DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 301727
SWODY2
SPC AC 301726

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT WED OCT 30 2013

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR THE ARKLATEX/LOWER MS RIVER
VALLEY TO THE TN/OH RIVER VALLEYS...

...ARKLATEX/LOWER MS RIVER VALLEY TO THE TN/OH RIVER VALLEYS...
THE POTENTIAL FOR WIDESPREAD DMGG WINDS...AND POSSIBLY A FEW
TORNADOES...WILL INCREASE THROUGHOUT THE DAY IN ASSOCIATION WITH A
POTENT UPPER TROUGH MOVING OUT OF THE SRN PLAINS. THE PRIMARY
CONCERNS/UNCERTAINTIES WITH REGARD TO THE MAGNITUDE OF SVR POTENTIAL
CONTINUE TO CENTER AROUND THE POSSIBILITY OF EARLY CONVECTION AND
THE RESULTANT DESTABILIZATION THAT CAN OCCUR DURING THE DAY.

THE DEGREE OF LOW-LEVEL MOISTURE PRESENT WITHIN THE WARM
SECTOR...COMBINED WITH AT LEAST WEAK MIDLEVEL HEIGHT FALLS AND
ISENTROPIC ASCENT EARLY IN THE PERIOD...SHOULD SUPPORT SCATTERED
SHOWERS/TSTMS THROUGHOUT THE MORNING. A SEWD MOVING MCS MAY ALSO BE
ONGOING AT THE START OF THE PERIOD ACROSS THE ARKLATEX...WITH
PROXIMITY FORECAST SOUNDINGS SUGGESTIVE OF LARGE LOOPING HODOGRAPHS.
BY LATE MORNING/EARLY AFTERNOON...DEEP-LAYER WIND FIELDS ARE
FORECAST TO STRENGTHEN SUBSTANTIALLY AS THE UPPER TROUGH ACQUIRES A
NEGATIVE TILT...WITH A BELT OF 60-70 KT 700 MB FLOW BECOMING
POSITIONED FROM THE LOWER MS VALLEY INTO THE OH VALLEY BY 18Z. THE
STRONGLY SHEARED BUT WEAKLY UNSTABLE ENVIRONMENT COULD BE SUPPORTIVE
FOR ORGANIZED TSTMS WITH ANY SEMI-DISCRETE STRUCTURES THAT CAN
EVOLVE WITHIN THE WARM SECTOR...WITH AN ATTENDANT THREAT FOR DMGG
WINDS AND TORNADOES /PERHAPS ONE OR TWO STRONG/ POSSIBLE.
HOWEVER...THE STORM MODE IS LIKELY TO BE SOMEWHAT COMPLEX/MESSY
INITIALLY PRECEDING AN UPSTREAM COLD FRONT.

MORE SUBSTANTIAL/FOCUSED FORCING FOR ASCENT ACCOMPANYING THE UPPER
TROUGH AND AN ACCELERATING COLD FRONT WILL ARRIVE ACROSS THE
ARKLATEX AND MID-MS VALLEY DURING THE AFTERNOON. WHILE THE DETAILS
ARE STILL SOMEWHAT UNCLEAR...A CONTINUOUS LOW-TOPPED CONVECTIVE LINE
APPEARS LIKELY TO DEVELOP AND RAPIDLY SHIFT EWD ATTENDANT TO A
RAPIDLY DEEPENING SFC LOW. WHILE THE PRIMARY THREAT WILL LIKELY BE
DMGG WINDS...BOWING/LEWP STRUCTURES COULD SUPPORT TORNADOES EMBEDDED
WITHIN THE LINE...GIVEN THE DEGREE OF LOW-LEVEL SRH PRESENT. THE
LINE SHOULD PERSIST OVERNIGHT INTO EARLY FRI MORNING ACROSS THE
APPALACHIANS/UPPER OH VALLEY...EVENTUALLY OUTRUNNING RICHER
LOW-LEVEL MOISTURE AND INSTABILITY...BUT AT LEAST SOME WIND/TORNADO
THREAT MAY CONTINUE GIVEN THE MAGNITUDE OF LOW-/MID-LEVEL WIND
FIELDS.

..ROGERS.. 10/30/2013

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