Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 100252
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
852 PM MDT WED JUL 9 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
UPDATE...MINOR UPDATE TO TEMPERATURES OTHERWISE THE SURFACE TROUGH
THROUGH THE CENTRAL PART OF THE STATE. STILL LOOKS LIKE A COUPLE
OF THUNDERSHOWERS ARE POSSIBLE OVERNIGHT. PROTON

PREVIOUS DISCUSSION...SYNOPTIC SET UP... HOT HIGH PRESSURE SETS OVER THE
INTERMOUNTAIN WEST WITH A RIDGE RUNNING UP THROUGH WESTERN MONTANA
AND INTO ALBERTA. A TROUGH IS ORIENTED OVER ONTARIO AND THE HUDSON
BAY... BUT IS HAVE INCREASINGLY LESS INFLUENCE OVER EASTERN
MONTANA WHERE NORTHWEST FLOW IS GIVING WAY TO THE INCOMING RIDGE.
TO THE WEST... A TROUGH RUNS FROM SOUTHERN ALASKA DOWN INTO
NORTHERN BRITISH COLUMBIA WHERE IT IS ANTICIPATED TO RAM THROUGH
THE WEAK POINT OF THE NEIGHBORING CONTINENTAL RIDGE.

THIS AFTERNOON THROUGH THURSDAY MORNING... THE TROUGH OVER BRITISH
COLUMBIA WILL CROSS THE MOUNTAINS AND DRIFT SOUTH INTO ALBERTA.
THIS WILL FORCE FLOW TO BECOME SEMI-ZONAL TO SOUTHWEST OVERNIGHT
AND ALLOW A WEAK SHORTWAVE DISTURBANCE TO PASS OVER THE CWA.
SHOWERS AND THUNDERSTORMS ARE ANTICIPATED WITH THIS PASSAGE...
BUT DUE TO LACK OF MOISTURE WILL BE VERY HIT AND MISS ACROSS THE
CWA.

THURSDAY AFTERNOON... THE SHORTWAVE WILL ALSO BRING A LEE SIDE
MOUNTAIN TROUGH ACROSS THE REGION MID DAY THURSDAY. WINDS BEHIND
THE TROUGH ARE EXPECTED TO REACH UP TO 15 TO 25 MPH DURING THE
AFTERNOON HOURS AND WARRANT A LAKE WIND ADVISORY. SHOWERS ARE ALSO
EXPECTED TO CLEAR OFF TO THE EAST DURING THIS TIME. MEANWHILE...
THE LARGE TROUGH TO THE NORTH WILL TAP INTO COLD AIR OVER THE
NORTHWEST TERRITORIES AND DROP IT DOWN ALONG THE INTERNATIONAL
BORDER.

THURSDAY NIGHT INTO FRIDAY... A WEAK COLD FRONT OVERNIGHT WILL
DROP LOWS BACK INTO THE 50S. A COUPLE MODELS ARE HINTING AT
SHOWERS DEVELOPING OVER THE CENTRAL MONTANA MOUNTAINS AND PASSING
ACROSS THE SOUTHERN SECTIONS OF THE CWA DURING THE MORNING HOURS...
BUT THIS IS NOT UNIVERSAL FROM MODEL TO MODEL OR RUN TO RUN. THE
COOLER AIR WILL HOLD FOR AWHILE THROUGH FRIDAY WITH MOSTLY DRY
CONDITIONS ANTICIPATED. GAH

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...

AFTERNOON UPDATE...
FEW CHANGES WERE MADE THIS AFTERNOON. A LITTLE EXTRA CARE WAS GIVE
TO MONDAY NIGHT TUESDAY WHICH APPEAR TO HAVE SOME CHANGE. MODELS
ARE NOT SURE HOW FAR SOUTHWEST THAT INFLUENCE FROM A LOW OVER THE
CANADIAN PRAIRIES WILL REACH. WHEN THE LOW IS BUTTING UP AGAINST A
STRONG RIDGE OVER WESTERN MONTANA...THIS IS PRODUCING A LARGE
RANGE OF VALUES FOR TEMPERATURES AND MOVING TOWARD THE CENTER OF
THESE VALUES WHILE WAITING FOR MODEL GUIDANCE TO SORT ITSELF OUT
FELT PRUDENT. GAH

