SWODY3
SPC AC 240830
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CST THU NOV 24 2011
VALID 261200Z - 271200Z
...SYNOPSIS...
IN MID-UPPER LEVELS...PHASING OF NRN/SRN STREAM PERTURBATIONS
DESCRIBED IN DAY2 OUTLOOK WILL RESULT IN HIGH-AMPLITUDE TROUGHING BY
START OF PERIOD...FROM MB/SK BORDER SSEWD ACROSS CENTRAL/ERN KS THEN
CURVING SWD/SWWD ACROSS OK...W TX AND NWRN MEX. BY 27/00Z...SOME
AMPLITUDE DIFFERENCES START TO APPEAR IN OPERATIONAL PROGS AND MOST
SREF MEMBERS...BUT THEY STILL ARE IN STG CONSENSUS WITH SCENARIO OF
DEEPENING MID-UPPER LOW OVER UPPER MS VALLEY...TROUGHING SSWWD
ACROSS ARKLATEX REGION...AND BREAKAWAY BANNER OF 500-MB VORTICITY
ACROSS N-CENTRAL/WRN MEX. BY END OF PERIOD...DEEP SYNOPTIC-SCALE
TROUGH SHOULD BE MOVING EWD ACROSS EXTREME N-CENTRAL GULF...TN
VALLEY...AND LOWER OH VALLEY...ANCHORED BY PRONOUNCED CYCLONE OVER
UPPER GREAT LAKES.
AT SFC...STG COLD FRONT SHOULD SWEEP SEWD FROM MID MS VALLEY AND W
TX EARLY IN PERIOD...EXTENDING FROM OH TO CENTRAL/SRN MS TO SRN LA
BY ABOUT 27/00Z. FRONT SHOULD MOVE ACROSS MUCH OF CENTRAL/SRN
APPALACHIANS AND INTO WRN FL PANHANDLE BY END OF PERIOD.
...WRN/CENTRAL GULF COASTAL REGION...
LINE OF CONVECTION IS LIKELY IN FORCED-ASCENT ZONE ACCOMPANYING
FRONT...EVEN WITH NEAR-NEUTRAL MEAN LAPSE RATES IN LOW-MIDDLE LEVELS
IN SOME AREAS. SEPARATE...INITIALLY N-S BAND OF CONVECTION ALSO MAY
DEVELOP FROM GULF NWD ACROSS MS/AL IN LOW-LEVEL
WAA/MOISTURE-TRANSPORT REGIME FRINGING ERN PART OF WARM SECTOR
WEDGE...EVENTUALLY MERGING WITH OR OVERTAKEN BY COLD-FRONTAL LIFT
ZONE. DEEP-LAYER WINDS/SHEAR WILL SUPPORT POTENTIAL FOR STG-SVR
GUSTS...HOWEVER ONLY MODEST LOW-LEVEL MOISTURE RETURN IS EXPECTED
OVER MOST OF THIS AREA PRIOR TO FROPA. SREF CONSENSUS SUGGESTS SFC
DEW POINTS NEAR 60 F OVER MS/AL...50S INTO WRN PORTIONS TN/KY...AND
JUST MID-60S OVER COASTAL AREA. SUCH MOISTURE MIGHT NOT BE ENOUGH
TO OFFSET WEAK LAPSE RATES ALOFT AND GENERATE THUNDER OVER MUCH OF
THIS CORRIDOR. EXPECT SPORADIC THUNDER WITHIN CONVECTIVE
BAND...STRONGER DEEP-LAYER FORCING FROM NRN MS/AL NWD AND RELATIVELY
MAXIMIZED LOW-LEVEL THETAE FROM THAT AREA SWD. LATE IN
PERIOD...FRONT SHOULD OUTPACE INLAND RETURN OF AT LEAST MRGLLY
FAVORABLE THETAE ACROSS SERN CONUS...EFFECTIVELY SHUTTING DOWN ANY
SVR THREAT FROM N-S WITH TIME...AND WITH EWD EXTENT.
..EDWARDS.. 11/24/2011
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