DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 300538
SWODY2
SPC AC 300536

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT SUN SEP 30 2012

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SERN
U.S....

...SERN U.S...

SHORT-RANGE MODEL GUIDANCE IS IN REASONABLY GOOD AGREEMENT REGARDING
THE EVOLUTION OF UPPER LOW THAT DEVELOPS OVER SERN OK THEN DRIFTS
INTO AR BY 02/00Z. IN RESPONSE TO THIS FEATURE...SFC LOW AND
ATTENDANT FRONT WILL PROGRESS INTO ERN MS AT DAYBREAK THEN EASE INTO
AL DURING THE AFTERNOON. MARITIME TROPICAL AIRMASS IS EXPECTED TO
MOVE INLAND AHEAD OF THE FRONT AS LLJ ON THE ORDER OF 40-45KT
STRENGTHENS ACROSS THE WARM SECTOR. FOR THIS REASON IT APPEARS
LOWER 70S SFC DEW POINTS SHOULD ENCOMPASS MUCH OF ERN MS/AL/GA AHEAD
OF THE WIND SHIFT. A FEW NEGATIVES FOR SIGNIFICANT INSTABILITY WILL
BE LAYERED CLOUDINESS AND SUBSEQUENT POOR LAPSE RATE
ENVIRONMENT...PSEUDO-ADIABATIC...THAT SHOULD LIMIT SBCAPE TO ROUGHLY
500-1000 J/KG.

LATEST GUIDANCE SUGGEST FRONTAL CONVECTION WILL BE ONGOING AT THE
START OF THE PERIOD ACROSS MS AND THIS ACTIVITY SHOULD ADVANCE EWD
DURING THE DAY AHEAD OF WIND SHIFT. FORECAST ENVIRONMENTAL SHEAR IS
CERTAINLY SUPPORTIVE OF ROTATING UPDRAFTS BUT ACTIVITY ALONG THE
FRONT MAY EXHIBIT MORE LINEAR CHARACTERISTICS WITH BOW-TYPE
STRUCTURES POSSIBLE. THE GREATEST THREAT FOR SUPERCELLS AND
ISOLATED TORNADOES WILL BE WITH ECHOES THAT EVOLVE AHEAD OF THE
FRONTAL CONVECTION. OTHERWISE DAMAGING WINDS ARE THE PRIMARY SEVERE
THREAT THROUGH THE PERIOD.

..DARROW.. 09/30/2012

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