SWODY1
SPC AC 151927
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0127 PM CST WED FEB 15 2012
VALID 152000Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM E TX INTO SW MS...
EARLIER THOUGHTS REGARDING THE POTENTIAL FOR SEVERE THUNDERSTORMS
ACROSS THE WRN/CNTRL GULF STATES PRIMARILY REMAIN. OVER THE LAST
FEW HOURS IT HAS BECOME MORE OBVIOUS THAT THE MCS OVER SERN TX WILL
CONTINUE TO EXPAND IN AREAL COVERAGE AS IT SPREADS ACROSS THE SABINE
RIVER INTO LA. DESPITE THE WEAK INSTABILITY OBSERVED DOWNSTREAM IT
APPEARS WARM ADVECTION ATOP THE RETREATING CONTINENTAL AIRMASS WILL
PROVIDE ASCENT NECESSARY FOR CONVECTIVE GROWTH OVER THE LOWER MS
VALLEY. WHILE HAIL MAY AT TIMES BE NOTED ACROSS THE SRN/WRN FLANK
WHERE LAPSE RATES ARE SOMEWHAT STEEPER...ISOLATED SEVERE WIND GUSTS
MAY ULTIMATELY BE THE PRIMARY SEVERE THREAT WITH THIS COMPLEX OF
STORMS AS IT SPREADS INTO LA.
..DARROW.. 02/15/2012
.PREV DISCUSSION... /ISSUED 1030 AM CST WED FEB 15 2012/
...SYNOPSIS...
A MIDLEVEL SHORTWAVE TROUGH WILL EJECT ENEWD FROM THE TX PANHANDLE
TO THE I-35 CORRIDOR IN KS/NRN OK BY THIS EVENING...AND THEN
CONTINUE TO THE LOWER OH VALLEY OVERNIGHT. A REMNANT LEE CYCLONE
NEAR THE NW OK/KS BORDER AS OF 16Z WILL LIKEWISE MOVE ENEWD TOWARD
THE LOWER OH VALLEY...THOUGH IT APPEARS THAT THE LOW WILL SLOWLY
WEAKEN AS THE MIDLEVEL TROUGH LOSES AMPLITUDE. OTHERWISE...A
MIDLEVEL LOW OVER W CENTRAL NV WILL PROGRESS SWD TO SRN CA WITH A
MARGINAL RISK FOR THUNDERSTORMS INVOF SRN NV/SRN CA BY AFTERNOON.
...SE TX/CENTRAL LA THROUGH THIS EVENING...
THE MIDLEVEL TROUGH AND ASSOCIATED HEIGHT FALLS WILL PASS WELL TO
THE NW OF THIS AREA...AS A BELT OF 25-35 KT SWLY LOW-LEVEL FLOW
DEVELOPS EWD/NEWD FROM AN E TX-AR AXIS THIS MORNING TO THE MS VALLEY
THIS EVENING...AND THE TN/OH VALLEYS OVERNIGHT. MEANWHILE...THE
RICHEST LOW-LEVEL MOISTURE NOW ACROSS THE TX COASTAL PLAIN /BOUNDARY
LAYER DEWPOINTS OF 65-70 F/ WILL SPREAD NEWD ACROSS SE TX TO SW LA
THROUGH THIS EVENING. BOTH THE 12Z CRP AND A SPECIAL 15Z SOUNDING
FROM CLL REVEAL A CAP NEAR 800 MB...WITH STEEP LAPSE RATES IN THE
800-600 MB LAYER. CONTINUED MOISTENING WILL BOOST MLCAPE TO THE
1000-1500 J/KG RANGE THIS AFTERNOON FROM THE MIDDLE TX COASTAL PLAIN
INTO SE TX /ALONG AND S OF THE MARINE WARM FRONT/.
WIDESPREAD CLOUDS WILL TEND TO LIMIT DAYTIME HEATING...BUT IT IS
CLEAR THAT ASCENT IS ONGOING ALONG THE CORRIDOR FROM VCT TO CLL
WHERE A POSSIBLE GRAVITY WAVE IS INTERACTING WITH THE WARM FRONT AND
MOIST AXIS. THE NEWLY DEVELOPED STORMS FROM VCT-CLL WILL LIKELY
EVOLVE INTO MORE SURFACE-BASED CONVECTION BY EARLY AFTERNOON AND
SPREAD ENEWD TOWARD THE TOLEDO BEND AREA LATER THIS AFTERNOON. THE
MODERATE INSTABILITY AND DEEP-LAYER VERTICAL SHEAR WILL SUPPORT A
RISK FOR EMBEDDED SUPERCELLS WITH AN ASSOCIATED RISK FOR DAMAGING
WINDS AND LARGE HAIL. THERE WILL ALSO BE SOME RISK FOR A TORNADO OR
TWO GIVEN EFFECTIVE SRH NEAR 150 M2/S2 AND A MOIST LOW-LEVEL
ENVIRONMENT. LATER THIS EVENING INTO TONIGHT...THE SEVERE STORM
RISK WILL GRADUALLY DIMINISH AS THE MIDLEVEL WAVE EXITS TO NE AND
ANY REMAINING ASCENT SPREADS NE OF THE SURFACE WARM SECTOR.
...N/NE OK/SE KS LATE THIS AFTERNOON...
A NARROW UNSTABLE WARM SECTOR MAY DEVELOP IMMEDIATELY IN ADVANCE OF
THE SURFACE LOW AND MIDLEVEL TROUGH CROSSING NRN OK/SRN KS THIS
AFTERNOON/EVENING. INSTABILITY MAY BECOME SUFFICIENT FOR LOW-TOPPED
STORMS WITH A MARGINAL HAIL RISK.
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