DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 291731
SWODY2
SPC AC 291729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT FRI MAR 29 2013

VALID 301200Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND
CNTRL PLAINS...

...SRN AND CNTRL PLAINS...
NORTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE GREAT PLAINS FROM
TONIGHT INTO SATURDAY AS AN UPPER-LEVEL TROUGH AMPLIFIES SEWD INTO
THE UPPER MS VALLEY AND MID-MO VALLEY. AT THE SFC ON SATURDAY...A
LOW PRESSURE AREA IS FORECAST TO MOVE EWD ACROSS SRN IA AND NRN MO
WITH A COLD FRONT ADVANCING SEWD INTO ERN KS AND NW MO BY AFTERNOON.
THE SRN PART OF THE FRONT EXTENDING FROM NW OK SWWD INTO WEST TX IS
EXPECTED TO MOVE SLOWLY SEWD. THE SFC LOW AND FRONTAL BOUNDARY
SHOULD BE A FOCUS FOR CONVECTIVE DEVELOPMENT DURING THE DAY.
SCATTERED THUNDERSTORMS MAY BE ONGOING AT THE START OF THE PERIOD
NEAR THE SFC LOW IN THE MID-MO VALLEY WITH CONVECTIVE INITIATION
TAKING PLACE IN THE SRN PLAINS LATE SATURDAY AFTERNOON AS A CAPPING
INVERSION WEAKENS. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT THAT
A CLUSTER OF THUNDERSTORMS WILL ORGANIZE ACROSS THE RED RIVER VALLEY
OF SRN OK AND NORTH TX DURING THE EARLY EVENING WHERE LOW-LEVEL FLOW
SHOULD BECOME ENHANCED.

FORECAST SOUNDINGS ALONG THE INSTABILITY AXIS AT 21Z SHOW SFC
DEWPOINTS RANGING FROM THE UPPER 50S F IN SE KS TO THE LOWER 60S F
AROUND WICHITA FALLS TX. MLCAPE VALUES ARE FORECAST TO REACH 1500 TO
2000 J/KG IN SE KS AND NE OK WITH HIGHER VALUES OF 3000 TO 3500 J/KG
POSSIBLE SWWD INTO SW OK AND NORTH TX. IN ADDITION...0-6 KM SHEAR
VALUES ARE FORECAST TO RANGE FROM AROUND 50 KT IN NE OK TO AROUND 40
KT NEAR THE RED RIVER. THIS ENVIRONMENT ALONG WITH 850 TO 500 MB
LAPSE RATES AROUND 8.0 C/KM SHOULD BE SUFFICIENT FOR SUPERCELL
DEVELOPMENT ESPECIALLY WITH CELLS THAT REMAIN DISCRETE. THE STEEP
LAPSE RATES AND COLD TEMPS ALOFT SHOULD BE FAVORABLE FOR LARGE HAIL
WITH ISOLATED VERY LARGE HAIL POSSIBLE ESPECIALLY IF STRONG
INSTABILITY IS REALIZED IN THE RED RIVER VALLEY. A POTENTIAL FOR
TORNADOES MAY ALSO DEVELOP BUT THE RELATIVELY WEAK FLOW BELOW 850 MB
COULD BE A LIMITING FACTOR. IF THE FAVORED MODE BECOMES LINEAR
DURING THE EARLY EVENING...THEN AN ISOLATED WIND DAMAGE THREAT MAY
ALSO DEVELOP. THUNDERSTORMS MAY PERSIST INTO THE OVERNIGHT PERIOD
ACROSS THE OZARKS EXTENDING SWWD INTO CNTRL TX BUT THE SEVERE THREAT
SHOULD BECOME INCREASINGLY MARGINAL AS INSTABILITY WEAKENS DURING
THE LATE EVENING AND OVERNIGHT PERIOD.

..BROYLES.. 03/29/2013

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