Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 011041
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
341 AM MST SUN FEB 1 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...
ONE SYSTEM WITH SNOWFALL THROUGH THE REGION THIS MORNING...TWO
MORE TO COME OVER THE NEXT FEW DAYS.

SKIES CLEARING AND ARCTIC AIR FILTERING SOUTH FROM CANADA THIS
MORNING. TEMPERATURES DROPPING BELOW ZERO AS THE CLOUDS DEPART
OVER SEVERAL INCHES OF FRESH SNOWFALL. UPPER RIDGE TO THE WEST
BEGINS TO PUSH A LITTLE EAST TODAY WITH WARMER MIDLEVEL AIR MOVING
OFF THE MOUNTAINS. WITH FRESH SNOW ACROSS THE CENTRAL PART OF THE
CWA TEMPERATURES MAY BE SLOW TO RECOVER EVEN WITH SUNSHINE TODAY.

WEAK SHORTWAVE BRINGS MOISTURE ACROSS THE ARCTIC BOUNDARY LATE
TONIGHT INTO MONDAY MORNING...FOR SOME LIGHT SNOW MAINLY FROM THE
NORTHWEST TO SOUTHEAST ACROSS THE CWA. SURGE OF COLD AIR BEHIND
THE WAVE WILL PUSH THE BOUNDARY SLIGHTLY SOUTHWEST ON MONDAY. A
STRONGER WAVE THEN SLIDES ALONG THE BOUNDARY MONDAY NIGHT INTO
TUESDAY WITH A BETTER POTENTIAL FOR MEASURABLE SNOW...WITH SEVERAL
INCHES POSSIBLE BY TUESDAY AFTERNOON. EBERT


.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
A PACIFIC RIDGE AND BROAD EASTERN CONUS TROUGH WILL MAINTAIN
NORTHWEST FLOW ALOFT ACROSS THE NORTHERN HIGH PLAINS AS THE
EXTENDED PERIOD BEGINS TUESDAY NIGHT. AN UPPER LEVEL SHORTWAVE
WILL BE EXITING NORTHEAST MONTANA AND PUSHING INTO THE DAKOTAS.
THE TIMING AND TRACK OF THIS FEATURE WILL BE CRITICAL FOR
TEMPERATURE FORECASTS OVERNIGHT. IF THE SYSTEM PUSHES OUT MORE
PROGRESSIVELY...SKY CONDITIONS COULD ABRUPTLY CLEAR. GIVEN 850MB
TEMPERATURES IN THE -15C TO -20C RANGE AND ABUNDANT NEW SNOW
COVER...EFFICIENT RADIATIONAL COOLING COULD RESULT. THE RESULT
WOULD BE LOWS WELL BELOW ZERO ACROSS THE REGION. HOWEVER...SHOULD
THE SYSTEM EXIT MORE SLOWLY THE RESULT WOULD BE LINGERING CLOUD
COVER AND TEMPERATURES SOMEWHAT LESS COLD. WILL HAVE A MIDDLE OF
THE ROAD APPROACH FOR NOW...SLIGHTLY COLDER THAN THE 00Z MODEL
GUIDANCE...ESPECIALLY CONSIDERING THAT GUIDANCE LIKELY DOES NOT
FACTOR IN ALL THE NEW SNOW COVER OUT THERE.

MODELS EXHIBIT FAIRLY GOOD AGREEMENT HAVING THE PACIFIC RIDGE
TRANSLATE EASTWARD DURING THE MIDDLE AND LATTER HALF OF THE
WEEK...LEADING TO GRADUALLY WARMING TEMPERATURES AND DRY
CONDITIONS. AT SOME POINT A SHORTWAVE TROUGH UPSTREAM MAY FLATTEN
THE RIDGE AND BRING ABOUT RENEWED PRECIPITATION CHANCES TO THE
CWA. WILL CARRY A SLIGHT CHANCE POP FOR FRIDAY AND SATURDAY AS
CURRENT MODEL GUIDANCE SHOWS A FAIR AMOUNT OF VARIANCE ON SPECIFIC
HANDLING OF SHORTWAVES. PRECIPITATION TYPE MAY ALSO PROVE TO BE A
CHALLENGE. ENSEMBLE 500MB HEIGHTS SHOW INCREASING SPREAD THIS FAR
OUT INTO THE EXTENDED PERIOD...LENDING TO FURTHER UNCERTAINTY.
FUTURE SHIFTS WILL BE ABLE TO MAKE REFINEMENTS AS GUIDANCE ARRIVES
AT CONSENSUS. MALIAWCO


&&

.AVIATION...
FLURRIES ARE POSSIBLE VERY EARLY THIS MORNING. OTHERWISE EXPECT
VFR CONDITIONS WITH LIGHT SOUTHERLY WINDS TO PREVAIL THROUGH THE
DAY. MALIAWCO

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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