Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 252131
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
231 PM MST THU DEC 25 2014

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

MAIN LONGWAVE TROUGH HAS DUG ITSELF INTO THE FOUR CORNERS AREA
WITH THE SURFACE LOW WELL SOUTH OF MONTANA. THIS HAS LEFT THE CWA
OUT OF AREAS RECEIVING SNOW TODAY. COLD AIR...HOWEVER...DOES
FOLLOWING BEHIND THIS SYSTEM ACROSS MONTANA WITH NORTHERLY FLOW
THROUGH THIS EVENING THAT WILL MAKE THE NEXT COUPLE DAYS CLOSER TO
SEASONAL NORMALS AND MUCH COLDER THAN RECENT HISTORY. 10 TO 15 MPH
NORTHERLY WINDS TODAY WILL SLACKEN TONIGHT TO AROUND 5 MPH AND BE
MORE VARIABLE THROUGH SATURDAY.

THERE IS A CHANCE OF SOME LIGHT SNOW FRIDAY LATE MORNING AND
AFTERNOON AS A SMALL SHORTWAVE MOVES DOWN FROM ALBERTA ACROSS THE
AREA. LIMITED FORCING AND VERY LIMITED MOISTURE SUGGESTS ONLY
SLIGHT AMOUNTS OF SNOW...MOST LIKELY LESS THAN HALF AN INCH.
CANADIAN RADARS HAVE BEEN SHOWING SOME LIGHT SNOW AT TIMES
UPSTREAM WITH THIS SYSTEM...SO DO EXPECTED SOME PATCHES OF LIGHT SNOW
TOMORROW IN NE MONTANA AS SYSTEM PASSES.  MARTIN

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...

A LARGE LONG-WAVE TROUGH DEVELOPS OVER CONUS. THE TROUGH WILL
ANCHORED BY AN ARCTIC LOW NEAR HUDSON BAY. THE COLD AIR OF THIS
TROUGH WILL KEEP MUCH OF THE THE EXTENDED PERIOD COLDER THAN
NORMAL.

THE PERIOD STARTS WITH NORTHWEST FLOW ALOFT OVER NORTHEAST MONTANA
AND THE MODIFIED ARCTIC BOUNDARY STRETCHING NW TO SE THROUGH
SOUTHERN SASKATCHEWAN. OFF TO THE WEST A SHORT-WAVE DISTURBANCE
WILL KICK ACROSS VANCOUVER ISLAND TO SEND PACIFIC MOISTURE OVER
THE DIVIDE. THE SHORT-WAVE DEEPENS THE WESTERN PORTION OF THE
TROUGH AND DRAGS THE BOUNDARY FURTHER SOUTH ACROSS THE FORECAST
AREA. OVERRUNNING MOISTURE WILL SPREAD SNOW ALONG THE FRONTAL
BOUNDARY ESSENTIALLY ALONG THE SAME TRACK AS THE CHRISTMAS EVE
STORM. EXPECT SNOW TO SPREAD ACROSS CENTRAL AND SOUTHEAST MONTANA
AND THE SOUTHWEST PORTION OF NEMONT. SO BY SUNDAY EVENING THE SNOW
WILL HAVE MOVED OUT OF THE AREA TO BE FOLLOWED BY MUCH COLDER AIR
OF A POLAR SURFACE HIGH.

A LARGE RIDGE OFF THE WEST COAST WILL MOVE IN BEHIND THE AMPLIFIED
TROUGH TO BEING ABOUT A RETURN TO NEAR NORMAL TEMPERATURES AFTER
MID-WEEK.

SCT


&&

.AVIATION...

LOW CLOUDINESS TODAY WITH CEILINGS AROUND 2000FT WILL PERSIST
THROUGH EARLY EVENING AT LEAST...HOWEVER SOME IMPROVEMENT IS
EXPECTED TONIGHT WITH SOME DRYING AT LOW LEVELS. CLOUDS WILL
INCREASE AND CEILINGS WILL DECLINE AGAIN FRIDAY MORNING WITH SOME
AREAS MVFR DUE TO LOWERED CEILINGS...DUE TO A WEAK STORM SYSTEM
CROSSING OVER THE AREA. SOME AREAS OF LIGHT SNOW ARE EXPECTED WITH
THE SYSTEM THAT COULD DECREASE VISIBILITY TO MVFR AS WELL.

NORTHERLY WINDS OF 10 TO 15 KTS WILL DECREASE TO AROUND 5 KTS TONIGHT
AND BECOME VARIABLE THROUGH FRIDAY.  MARTIN

&&

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

&&

$$

WEATHER.GOV/GLASGOW





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