLY EVIDENT IN THE 06Z NAM. WILL LEAVE THEM OUT OF THE
ADVISORY FOR NOW BUT BEARS WATCHING AS TRENDS EVOLVE. ALSO EXPECT
THAT DRIFTING AND PATCHY BLOWING SNOW MAY BECOME A CONCERN AS WELL
WITH STIFF NORTHEAST WINDS ACROSS THE REGION.

OTHERWISE...EXPECT SNOW TO EXIT TO THE SOUTH THIS AFTERNOON AND
EVENING. MODELS SHOW A MARKED DROP IN HIGH 700MB MIXING RATIO AIR
FROM NORTH TO SOUTH DURING THIS TIME. THE FOCUS FOR THIS EVENING
WILL BE BITTER WIND CHILLS AS ARCTIC AIR SETTLES IN. LOWS
OVERNIGHT SHOULD PLUMMET BELOW ZERO. NORTH TO NORTHEAST WINDS
AROUND 10-15 MPH WILL LEAD TO DANGEROUS WIND CHILL READINGS
RANGING FROM 20 TO 30 BELOW. HIGHLIGHTS MAY BE NECESSARY BUT THAT
MAY BE BETTER DETERMINED AFTER CURRENT ADVISORIES ARE FINISHED.

EXPECT ARCTIC AIR TO REMAIN IN PLACE THROUGH EARLY IN THE WEEK
WITH OVERNIGHT LOWS WELL BELOW ZERO AND HIGHS ONLY RECOVERING TO
EITHER SIDE OF ZERO. ANY FRESH SNOW PACK WILL ONLY HELP
RADIATIONAL COOLING BE CARRIED OUT MORE EFFICIENTLY.

A RIDGE PUSHING IN TO THE HIGH NORTHERN PLAINS BY WEDNESDAY MAY
BRING A BRIEF REPRIEVE FROM THE ARCTIC INTRUSION BUT IT IS
EXPECTED TO BE SHORT LIVED. MALIAWCO

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE LONG RANGE PERIOD BEGINS WITH A BROAD LONG-WAVE TROUGH OVER
THE CONUS WITH A SHARP RIDGE OFF THE WEST COAST. AS STRENGTHENING
HUDSON BAY LOW MAINTAINS TROF OVER THE EAST...RIDGE FOLDS OVER
INTO WESTERN CANADA AND CUT OFF LOW FORMS IN THE DESERT SOUTHWEST.

FOLDING UPPER RIDGE WILL PUSH WARM AIR ACROSS THE DIVIDE INTO
ALBERTA ON WEDNESDAY THEN DOWN THE FRONT RANGE INTO CENTRAL
MONTANA ON THURSDAY. HOWEVER WITH UPPER FLOW REMAINING FROM THE
NORTHWEST DUE TO THE STRONG HUDSON BAY LOW...THE WARM AIR WILL BE
SLOW TO MOVE EAST...AND SOME COLD AIR WILL LINGER A THE SURFACE
EVEN INTO THURSDAY.

A SHORTWAVE DROPPING THROUGH CENTRAL CANADA WILL BRING ANOTHER
ARCTIC FRONT INTO MONTANA ON THURSDAY NIGHT. MODELS PUSHING THE
WAVE FURTHER WEST...SUGGESTING THAT ONCE AGAIN THE BEST CHANCES OF
SNOW WILL BE ACROSS CENTRAL MONTANA BUT SOME POTENTIAL FOR A
LITTLE ACCUMULATION ACROSS THE EASTERN PLAINS INTO FRIDAY. THE
WESTWARD PUSH ALSO WITH THE MODELS ALSO BRINGS MUCH COLDER AIR
INTO EASTERN MONTANA WITH 850MB TEMPERATURES AROUND -24C SUNDAY
NIGHT. EBERT


&&

.AVIATION...
IFR CONDITIONS WITH LOW CLOUD WILL IMPACT THE TAFS SITES TODAY
WITH CEILINGS IMPROVING HAS HIGH PRESSURE PUSHES SOUTH TONIGHT.


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR
GARFIELD...PETROLEUM...SOUTHWEST PHILLIPS.

&&

$$

WEATHER.GOV/GLASGOW





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