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000
FXUS65 KGGW 240307
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
907 PM MDT THU MAY 23 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
UPDATE...MINOR TWEAKS TO THE SHORT TERM TONIGHT. ADJUSTED SKY
COVER AND POPS TO CURRENT TRENDS AS WEAK CONVECTION AND SHOWER
ACTIVITY MOVES NORTHWARD AND JUST BEGAN TO AFFECT THE SOUTHWEST
ZONES. MODEL GUIDANCE STILL HINTS AT PRECIP SPREADING EASTWARD
SLIGHTLY TO AFFECT THE MISSOURI RIVER VALLEY...SO DECIDED TO LEAVE
THAT IN. ALSO ADJUSTED WINDS IN THE SOUTHEAST AS SUSTAINED WINDS
AND GUSTS REMAIN QUITE HIGH...BUT STILL LOOK TO TAPER OFF THROUGH
THE NIGHT. OTHERWISE...FORECAST LOOKS GOOD. BARNWELL

PREVIOUS SHORT TERM DISCUSSION...WATER VAPOR IMAGERY AND 500 MB
HEIGHT FIELD SHOWS A HIGHLY AMPLIFIED AND DYNAMIC WEATHER PATTERN
ACROSS THE CONUS. FOR NORTHEAST MONTANA...THE OBVIOUS AND GREATEST
IMPACTS PERTAIN TO THE NEAR-STATIONARY OR SLIGHTLY RETRO-GRADING
LARGE LOW- PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST AND NORTHERN
ROCKIES REGIONS THROUGHOUT THE SHORT TERM FORECAST PERIOD.

FORECAST CHALLENGES WILL FOCUS ON THE STRONG...YET DIMINISHING WINDS
TONIGHT AND POSSIBLE SEVERE THUNDERSTORMS SATURDAY AFTERNOON AND EVENING.

ALTHOUGH A FEW LOCATIONS BRIEFLY REACHED SUSTAINED WINDS OF 40
MPH TODAY...IT DID NOT LAST MORE THAN 15 TO 30 MINUTES AT A TIME.
WE CLOSELY WATCHED AREA WIND OBSERVATIONS AND IT LOOKS LIKE IT
WAS A GOOD CALL TO HOLD BACK AND NOT ISSUE A HIGH WIND
WARNING...BUT IT WAS VERY CLOSE.

THIS REGIONAL STORM SYSTEM SEEMS TO BE DIRECTING SUBSTANTIAL
AMOUNTS OF MOISTURE FROM BOTH THE PACIFIC AND GULF OF MEXICO
NORTHWARD THROUGH THE ROCKY MOUNTAINS AND HIGH PLAINS REGIONS.

CHOSE TO GIVE THE POPS GRIDS A BIT MORE FINE TUNING GIVEN
CONTINUED RUN TO RUN CONSISTENCY AND GOOD CONSENSUS BETWEEN THE
SHORT TERM MODEL SOLUTIONS. AFTER SPENDING MOST OF THE DAY TODAY
THROUGH CENTRAL MONTANA...THE SCATTERED SHOWERS AND A FEW
THUNDERSTORMS WILL LIKELY INCREASE AND SPREAD EASTWARD TO IMPACT
MORE OF OUR WESTERN CWA. THEN...THROUGH THE MIDNIGHT
HOURS...EXPECT SHOWERS TO ROTATE AROUND AND EASTWARD THROUGH OUR
NORTHERN TIER ZONES.

FRIDAY WILL BRING GENERALLY CLEARING SKIES AND NO PRECIP...FOR
SITES SOUTH OF THE NORTHERN TIER...AS THE NORTHWESTERN STATES LOW
PRESSURE SYSTEM IS PUSHED BACK BY HIGHER PRESSURES FROM THE
SOUTHEAST AMID SOME MODERATE SUBSIDENCE.