PREVIOUS LONG TERM DISCUSSION...
THE EXTENDED PERIOD BEGINS SATURDAY EVENING WITH AN UPPER LEVEL
RIDGE EXTENDING UP THROUGH WESTERN CANADA FROM THE GREAT BASIN
HIGH...AND A PERSISTENT UPPER LOW IN THE VICINITY OF THE HUDSON
BAY. AS A RESULT NORTHEAST MONTANA WILL BEGIN UNDER ZONAL FLOW
ALOFT. SO TEMPERATURES WILL BEGIN NEAR NORMAL.

THE CANADIAN LOW TO THE NORTH WILL ROTATE A SHORTWAVE AROUND ITS
BACKSIDE...SENDING A SUBTLE COLD FRONT SOUTH. THIS MAY INITIATE
SOME SHOWERS AND THUNDERSTORMS OVERNIGHT INTO SATURDAY MORNING.
BUT THIS IS NOT REALLY A WETTING RAIN SITUATION.

SATURDAY/SUNDAY...THE RIDGE AXIS BEGINS TO SHIFT EAST...NUDGING
THE DESERT AIR TO THE NORTH TO RAMP UP TEMPERATURES INTO THE 90S
AGAIN.

SUNDAY NIGHT AND MONDAY...ANOTHER SHORTWAVE ROTATING AROUND THE
EAST SIDE OF THE CANADIAN LOW WILL SEND YET ANOTHER COLD FRONT
SOUTH INTO THE LOCAL REGION. ADDITIONALLY...AN EMBEDDED PACIFIC
TROUGH FLATTENS THE RIDGE AS IT TRAVELS ACROSS THE DIVIDE. SHOWERS
AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE STATIONARY
BOUNDARY...WHICH WILL MOSTLY BE SOUTH OF NEMONT. BUT THERE WILL BE
A CHANCE SOME STORM WILL DEVELOP OR MOVE INTO OUR AREA.

MONDAY NIGHT AND TUESDAY...REMNANTS OF THE EMBEDDED TROUGH COULD
MOVE INTO NEMONT TO INITIATE A FEW MORE STORMS. BUT AGAIN...THE
CHANCES ARE NOT HIGH AND MOST WETTING RAINS APPEAR TO DEVELOP MORE
TO THE SOUTH.

THERE DOES NOT SEEM TO BE MUCH DISAGREEMENT BETWEEN THE GFS AND
THE EC IN GENERAL. SO OVERALL...CONDITIONS WILL CONTINUE WITH
NORMAL TO ABOVE NORMAL TEMPERATURES AND ISOLATED SHOWERS AND
THUNDERSTORMS.

SCT

&&

.AVIATION...
SMOKEY HAZE DIMINISHED: NORTHWEST WIND ALOFT LAST NIGHT HAS BECOME
WESTERLY TODAY. THE RESULT IS THAT VISUAL SATELLITE IMAGERY
SHOWS THE SMOKE PLUME FROM THE CANADIAN FIRES TO HAVE DRIFTED
FARTHER TO THE EAST...SO LOCAL TERMINAL VISIBILITIES HAVE IMPROVED
TO AT LEAST 10SM THIS EVENING.

LATE TONIGHT AND THURSDAY...A MEDIUM WAVE UPPER TROUGH SWINGING
ACROSS NORTHERN ALBERTA/SASKATCHEWAN WILL SEND A COLD FRONT SOUTH
INTO THE LOCAL REGION. IN ADDITION...WEAK EMBEDDED DISTURBANCES IN
THE WESTERLY FLOW ACROSS MONTANA IN COINCIDENCE WITH THE FRONT
WILL GENERATE RAIN SHOWERS AND THUNDERSTORMS. A SURFACE TROUGH
SWEEPING ACROSS THE AREA WILL ALSO SHIFT WIND AROUND TO THE
NORTHWEST THURSDAY AFTERNOON AND INCREASE TO 15-25KT. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TO 6 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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