SWODY1
SPC AC 081956
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0156 PM CST TUE MAR 08 2011
VALID 082000Z - 091200Z
...THERE IS A MDT RISK OF SVR TSTMS FOR PARTS OF LA AND SRN MS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF EAST TX/OK
INTO THE LOWER MS VALLEY...
...LA/MS THIS AFTERNOON AND TONIGHT...
A 40 KT SLY LOW-LEVEL JET AND ASSOCIATED WAA REGIME WILL CONTINUE TO
SUPPORT SHOWER AND THUNDERSTORM DEVELOPMENT OVER LA/WRN MS THIS
AFTERNOON...AND WILL ALSO AID IN NWD TRANSPORT OF HIGHER THETA-E
AIRMASS. AS A RESULT...DESTABILIZATION AND INCREASING MLCAPE VALUES
/UPWARDS OF 1000-1500 J PER KG/ WILL OCCUR ACROSS THE AREA...AND
SHOULD LEAD TO STORM INTENSIFICATION THROUGH EVENING. AREA VWP/S AND
RUC FORECAST SOUNDINGS SHOW STRONG VERTICAL WIND SHEAR PROFILES ARE
ALREADY IN PLACE...FAVORING SUPERCELLS POSING A THREAT OF
TORNADOES/DAMAGING WINDS AND PERHAPS LARGE HAIL. REF WW 42 FOR SHORT
TERM SVR WEATHER THREAT OVER THIS AREA. OTHERWISE...PREVIOUS
FORECAST REMAINS VALID FOR OVERNIGHT PERIOD.
...OK/TX/AR/NRN LA...
DEEPENING CUMULUS IS OBSERVED IN LATEST VIS SATELLITE LOOP FROM THE
TRIPLE POINT OVER CNTRL OK SWD INTO N-CNTRL TX. THICK STRATUS IS
PRESENT ACROSS MUCH OF ERN OK...BUT CLOUD EROSION IS NOTED FROM THE
RED RIVER SWD...WHICH IS ALLOWING STRONGER SURFACE HEATING AND
TEMPERATURES WARMING INTO THE 70S F. NARROW ZONE OF DESTABILIZATION
EXTENDING NWD INTO CNTRL OK MAY ALLOW BRIEF STORM INTENSIFICATION
AND A THREAT FOR MAINLY LARGE HAIL AND DAMAGING WIND GUSTS.
HOWEVER...BETTER INSTABILITY WILL BE LOCATED ALONG AND S OF THE WARM
FRONT OVER NERN TX. HERE...STEEP MIDLEVEL LAPSE RATES AND EFFECTIVE
BULK SHEAR AROUND 60 KT WILL FAVOR SUPERCELLS PRODUCING LARGE HAIL
/PERHAPS ISOLATED SIGNIFICANT HAIL OVER SRN OK AND NRN
TX/...DAMAGING WIND GUSTS...AND TORNADOES. AS THE WARM FRONT LIFTS
NWD TOWARD THE LA/AR BORDER...EXPANDING WARM SECTOR MAY ALLOW STORMS
TO PERSIST EWD INTO SRN AR/NRN LA WITH A CONTINUED SVR THREAT. REF
WW 43 FOR SHORT TERM SVR WEATHER POTENTIAL OVER THE AREA.
..GARNER/EDWARDS.. 03/08/2011
.PREV DISCUSSION... /ISSUED 1025 AM CST TUE MAR 08 2011/
...SYNOPSIS...
LARGE SCALE TROUGH SHIFTS EWD ACROSS PLAINS THRU THE FORECAST
PERIOD. ONE S/WV NOW ROTATING NEWD THRU KS/NRN OK WHILE UPSTREAM
VORT MAX CENTRAL NM MOVES EWD ACROSS SRN PLAINS TO LOWER MS VALLEY
12Z WED.
IMPRESSIVE MOISTURE STREAMING NWD FROM WRN GULF INTO SRN PLAINS AND
LOWER MS VALLEY THRU THIS EVENING AS A WARM FRONT DEVELOPS INLAND
ACROSS SERN TX EWD INTO SRN MS BY LATER THIS AFTERNOON. STEEP MID
LEVEL LAPSE RATES HAVE SPREAD EWD ACROSS SRN PLAINS INTO LOWER MS
VALLEY THIS MORNING ATOP THE DEEPENING LOW LEVEL MOISTURE AS
DEWPOINTS RISE THRU THE 60S BY THIS AFTERNOON ACROSS LWR MS VALLEY.
..LA/MS LATER THIS AFTERNOON AND TONIGHT...
THE FOCUSING MECHANISMS FOR CONVECTIVE DEVELOPMENT REMAIN A QUESTION
ATTM HOWEVER A WEAK CAPPING INVERSION AND INCREASING LARGE SCALE
FORCING ARE EXPECTED TO RESULT IN SCATTERED DISCRETE THUNDERSTORM
DEVELOPMENT IN A RATHER STRONGLY SHEARED ENVIRONMENT. FORECAST
SOUNDINGS SUGGEST EFFECTIVE SHEAR VALUES OF 40-50 KNOTS AND 0-3KM
SRH OF 250-350 M2/S2. WITH LARGE SCALE ASCENT INCREASING BOTH DUE TO
CONTINUED WARM ADVECTION AND APPROACH OF THE NM IMPULSE AND
MID/UPPER LEVEL WIND MAX... DISCRETE THUNDERSTORM DEVELOPMENT
APPEARS LIKELY BY LATER THIS AFTERNOON AND EVENING VICINITY OF THE
WARM FRONT MOVING INLAND ACROSS LA AND SRN MS. GIVEN THAT MLCAPES
INCREASE TO 1500 J/KG AND FAVORABLE SHEAR ENVIRONMENT NOW IN PLACE
WILL JUST IMPROVE THRU THE AFTERNOON...THE THREAT OF SUPERCELLS
DEVELOPING INCLUDING TORNADOES ARE LIKELY BEGINNING BY LATE THIS
AFTERNOON AND CONTINUING TONIGHT ACROSS LA INTO SRN MS. THERE IS
THE RISK OF STRONG TORNADOES. UPSCALE ORGANIZATION INTO BOWS/LEWPS
IS POSSIBLE OVERNIGHT WITH THE POTENTIAL FOR DAMAGING WINDS
SPREADING EWD INTO WRN AL.
PORTION OF THIS AREA HAS BEEN UPGRADED TO A MDT RISK DUE TO THE
GREATER CONFIDENCE OF THE POTENTIAL FOR STRONG TORNADOS.
...OK/TX/AR/LA...
BY LATER THIS AFTERNOON...THE SURFACE DRYLINE WILL SURGE EASTWARD
INTO EAST-CENTRAL OK AND CENTRAL TX. MODELS STILL DIFFER ON THE
EXTENT OF CONVECTIVE DEVELOPMENT ALONG THE BOUNDARY...BUT SUFFICIENT
RISK IS PRESENT TO MAINTAIN SLIGHT RISK ALONG THIS CORRIDOR. THOSE
STORMS THAT DO DEVELOP WILL POSE A THREAT OF LARGE HAIL... DAMAGING
WINDS...AND EVEN ISOLATED TORNADOES. IT APPEARS THE MOST LIKELY
AREA FOR THUNDERSTORMS ALONG THE DRYLINE WILL BE ALONG AND
IMMEDIATELY SOUTH OF THE RED RIVER LATER TODAY. THESE STORMS WILL
SPREAD EASTWARD INTO PORTIONS OF AR/LA THIS EVENING WITH A CONTINUED
SEVERE THREAT.
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