Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 010855
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
255 AM MDT TUE SEP 1 2015

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

SYNOPTIC SET UP... HOT HIGH PRESSURE CURRENTLY RESIDES OVER THE
LOWER INTERMOUNTAIN WEST AND SOUTHERN AND CENTRAL US ROCKIES. A
LARGE TROUGH OF COOLER AIR RESIDES OVER THE COAST OF BRITISH
COLUMBIA WITH ITS INFLUENCE EXPANDED EAST INTO NORTHERN ALBERTA.
SOUTHWEST TO ZONAL FLOW RUNS FROM THE PACIFIC NORTHWEST THROUGH
MONTANA AND NORTH DAKOTA. NORTHEAST MONTANA CURRENTLY LIES ON THE
WARMER SIDE OF THIS FLOW.

TODAY THROUGH WEDNESDAY... TROUGH TO THE WEST WILL DRIFT SOUTH
SLIGHTLY AND INCREASE THE LARGE WARM RIDGE`S INFLUENCE INTO
EASTERN MONTANA AND NORTH DAKOTA. EXPECT CONDITIONS TO WARM UP
AND REMAIN DRY. FLOW WILL ALSO BECOME MORE SOUTHWESTERLY OVER
TIME. THERE CONTINUES TO BE A SMALL POSSIBILITY FOR SMOKE TO ENTER
IN THE FORECAST OVER THE NEXT DAY OR TWO WHEN LOOKING AT THE
NWS AIR QUALITY SURFACE SMOKE MAPS.

WEDNESDAY NIGHT THROUGH THURSDAY... TROUGH WILL MOVE INLAND
SLIGHTLY AND FORCE SOUTHWEST FLOW OVERHEAD. COOLER AIR WILL BEGIN
TO DRIFT INTO THE AREA ALOFT AND MIX DOWN MECHANICALLY. LEE
MOUNTAIN SURFACE TROUGH THAT DEVELOPED EARLIER IN THE DAY WILL
SLOWLY MORPH INTO A COLD FRONT OVERNIGHT AND MOVE THROUGH THE
AREA BY THURSDAY. THE POTENTIAL FOR SHORTWAVE JETS IN THE FLOW
EXISTS... BUT MODELS ARE PUTTING THE EXTENT OF THEIR INFLUENCE ON
PRECIP GENERATION AS VERY LOW INITIALLY. SO... ONLY A FEW SLIGHT
CHANCES APPEAR ACROSS THE NORTHERN MOST EXTENT OF THE CWA DURING
THESE PERIODS. GAH


.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
BETWEEN THURSDAY NIGHT AND SATURDAY NIGHT...EASTERN MONTANA WILL
BE IN SOUTHWEST FLOW ALOFT BETWEEN AN UPPER TROUGH/LOW TO THE
WEST. THERE WILL BE A QUASI-STATIONARY FRONT OVER THE DAKOTAS AT
THE SAME TIME WITH AN 850 MB TEMPERATURE GRADIENT (WARM
EAST...COOL WEST) ACROSS THE FORECAST AREA.

THURSDAY NIGHT AND FRIDAY...IT LOOKS LIKE THE SHORTWAVES IN THE SW
FLOW ALOFT WILL BE PRIMARILY OVER CENTRAL MONTANA WITH NORTHEAST
MONTANA IN A DRY SLOT. COULD STILL SEE SOME SHOWERS AND
THUNDERSTORMS DEVELOP IN SOMEWHAT UNSTABLE AIRMASS. WILL MENTION
CHANCE WEST AND SLIGHT CHANCE EAST.

FRIDAY NIGHT AND SATURDAY...THE UPPER TROUGH DIGS DEEPER INTO THE
PACIFIC NW AND AS FAR SOUTH AS NEVADA WHILE SHORTWAVES MOVE
THROUGH EASTERN MONTANA WITH MORE MOISTURE. WILL BROADBRUSH A GOOD
CHANCE OF SHOWERS WITH THUNDERSTORMS AT TIMES.

SATURDAY NIGHT AND SUNDAY... THE UPPER TROUGH/LOW MOVES EAST
ACROSS MONTANA. ECMWF HAS CLOSED LOW AND GFS HAS OPEN TROUGH.
EITHER WAY... IT LOOKS WET AND COOL FOR NORTHEAST MONTANA. WILL
MAINTAIN GOOD CHANCE OF SHOWERS WITH THUNDERSTORMS AT TIMES.

MODELS DIFFER ON HOW QUICKLY TO LIFT THE TROUGH TO THE NORTHEAST
SUNDAY NIGHT AND MONDAY. WILL HAVE A SLIGHT CHANCE OF SHOWERS FOR
NOW.

SHORTWAVE RIDGE BUILDS INTO THE AREA MONDAY NIGHT AND TUESDAY WITH
DRY AND WARMER WEATHER. FORRESTER


&&

.AVIATION...
VFR.

LOOK FOR EITHER CLEAR SKIES OR SCT MID AND HIGH CLOUDS TODAY AND
TONIGHT.

LIGHT AND VARIABLE WINDS THIS MORNING WILL BECOME WEST AROUND 10
KNOTS BY 18Z (NOON MDT). WINDS WILL BECOME LIGHT AND VARIABLE
AFTER SUNSET THIS EVENING IN MOST AREAS WITH KGGW HAVING A
NOCTURAL EAST WIND AT 10 KNOTS.


&&

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


&&

$$

WEATHER.GOV/GLASGOW



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