SWODY2
SPC AC 030545
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1245 AM CDT SAT SEP 03 2011
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE ERN GREAT LAKES AND
UPPER OH VALLEY...
...ERN GREAT LAKES/OH VALLEY/NRN APPALACHIAN MTNS...
AN UPPER-LEVEL TROUGH WILL MOVE ACROSS THE NRN MS VALLEY SUNDAY AS A
COLD FRONT ADVANCES SEWD ACROSS THE ERN GREAT LAKES AND OH VALLEY.
NUMEROUS THUNDERSTORMS ARE FORECAST TO INITIATE ALONG THE ENTIRE
LENGTH OF THE BOUNDARY FROM THE NRN APPALACHIAN MTNS SWWD INTO THE
MID-MS VALLEY. SFC DEWPOINTS ALONG THE BOUNDARY SHOULD MOSTLY BE
FROM 65 TO 70 F WITH MLCAPE FORECAST TO BE IN THE 1500 TO 2500 J/KG
RANGE WITH THE GREATEST INSTABILITY IN THE UPPER OH VALLEY AND ERN
GREAT LAKES REGION. IN ADDITION...FORECAST SOUNDINGS IN THIS REGION
SHOW 0-6 KM SHEAR AROUND 30 KT WITH STRONG DIRECTIONAL SHEAR IN THE
BOUNDARY LAYER. THIS SHOULD BE SUFFICIENT FOR SUPERCELL DEVELOPMENT
WHERE STORMS CAN REMAIN DISCRETE FROM OH NEWD INTO WRN NY WHERE
MODEL FORECASTS ALSO SHOW THE STRONGEST LOW-LEVEL FLOW AND GREATEST
LARGE-SCALE ASCENT. IN SPITE OF THE POTENTIAL FOR
SUPERCELLS...LOW-LEVEL CONVERGENCE ALONG THE COLD FRONT MAY TEND TO
FORM LINE-SEGMENTS AS THE STORMS CONGEAL SUGGESTING WIND DAMAGE
COULD BE THE GREATER THREAT. A SLIGHT RISK AREA HAS BEEN INTRODUCED
IN THE UPPER OH VALLEY AND ERN GREAT LAKES. AN ISOLATED SEVERE
THREAT MAY ALSO DEVELOP NEWD INTO NEW ENGLAND BUT THE AMOUNT OF
DESTABILIZATION SHOULD DETERMINE THE MAGNITUDE OF THE SEVERE THREAT.
FURTHER SOUTHWEST IN THE MID-MS VALLEY AND MIDDLE OH
VALLEY...LARGE-SCALE ASCENT AND DEEP LAYER SHEAR WILL BE WEAKER
LIMITING THE SEVERE THREAT SOMEWHAT.
...CNTRL GULF COAST...
THE NATIONAL HURRICANE CENTER IS FORECASTING TROPICAL STORM LEE TO
MOVE ONSHORE LATE SATURDAY AND ACROSS SERN LA ON SUNDAY. ALTHOUGH
SOME WEAKENING SHOULD OCCUR WITH THE STORM ON SUNDAY...HEAVY
RAINBANDS WILL LIKELY EXTEND FROM THE CENTER NEWD AND EWD ACROSS THE
MS DELA AND CNTRL GULF COAST. FORECAST SOUNDINGS ON SUNDAY IN THE
CNTRL GULF COAST STATES SHOW 30-40 KT OF 0-1 KM SHEAR WITH
SUBSTANTIAL DIRECTIONAL SHEAR IN THE BOUNDARY LAYER. THIS SHOULD BE
SUFFICIENT FOR STORM ROTATION AND A TORNADO THREAT. A FEW TORNADOES
MAY OCCUR ESPECIALLY AS DESTABILIZATION OCCURS SUNDAY AFTERNOON
ACROSS SE LA...SRN MS...SRN AL AND THE FL PANHANDLE.
..BROYLES.. 09/03/2011
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