DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 161720
SWODY2
SPC AC 161719

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CST THU FEB 16 2012

VALID 171200Z - 181200Z

...NO SVR TSTM AREAS FORECAST...

...SOUTH TX/TX AND LA COASTS...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE EWD ACROSS NORTHERN MEXICO
ON FRIDAY. AHEAD OF THE UPPER-LEVEL TROUGH ACROSS SOUTH
TX...FORECAST SOUNDINGS SHOW A CAPPED AIRMASS IN PLACE FRIDAY
AFTERNOON. THIS SHOULD KEEP THUNDERSTORM DEVELOPMENT VERY ISOLATED
DURING THE DAY. THE CAP SHOULD WEAKEN ENOUGH FRIDAY EVENING FOR THE
DEVELOPMENT OF SCATTERED THUNDERSTORMS AS THE LOW-LEVEL JET
STRENGTHENS. EVENTUALLY DURING THE OVERNIGHT PERIOD...STORM COVERAGE
SHOULD BECOME WIDESPREAD DUE TO INCREASING LARGE-SCALE ASCENT WITH
THE APPROACH OF THE UPPER-LEVEL TROUGH.

FORECAST SOUNDINGS ACROSS SOUTH TX EARLY FRIDAY EVENING SHOW A MOIST
AND MODERATELY UNSTABLE AIRMASS. SFC DEWPOINTS ARE FORECAST TO BE IN
THE LOWER 60S F WITH MLCAPE VALUES RANGING FROM 1200 TO 2000 J/KG.
THIS ALONG WITH INCREASING VERTICAL SHEAR DUE TO THE APPROACH OF A
65 TO 80 KT MID-LEVEL JET SHOULD BE SUFFICIENT FOR A SEVERE THREAT
BUT THE MAGNITUDE OF THE THREAT REMAINS CONDITIONAL. STEEP MID-LEVEL
LAPSE RATES AROUND 7.5 C/KM SHOULD BE ENOUGH FOR HAIL WITH THE MORE
INTENSE CORES. HOWEVER...FORECAST SOUNDINGS DURING THE EVENING AND
OVERNIGHT PERIOD CONTINUE TO SHOW A WARM LAYER AT 850 MB SUGGESTING
THE CONVECTION MAY HAVE TROUBLE BECOMING SFC-BASED. ALSO...THE
GREATEST SEVERE THREAT SHOULD BE DURING THE LATE NIGHT PERIOD. THESE
TWO FACTORS SHOULD KEEP THE SEVERE THREAT ISOLATED. IF THE
UPPER-LEVEL TROUGH APPROACHES SOUTH TX FASTER THAN IS CURRENTLY
FORECAST...THEN AN UPGRADE TO SLIGHT RISK COULD BECOME NECESSARY.
THE MARGINAL SEVERE THREAT SHOULD ALSO EXTEND NEWD ALONG THE TX AND
LA COASTS MAINLY AFTER 09Z.

..BROYLES.. 02/16/2012

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