Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 051548
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
948 AM MDT SAT SEP 5 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
UPDATE...
POPS WERE ADJUSTED THIS MORNING TO MORE ACCURATELY REPRESENT
OBSERVATIONS ACCORDING TO RADAR AS WELL AS NEAR TERM EXPECTATIONS.
SOME SPREAD IN SHORT TERM GUIDANCE EXISTS WITH REGARD TO COVERAGE
IN THE WESTERN ZONES...LEADING TO REDUCED CONFIDENCE...WHILE
REALLY GOOD CONSENSUS EXISTS NEAR THE NORTH DAKOTA BORDER.
THEREFORE FEEL MOST COMFORTABLE WITH CATEGORICAL POPS FURTHER
EAST...AND THIS IS WHERE ADDITIONAL RAINFALL TOTALS MAY APPROACH
AND EVEN EXCEED AN INCH.

OTHER MAIN CONCERN WILL BE SEVERE WEATHER THIS AFTERNOON AND
ESPECIALLY THIS EVENING. FOLLOWING THE SSEO THE GREATEST RISK
APPEARS TO BE SOUTH OF THE MISSOURI RIVER AS STORMS TRACK IN FROM
THE SOUTH IN A MORE UNSTABLE AIR MASS. WHILE AN ISOLATED STRONG TO
SEVERE STORM CANNOT BE RULED OUT AT ANY TIME TODAY...FEEL THAT THE
MOST LIKELY TIME FRAME OF CONCERN WILL BE AFTER ABOUT 6 PM THIS
EVENING. EXPECT UPDATES TO THE FORECAST AS THE SITUATION EVOLVES
THROUGH THE DAY. MALIAWCO

PREVIOUS DISCUSSION...

WITH THE FIRST WAVE OF THUNDERSTORMS THROUGH NE MONTANA AS OF
EARLY THIS MORNING...THE LABOR DAY WEEKEND STORM SYSTEM WILL
CONTINUE TO SUSTAIN MULTIPLE WAVES OF SHOWERS AND THUNDERSTORMS
OVER THE REGION THROUGH EARLY SUNDAY MORNING.

FORECAST CHALLENGES WILL INCLUDE TIMING OF THE DRY SLOT NOW
PROGGED IN EXCELLENT MODEL CONSENSUS. FOR NOW...SHOWED THE DRY
SLOT WITH LOWER POPS...BUT STILL LEFT SOME SLIGHT CHANCE IN THERE.

THE SECOND WAVE OF STORMS IS EXPECTED NOW THROUGH EARLY THIS
AFTERNOON. WITH PARTIAL CLEARING IN THE DRY SLOT LATER THIS
AFTERNOON...THE THIRD WAVE OF STORMS WILL BREAK THE CAP AND
STRENGTHEN INTO MARGINALLY SEVERE STORMS LATER THIS AFTERNOON AND
EVENING GENERALLY NEAR AND SOUTH OF A LINE FROM JORDAN TO
SIDNEY...LASTING THROUGH LATE SATURDAY NIGHT.

SUNDAY AND MONDAY...WITH THE MAIN CIRCULATION HAVING LIFTED NORTH
OVER SASKATCHEWAN...MAIN FORCING FOR ASCENT AND RESULTING
PRECIPITATION WILL LIFT AWAY FROM NE MONTANA WITH ONLY A FEW
LINGERING SHOWERS POSSIBLE NEAR OUR CWA NW CORNER LATE SUNDAY
NIGHT. IN ITS WAKE...STRONG SUBSIDENCE WILL TAKE ITS PLACE AND
MIX DOWN STRONG AND GUSTY MID-LEVEL WINDS...EASILY IN THE 30 G 40
MPH RANGE. A LAKE WIND ADVISORY IS EXPECTED FOR SUNDAY.

EXPECT COLDEST LOW TEMPERATURES WITH THIS STORM SYSTEM TO BE
SUNDAY NIGHT AND MONDAY MORNING WITH 30S SETTLING IN OVER SOME
LOCATIONS NEAR THE CANADIAN BORDER. BMICKELSON


.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
NORTHEAST MONTANA WILL REMAIN IN NORTHWEST FLOW ALOFT TUESDAY AND
WEDNESDAY AS UPPER LOW REMAINS OVER MANITOBA. THE NW FLOW ALOFT
WILL KEEP TEMPERATURES COOLER THAN NORMAL. A SHORTWAVE TROUGH
TUESDAY NIGHT AND WEDNESDAY MORNING WILL BRING A COLD FRONT
THROUGH THE AREA WITH ENOUGH MOISTURE FOR A SLIGHT CHANCE OF
SHOWERS OVER MOST OF THE AREA.

THE UPPER LOW SLOWLY DRIFTS EAST ACROSS HUDSON BAY ON THURSDAY
WHILE NW FLOW ALOFT CONTINUES OVER THE FORECAST AREA. THE
SHORTWAVE TROUGH MOVES THROUGH NORTHEAST MONTANA WITH THE GFS DRY
AND ECMWF HAVING SOME MOISTURE. WILL MAINTAIN GOING DRY FORECAST
FOR NOW.

AN UPPER RIDGE WILL BUILD IN THE EASTERN PACIFIC LATE IN THE WEEK
WHICH WILL KEEP NW FLOW ALOFT GOING OVER THE FORECAST AREA.
SURFACE HIGH PRESSURE WILL BRING DRY WEATHER FRIDAY AND SATURDAY.
FORRESTER


&&

.AVIATION...
SYNOPSIS: AN UPPER LOW FROM THE PACIFIC NORTHWEST WILL MOVE
NORTHEAST ACROSS MONTANA TONIGHT AND SUNDAY MORNING.

FLIGHT CATEGORY: HIGHLY VARIABLE TODAY AND TONIGHT AS SHOWERS...LOW
CLOUDS AND DRY SLOTS WILL OCCUR AT VARIOUS TIMES. CONDITIONS COULD
CHANGE RAPIDLY FROM VFR TO IFR AND BACK TO VFR IN A SHORT PERIOD
OF TIME. SO LOOK A MIX OF VFR... MVFR AND IFR CONDITIONS.

WX: SHOWERS AND THUNDERSTORMS WILL OCCUR AT TIMES THROUGH THE
ENTIRE PERIOD. SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON
AND EVENING.

WIND: MAINLY NORTHEAST 10 TO 20 KNOTS WITH HIGHER GUSTS AT TIMES
TODAY. WINDS BACKING TO THE NORTH AND NORTHWEST AT 10 TO 15 KNOTS
TONIGHT.


&&

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

&&

$$

WEATHER.GOV/GLASGOW


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