Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 281736
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1036 AM MST SUN DEC 28 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...

SENT AN UPDATE THIS MORNING...MAINLY TO ADD WORDING OF BLOWING
SNOW WHERE THE SNOW IS MORE LIKELY TO FALL...AND SOME FREEZING FOG
BASED ON RECENT WEB CAM IMAGERY AROUND THE LITTLE ROCKIES AND FORT
PECK LAKE. GENERAL FORECAST CONCEPT REMAINS ON TRACK WITH SNOWFALL
GRADUALLY DIMINISHING FROM NORTH TO SOUTH THROUGHOUT THE DAY.
TEMPERATURES MAY ONLY REBOUND A DEGREE OR TWO TODAY BEFORE THE
COLDER AIR MASS SETS IN FROM CANADA. WILL RE-EVALUATE TEMPERATURES
AND WIND TODAY FOR POSSIBLE WIND CHILL HEADLINE PRODUCTS FOR THE
NEXT FORECAST PACKAGE COMING THIS AFTERNOON. BMICKELSON

PREVIOUS SHORT TERM DISCUSSION...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...
CIGS: IFR CONDITIONS THROUGH 00Z DUE TO LOW CEILINGS WILL IMPACT
THE TAFS SITES TODAY. CEILINGS AND LIGHT SNOWFALL WILL DECREASE
FROM THE NORTH AFTER 00Z AS UPPER TROUGH MOVES TO SOUTH OF
AERODROMES.

WINDS: WINDS WILL GENERALLY BE NORTHERLY AT 10 TO 15 KTS.

&&

.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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