SPC AC 170600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT WED OCT 17 2007
VALID 181200Z - 191200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SERN WI...LOWER
MI...NRN AND ERN IL...INDIANA...WRN OH...AND PARTS OF NRN KY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A LARGE AREA FROM THE
GREAT LAKES REGION SWD TO THE GULF COAST STATES...
...SYNOPSIS...
LARGE MID-LEVEL TROUGH/LOW OVER THE CENTRAL CONUS AT THE START OF
THE PERIOD IS FORECAST TO STRENGTHEN/SHARPEN AS IT MOVES EWD ACROSS
THE MS VALLEY REGION. THIS TROUGH WILL BE ACCOMPANIED BY A VERY
STRONG DEEP-LAYER WIND FIELD...INCLUDING A 90 KT SWLY H5 JET S AND E
OF THE LOW CENTER.
AT THE SURFACE...STRONG LOW IS FORECAST TO DRIFT NEWD ACROSS THE
UPPER MS VALLEY REGION...WHILE TRAILING COLD FRONT MOVES ACROSS THE
MS VALLEY AND INTO THE OH/TN VALLEYS THROUGH THE END OF THE PERIOD.
...GREAT LAKES REGION SWD TO THE GULF COAST STATES...
WIDESPREAD/POTENTIALLY-SIGNIFICANT SEVERE WEATHER EVENT APPEARS
INCREASINGLY LIKELY ACROSS PORTIONS OF A WIDESPREAD AREA EXTENDING
FROM THE GREAT LAKES REGION SWD TO THE GULF COAST STATES.
WIDESPREAD THUNDERSTORMS SHOULD BE ONGOING ACROSS PARTS OF THE RISK
AREA AT THE START OF THE PERIOD...DRIVEN BY LARGE-SCALE WARM
ADVECTION ASSOCIATED WITH 70 KT LOW-LEVEL JET. AS THIS JET
WEAKENS/SHIFTS NEWD DURING THE DAY...CONVECTION SHOULD DIMINISH
SOMEWHAT...ALLOWING POCKETS OF LIMITED HEATING AND AT LEAST MARGINAL
DESTABILIZATION OF VERY MOIST WARM SECTOR IN PLACE AHEAD OF THE
APPROACHING STORM SYSTEM.
BY EARLY AFTERNOON...BANDS OF THUNDERSTORMS SHOULD REDEVELOP NEAR
AND AHEAD OF THE COLD FRONT...AND THEN INCREASE THROUGH THE
REMAINDER OF THE AFTERNOON AND EVENING AS THE FRONT SHIFTS EWD.
STORMS DEVELOPING AHEAD OF THE FRONT WILL RAPIDLY BECOME SEVERE...AS
INTENSE FLOW THROUGH THE LOWER AND MID TROPOSPHERE -- VEERING WITH
HEIGHT FROM THE LOWER TO MID LEVELS -- RESULTS IN SHEAR SUPPORTIVE
OF SUPERCELLS AND/OR WELL-ORGANIZED LINE SEGMENTS. LARGE HAIL WILL
BE POSSIBLE -- PARTICULARLY NEAR THE COLDER MID-LEVEL TEMPERATURES
ACROSS NRN PORTIONS OF THE RISK AREA...AND VERY STRONG/DAMAGING
WINDS ARE LIKELY GIVEN STRENGTH OF THE AMBIENT FLOW FIELD.
FURTHER...GIVEN MOIST BOUNDARY LAYER AND LOW LCLS ALONG WITH AMPLE
VEERING/SPEED SHEAR IN THE BOUNDARY LAYER...TORNADOES WILL ALSO BE
LIKELY -- INCLUDING THE POTENTIAL THAT A FEW MAY BE
STRONG/LONG-LIVED. THE THREAT WILL SPREAD EWD WITH TIME...LIKELY
LINGERING THROUGH THE END OF THE PERIOD AS STORMS CROSS THE
APPALACHIANS.
..GOSS.. 10/17/2007
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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