DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 291729
SWODY2
SPC AC 291728

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT TUE OCT 29 2013

VALID 301200Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF THE SRN/CNTRL
PLAINS TO THE MID MO VALLEY...

...SYNOPSIS...
A LARGE UPPER TROUGH WILL PROGRESS EWD OUT OF THE GREAT BASIN...AS
AN ACCOMPANYING BELT OF STRONG SWLY FLOW ALOFT OVERSPREADS THE GREAT
PLAINS. A LEAD SHORTWAVE TROUGH EMBEDDED WITHIN THE LARGE-SCALE
TROUGH WILL MOVE ACROSS NEB AND THE DAKOTAS...WHILE LATER IN THE
PERIOD...THE PRIMARY VORT LOBE ASSOCIATED WITH THE UPPER TROUGH
SPREADS INTO THE SRN PLAINS. AT THE SFC...LOW PRESSURE WILL DEVELOP
NEWD FROM THE CNTRL PLAINS ACROSS THE MID MO VALLEY. AN ATTENDANT
ADVANCING WARM FRONT WILL SPREAD RICH GULF MOISTURE NWD INTO THE
UPPER MS VALLEY. BY LATE IN THE PERIOD...A COLD FRONT WILL
ACCELERATE EWD ACROSS THE SRN/CNTRL PLAINS INTO THE UPPER GREAT
LAKES. WIDESPREAD PRECIPITATION IS LIKELY ACROSS THE CNTRL
CONUS...WITH SOME STRONG TO SVR TSTMS POSSIBLE WHERE POCKETS OF
STRONGER HEATING OCCUR.

...SRN/CNTRL LOWER PLAINS TO MID MO VALLEY...
WIDESPREAD CLOUD COVER AND SCATTERED SHOWERS/TSTMS ARE EXPECTED TO
BE ONGOING AT THE BEGINNING OF THE PERIOD...ESPECIALLY FROM OK NWD
INTO NEB. A SEASONABLY MOIST /PW GENERALLY ABOVE 1 INCH/ AND
RELATIVELY HOMOGENEOUS WARM SECTOR IS EXPECTED TO EVOLVE ACROSS MUCH
OF THE PLAINS...AHEAD OF A COLD FRONT INITIALLY OVER THE CNTRL HIGH
PLAINS...AND A DRYLINE EXTENDING SSWWD FROM S-CNTRL KS INTO W TX.

IT IS LIKELY THAT AT LEAST SOME PRECIPITATION WILL PERSIST
THROUGHOUT THE DAY GIVEN MIDLEVEL HEIGHT FALLS OCCURRING THROUGHOUT
THE PERIOD AND THE PERSISTENCE OF THE LLJ. THIS...ALONG WITH
ASSOCIATED CLOUD COVER...IS EXPECTED TO SUBSTANTIALLY LIMIT THE
AMOUNT OF HEATING AND SUBSEQUENT DESTABILIZATION THAT CAN
OCCUR...AND WILL PROVE DIFFICULT FOR VIGOROUS UPDRAFTS TO DEVELOP.
HOWEVER...IF POCKETS OF HEATING CAN ALLOW TEMPERATURES TO REACH THE
LOWER 70S F...MOIST CHARACTER OF THE BOUNDARY LAYER AND MODERATELY
STEEP LAPSE RATES COULD YIELD MLCAPE VALUES AS HIGH AS 1000-1500
J/KG IN SOME LOCATIONS. VERTICAL SHEAR PROFILES ARE SUFFICIENT FOR
STORM ORGANIZATION AND AN ATTENDANT THREAT FOR HAIL AND WIND...AND
PERHAPS A TORNADO OR TWO...IF MORE ROBUST CONVECTION CAN
DEVELOP...BUT INITIALLY BROAD AND WEAKLY FOCUSED FORCING FOR ASCENT
ACROSS MUCH OF THE SLIGHT RISK AREA YIELDS HIGH UNCERTAINTY
REGARDING POTENTIAL CONVECTIVE EVOLUTION.

THE PRIMARY SFC LOW PRECEDING A LEAD SHORTWAVE UPPER TROUGH ACROSS
THE NRN PLAINS IS FORECAST TO BECOME CENTERED OVER ERN NEB BY
31/00Z...BUT THE DEGREE OF HEATING/DESTABILIZATION THAT CAN OCCUR
INVOF THE LOW IS QUESTIONABLE. BY LATE IN THE PERIOD...CONVECTIVE
RE-DEVELOPMENT IS POSSIBLE AS THE COLD FRONT OVERTAKES THE DRYLINE
FROM WRN OK INTO ERN KS...AND THE PRIMARY VORT LOBE ASSOCIATED WITH
THE UPPER TROUGH PROGRESSES EWD. A MARGINAL WIND/HAIL THREAT COULD
ACCOMPANY THIS ACTIVITY INTO EARLY THU MORNING...BUT THE PRIMARY
RISK SHOULD BE HEAVY RAINFALL.

..ROGERS.. 10/29/2013

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