Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 270555
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1055 PM MST FRI DEC 26 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
11PM UPDATE...
CURRENT TEMPERATURES HAVE FALLEN BELOW FORECAST MINIMUMS IN A FEW
PLACES ALONG WESTERN EDGES OF THE CWA. THIS IS MAINLY DUE TO CLEAR
SKY CONDITIONS AND LIGHT WINDS HELPING TO PROMOTE HIGHLY EFFICIENT
RADIATIONAL COOLING. THE FORECAST HAS BEEN ADJUSTED TO REFLECT
THESE TRENDS ALTHOUGH WILL NEED TO CONTINUE TO MONITOR CONDITIONS
OVERNIGHT. MALIAWCO

825PM UPDATE... LOW CLOUDS WILL LINGER NEAR THE NORTH DAKOTA
BORDER OVERNIGHT WITH SOME CLEARING FURTHER TO THE WEST. LIGHT
WINDS WILL MEAN EFFICIENT RADIATIONAL COOLING SO EXPECT LOWS IN
THE SINGLE DIGITS ABOVE ZERO...ESPECIALLY WHERE SKY CONDITIONS
BECOME CLEAR. MALIAWCO

PREVIOUS DISCUSSION...

LIGHT SNOW SHOWERS WERE OBSERVED THIS AFTERNOON OVER PORTIONS OF
NORTHEAST MONTANA AS A WEAK IMPULSE CAME DOWN FROM CANADA.

MINOR RIDGING OVER THE REGION WILL KEEP TEMPERATURES FAIRLY WARM
EAST OF THE ROCKIES THROUGH SATURDAY BEFORE THEY DROP
CONSIDERABLY BY MONDAY. A SHORTWAVE TROUGH SLIDING DOWN THE BC
COAST WILL CURVE INLAND AND DROP SOUTH ALONG THE ROCKIES ON
SUNDAY. THIS WILL KEEP MOST OF THE MOISTURE ALONG THE MOUNTAINS
BUT COULD SPREAD FAR ENOUGH EAST FOR A LITTLE SNOW ACROSS THE
PLAINS SATURDAY NIGHT INTO SUNDAY. PRECIPITATION TYPE WITH THIS
SYSTEM IS EXPECTED TO BE ALL SNOW. COLD AIR INFILTRATE THE REGION
IN THE WAKE OF THE WAVE RESULTING IN STEADY OR FALLING TEMPERATURES
ON SUNDAY.AEC


.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
THE LONG RANGE PERIOD BEGINS WITH A BROAD LONG-WAVE TROUGH OVER
THE CONUS WITH NORTHWEST FLOW OVER THE NORTHERN HIGH PLAINS SUNDAY
NIGHT AS LIGHT SNOW AND ARCTIC BOUNDARY EXITS THE FORECAST AREA TO
THE SOUTH.

ARCTIC TEMPERATURES ARE EXPECTED EARLY NEXT WEEK. IN FACT...THE
00Z ECMWF ADVERTISES 850MB TEMPERATURES INTO THE LOWER MINUS 20S
CELSIUS ACROSS NORTHEAST MONTANA BY TUESDAY MORNING. EXPECT
TEMPERATURES TO BE WELL BELOW ZERO AT THAT TIME...ESPECIALLY AREAS
WITH SNOW COVER.

A NW TO SE ORIENTED EXTENSION OF A LARGE RIDGE OFF THE PACIFIC
NORTHWEST COAST WILL SPREAD INTO THE REGION FOR MIDWEEK ALLOWING
FOR MODERATING TEMPERATURES BEFORE THE NEXT ARCTIC BOUNDARY
PLUNGES SOUTH BY LATE NEXT WEEK OR BY THE WEEKEND. AT THIS POINT
ENSEMBLE 500MB HEIGHTS SHOW A LARGER DEGREE OF SPREAD AND SO THE
COLDEST AIR COULD STILL PUSH OFF TO THE NORTHEAST...BUT DO EXPECT
THAT THE CWA WILL FEEL AT LEAST SOME EFFECTS OF ARCTIC AIR AS THE
EXTENDED PERIOD COMES TO FINISH. ADDITIONALLY...ENOUGH MOISTURE
MAY SPILL OVER THE ARCTIC AIR MASS BEHIND THE FRONT TO ALLOW FOR A
PERIOD OF LIGHT SNOW. WILL HAVE SLIGHT CHANCE POPS TO COVER THAT
POTENTIAL FOR NOW WITH TIMING/PLACEMENT DETAILS FAR UNCERTAIN AT
THIS TIME. MALIAWCO


&&

.AVIATION...
OVERALL VFR CONDITIONS ARE ANTICIPATED ACROSS THE AREA...HOWEVER
LOW CLOUDS WILL LINGER MOST OF THE NIGHT AT KSDY AND KGDV WITH
CEILINGS 2500 TO 4000 FEET WHICH MEANS MVFR CEILINGS AT TIMES. A
MIX OF MID AND HIGH LEVEL CLOUDS WILL MOVE INTO NORTHEAST MONTANA
DURING THE DAY ON SATURDAY AHEAD OF LIGHT SNOW THAT COULD IMPACT
THE TAF SITES SATURDAY NIGHT AND SUNDAY. LIGHT WINDS OVERNIGHT
WILL TURN WESTERLY AROUND 10 KNOTS SATURDAY AFTERNOON.

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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