SWODY1
SPC AC 251958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0158 PM CST THU NOV 25 2010
VALID 252000Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER MS
VALLEY...
...LOWER MS VALLEY...
EARLY AFTERNOON SURFACE ANALYSIS SHOWED A NARROW MOIST/WARM SECTOR
/TEMPERATURES IN THE 70S-LOWER 80S AND DEWPOINTS IN THE MID-UPPER
60S/ EXTENDING FROM E TX/LA TO WRN TN. LOWER 60S SURFACE DEWPOINTS
EVEN EXTENDED AS FAR N AS WRN KY. WEAK MIDLEVEL LAPSE RATES
CONTINUE TO LIMIT THE DEVELOPMENT OF STRONGER INSTABILITY AND THE
OVERALL NUMBER OF MORE ROBUST UPDRAFTS. HOWEVER...40-50 KT OF DEEP
LAYER SHEAR AND EFFECTIVE SRH VALUES 200-400 M2/S2 EXTENDING FROM
FAR NRN LA TO WRN TN HAVE SUPPORTED AND WILL CONTINUE TO SUPPORT
ROTATING UPDRAFTS WITH STORMS THAT DO FORM EITHER ALONG THE COLD
FRONT AND/OR MORE DISCRETELY WITHIN THE WARM SECTOR. GIVEN THE NEW
ORIENTATION OF THE WARM SECTOR WITH FAVORABLE SHEAR VALUES...SLIGHT
RISK AREA HAS BEEN EXTENDED SWD INTO FAR NRN LA AND EWD/NWD INTO
MORE OF NRN MS AND WRN TN...RESPECTIVELY.
...OH VALLEY...
REST OF FORECAST REMAINS THE SAME AS EARLIER FORECAST WITH A LOW
SEVERE WEATHER THREAT NNEWD INTO THE OH VALLEY.
..PETERS.. 11/25/2010
.PREV DISCUSSION... /ISSUED 1008 AM CST THU NOV 25 2010/
...LOWER MS VALLEY...
DEEP/COLD UPPER LOW NRN PLAINS WILL CONTINUE EWD TO UPPER GREAT
LAKES TONIGHT WITH ASSOCIATED TROUGH TRAILING SWWD INTO SRN ROCKIES.
VERY STRONG SWLY FLOW IN ADVANCE OF THE TROUGH...WITH STRONGEST
WINDS WELL N OF WARM SECTOR AHEAD OF COLD FRONT.
COLD FRONT CURRENTLY FROM SRN IL SWWD THRU WRN AR TO NRN TX WILL
MOVE ACROSS TN AND LOWER MS VALLEYS BY TONIGHT. VERY MOIST AIR MASS
WITH DEWPOINTS INTO THE MID/UPR 60S HAVE SPREAD NWD AHEAD OF FRONT
THRU ERN AR/WRN MS. EXTENSIVE CLOUD COVER AND WEAK MID LEVEL LAPSE
RATES WILL LIMIT AMOUNT OF INSTABILITY AVAILABLE FOR STRONG UPDRAFTS
IN THE WARM SECTOR. HOWEVER THE 30-35 KT OF LOW LEVEL SHEAR COUPLED
WITH 60-70 KT OF DEEP SHEAR WILL SUPPORT POTENTIAL FOR ROTATING LOW
TOP STORMS/SUPERCELLS WHERE SURFACE CONVECTION IS ABLE TO DEVELOP.
IT NOW APPEARS SUFFICIENT MLCAPE UP TO 500 J/KG WILL BE AVAILABLE AS
FAR N AS WRN TN THIS AFTERNOON AS SURFACE TEMPS RISE INTO LOW/MID
70S AHEAD OF FRONT.
HAVE INCREASED THE RISK OF BOTH ISOLATED TORNADO'S AND WIND DAMAGE
BASED ON THE NOW GREATER CONCERN FOR SURFACE BASED STORMS GIVEN THE
VERY WEAK CINH REMAINING.
SEE MCD 2081 FOR ADDITIONAL INFO ON THIS AREA.
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