Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 292039
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
239 PM MDT SUN MAR 29 2015

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

CURRENT CONDITIONS ACROSS NORTHEAST MONTANA ARE PLEASANT...SLIGHTLY
WARM...SLIGHTLY COOL AND A BIT BREEZY WITH MOSTLY SUNNY TO PARTLY
CLOUDY SKIES UNDER A WEAK UPPER-LEVEL RIDGE. SURFACE BOUNDARY IS
EASILY DRYING OUT AFTER A WIDESPREAD WETTING RAIN FROM LAST NIGHT.
WIDESPREAD FOG IS NOT EXPECTED TONIGHT...BUT SOME ISOLATED AREAS
OF MIST AND RIVER VALLEY PATCHY FOG MAY BE POSSIBLE FROM MIDNIGHT
TONIGHT TO SUNRISE MONDAY MORNING.

TONIGHT THROUGH TUESDAY MID-DAY...EXPECT WARMING TEMPERATURES
UNDER A STRENGTHENING UPPER-LEVEL RIDGE WITH PARTLY CLOUDY TO
SUNNY SKIES AND WINDS GENERALLY BELOW 15 MPH. IN OTHER
WORDS...MONDAY AND TUESDAY WILL BE JUST ABOUT PERFECT FOR THIS
TIME OF YEAR.

BY TUESDAY AFTERNOON...A LARGE UPPER-LEVEL TROUGH FROM THE GULF OF
ALASKA TO THE NORTHERN ROCKIES WILL TURN THE FLOW OVER NORTHEAST
MONTANA FROM WESTERLY TO SOUTHWESTERLY AND ALLOW A FEW SHOWERS AND
ISOLATED THUNDERSTORMS TO FORM OVER CENTRAL MONTANA AND DRIFT OVER
OUR WESTERN ZONES. RAIN SHOWERS ARE EXPECTED TO INCREASE IN
COVERAGE AND PRECIP AMOUNTS BEGINNING TUESDAY EVENING AS A THE
LEADING EDGE OF A COLD FRONT PASSES THROUGH THE AREA. BMICKELSON


.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...

TWEAKS WERE MADE TO THE EARLY PORTION. WINDY CONDITIONS ARE
EXPECTED WEDNESDAY BUT WRAP-AROUND MOISTURE AND COLD AIR WILL GIVE
SNOW TO AREAS JUST NORTHEAST OF THE CWA WEDNESDAY NIGHT. MODELS
SEEM TO BE ADVERTISING A CUT-OFF LOW RATHER THAN AN UPPER TROUGH
DIGGING INTO THE PAC NW NEXT WEEKEND. THIS WOULD GIVE NE MT A
BETTER CHANCE OF MILD CONDITIONS WHILE THE PAC NW GETS MUCH NEEDED
MOISTURE/SNOW. TFJ

PREVIOUS DISCUSSION...
THE LATEST 12Z MODEL GUIDANCE CONTINUES WITH A COLD FRONT TUESDAY
NIGHT REACHING NORTHEAST MONTANA. A SURFACE LOW AND CLOSED UPPER
LOW WILL TRACK NORTH OF THE REGION ACROSS SOUTHERN SASKATCHEWAN.
THIS WILL ACT TO GREATLY ENHANCE THE SURFACE PRESSURE GRADIENT
ACROSS THE CWA. THUS...WHILE SHOWER AND POSSIBLY THUNDERSTORM
ACTIVITY CAN BE EXPECTED TUESDAY NIGHT AND WEDNESDAY...THE LARGER
CONCERN LOOKS TO SURROUND GUSTY WESTERLY WIND POTENTIAL.

DECENT CAA BEHIND THE COLD FRONT ALONG WITH THIS TIGHT PRESSURE
GRADIENT WILL LIKELY MEAN BUSINESS. LATEST GUIDANCE IS POINTING TO
SUSTAINED WIND SPEEDS IN THE 20-30 MPH WITH GUSTS IN THE 40-50 MPH
RANGE. IN TIME THIS COULD EASILY BECOME A STRONGLY WORDED LAKE
WIND ADVISORY SITUATION...AND WILL HAVE TO WATCH THE USUAL WINDY
LOCATIONS FOR HIGH WIND. THIS IS SEVERAL DAYS OUT FROM NOW AND
WITH SEVERAL FACTORS INVOLVED CONFIDENCE IS NOT YET THERE ON
THAT...BUT IF NOTHING ELSE EXPECT VERY GUSTY CONDITIONS TUESDAY
NIGHT AND WEDNESDAY ACROSS NORTHEAST MONTANA. AS THIS EVENT ENTERS
THE DAY 3 PERIOD...WOULD LIKE TO INSPECT MORE CLOSELY LAPSE
RATES...AMONG OTHER PARAMETERS...AVAILABLE IN THE NAM BUFKIT
FORECAST SOUNDINGS ACROSS THE REGION TO ASCERTAIN MORE DETAIL.
AFTER A COUPLE OF DAYS...SOME MESOSCALE GUIDANCE WILL BE ABLE TO
ALSO OFFER SOME INPUT AS TO WHAT TO EXPECT.

NORTHWEST FLOW ALOFT IN ADVANCE OF A PACIFIC SHORTWAVE RIDGE WILL
BECOME ESTABLISHED ACROSS THE NORTHERN HIGH PLAINS IN THE WAKE OF
THE TUESDAY NIGHT/WEDNESDAY SYSTEM. EMBEDDED IN THIS FLOW WILL BE
SHORTWAVES...SOMEWHAT DIFFICULT TO TIME GIVEN INCREASING SPREAD IN
THE 500MB HEIGHT ENSEMBLES THIS FAR OUT IN THE EXTENDED PERIOD.
NEVERTHELESS THIS PATTERN SUPPORTS NEAR CLIMO POPS WITH A DAYTIME
SLIGHT CHANCE OF RAIN SHOWERS AND NOCTURNAL RAIN/SNOW MIX WITH
COOLER THERMAL PROFILES AT NIGHT.

WHILE PRECISE TIMING IS DIFFICULT TO PIN DOWN...12Z ECMWF/GFS HAVE
BROAD CONSENSUS ON HAVING A PACIFIC RIDGE TRANSLATE EAST ACROSS
MONTANA WHICH WOULD LEAD TO DRIER CONDITIONS AND MODERATING
TEMPERATURES. GIVEN THIS INFORMATION...WILL HAVE A DRY FORECAST TO
FINISH OUT THE LONG RANGE PERIOD...FOR NOW. MALIAWCO


&&

.AVIATION...

FLIGHT CATEGORY: VFR.

MAINLY CLEAR SKIES WITH VARIABLE HIGH CLOUDINESS INTO MONDAY. WINDS
WILL REMAIN LIGHT WEST...15 KTS OR LESS. TFJ

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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