SPC AC 181615
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1115 AM CDT FRI APR 18 2008
VALID 181630Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF THE CENTRAL GULF
COAST...
...CENTRAL GULF COAST...
UPPER LOW NERN KS WITH TROUGH EXTENDING SWD INTO ERN TX WILL
CONTINUE EWD. TROUGH ROTATES ACROSS LOWER MS VALLEY BY THIS EVENING
ACCOMPANIED BY A STRONG MID LEVEL WIND MAX. PRE-FRONTAL SQUALL LINE
FROM LAST NIGHT HAS CONTINUED INTO WRN MS SWWD INTO SWRN LA AND HAS
STEADILY WEAKENED THIS MORNING AS IT ENCOUNTERS A LESS FAVORABLE
THERMODYNAMIC ENVIRONMENT.
LIMITED INSTABILITY WILL BE AN ISSUE WITH REGARD TO ANY SEVERE STORM
POTENTIAL THIS FORECAST PERIOD AS UPPER TROUGH MOVES ACROSS LOWER MS
VALLEY. WITH 20-30KT LOW LEVEL JET SERN LA INTO SRN MS WILL
GRADUALLY DESTABILIZE THIS AFTERNOON AS DEWPOINTS RISE TO MID 60S F
AND TEMPS WARM THRU THE 70S. MLCAPES TO NEAR 1000 J/KG ARE POSSIBLE
WHERE BETTER HEATING CAN OCCUR IN THIS AREA AHEAD OF INSTABILITY
LINE. THE OBSERVED CAP ON BOTH 12Z JAN AND LIX SOUNDINGS SHOULD
ERODE WITH LARGE SCALE ASCENT AND MID LEVEL COOLING WITH APPROACHING
UPPER TROUGH.
SURFACE BASED THUNDERSTORMS EXPECTED TO INCREASE IN NUMBER AND
INTENSITY DURING THE AFTERNOON SRN MS/SERN LA ALONG/AHEAD OF OLD
INSTABILITY LINE. WITH 40-50KT OF SHEAR COUPLED WITH EXPECTED
INSTABILITY...A FEW SEVERE STORMS ARE POSSIBLE BY MID AFTERNOON.
PRIMARY CONCERN WILL BE DAMAGING WINDS AS LIMITED INSTABILITY/LAPSE
RATES PRECLUDE MUCH OF A LARGE HAIL THREAT. SPEED AND DIRECTIONAL
SHEAR ACCOMPANYING MID LEVEL WIND MAX/TROUGH SUGGESTS POTENTIAL FOR
SUPERCELLS PROVIDED ADEQUATE INSTABILITY CAN DEVELOP. THUS WILL
CONTINUE A LOW THREAT OF A TORNADO OR TWO BUT SHIFT THE THREAT TO
THE S WHERE INSTABILITY WILL BE HIGHER.
..HALES/HURLBUT.. 04/18/2008
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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