Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 040855
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
255 AM MDT FRI SEP 4 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
UPPER TROUGH/LOW WILL CONTINUE TO DIG THROUGH THE PACIFIC
NORTHWEST TODAY WITH SOUTHWEST FLOW ALOFT CONTINUING OVER MONTANA.
A SHORTWAVE TROUGH WITHIN THE SW FLOW ALOFT IS CURRENTLY BRINGING
SCATTERED SHOWERS AND THUNDERSTORMS TO THE EASTERN HALF OF THE
FORECAST AREA. THERE ARE ADDITIONAL SHOWERS AND ISOLATED
THUNDERSTORMS OVER PARTS OF PHILLIPS AND PETROLEUM COUNTIES. ALL
OF THE SHOWERS ARE MOVING NNE.

WEAK WAVES WILL CONTINUE TODAY TO MOVE THROUGH EASTERN MONTANA.
MOISTURE WILL CONTINUE TO OVERRUN A QUASI-STATIONARY FRONTAL
BOUNDARY TO THE SOUTH OF THE FORECAST AREA ALLOWING FOR SCATTERED
SHOWERS ALONG WITH ISOLATED THUNDERSTORMS AT TIMES WITH A SOMEWHAT
UNSTABLE ATMOSPHERE. SURFACE LOW WILL DEVELOP OVER EASTERN WYOMING
AND WESTERN SOUTH DAKOTA WHICH WILL KEEP THE NORTHEAST WINDS GOING
OVER NORTHEAST MONTANA. THE WINDS HAVE BEEN STRONG ENOUGH
OVERNIGHT TO WARRANT ISSUING A LAKE WIND ADVISORY FOR FORT PECK
LAKE AND AT THIS POINT IT LOOKS LIKE THOSE WINDS WILL CONTINUE
TODAY.

DEEPER MOISTURE TONIGHT WILL COMBINE FRONTOGENSIS TO ENHANCE
PRECIP CHANCES OVER NORTHEAST MONTANA. SHOULD SEE WIDESPREAD RAIN
OVER MOST OF THE AREA ESPECIALLY AFTER MIDNIGHT. THE RAIN WILL
LIKELY CONTINUE INTO SATURDAY MORNING BUT COULD DIMINISH FOR A
WHILE IN THE SOUTH AS A DRY SLOT WORKS NORTH INTO THE FORECAST
AREA. HOWEVER...AIR MASS IS EXPECTED TO BECOME UNSTABLE IN THE
AFTERNOON AND ANY DRY SLOT THAT OCCURS WILL LIKELY FILL IN WITH
SHOWERS AND THUNDERSTORMS ESPECIALLY IN THE AFTERNOON. ATMOSPHERE
MAY BECOME UNSTABLE ENOUGH FOR A FEW SEVERE THUNDERSTORMS.

THE UPPER TROUGH MOVES INLAND ON SATURDAY AND THROUGH MONTANA
SATURDAY NIGHT. A TROWAL WILL ALSO FORM ACROSS SOUTHERN MONTANA
SATURDAY AFTERNOON AND MOVE NORTH ACROSS THE FORECAST AREA
ENHANCING PRECIPITATION. EXPECT WIDESPREAD RAIN ALONG WITH
THUNDERSTORMS AT TIMES SATURDAY NIGHT. RAIN CHANCES WILL DECREASE
IN THE SOUTH AFTER MIDNIGHT AS THE UPPER TROUGH AND TROWAL MOVES
NORTH.

THE UPPER TROUGH DEVELOPS INTO AN UPPER LOW IN SOUTHERN
SASKATCHEWAN SUNDAY MORNING AND BECOMES STACKED WITH THE SURFACE
LOW. MOST OF THE MOISTURE WILL BE NORTH OF THE CANADIAN BORDER
WHICH WILL DIMINISH PRECIP CHANCES. HOWEVER...THERE WILL BE A
TIGHT SURFACE GRADIENT OVER MONTANA WHICH WILL RESULT IN STRONG
WEST WINDS. TEMPERATURES WILL REMAIN ON THE COOL SIDE WITH HIGHS
IN THE 60S. FORRESTER



.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...

LONG TERM FORECAST PERIOD BEGINS AS THE CLOSED UPPER-LEVEL LOW
PRESSURE SYSTEM CENTER HAS ALREADY SHIFTED NORTH OF THE CANADIAN
BORDER WITH MONTANA. MOST OF THE PRECIPITATION WITH THIS LARGE
LABOR DAY WEEKEND STORM WILL HAVE FALLEN ACROSS NORTHEAST MONTANA
BY THIS TIME...BUT A FEW MODELS ARE INDICATING THAT THERE MAY BE
SOME LINGERING RAIN SHOWERS AND GUSTY NW WINDS LEFT OVER DUE TO A
TRAILING SHORT-WAVE DISTURBANCE WHICH MAY CLIP OUR CWA SUNDAY
NIGHT AND MONDAY.

TUESDAY AND BEYOND...EVEN THOUGH THE SYNOPTIC FLOW SHOWS A FEW
MODEL DISCREPANCIES...THE OVERALL PATTERN SUGGESTS A DRY AND
WARMER TREND WITH A STRONG RIDGE OF HIGH PRESSURE BUILDING IN
OVER THE SW STATES...THE INFLUENCE OF WHICH WILL REACH NE
MONTANA...AT LEAST IN PART.

TEMPERATURES ARE EXPECTED TO RETURN TO JUST BELOW NORMAL TOWARD
THE END OF THE FORECAST PERIOD. COMFORTABLE FOR THIS TIME OF YEAR.
BMICKELSON



&&

.AVIATION...

VFR CIGS AND VSBYS ARE EXPECTED TO GENERALLY PREVAIL THROUGHOUT
THE TAF PERIOD...WITH BRIEF MVFR INTERRUPTIONS IF A RAIN SHOWER
HAPPENS TO PASS DIRECTLY OVERHEAD THROUGH THE MORNING
HOURS. SOME GUSTY NORTHEAST WINDS COULD RAISE CROSSWIND CONCERNS
THIS MORNING. LESS RAIN SHOWER ACTIVITY IS EXPECTED DURING THE
AFTERNOON HOURS. MICKELSON


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW



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