Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 190305 AAA
AFDGGW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
905 PM MDT FRI APR 18 2014

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

SENT ANOTHER UPDATE TONIGHT NOW THAT THE THREAT FOR SEVERE
THUNDERSTORMS HAS PASSED. THE REST OF THIS EVENING WILL BRING
PERIODS OF BANDED RAIN SHOWERS TO PORTIONS OF OUR EASTERN CWA.
CLEARING SKIES APPROACH FROM THE WEST. BMICKELSON

COLD FRONT MARCHING ACROSS THE STATE THIS AFTERNOON WITH A BAND OF
LIGHT RAIN MOVING AHEAD OF IT. RAIN WILL MOVE ACROSS EASTERN
MONTANA THROUGH THE LATE AFTERNOON BEFORE EXITING INTO NORTH
DAKOTA THIS EVENING. UPPER TROF IS ASSOCIATED WITH A STACKED LOW
OVER SOUTHERN ALBERTA WILL ALSO MOVE EAST OVERNIGHT. WITH A LITTLE
COLD AIR ADVECTION AND TIGHT PRESSURE GRADIENT...EXPECT GUSTY
WEST WINDS BEHIND THE COLD FRONT PASSAGE.

WINDS DIMINISH SATURDAY MORNING WITH WEAK UPPER RIDGE BUILDING
INTO THE STATE AND LEE TROF REDEVELOPING IN CENTRAL MONTANA. WARM
AND DRY WEATHER FOR SATURDAY WITH PLENTY OF SUNSHINE EXPECTED.

NEXT SHORTWAVE SWINGS THROUGH THE NORTHERN ROCKIES SATURDAY NIGHT
AND EAST INTO THE PLAINS ON SUNDAY. MOISTURE LIMITED WITH THE
SYSTEM AND STRONG DOWNSLOPE FLOW WILL TEND TO DRY LOW LEVELS BUT
COULD SEE A SPRINKLE OR MORE SUNDAY MORNING BEFORE WINDS MIX DOWN.
EBERT


.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...

THE LONG RANGE KICKS OFF WITH A 500MB RIDGE MOVING ACROSS THE
NORTHERN PLAINS SUNDAY NIGHT THROUGH TUESDAY. EXPECT DRYING
SUBSIDENCE AND WARM TEMPERATURES THROUGH THIS PERIOD. AS THE
RIDGE AXIS SLIDES EAST OF THE CWA MONDAY NIGHT...EXPECT INCREASING
CLOUDINESS IN ADVANCE OF THE NEXT WEATHER SYSTEM FOR MID TO LATE
NEXT WEEK.

FLOW ALOFT WILL BECOME SOUTHWESTERLY TUESDAY NIGHT AS A LARGE
UPPER TROUGH BECOMES ESTABLISHED ACROSS THE WESTERN CONUS. SURFACE
LOW PRESSURE WILL INITIALLY TRACK TO THE EAST OF THIS TROUGH. THIS
SYNOPTIC FEATURE WILL DRAW IN AN ABUNDANCE OF PACIFIC AND GULF OF
MEXICO. THE SYSTEM MAY BECOME VERTICALLY STACKED AND SIT AND SPIN
OVER THE DAKOTAS LATE NEXT WEEK ALLOWING FOR PRECIPITATION TO
CONTINUE TO WRAP AROUND INTO NORTHEAST MONTANA. GIVEN THAT MODELS
HAVE TRENDED WETTER FOR THURSDAY...HAVE EXTENDED HIGH END
CHANCE/LOW END LIKELY POPS INTO THIS PERIOD. EXPECT TEMPERATURES
TO BE SUPPORTIVE OF MAINLY RAIN. GIVEN THE DYNAMIC SUPPORT AND
ABUNDANCE OF MOISTURE...DO EXPECT AT LEAST THE POTENTIAL FOR
WIDESPREAD WETTING RAINS.

GIVEN MODELS SHIFTING TO A WETTER THURSDAY AND POOR RUN TO RUN
CONTINUITY WITH THE PRECISE TRACK OF THIS SYSTEM...CONFIDENCE IS
STILL IN THE LOW TO MODERATE RANGE IN TERMS OF THE DETAILS OF
EXACTLY WHERE AND WHEN THE STEADIEST RAIN MAY OCCUR. FOR NOW THE
TAKE HOME MESSAGE IS THAT A WIDESPREAD WETTING RAIN MAY IMPACT
TRAVEL AND PERHAPS BE A THREAT TO NEWBORN LIVESTOCK DURING THE
MIDDLE TO LATTER PORTIONS OF NEXT WEEK. THE RAIN MAY ALSO MIX WITH
OR CHANGE TO SNOW BEFORE ENDING AS THE SYSTEM PULLS AWAY THURSDAY
NIGHT. MALIAWCO

PREVIOUS LONG TERM DISCUSSION...

