DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 150732
SWODY3
SPC AC 150730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT MON OCT 15 2007

VALID 171200Z - 181200Z

..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF THE CENTRAL AND SRN
PLAINS...

..SYNOPSIS...
LARGE-SCALE TROUGHING WILL PERSIST ACROSS THE WRN HALF OF THE U.S.
THROUGH THE PERIOD...WHILE THE MAIN FEATURE WITH RESPECT TO SEVERE
CONVECTIVE WEATHER WILL BE A NEGATIVELY-TILTED SHORT-WAVE TROUGH ON
THE SERN PERIPHERY OF THIS LARGER-SCALE FEATURE. THIS SHORT-WAVE
TROUGH IS FORECAST TO MOVE INTO THE CENTRAL AND SRN PLAINS DURING
THE AFTERNOON...WHILE ASSOCIATED SURFACE LOW DEEPENS INVOF WRN KS.
A TROUGH/DRYLINE EXTENDING S FROM THIS LOW WILL LIKELY SERVE AS A
FOCUS FOR SEVERE STORMS.

..CENTRAL AND SRN PLAINS FROM NEB SWD INTO CENTRAL TX...
SLY BOUNDARY-LAYER FLOW AHEAD OF APPROACHING SHORT-WAVE TROUGH
SHOULD ALLOW UPPER 50S TO MID 60S DEWPOINTS TO SPREAD NWD ACROSS WRN
PORTIONS OF THE CENTRAL AND SRN PLAINS AHEAD OF SURFACE
TROUGH/DRYLINE. CLUSTERS OF STORMS -- AND POSSIBLY FAIRLY EXTENSIVE
CLOUD COVER -- MAY BE ONGOING ACROSS PARTS OF THE RISK AREA AT THE
START OF THE PERIOD...WHICH SHOULD RETARD AFTERNOON DESTABILIZATION
ACROSS PARTS OF THE AREA. HOWEVER...EXPECT POCKETS OF 500 TO 1000
J/KG MIXED-LAYER CAPE TO DEVELOP...WHICH COMBINED WITH THE APPROACH
OF THE UPPER SYSTEM AND LOW-LEVEL MIXING FOCUSED INVOF DRYLINE
SHOULD ALLOW SCATTERED STORM DEVELOPMENT TO OCCUR.

WITH 60 KT SWLY MID-LEVEL FLOW FORECAST TO SPREAD ACROSS THE RISK
AREA ATOP LOW-LEVEL SLYS/SELYS...DEEP-LAYER SHEAR WILL BE QUITE
STRONG -- SUGGESTING THAT STORMS WILL RAPIDLY ACQUIRE UPDRAFT
ROTATION. ALONG WITH THE POTENTIAL FOR LARGE HAIL AND
LOCALLY-DAMAGING WINDS...DEGREE OF LOW-LEVEL VEERING/SHEAR ALSO
APPEARS SUPPORTIVE OF A TORNADO THREAT. WHILE QUESTIONS REMAIN ATTM
-- AS DEGREE OF DESTABILIZATION AND OVERALL COVERAGE OF STORMS ARE
DIFFICULT TO ASCERTAIN ATTM...WILL INTRODUCE SLIGHT RISK/15% SEVERE
PROBABILITY THIS FORECAST. SHOULD IT BECOME CLEARER IN LATER
FORECASTS THAT MORE FAVORABLE DESTABILIZATION MAY BE POSSIBLE --
THUS SUPPORTING MORE WIDESPREAD STORM DEVELOPMENT...AN UPGRADE IN
SEVERE WEATHER PROBABILITY WOULD BE REQUIRED.

.GOSS.. 10/15/2007

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