DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 190602
SWODY2
SPC AC 190600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT TUE MAY 19 2009

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AN AMPLIFIED/BLOCKY UPPER FLOW REGIME WILL CONTINUE INTO WEDNESDAY
ACROSS THE SOUTHERN TWO-THIRDS OF THE CONUS...AS A STAGNANT UPPER
LOW REMAINS IN THE VICINITY OF FL...WITH ANOTHER SLOW MOVING UPPER
LEVEL LOW DEVELOPING NORTHEASTWARD ACROSS THE SOUTHWEST
DESERTS/NORTHWEST MEXICO. FARTHER NORTH...A POTENT SHORTWAVE TROUGH
WILL CONTINUE TO SPREAD EASTWARD ACROSS THE CENTRAL CANADIAN
PROVINCES AND ADJACENT NORTHERN PLAINS/UPPER MIDWEST AMIDST THE MAIN
BELT OF STRONGER WESTERLIES.

...NORTH CENTRAL PLAINS...
AS THE SHORTWAVE TROUGH STEADILY ADVANCES EASTWARD ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST...AN ASSOCIATED COLD FRONT WILL SPREAD
SOUTH-SOUTHEASTWARD ACROSS THE NORTH CENTRAL PLAINS AND UPPER
MIDWEST. AIDED BY THE GRADUAL DECAY OF THE ROCKIES UPPER RIDGE AND
STRONG AFTERNOON/BOUNDARY LAYER HEATING...ALONG WITH LATER DAY ONSET
OF LOW LEVEL POST-FRONTAL UPSLOPE INTO THE HIGHER TERRAIN/FRONT
RANGE...ISOLATED TO SCATTERED TSTMS SHOULD DEVELOP AND INCREASE
THROUGH MID/LATE AFTERNOON...INITIALLY MOST PROBABLE ACROSS
SOUTHEAST WY/NEB PANHANDLE AND THE ADJACENT PORTIONS OF NORTHEAST
CO/SOUTHERN SD. WHILE MULTICELLULAR STORMS CAPABLE OF STRONG WIND
GUSTS/HAIL WOULD LIKELY BE THE DOMINANT MODE...A FEW HIGH-BASED
SUPERCELLS WILL BE POSSIBLE ALONG/JUST NORTH OF THE SOUTHWARD
SAGGING FRONTAL BOUNDARY MAINLY ACROSS WESTERN/NORTHERN NEB...AS THE
STRONGEST SHEAR WILL LAG THE FRONT. THE SEVERE THREAT WOULD LIKELY
BEGIN TO DIMINISH BY AROUND SUNSET AS THE BOUNDARY LAYER BEGINS TO
DECOUPLE.

...NORTHERN MN...
SHOWERS/TSTMS WILL BE POSSIBLE ACROSS NORTHERN MN IN ACCORDANCE WITH
THE APPROACHING SHORTWAVE TROUGH/SURFACE COLD FRONT. IN THE PRESENCE
OF LIMITED BOUNDARY LAYER MOISTURE...00Z BASED MODEL GUIDANCE
SUGGESTS THAT THIS CONVECTION WILL TEND TO BE ELEVATED AND BASED IN
THE MID LEVELS...WITHIN A VERY STEEP LAPSE RATE ENVIRONMENT. WHILE
SOME SMALL HAIL MAY BE POSSIBLE...LIMITED MOISTURE/WEAK
BUOYANCY...AND SEEMINGLY LIMITED POTENTIAL FOR SURFACE-BASED
CONVECTIVE INITIATION ALONG THE FRONT GIVEN THE DEGREE OF
CAPPING...SUGGEST SEVERE PROBABILITIES ARE NOT WARRANTED AT THIS
TIME.

...SOUTHERN FL PENINSULA...
ALTHOUGH MODEL VARIABILITY EXISTS...GENERAL CONSENSUS OF SOLUTIONS
SUGGESTS THAT THE STAGNANT LOW MAY BEGIN TO DRIFT WESTWARD AWAY FROM
THE COAST. AS THIS OCCURS...POTENTIAL WILL EXIST FOR MID-LEVEL
DRYING AND SOMEWHAT STRONGER AFTERNOON HEATING...IN ADDITION TO LOW
LEVEL MOISTENING FROM THE EAST...ACROSS THE SOUTHERN FL PENINSULA.
THIS COULD LEAD TO AN UPSWING IN TSTM VIGOR WITH HAIL/DOWNBURST
POTENTIAL MAINLY WEDNESDAY AFTERNOON.

..GUYER.. 05/19/2009

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