DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 311252
SWODY1
SPC AC 311250

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CDT THU OCT 31 2013

VALID 311300Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS WRN GULF COAST TO
MID-SOUTH...LOWER-MID MS RIVER VALLEY AND LAKE ERIE REGION...

...SYNOPSIS...
MAIN SYNOPTIC-SCALE FEATURE FOR THIS OUTLOOK WILL REMAIN
WELL-DEFINED TROUGH -- LOCATED INITIALLY FROM ERN DAKOTAS SSWWD
ACROSS SRN HIGH PLAINS. TWO EMBEDDED/PRIMARY VORTICITY MAXIMA AND
RELATED MESOSCALE CIRCULATIONS ALOFT ARE EVIDENT IN MOISTURE CHANNEL
IMAGERY...
1. OVER ERN SD AT 31/12Z -- FCST TO MOVE EWD ACROSS UPPER MS VALLEY
TO WI BY 1/00Z AND ACCELERATE ENEWD ACROSS LH TO NECK OF ONT BY
1/12Z.
2. OVER OK PANHANDLE AS 31/12Z...WITH SHORTWAVE TROUGH SWD ACROSS
MERIDIONAL SEGMENT OF TX/NM BORDER. THIS PERTURBATION SHOULD WEAKEN
SLIGHTLY UNTIL MOVING ENEWD OVER OZARKS BY 1/00Z...THEN
ACCELERATE/WEAKEN CONSIDERABLY WHILE EJECTING OVER IL/INDIANA/OH/LE
REGION OVERNIGHT.

ASSOCIATED SFC LOW OVER SERN WI SHOULD BECOME BETTER-DEFINED
THROUGHOUT DAYLIGHT HOURS...AS IT CROSSES REMAINDER WI AND WRN/NRN
LM. BY 00Z...COLD FRONT SHOULD EXTEND FROM LOW ACROSS NWRN
INDIANA...NEAR WRN TIP OF KY...NWRN LA...AND DEEP S TX. BY END OF
PERIOD...LOW SHOULD BECOME SUBSTANTIALLY OCCLUDED AND VERTICALLY
STACKED WITH NRN PERTURBATION OVER ONT. COLD FRONT SHOULD BE
CROSSING PORTIONS CENTRAL APPALACHIANS...AL...AND SERN LA BY 1/12Z.

...WRN GULF COAST...LOWER MS VALLEY TO LOWER GREAT LAKES...
WRN GULF COAST REGION IS EXPERIENCING PERIPHERAL INFLUENCE OF
MID-UPPER LEVEL PERTURBATION IN FORM OF STRENGTHENING DEEP SHEAR AND
DEEP-LAYER LIFT...JUXTAPOSED WITH VERY RICHLY MOST BOUNDARY LAYER --
E.G. SFC DEW POINTS INTO MID-70S F. SUCH MOISTURE IS NEEDED TO
OFFSET WEAK LAPSE RATES ALOFT TO MAINTAIN BUOYANCY ROOTED IN
BOUNDARY LAYER. ACCORDINGLY...CONVECTION HAS BEEN GETTING BETTER
ORGANIZED IN BROAD LOW-LEVEL CONFLUENCE ZONE ACROSS PORTIONS SE TX
AND LA. OCNL DAMAGING GUSTS ARE POSSIBLE...AND A FEW TORNADOES
CANNOT BE RULED OUT GIVEN LARGE SIZE OF LOW-LEVEL VWP/RAOB
HODOGRAPHS E OF MAIN CONFLUENCE/CONVECTIVE AXIS. REF SPC MESOSCALE
DISCUSSION 1989 AND WW 551 FOR ADDITIONAL NEAR-TERM GUIDANCE.

WITH NWD EXTENT...BOUNDARY-LAYER THETAE WILL DIMINISH WHILE
STRENGTHENING WIND FIELDS ALOFT WILL YIELD MORE SUBSTANTIAL
DEEP-LAYER SHEAR. AS SUCH...OUTLOOK BECOMES MORE CONDITIONAL.
ANTECEDENT CLOUDS/PRECIP ACROSS MUCH OF PREFRONTAL CORRIDOR FROM
MID-SOUTH REGION NWD SUGGEST LOW-LEVEL LAPSE RATES WILL REMAIN
WEAK...ALTHOUGH FCST SOUNDINGS CAN PRODUCE EFFECTIVELY SFC-BASED
INFLOW PARCELS WITH ONLY A FEW DEG F ADJUSTMENT OF SFC TEMPS
RESULTING FROM POCKETS OF MUTED INSOLATION. ONE OR MORE
QUASI-LINEAR CONVECTIVE BANDS MAY DEVELOP ALONG OR AHEAD OF SFC COLD
FRONT -- SOMETIMES WITHOUT LIGHTNING DUE TO STUNTED CAPE DEPTH WITH
RESPECT TO OPTIMAL ICING LAYER -- BUT STILL WITH POTENTIAL TO
TRANSFER STG-SVR GUSTS TO SFC OR SPAWN A BRIEF QLCS TORNADO.

ADDITIONAL SVR POTENTIAL MAY ARISE OVER OZARKS REGION AS SERN
PORTIONS OF STRONGEST MIDLEVEL ASCENT/COOLING...RELATED TO DCVA
REGION OF SHORTWAVE PERTURBATION -- JUXTAPOSE WITH AREAS OF SFC
DIABATIC HEATING. RESULTANT STEEPENING OF LOW-MIDDLE LEVEL LAPSE
RATES...RESIDUAL MOISTURE WITH DEW POINTS 60S F...AND STG DEEP SHEAR
MAY YIELD ENVIRONMENT FAVORABLE FOR STG/DAMAGING WINDS AND ISOLATED
HAIL.

..EDWARDS/COHEN.. 10/31/2013

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