TWO MAIN FEATURES DOMINATE THE LONG TERM FORECAST PERIOD.

FIRST...MONDAY THROUGH TUESDAY...AND LARGE AND EXPANSIVE UPPER
LEVEL TROUGH WILL SPREAD FROM THE ROCKY MOUNTAINS THROUGH THE
CENTRAL PLAINS...KEEPING ANY AND ALL PRECIPITATION AWAY FROM
NORTHEAST MONTANA. EXPECT HIGH GENERALLY IN THE 60S AND LOWS
GENERALLY IN THE 30S. BREEZY WEST WINDS ON MONDAY WILL SWITCH
AROUND TO GUSTY FROM THE SOUTHEAST ON TUESDAY.

NEXT...TUESDAY NIGHT THROUGH THURSDAY NIGHT...AN UPPER LEVEL
TROUGH EXTENSION OF THE LOW PRESSURE SYSTEM FROM THE GULF OF
ALASKA WILL SPILL OVER THE CONTINENTAL DIVIDE AND SLOWLY MAKE ITS
WAY ACROSS THE NORTHERN HIGH PLAINS. ALTHOUGH THERE OBVIOUSLY
STILL EXIST SOME SIGNIFICANT MODEL DISCREPANCIES REGARDING TIMING
AND PRECIPITATION AMOUNTS WITH THIS SYSTEM...A GENERAL PICTURE IS
BEGINNING TO FORM.

TUESDAY AFTERNOON AND EVENING...A SOUTHWESTERLY FLOW ALOFT WILL
DELIVER THE INITIAL SCATTERED RAIN SHOWERS FROM CENTRAL AND
SOUTHERN MONTANA TO NORTHEAST MONTANA BY TUESDAY NIGHT. IT WILL
LIKELY BE SCATTERED AND SPOTTY IN COVERAGE TO START WITH. BY
WEDNESDAY MORNING...A MORE ORGANIZED AND WIDESPREAD RAIN WILL
BEGIN...ALTHOUGH SOME SIGNS OF A DRY SLOT ARE SHOWING UP IN THE
MODELS ACROSS OUR WESTERN ZONES BY WEDNESDAY AFTERNOON AND
EVENING WHILE A MORE ORGANIZED AND POSSIBLE CONVECTIVE ENVIRONMENT
WILL FAVOR OUR EASTERN AND SOUTHEASTERN ZONES. INCLUDED SOME
MENTION OF THUNDERSTORMS HERE TO COVER THAT POSSIBILITY.

OVERNIGHT WEDNESDAY NIGHT INTO THURSDAY MORNING...THE DRY SLOT IS
EXPECTED TO SHIFT THROUGH OUR SOUTH-CENTRAL ZONES. THURSDAY
THROUGH FRIDAY MORNING...SHOULD BE THE END OF THE STORM SYSTEM AS
THE BACKSIDE COLD FRONT PUSHES THROUGH NORTHEAST MONTANA FROM THE
NORTHWEST. IT SHOULD BE NOTED THAT BY THIS TIME...THE BIGGEST
MODEL DISCREPANCY IS EVIDENCED BY THE EC HOLDING ON TO THE DRY
SLOT AND NOT ALLOWING ANY BACKSIDE PRECIPITATION TO MOVE OVER THE
AREA...WHILE THE GFS BLANKETS THE ENTIRE CWA WITH A WIDESPREAD
WETTING RAIN AS THE SYSTEM FINISHED WITH NORTHEAST MONTANA THROUGH
EARLY FRIDAY MORNING. BOTH THURSDAY AND FRIDAY MORNING...JUST
ENOUGH COLD AIR MAY SNEAK OVER THE CANADIAN BORDER TO ALLOW MIXED
PRECIPITATION OR EVEN SOME ACCUMULATING SNOW FOR OUR CENTRAL AND NORTHERN
ZONES.

BIGGEST IMPACTS WILL LIKELY BE THE EARLIER SUDDEN HEAVY RAIN
SHOWERS WEDNESDAY EVENING AND THEN THE MORE WIDESPREAD WETTING
RAIN ON THURSDAY EVENING. BMICKELSON


&&

.AVIATION...

SYNOPSIS: AN UPPER LEVEL DISTURBANCE CONTINUES TO PUSH THROUGH
NORTHEAST MONTANA THIS EVENING. AFT 05Z IT SHOULD CLEAR ACROSS ALL
LOCATIONS WITH HIGH PRESSURE BUILDING IN.

FLIGHT CATEGORY: VFR.

IMPACTS: A VERY SMALL POSSIBILITY OF FOG ALONG THE RIVER VALLEY
BOTTOMS COULD BRIEFLY LOWER FLIGHT CATEGORIES TO LESS THAN 1/2
MILE BRIEFLY. WILL NOT ADD THEM TO THE TERMINALS AT THIS TIME.

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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