Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 252111
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
311 PM MDT MON MAY 25 2015

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

AS A WEAK...DEPARTING LOW PRESSURE SYSTEM LIFTS NORTHWARD OVER THE
DAKOTAS...SOME RESIDUAL INSTABILITY ON THE BACKSIDE OF THAT
CIRCULATION IS SETTING OFF SOME SMALL...SCATTERED...AND SLOW-
MOVING RAIN SHOWERS TODAY MIXED WITH A FEW THUNDERSTORMS HERE AND
THERE. ACTUALLY THE ORIENTATION AND LOCATION OF THESE
THUNDERSTORMS CORRESPONDS QUITE NICELY WITH THE GFS DEPICTION OF
THE AXIS OF CAPE TODAY NEAR AND WEST OF THE BIG SHEEP MOUNTAINS.
EXPECT PRECIP TO REMAIN VERY ISOLATED IN COVERAGE AND SHOULD DIE
DOWN TONIGHT. AS A FEW LOCATIONS EXPERIENCED MIST AND PATCHY FOG
OVERNIGHT LAST NIGHT...AND MODELS INDICATE ANOTHER MARGINAL MOISTURE
SURGE TONIGHT...FELT IT WAS BEST TO MENTION SOME PATCHY FOG FOR
OUR FAR SOUTHEASTERN LOCATIONS OVERNIGHT. NOT EXPECTING MUCH OF AN
IMPACT.

THROUGH THE EARLY PART OF THIS WEEK...ANOTHER CLOSED UPPER-LEVEL
LOW CENTER VERY SLOWLY MAKES ITS WAY OVER THE PACIFIC
NORTHWEST...KEEPING THE WEATHER OVER NE MONTANA FAIRLY BENIGN IN
WEAK FLOW TONIGHT THROUGH TUESDAY WITH INCREASING CHANCES FOR
DAYTIME SHOWERS AND THUNDERSTORMS INCREASING OVER THE LARGER-SCALE
AREA FROM THE WEST AND SOUTHWEST ON TUESDAY AND GENERALLY FROM THE
SOUTH ON WEDNESDAY.

IT SEEMS THE GREATEST CHANCES FOR THUNDERSTORMS WILL BE ON
WEDNESDAY WITH SOME GENERAL MODEL AGREEMENT SHOWING AN UNSTABLE
ATMOSPHERE...600-900 J/KG AND -2 TO -4 LIFTED INDEX VALUES...AND
ACCUMULATING PRECIP FOR OUR SOUTHERN AND SOUTHEASTERN ZONES. WILL
NEED TO WATCH MODEL EVOLUTION OF THIS AND BEGIN MENTIONING
ASSOCIATED HAZARDS IN AN HWO AND SOCIAL MEDIA IF TRENDS CONTINUE
THIS WAY.

OVERALL...SURFACE WINDS SHOULD REMAIN EITHER CALM OR LIGHT FROM
THE EAST AND SOUTHEAST UNTIL A COOL FRONT ARRIVES LATER ON
THURSDAY. BMICKELSON


.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...

MODELS DIDN/T SHOW AN IMPRESSIVE MOISTURE FIELD IN THE AREA
WEDNESDAY NIGHT INTO THURSDAY...THEREFORE LOWERED POPS. STRONG BACKDOOR
COLD FRONT LOOKS TO BRING A COOL AIR IN FRO THURSDAY NIGHT AND
FRIDAY. LEANED TOWARD MODEL BLENDED SOLUTION AND LOWERED TEMPS A
BIT. COULD BE A TOUCH OF FROST IN SPOTS WITH TEMPERATURES DROPPING
INTO THE 30S. REST OF FORECAST LOOKED GOOD. TFJ

PREVIOUS DISCUSSION...
PERIOD STARTS OUT WITH AN AN UPPER TROUGH ACROSS MONTANA THURSDAY
AND THURSDAY NIGHT. MODELS DIFFER ON HOW QUICKLY THIS TROUGH WILL
SPLIT. GFS GENERALLY SPLITS THE TROUGH AND TAKES IT TO THE SOUTH
BEFORE IT REACHES EASTERN MONTANA WHILE THE ECMWF WAITS UNTIL THE
SYSTEM REACHES NORTH DAKOTA. MEANWHILE...THEY AGREE ON A COLD
FRONT THURSDAY NIGHT AND GENERATE SOME PRECIP WITH IT. WILL
MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS.

HIGH PRESSURE BUILDS INTO NORTH DAKOTA THURSDAY NIGHT AND FRIDAY
WHICH WILL BRING MAINLY DRY WEATHER TO THE NORTHEAST HALF OF THE
FORECAST AREA. MEANWHILE...IT LOOKS LIKE THE FRONT COULD STALL
OVER CENTRAL MONTANA. WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS AT TIMES IN THE SOUTHWEST.

AFTER A SHORTWAVE RIDGE MOVES THROUGH EASTERN MONTANA FRIDAY
NIGHT... THE FRONT MOVES BACK EAST AS A WARM FRONT ON SATURDAY.
A SHORTWAVE TROUGH AND COLD FRONT SATURDAY NIGHT AND SUNDAY COULD
BRING AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS.

ANOTHER SHORTWAVE TROUGH IN NEARLY ZONAL FLOW ALOFT COULD BRING
ANOTHER CHANCE OF SHOWERS NEXT MONDAY. FORRESTER

&&

.AVIATION...

VFR.

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE DRIFTING WEST
BUT ARE EXPECTED TO MISS THE TERMINALS. THEY SHOULD DIMINISH BY
EVENING.

THERE IS A SLIGHT POSSIBILITY OF PATCHY FOG EARLY TUESDAY
MORNING.

WINDS: LIGHT SOUTHEAST BECOMING LIGHT AND VARIABLE TONIGHT. TFJ

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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