Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 190846
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
246 AM MDT FRI SEP 19 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
COLD FRONT WILL MOVE THROUGH EASTERN MONTANA THIS MORNING TURNING
WINDS TO THE NORTHWEST. ISOLATED SHOWERS AND THUNDERSTORMS HAVE
OCCURRED AT TIMES OVERNIGHT ALONG THIS FRONT. WILL MAINTAIN A
SLIGHT CHANCE IN THE EAST THIS MORNING. EXPECT NORTHWEST WINDS TO
INCREASE ENOUGH THIS MORNING TO WARRANT KEEPING THE LAKE WIND
ADVISORY IN EFFECT.

WSW FLOW ALOFT WILL TURN WNW TODAY AS A SHORTWAVE TROUGH MOVES
THROUGH THE AREA THIS MORNING. A SECOND SHORTWAVE MOVES THROUGH
THE FORECAST AREA THIS AFTERNOON. MOISTURE AND UPPER LEVEL
DYNAMICS WILL BE FOCUSED IN THE NE CORNER OF THE STATE WITH THIS
WAVE. THERE WILL ALSO BE ENOUGH INSTABILITY THAT A FEW
THUNDERSTORMS ARE POSSIBLE. WILL MENTION A CHANCE OF SHOWERS AND
THUNDERSTORMS THAT WILL EXTEND THROUGH TONIGHT AS MODELS WANT TO
BRING A THIRD SHORTWAVE THROUGH THE SAME AREA LATE TONIGHT AND
SATURDAY MORNING.

SURFACE HIGH PRESSURE BUILDS INTO THE AREA ON SATURDAY WITH COOLER
TEMPERATURES. EXPECT DRY WEATHER AFTER THE SHORTWAVE DEPARTS IN
THE MORNING. NORTHWEST MAY BE STRONG ENOUGH AGAIN FOR ANOTHER
LAKE WIND ADVISORY. WILL NOT EXTEND THE LAKE WIND INTO SATURDAY
FOR NOW AS WIND SPEEDS ARE FORECASTED TO BE MARGINAL.

SURFACE HIGH WILL DIMINISH THE WINDS SATURDAY NIGHT AND REMAIN
OVER THE AREA ON SUNDAY KEEPING WINDS LIGHT AND SKIES MOSTLY
CLEAR. FORRESTER


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

THE EXTENDED PERIOD BEGINS MONDAY NIGHT WITH AN AMPLIFIED LONG-
WAVE RIDGE IN PLACE OVER WESTERN CONUS AND CANADA. A CLOSED OFF
LOW CENTERED OVER THE NORTHERN REACHES OF THE GREAT BASIN WILL CUT
ACROSS THE RIDGE AS THE RIDGE AXIS SHIFTS EAST. THE LOW WILL
GENERALLY CUT UNDER NORTHEAST MONTANA...MAINLY AFFECTING SOUTHERN
MONTANA. THE RIDGE IN PLACE WILL BRING MORE WARMING TO THE REGION
WITH TEMPERATURES RAMPING UP ABOVE NORMAL AGAIN.

MONDAY NIGHT THE LOW OPENS AND MOVES ACROSS A SURFACE TROUGH. THIS
COULD LEAD TO SOME INSTABILITY THAT COULD PRODUCE A FEW SHOWERS
AND ISOLATED THUNDERSTORMS INTO TUESDAY. ON WEDNESDAY THE RIDGE
REESTABLISHES ITSELF AS A DEEP TROUGH/EASTERN PACIFIC STORM PUSHES
UP AGAINST THE CASCADE RANGE. THERE IS A VERY DISTINCT COLD FRONT
ASSOCIATED WITH THIS STORM SYSTEM. THE MAIN QUESTION IS IF IT HAS
ENOUGH STRENGTH TO BREAK DOWN THE RIDGE OVER EASTERN MONTANA. HERE
IS WHERE THE MODELS DIFFER. THE EC HAS THE FRONT STALLING OUT TO
OUR WEST...WHILE THE GFS PUSHES THE FRONT ACROSS EASTERN MONTANA
FRIDAY NIGHT AND SATURDAY. THE SIGNIFICANCE OF THE STRONG FRONT IS
THE WARM TEMPERATURES IN PLACE. SO WHERE THE FRONT HITS THERE WILL
BE RAIN AND THUNDER FROM THE CANADIAN BORDER TO THE MEXICAN
BORDER. MODEL DIFFERENCES ADD TO THE UNCERTAINTY AFTER MID WEEK. SCT


&&

.AVIATION...

A WEAK SHALLOW TROUGH AND COLD FRONT WILL MOVE ACROSS THE AREA
TODAY. THIS WILL BRING BROKEN MID-TO-LOW CLOUDS OVER THE TAF
SITES. IN ADDITION...BRIEF ISOLATED-TO-SCATTERED SHOWERS AND
THUNDERSTORMS COULD BE GENERATED. THIS COULD TEMPORARILY DROP
CEILINGS TO LESS THAN VFR AS ANY AFTERNOON STORM PASSES.

WIND...TODAY EXPECT WESTERLY WIND TO VEER NORTHWEST AND INCREASE
TO AROUND 15KT TO 25KT...DIMINISHING IN THE EVENING. SCT

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 11 AM THIS MORNING TO 9 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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