SWODY1
SPC AC 181610
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1110 AM CDT SAT SEP 18 2010
VALID 181630Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL PLAINS
INTO OH VALLEY...
...CNTRL PLAINS INTO OH VALLEY...
15Z MESOANALYSIS INDICATES A WELL-DEFINED COLD FRONT FROM CNTRL
LOWER MI SWWD THROUGH NRN PARTS OF IL/MO TO W-CNTRL KS AND SERN CO.
DIFFERENTIAL HEATING WILL SUPPORT FURTHER INTENSIFICATION OF THIS
BAROCLINIC ZONE TODAY AS IT PROGRESSES SEWD/SWD THROUGH THE REGION.
THE STRONGEST WARM SECTOR DESTABILIZATION IS FORECAST ACROSS ERN KS
INTO MO WHERE A MOIST BOUNDARY LAYER /I.E. DEW POINTS IN THE UPPER
60S TO LOWER 70S/ WILL CO-EXIST WITH STEEP MIDLEVEL LAPSE
RATES...CONTRIBUTING TO MLCAPE OF 2000-3000+ J/KG BY AFTERNOON.
ELEVATED BANDS/CLUSTERS OF TSTMS ONGOING FROM SRN LAKE MI/IL WWD
INTO NEB ARE EXPECTED TO CONTINUE THROUGH THE DAY...FORCED BY
LOWER-TROPOSPHERIC FRONTOGENESIS AND INFLUENCE OF WEAK PERTURBATIONS
EMBEDDED WITHIN A ZONAL MIDLEVEL FLOW REGIME. THE STRONGER STORMS
WILL BE CAPABLE OF SOME HAIL GIVEN THE PRESENCE OF STEEP MIDLEVEL
LAPSE RATES AND 30-40 KT OF EFFECTIVE BULK SHEAR.
THE ERN EXTENSION OF ELEVATED STORMS OVER IL MAY EVENTUAL DEVELOP
EWD/SWD ENOUGH TO BECOME ROOTED IN THE BOUNDARY LAYER LATER TODAY
WITH AN ATTENDANT RISK FOR ISOLATED DAMAGING WIND GUSTS. ADDITIONAL
SURFACE-BASED STORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG
THE SYNOPTIC COLD FRONT OR PRECEDING OUTFLOW BOUNDARY OVER KS/MO
WITHIN THE AXIS OF MODERATE TO STRONG CONVECTIVE INSTABILITY. WHILE
REGION WILL RESIDE TO THE S OF STRONGER MID AND HIGH-LEVEL WIND
FIELD...FORECAST HODOGRAPHS INDICATE VERTICALLY VEERING WINDS WITH
AROUND 30 KT OF DEEP-LAYER SHEAR. AS SUCH...THE SETUP WILL SUPPORT
THE DEVELOPMENT OF ORGANIZED MULTICELL OR MARGINAL SUPERCELL
STRUCTURES WHICH MAY EVENTUALLY GROW UPSCALE INTO ONE OR MORE
SWD-MOVING CONVECTIVE COMPLEXES. WHILE A TORNADO OR TWO IS POSSIBLE
WITHIN THE FIRST COUPLE OF HOURS AFTER SURFACE-BASED STORM
INITIATION...DAMAGING WINDS AND HAIL APPEAR TO BE THE PRIMARY
HAZARDS THIS AFTERNOON INTO TONIGHT.
...MIDDLE/UPPER TX COAST...
A CURRENT OF HIGHER MOMENTUM ELY LOW-LEVEL FLOW IS FORECAST TO
DEVELOP WWD ACROSS THE NRN GULF BASIN INTO CNTRL TX THIS
PERIOD...RESULTING IN A CONCOMITANT INCREASE IN NEAR-GROUND SHEAR
ALONG THE COASTAL PLAIN DURING THE PEAK OF THE DIURNAL HEATING
CYCLE. GIVEN THE MOIST BOUNDARY LAYER CONDITIONS...SOME POTENTIAL
WILL EXIST FOR A BRIEF TORNADO WITH CONVECTION MOVING ONSHORE LATER
TODAY.
..MEAD/BROYLES.. 09/18/2010
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