SATURDAY...WITH A SHORT WAVE IMPULSE RIDING ALONG THE
SOUTHWESTERLY FLOW ALOFT...CONVECTIVE PARAMETERS FAVOR THE
DEVELOPMENT OF STRONG TO SEVERE THUNDERSTORMS THROUGH SATURDAY
NIGHT. LATE MORNING SHOWERS ARE EXPECTED TO DEVELOP GENERALLY
ALONG A LINE FROM WIBAUX COUNTY NORTHWESTWARD THROUGH NORTHERN
VALLEY COUNTY. LIFTED INDEX VALUES FROM -4 TO -8 ARE FORECAST FOR
THE EASTERN TWO-THIRDS OF OUR CWA. 1000 TO 2000 J/KG OF CAPE WILL
SPREAD THROUGH THE SAME REGION AND EVEN PUSH A BIT MORE WESTWARD
SATURDAY EVENING. CHOSE TO INCLUDE WIND AND HAIL WORDING IN THE
FORECAST FOR SATURDAY AND SATURDAY NIGHT. BMICKELSON

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
THE GOING FORECAST IN OVERALL EXCELLENT SHAPE DEPICTING UNSETTLED
CONDITIONS AS NORTHEAST MONTANA REMAINS UNDER THE INFLUENCE OF AN
UPPER TROUGH THROUGH THE PERIOD. THE ONLY TWEAK MADE WAS TO TREND
UP POPS FOR SATURDAY EVENING AS EXCELLENT POTENTIAL FOR STRONG TO
SEVERE THUNDERSTORM ACTIVITY WILL CONTINUE ACROSS THE EAST THROUGH
THE EVENING HOURS. GILCHRIST

PREVIOUS DISCUSSION...UPPER TROF ALONG THE WEST COAST WILL
CONTINUE TO DOMINATE THE WEATHER PATTERN THROUGH THE EXTENDED
PERIOD...RESULTING IN UNSETTLED WEATHER AND NEAR NORMAL
TEMPERATURES.

CLOSED LOW CURRENTLY OVER THE PACIFIC NORTHWEST EXPECTED TO LIFT
INTO WESTERN CANADA DURING THE WEEKEND. WITH INVERTED TROF/DRY
LINE IN PLACE OVER EASTERN MONTANA...WITH SOUTHEAST LOW LEVEL FLOW
SPREADING GULF MOISTURE INTO THE NORTHERN PLAINS ALONG WITH
ANOTHER UPPER LEVEL SOUTHWEST JET CROSSING THE NORTHERN ROCKIES
EXPECT ORGANIZED CONVECTION MAINLY OVER THE EASTERN ZONES SATURDAY
EVENING.

PATTERN FOR THE REMAINDER OF THE PERIOD IS MORE DISORGANIZED WITH
GREATER MODEL SPREAD. OVERALL PATTERN IS FOR WEST COAST TROF TO
DIG INTO THE DESERT SOUTHWEST WITH SOME SPLITTING OCCURRING AS
ANOTHER UPPER LOW SLIDES FROM ALASKA TOWARD THE PACIFIC NORTHWEST.
SOME HINTS IN THE GEFS/GEM OF RIDGE TILTING BACK INTO THE NORTHERN
PLAINS AROUND MID WEEK TO SHUT OFF CONVECTION BUT WITH MODEL
SPREAD KEPT POPS NEAR CLIMO. EBERT

&&

.AVIATION...
VFR WITH MID TO HIGH CLOUDS THROUGH THIS EVENING. SHOWERS AND/OR
THUNDERSTORMS COULD IMPACT THE TERMINALS OVERNIGHT WITH BRIEF
MVFR CONDITIONS. A LOWER CEILING MVFR WILL BUILD INTO ALL THE THE
TERMINALS EARLY FRIDAY MORNING...LINGERING THROUGH MIDDAY BEFORE
SKIES CLEAR IN THE EARLY AFTERNOON.

STRONG AND GUSTY SOUTHEAST WINDS WILL CONTINUE INTO EARLY FRIDAY
MORNING...BEFORE GOING WESTERLY AND DECREASING TO 10 TO 20 KTS BY
MID MORNING.


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 4 AM MDT FRIDAY FOR FORT PECK LAKE FOR
CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...
GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW