DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 161732
SWODY2
SPC AC 161730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT JUN 16 2012

VALID 171200Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
DAKOTAS/UPPER MIDWEST...

...SYNOPSIS...
ON THE SOUTHERN PERIPHERY OF A LONGWAVE TROUGH OVER THE WESTERN
TWO-THIRDS OF CANADA...A SOMEWHAT FLATTER/MORE ZONAL LARGE SCALE
PATTERN WILL EVOLVE OVER THE MAJORITY OF THE CONUS ON SUNDAY. WITHIN
THIS REGIME...THE PRIMARY DEEP CONVECTIVE POTENTIAL FOR THE PERIOD
WILL BE INFLUENCED BY THE EASTWARD TRANSITION OF LOW AMPLITUDE
WESTERLIES/STRENGTHENING POLAR JET OVER THE NORTHWEST/NORTH-CENTRAL
CONUS THROUGH SUNDAY NIGHT/EARLY MONDAY.

...EASTERN DAKOTAS/MIDDLE MO VALLEY/UPPER MIDWEST...
GIVEN THE AFOREMENTIONED LARGE SCALE SCENARIO...A RELATIVELY MOIST
AIRMASS /GENERALLY LOWER TO MIDDLE 60S F SURFACE DEWPOINTS/ WILL
QUICKLY SPREAD NORTHWARD ACROSS THE NORTH-CENTRAL PLAINS/MO RIVER
VALLEY ON SUNDAY. THIS WILL BE IN TANDEM WITH A
NORTHWARD-SHIFTING/SHARPENING WARM FRONT AND ANTICIPATED SURFACE
CYCLOGENESIS ACROSS THE NORTHERN HIGH PLAINS. WEAK SHORTWAVE
RIDING/CAPPING SHOULD GIVE WAY TO ISOLATED TO SCATTERED DEEP
CONVECTIVE DEVELOPMENT BY LATE AFTERNOON/EARLY EVENING WITH AID OF
AN APPROACHING SPEED MAX ALOFT. THIS SHOULD INITIALLY BE THE CASE IN
VICINITY OF A TRIPLE POINT NEAR/EAST OF THE MISSOURI RIVER ACROSS
THE DAKOTAS. STRONG/SEVERE TSTMS SHOULD INCREASE IN EARNEST
ESPECIALLY TOWARD/AFTER DARK...ESPECIALLY ALONG AND NORTH-NORTHEAST
OF THE NORTHWARD-SHIFTING WARM FRONT WITH AID OF A NOCTURNALLY
STRENGTHENING LOW LEVEL JET/ASSOCIATED WARM ADVECTION REGIME.
FARTHER SOUTH...A MORE APPRECIABLE EML WILL CONSIDERABLY HINDER THE
LIKELIHOOD/EXTENT OF DEEP CONVECTIVE DEVELOPMENT SOUTHWARD INTO THE
CENTRAL PLAINS SUNDAY AFTERNOON/EVENING IN VICINITY OF A
DRYLINE/SURFACE TROUGH.

PROVIDED BOUNDARY LAYER MOISTURE RETURNS AS EXPECTED...FORECAST
SOUNDINGS ESPECIALLY NEAR THE SURFACE LOW/S AND WARM FRONT FAVOR
SUPERCELLS POTENTIALLY CAPABLE OF VERY LARGE HAIL. ALTHOUGH BOUNDARY
LAYER MIXING MAY BE A LIMITING FACTOR...AMPLE VERTICAL SHEAR/SRH MAY
YIELD A TORNADO THREAT ESPECIALLY NEAR THE WARM FRONT DURING THE
EARLY EVENING HOURS ACROSS THE EASTERN DAKOTAS/WESTERN MN. A
DAMAGING WIND THREAT MAY ALSO EXIST FOR A TIME WITH POTENTIAL FOR
UPSCALE GROWTH FOCUSED NEAR THE WARM FRONT SUNDAY EVENING. SEVERE
POTENTIAL WILL OTHERWISE SHIFT EAST-SOUTHEASTWARD ACROSS PORTIONS OF
MN/MAINLY NORTHERN IA SUNDAY NIGHT...ALTHOUGH ON AN INCREASINGLY
ISOLATED/MARGINAL BASIS BY OVERNIGHT AS THE BOUNDARY LAYER
COOLS/INFLOW BECOMES ELEVATED.

...SOUTHERN PLAINS/OZARKS TO THE OH VALLEY...
WEAK WESTERLY/NORTHWESTERLY FLOW ALOFT WILL COINCIDE WITH AN
ANTICIPATED DIURNAL INCREASE OF ISOLATED-SCATTERED DEEP CONVECTIVE
DEVELOPMENT SUNDAY AFTERNOON/EARLY EVENING ALONG AND SOUTH OF AN
EFFECTIVE FRONT ANGLING SOUTHWEST TO NORTHEAST FROM THE SOUTHERN
PLAINS TO UPPER OH VALLEY. CURRENT THINKING IS THAT POCKETS OF
SEVERE HAIL/LOCALIZED WIND DAMAGE WILL BE POSSIBLE DURING THE
AFTERNOON/EVENING HOURS ACROSS THIS BROAD CORRIDOR. WHILE VERTICAL
SHEAR IS ANTICIPATED TO BE MEAGER /20-25 KT OR LESS/...AREAS SUCH AS
THE OH VALLEY COULD WARRANT A CATEGORICAL SLIGHT RISK FOR
PULSE/MULTICELLULAR INDUCED BOUTS OF DAMAGING WIND/HAIL GIVEN
POTENTIAL FOR MODERATE DESTABILIZATION WITHIN THE WARM SECTOR.

..GUYER.. 06/16/2012

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