Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 232030
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
230 PM MDT WED APR 23 2014

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

SYNOPTIC SET UP... A RIDGE RUNS FROM THE TEXAS PANHANDLE THROUGH
THE CENTRAL AND NORTHERN PLAINS WHILE A TROUGH JUTS DOWN FROM
SOUTHERN BRITISH COLUMBIA THROUGH IDAHO AND WESTERN MONTANA.
NORTHEAST MONTANA LIES BETWEEN THESE TWO FEATURES IN A SOUTHERN TO
SOUTHWESTERN FLOW PATTERN. FARTHER WEST... A WEAK RIDGE RUNS UP
THE COAST OF THE US AND CANADA WITH A LARGE TROUGH RIGHT BEHIND IT
OVER THE GULF OF ALASKA AND BEARING SEA.

TONIGHT THROUGH THURSDAY... COOL AIR ALOFT WILL MOVE THROUGH THE
AREA WITH THE TROUGH. THIS WILL STABILIZE THE ATMOSPHERE AND
CREATE DRY CONDITIONS. THE TROUGH IS EXPECTED TO BE BUMPED OUT
RAPIDLY AS THE COASTAL RIDGE MOVES INLAND THURSDAY.

THURSDAY NIGHT... A RIDGE WILL MOVE OVER THE AREA WITH A WARM
FRONT NEAR THE SURFACE. WARM FRONT COULD BECOME THE FOCAL POINT
FOR LOW CLOUDS AND SOME WEAK RAIN SHOWERS. THE GULF OF ALASKA
TROUGH WILL DROP SOUTH AND BEGIN PUMPING MOISTURE OVER THE
INTERMOUNTAIN WEST AND SOME OF THIS MAY ALSO INTERACT WITH THE
WARM FRONT OVERNIGHT BEFORE IT MOVES INTO CANADA.

FRIDAY... THE NEW RIDGE ALOFT WILL AMPLIFY AND WARM THE REGION.
THIS WARM AIR ALOFT SHOULD STABILIZE THE MID ATMOSPHERE AND
PREVENT ANY SHOWERS AND THUNDERSTORMS INITIALLY FRIDAY. HOWEVER...
THE TROUGH OFF THE US SHORE WILL MOVE INLAND AND SHOULD BE PUMPING
A LOT OF COOLER AIR AND PACIFIC MOISTURE AROUND ITS EDGES INTO
EASTERN MONTANA. THIS WILL SHOW UP AS HIGH TO MID LEVEL CLOUDS DURING
THE LATE AFTERNOON AND EVENING HOURS. SO... CONDITIONS WILL BEGIN
TO DESTABILIZE AT THIS POINT. GAH


.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
MODELS HAVE WARMED A BIT WITH WEEKEND SYSTEM AND THEREFORE HAVE
TRIMMED MENTION OF SNOW IN MOST PLACES. SOME ELEVATED COOL SPOTS
WILL BE THE MOST LIKELY PLACES TO SEE A LITTLE SNOW OR MIX. THE
ECMWF HAS BEEN THE COOL MODEL OF LATE BUT NOW WARMED UP THINGS WITH
0*C 850 MB ISOTHERM NEAR THE CANADIAN BORDER. QPF/S LOOK PRETTY GOOD
FOR MOST PLACES WITH TOTAL AMOUNTS NEAR AN INCH BY MONDAY. TFJ

PREVIOUS DISCUSSION...
THE EXTENDED FORECAST PERIOD BEGINS FRIDAY EVENING WITH A TROUGH
OVER THE WEST COAST WITH ITS BASE PICKING UP PACIFIC MOISTURE OFF
SOUTHERN CALIFORNIA. THIS MOISTURE WILL BE EJECTED NORTHEAST INTO
MONTANA BEGINNING FRIDAY NIGHT. THIS TROUGH...AND THE COLD TROUGH
CENTERED OVER HUDSON BAY...WILL HAVE SQUEEZED UP A RIDGE OVER
MONTANA THAT WILL SWIFTLY MOVE SOUTHEAST. THIS WILL PLACE THE
BOUNDARY...SEPARATING THE NORTHERN COLD AIR MASS FROM THE SOUTHERN
AIR MASS...OVER NORTHEAST MONTANA. THE OVERRUNNING MOISTURE WILL
FIND THIS BOUNDARY AS A FOCAL POINT FOR PRECIPITATION INTO
SATURDAY AND SATURDAY NIGHT. BY SUNDAY MORNING THE TROUGH MOVES
INTO COLORADO WHERE IT STACKS UP THE THE SURFACE LOW TO FORM AN
INVERTED TROUGH OVER EASTERN MONTANA. THIS WILL CHANNEL MORE
MOISTURE IN FROM THE SOUTHEAST FOR WRAP-AROUND PRECIPITATION
THROUGH SUNDAY...TAPERING OFF THROUGH MONDAY. A SIGNIFICANT
UNCERTAINTY IS THE PRECIPITATION TYPE...WITH THE GFS FAVORING RAIN
AND THE EC FAVORING SNOW. WENT MIDDLE OF THE ROAD AND KEPT BOTH
RAIN AND SNOW IN THE GRIDS.

THE SITUATION BECOMES EVEN MORE CLOUDED AFTER MONDAY WHEN A RIDGE
BEGINS TO BUILD UP OVER THE WEST. THE GFS PUSHES A WARM FRONT OVER
EASTERN MONTANA ON TUESDAY. THE EC HOWEVER KEEPS THE WARM AIR MASS
WELL TO THE SOUTHWEST...OVER CALIFORNIA. SO...THE EC MAINTAINS WET
AND COOL. THUS...THERE IS GREAT UNCERTAINTY WITH TEMPERATURES BETWEEN
THE MODELS TOWARDS THE END OF THE EXTENDED PERIOD CONCERNING
NORTHEAST MONTANA.


&&

.AVIATION...
VFR. THE BIG STORY WILL BE THE DIMINISHING WINDS EARLY THIS EVENING.
THE COLD FRONT HAS SWEPT INTO THE DAKOTAS THIS AFTERNOON AND
RAINSHOWERS ARE EXPECTED TO EXIT THE SIDNEY AREA BY EVENING. EXPECT
PATCHY MID-LEVEL CLOUDS INTO THURSDAY. WEST WINDS ARE EXPECTED TO
PICK-UP THURSDAY WITH SPEEDS BETWEEN 10 AND 20 KTS. TFJ


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 9 PM MDT THURSDAY FOR FORT PECK LAKE
FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW





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