Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 240258 AAA
AFDGGW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
858 PM MDT WED APR 23 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
VERY ISOLATED SHOWERS IN THE WESTERLY FLOW ARE WANING WITH THE
SUNSET THIS EVENING. SO POP/WX GRIDS ARE FINE FOR TONIGHT. THERE
STILL IS AN AREA IN THE NE CORNER WHERE OVERRUNNING MOISTURE HAS
FOUND A REMNANT OF THE COLD FRONT. SO A FEW SHOWERS ARE STILL
POSSIBLE THERE. BUT THAT IS COVERED IN THE GRIDS. THERE WILL BE
SCATTERED CLOUDS ABOUT TONIGHT WITH THE COLDER AIR-MASS IN PLACE.
SO TEMPERATURES SHOULD FALL INTO THE LOWER 30S TONIGHT. THE MAIN
WEATHER EVENT SHOULD BE THE CONTINUING WESTERLY WIND TONIGHT. A
CLOSED SURFACE LOW PARKED OVER SOUTHERN SASKATCHEWAN WILL KEEP
A BRISK WIND CHURNING ALL NIGHT AND INTO THURSDAY MORNING. SO
ADJUSTED WIND GRIDS BASED ON CURRENT OBSERVATIONS AND THE LATEST
GUIDANCE. SCT

LATE AFTERNOON UPDATE...
UPDATE TO THE FORECAST WAS TO ACCOUNT FOR A FEW SURFACE BASED
SHOWERS WHICH HAVE MOVED INTO PHILLIPS GARFIELD AND PETROLEUM
COUNTIES. THESE ARE EXPECTED TO DIE OFF IN THE NEXT FEW HOURS AND
BE GONE BY THE LATE EVENING. GAH

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 INTER-
MOUNTAIN 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...
FLIGHT CATEGORY: VFR.

SYNOPSIS: THE LOW PRESSURE SYSTEM THAT BROUGHT SHOWERS TO MUCH OF
THE REGION EARLIER TODAY...WILL CONTINUE TO EXIT INTO THE DAKOTAS
THROUGH THURSDAY MORNING. BY THURSDAY AFTERNOON WEAK RIDGING ALOFT
WILL MAKE FOR CONTINUED GOOD FLYING WEATHER.

VISIBILITY: NO RESTRICTIONS.

CIGS: SCATTERED HIGH CLOUDS.

WINDS: WESTERLY WINDS WILL CONTINUE TO TAPER OFF THIS EVENING TO 8
TO 12 KTS OVERNIGHT...BEFORE AGAIN INCREASING TO 10 TO 20 KTS BY
LATE MORNING.


&&

.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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