Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 280952
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
352 AM MDT THU MAY 28 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY...
UPPER TROF MOVING THROUGH THE STATE TODAY WILL PULL A COLD FRONT
OUT OF CANADA LATE THIS AFTERNOON. PLENTY OF MOISTURE STILL
AVAILABLE FOR ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS AS THE
FRONT MOVES SOUTH. MODEST INSTABILITY BUT WEAK SHEAR SHOULD LIMIT
MAIN THREAT TO HEAVY RAIN AGAIN WITH PW STILL NEAR 1 INCH. TIGHT
PRESSURE GRADIENT AND SHALLOW COLD AIR ADVECTION BEHIND THE FRONT
SHOULD RESULT IN SOME GUSTY WINDS DURING THE LATE AFTERNOON OR
EVENING HOURS. STRONGEST WINDS EXPECTED TO BE OF SHORT DURATION
AND MAINLY OVER THE EASTERN ZONES...SO LAKE WIND CRITERIA NOT
EXPECTED TO BE MET AT THIS TIME.

COLDER AND DRIER AIRMASS FOLLOWS THE FRONT WITH TEMPERATURES
DIPPING INTO THE 40S AND EVEN SOME 30S POSSIBLE CLOSER TO THE
CANADIAN BORDER FOR FRIDAY MORNING. SUNNY CONDITIONS WILL HELP
TEMPERATURES REBOUND BUT HIGHS ON FRIDAY EXPECTED TO BE AROUND 10
DEGREES LOWER THAN RECENT READINGS.

NEXT SHORTWAVE PUSHES THROUGH THE NORTHERN ROCKIES ON SATURDAY
WITH SOME POSSIBILITY OF SHOWERS AND THUNDERSTORMS WITH DEVELOPMENT
OF LEE TROF IN CENTRAL MONTANA AND PACIFIC MOISTURE AGAIN
STREAMING ACROSS THE DIVIDE. EBERT


.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
THE LONG RANGE PERIOD GETS UNDERWAY SATURDAY NIGHT WITH AN UPPER
LEVEL SHORTWAVE TROUGH RIDING THROUGH ZONAL FLOW ALOFT AS IT TREKS
ACROSS THE STATE OF MONTANA AND INTO THE DAKOTAS. THIS FEATURE
WILL PROVIDE ENOUGH DYNAMIC FORCING FOR ASCENT AND COMBINE WITH
ENOUGH MOISTURE TO NECESSITATE CARRYING A CHANCE FOR SHOWERS AND
THUNDERSTORMS.

THE LATEST 00Z GUIDANCE SHOWS A BUILDING UPPER RIDGE ACROSS THE
NORTHERN HIGH PLAINS ON SUNDAY WITH THE RIDGE AXIS TRANSLATING
EAST OF THE CWA BY MONDAY AS AN ENERGETIC TROUGH DIGS INTO THE
PACIFIC SHORE. THIS WILL USHER IN SOUTHWEST FLOW ALOFT AS AN UPPER
SHORTWAVE APPROACHES. OUT AHEAD OF THIS TROUGH WILL BE VERY WARM
850MB TEMPERATURES...IN THE NEIGHBORHOOD OF +20C. AS SUCH EXPECT
HIGHS MONDAY COULD REACH THE LOWER AND MIDDLE 80S. SURFACE EAST
WINDS WILL HELP PUMP IN LOW LEVEL MOISTURE AND SO HAVE DEW POINTS
IN THE LOWER AND MID 50S. MODEL ANALYSIS SHOWS THE CWA IN SORT OF
A THETA-E RIDGE AS THE SHORTWAVE APPROACHES MONDAY AFTERNOON.
EXTENDED FORECAST GFS BUFKIT SOUNDINGS ARE BEGINNING TO SHOW
FAVORABLE CONVECTIVE PARAMETERS FOR THUNDERSTORMS EARLY NEXT WEEK
AS WELL WITH 500-1500 J/KG CAPE ACROSS NORTHEAST MONTANA...HIGHEST
SOUTH OF THE MISSOURI RIVER. FUTURE SHIFTS WILL NEED TO MONITOR
THIS TIME PERIOD FOR THE POTENTIAL OF A COUPLE OF STRONGER STORMS.
AS THIS SYSTEM ENTERS THE SHORT TERM OVER THE NEXT FEW
DAYS...HIGHER RESOLUTION MODELS WILL BE ABLE TO PICK IT UP AND
CONFIDENCE SHOULD START TO INCREASE REGARDING DETAILS. FOR NOW
WILL MAINTAIN LIKELY POPS FOR EARLY NEXT WEEK WITH AT LEAST A
CHANCE FOR THUNDERSTORMS.
WEDNESDAY AND BEYOND...WITH A TROUGH IN THE VICINITY MAINTAINING
LOWER 500MB HEIGHTS...WILL HAVE A COOLING TREND IN PLACE. MODEL
GUIDANCE STARTS SHOWING INCREASING SPREAD THIS FAR OUT SO AS
CONFIDENCE DECLINES...DECIDED TO TREND POPS TOWARD CLIMATOLOGY TO
FINISH OUT THE FORECAST PERIOD. MALIAWCO

&&

.AVIATION...
PATCHY FOG WILL LEAD TO IFR/MVFR VSBYS AT TAF SITES EARLY THIS
MORNING BEFORE A RETURN TO VFR AFTER SUNRISE. DURING THE LATE
MORNING AND EARLY AFTERNOON EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS TO DEVELOP. REDUCED CIGS AND RESTRICTED VSBYS MAY
ACCOMPANY ANY OF THE STEADIER SHOWER ACTIVITY. WINDS ARE EXPECTED
TO INCREASE FROM THE NORTH BY THIS AFTERNOON TO 10 TO 20 KTS WITH
GUSTS TO 25 KTS. MALIAWCO

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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