DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 170732
SWODY3
SPC AC 170730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT THU MAY 17 2012

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE CNTRL/SRN
PLAINS ON SAT AFTERNOON/EVENING...

...SYNOPSIS...
A SHORT WAVE IMPULSE EMBEDDED WITHIN A DAMPENING UPPER-LEVEL TROUGH
SHOULD EJECT NEWD FROM THE SRN ROCKIES TOWARDS THE MID-MO VALLEY
DURING THE PERIOD...IMPINGING ON A RIDGE FROM THE SRN PLAINS TO THE
GREAT LAKES. SURFACE COLD FRONT WILL ADVANCE EWD ACROSS THE UPPER MS
VALLEY...AND S/SEWD IN THE CNTRL TO THE SRN HIGH PLAINS. THIS FRONT
SHOULD INTERSECT THE DRYLINE RUNNING S/SWWD IN WRN TX AND ATTENDANT
SURFACE LOW INVOF ERN TX PANHANDLE AT 20/00Z.

...UPPER MS VALLEY TO SRN PLAINS...
DESPITE A GRADUAL DAMPENING NATURE OF THE SHORT WAVE TROUGH EXPECTED
TO EJECT ON THE PLAINS DURING THE DAY...AT LEAST 30-40 KT S/SWLYS AT
500 MB SHOULD PERSIST ALONG THE COLD FRONT AND DRYLINE. GUIDANCE
CONTINUES TO DIFFER GREATLY WITH THE DEGREE OF MOISTURE RETURN AHEAD
OF THESE BOUNDARIES...DESPITE SIMILARITIES IN LLJ EVOLUTION OVER THE
PLAINS AND ONLY MODEST RETURN FLOW ALONG THE WRN GULF COAST.
PREFERENCE REMAINS STRONGLY TIED TO THE DRIER SPECTRUM OF GUIDANCE
/ESSENTIALLY THE NAM/...WITH ITS MORE REALISTIC DEPICTION OF
GENERALLY MID TO UPPER 50S SURFACE DEW POINTS ALONG THE
FRONT/DRYLINE BY SAT AFTERNOON.

REMNANTS OF CONVECTION FROM LATE D2 MAY PERSIST AND INCREASE WITH
DIURNAL HEATING OVER THE UPPER MS VALLEY. FARTHER S/SW...STRONGER
CAPPING SHOULD INHIBIT TSTM DEVELOPMENT UNTIL PEAK HEATING WHEN
CONVERGENCE ALONG THE FRONT SHOULD BE SUFFICIENT FOR TSTMS FORMING
IN THE LATE AFTERNOON/EARLY EVENING. GIVEN THE PRESENCE OF VERY
STEEP MID-LEVEL LAPSE RATES IN THE CNTRL PLAINS...A RISK FOR LARGE
HAIL WILL EXIST. BUT WITH DEEP-LAYER FLOW ROUGHLY PARALLELING THE
FRONT AND THE WARM SECTOR REMAINING CAPPED AWAY FROM THE IMMEDIATE
FRONTAL ZONE...CONVECTION SHOULD LARGELY REMAIN ALONG THE BOUNDARY
AND BE A LIMITING FACTOR TO A MORE ROBUST SEVERE THREAT. FARTHER S
ALONG THE DRYLINE...HODOGRAPHS AND ORIENTATION OF THE FLOW SHOULD BE
MORE FAVORABLE FOR DISCRETE HIGH-BASED SUPERCELLS...BUT THE SRN
EXTENT BECOMES INCREASINGLY UNCERTAIN REMOVED FROM THE TRACK OF THE
SHORT WAVE TROUGH.

..GRAMS.. 05/17/2012

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