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000
FXUS65 KGGW 240921
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
321 AM MDT FRI MAY 24 2013

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
ONGOING RAIN SHOWERS ARE CURRENTLY AFFECTING THE FAR WESTERN ZONES
AS A PLUME OF LOW TO MID LEVEL MOISTURE CONTINUES TO TRACK NORTH
AHEAD OF THE PACIFIC NORTHWEST LOW. THIS SLOW MOVING LOW WILL BE
THE MAIN FOCUS FOR THE DURATION OF THE SHORT TERM AS IT WILL BRING
WAVES OF LIFT AND SUBSIDENCE INTO THE WEEKEND...THEN CHANCES FOR
SEVERE CONVECTION MOVES IN LATER ON SATURDAY AND AGAIN LATER IN
THE DAY ON SUNDAY.

THE LINGERING SHOWERS AND CLOUD COVER LOOKS TO DISSIPATE THIS
MORNING AND INTO THE AFTERNOON AS NVA AND ASSOCIATED SUBSIDENCE BEHIND
A LOBE OF THE UPPER LOW CONTINUES NORTH INTO CANADA. WINDS SHOULD
DIE DOWN A BIT AS WELL...HOWEVER WINDS ARE HOLDING STRONG ENOUGH
TO EXTEND THE LAKE WIND ADVISORY INTO MID MORNING. THE SUBSIDENCE SHOULD
KEEP THINGS QUIET BEFORE THE NEXT SUBTLE SHORTWAVE AFFECTS THE
REGION EARLY ON SATURDAY...THEN ANOTHER FOR LATER IN THE AFTERNOON
AND EVENING.

RIDGING OFF TO THE EAST AND THE LOW OFF IN THE PACIFIC NORTHWEST
WILL CONTINUE TO BRING SOUTHWEST FLOW ALOFT...AND SOUTHEAST FLOW
AT THE SURFACE. THIS WILL ADVECT PLENTY OF MOISTURE INTO THE
REGION ON SATURDAY...AND PAVE THE WAY FOR SEVERE POTENTIAL WITH
EXCELLENT LOW LEVEL CURVATURE ON HODOGRAPHS. ALSO 0-6 KM SHEAR AT
40 TO 50 KNOTS...LIFTED INDICIES OF -4C TO -8C...AND SBCAPE VALUES
OVER 2000 J/KG AT IN THE SOUTHEAST ZONES SHOULD BE ENOUGH FOR
ORGANIZED CONVECTION TO BRING THE CHANCE FOR LARGE HAIL AND
DAMAGING WINDS. THE LCL AND LFC LOOK TO MEET AT ABOUT 22Z TO 02Z
PER MODEL SOUNDINGS...AND THUS THE CAP LOOKS TO ERODE BY THEN...SO
EARLY CELLS MAY DEVELOP RAPIDLY SHORTLY AFTER THAT TIMEFRAME. BOTH
THE NAM AND GFS HAVE THE HIGHEST CONVECTIVE VARIABLE VALUES...WITH
THE ECMWF SLIGHTLY LOWER AND THE SREF SHOWING THE WEAKEST. FOR
NOW...PUT SEVERE MENTION INTO THE GRIDS BETWEEN 18Z SATURDAY AND
06Z SUNDAY FOR THE SOUTHEAST IN ADDITION TO MENTION OF LARGE HAIL
AND GUSTY WINDS. SEVERE PARAMETERS MAY BECOME SIGNIFICANT ENOUGH
TO SPREAD FURTHER NORTH AND EAST AFTER 00Z...BUT HIGHEST POTENTIAL
FOR NOW LOOKS TO BE IN THE SOUTHEAST.

THE NAM...GFS AND ECMWF DO NOT LOOK TO BACK OFF THE SBCAPE VERY
MUCH OVERNIGHT AND INTO THE DAY SUNDAY. DECENT SOUTHEAST FLOW
LOOKS TO CONTINUE TO ADVECT MOISTURE INTO THE REGION...AND THUS
LCL HEIGHTS WILL REMAIN LOW AND KEEP THE CAPE HIGH WITH LITTLE OR
NO CIN. THEREFORE CONVECTION MAY PERSIST INTO THE EARLY MORNING ON
SUNDAY AND WILL CONTINUE TO POSE A THREAT BEFORE THE NEXT ROUND
LATER IN THE AFTERNOON AND EVENING FOR ROUGHLY THE SAME LOCATIONS
AS SATURDAY. DID NOT PUT A MENTION OF SEVERE FOR SUNDAY AFTERNOON OR
EVENING AS THE PRIMARY THREAT LOOKS TO BE SATURDAY ATTM. BARNWELL

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
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 A MORE DISORGANIZED
PATTERN DEVELOPING 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. THERE CONTINUES TO BE SOME HINTS IN THE
OF RIDGE TILTING BACK INTO THE NORTHERN PLAINS AROUND MID WEEK TO
DIMINISH CONVECTION BUT WITH MODEL SPREAD KEPT POPS NEAR CLIMO.
PRECIPITATION CHANCES WILL INCREASE AGAIN TOWARD THE END OF THE
FORECAST PERIOD WITH BROAD UPPER TROF SPREADING EAST. EBERT

&&

.AVIATION...
VFR WITH MID TO HIGH CLOUDS. SHOWERS AND/OR THUNDERSTORMS COULD
IMPACT THE WESTERN TERMINALS EARLY THIS MORNING WITH BRIEF MVFR
CONDITIONS. STRONG AND GUSTY SOUTHEAST WINDS WILL DIMINISH THIS
MORNING ...BEFORE GOING WESTERLY AS A FRONT LIFTS ACROSS THE
REGION.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 9 AM MDT THIS MORNING FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.

&&

$$

WEATHER.GOV/GLASGOW