Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 210914
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
314 AM MDT SUN SEP 21 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH TUESDAY...

THE DAY BEGINS WITH AN AMPLIFIED UPPER LEVEL LONG-WAVE PATTERN
OVER CONUS. THE EASTERN HALF WILL FEATURE A TROUGH...WHILE THE
WEST WILL BE UNDER A RIDGE. HOWEVER THERE WILL ALSO BE AN UPPER
LEVEL CUT-OFF CLOSED LOW OVER CENTRAL CALIFORNIA AND WESTERN
NEVADA. THE RIDGE AXIS WILL BE ON THE EAST SIDE OF THE CANADIAN
ROCKIES DIVIDE. THEREFORE NORTHEAST MONTANA WILL SEE NORTHWEST
FLOW ALOFT AND MOSTLY CLEAR SKIES WITH UNLIMITED VISIBILITY TODAY.

TODAY...THE SURFACE HIGH WILL MOVE OFF TO THE EAST WHICH WILL
DEVELOP A LIGHT SOUTHERLY BREEZE. WITH THE RIDGE AXIS SHIFTING
EAST TOWARDS NEMONT...THICKNESS HEIGHTS WILL BEGIN TO INCREASE.
THESE CONDITIONS WILL BEGIN A GENERAL WARMING THAT WILL CONTINUE
THROUGH THE SHORT TERM PERIOD. HIGHS TODAY...ON THE LAST FULL DAY
OF SUMMER...SHOULD RAMP UP SLIGHTLY ABOVE NORMAL.

TONIGHT...THE CUT-OFF LOW OPENS AND MOVES INTO SOUTHERN IDAHO AND
WESTERN WYOMING...DRAGGING SHOWERS AND THUNDERSTORMS ALONG WITH
IT. THESE STORMS WILL REMAIN WELL TO OUR SOUTH AND SHOULD NOT
EFFECT OUR AREA.

MONDAY/MONDAY NIGHT...THE TROUGH MOVES FULLY INTO WYOMING AND
SOUTHERN MONTANA. BY MONDAY AFTERNOON...BROKEN HIGH CLOUD COVER
WILL SPREAD NORTH INTO NORTHEAST MONTANA AND SHOWERS AND
THUNDERSTORMS MOVE INTO SOUTHERN MONTANA. SOME OF THESE STORMS MAY
JUST NUDGE INTO OUR SOUTHERN ZONES MONDAY NIGHT.

TUESDAY...ON THE FIRST FULL DAY OF FALL...A VERY SUBTLE SHORT-
WAVE TROUGH MOVES NORTHEAST ACROSS CENTRAL MONTANA THAT WILL SEND
A WEAK COLD FRONT OVER NEMONT. THIS WILL SHIFT THE SOUTHERLY
BREEZE AROUND TO THE WEST/NORTHWEST. WITH A SURFACE LOW OVER
NEMONT...THE MAIN EFFECT WILL BE SOME CLOUDINESS. OTHERWISE WITH
THE CONTINUED INCREASE IN THICKNESS HEIGHTS THIS WILL BE THE
WARMEST DAY OF THE PERIOD WITH HIGHS RISING TO AROUND 15F DEGREES
ABOVE NORMAL. SCT



.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
UPPER RIDGE WILL PREVAIL OVER MONTANA ON WEDNESDAY AS FLOW ALOFT
BECOMES INCREASINGLY AMPLIFIED WITH DIGGING UPPER TROUGH ON WEST
COAST. THIS WILL BRING WARM AND DRY WEATHER TO THE FORECAST AREA.

MODEL DIFFERENCES DEVELOP STARTING ON THURSDAY AS THE GFS WANTS TO
BRING THIS DEEP TROUGH INLAND AND BRING COOLER AND WETTER WEATHER
TO THE FORECAST AREA BY THE WEEKEND. THE ECMWF WANTS TO KEEP THIS
TROUGH TO THE WEST THROUGH THE WEEKEND AND KEEP WARM AND DRY
WEATHER OVER MONTANA ALTHOUGH NOT AS WARM AS MIDWEEK. GIVEN THE
MODEL UNCERTAINTY... WILL GRADUALLY COOL TEMPERATURES INTO THE
WEEKEND AND MAINTAIN A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
FOR THE WEEKEND. FORRESTER


&&

.AVIATION...
VFR WITH CLEAR SKIES TODAY AND TONIGHT. LIGHT WINDS THIS MORNING
WILL TURN SOUTH TO SOUTHEAST 5 TO 10 KNOTS THIS AFTERNOON. LIGHT
WINDS TONIGHT EXCEPT FOR KGGW 10 KNOT NOCTURNAL EASTERLY.


&&

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

&&

$$

WEATHER.GOV/GLASGOW





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