[Ccarc] Latest Severe weather outlook

[Tom Murray]

DAY 1 CONVECTIVE OUTLOOK
   NWS STORM PREDICTION CENTER NORMAN OK
   1123 AM CDT THU OCT 18 2007

   VALID 181630Z - 191200Z

   ...THERE IS A MDT RISK OF SVR TSTMS FROM LOWER MI INTO WRN TN...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL GULF COAST
   SURROUNDING THE MDT RISK TO THE U.P. OF MI...

   ...POTENTIALLY SIGNIFICANT SEVERE WEATHER EVENT UNFOLDING ACROSS THE
   GREAT LAKES SOUTHWARD INTO THE NRN GULF STATES...

   VERY MOIST AND BUOYANT AIRMASS IS RETURNING NWD ACROSS THE MID MS
   AND LOWER OH RIVER VALLEY REGION INTO THE UPPER GREAT LAKES THIS
   MORNING.  THIS NWD SURGE IS IN RESPONSE TO AN INTENSE AND DEEPENING
   LOW PRESSURE SYSTEM OVER MN.  DAYTIME HEATING WILL PROVE
   INSTRUMENTAL IN AFTERNOON THUNDERSTORM DEVELOPMENT...INITIALLY OVER
   WI...THEN ARCING SWD ACROSS ERN IL INTO EXTREME NERN AR BY EARLY
   EVENING.  STRONG VERTICAL SHEAR WILL LEAD TO SUPERCELL
   DEVELOPMENT...ESPECIALLY EARLY IN THE CONVECTIVE CYCLE WITH AN
   EVOLUTION TOWARD DAMAGING BOW ECHOES DURING THE OVERNIGHT HOURS.  A
   FEW LONG-TRACK TORNADOES ARE POSSIBLE IN ADDITION TO DESTRUCTIVE
   WINDS...ESPECIALLY ACROSS THE MODERATE RISK AREA.

   EARLY MORNING DIAGNOSTIC DATA AND SATELLITE TRENDS SUGGEST STRONG
   HEATING WILL CONTINUE ACROSS MO INTO IL WHERE ABUNDANT SUNSHINE AND
   SLIGHTLY VEERED LOW LEVEL FLOW SHOULD BE MAINTAINED THROUGH THE
   AFTERNOON HOURS.  THIS PLUME OF STEEPENING LOW LEVEL LAPSE RATES
   WILL UNDOUBTEDLY ASSIST THUNDERSTORM INITIATION LATER THIS AFTERNOON
   ALONG CONFLUENCE AXIS ACROSS IL WHERE SFC DEW POINTS ARE RISING
   THROUGH THE 60S INTO THE LOWER 70S.  LATEST HIGH RES WRF-NMM4 AND
   WRF-NSSL4 MODELS SUGGEST INITIAL DEVELOPMENT WILL OCCUR ACROSS
   PORTIONS OF WI WHERE THERMAL PROFILES ARE SOMEWHAT COOLER.  THIS
   SEEMS REASONABLE GIVEN THE LARGE SCALE FORCING ACROSS THIS REGION.
   HOWEVER...POTENTIALLY MORE SIGNIFICANT DEVELOPMENT IS EXPECTED
   FARTHER SOUTH BUT EARLIER THAN 22-23Z TIME FRAME SUGGESTED BY THESE
   SOLUTIONS.  GIVEN THE STRONG HEATING IT SEEMS REASONABLE THAT
   CONVECTION SHOULD DEVELOP BY MID AFTERNOON ACROSS SERN MO/ERN IL.
   FORECAST SOUNDINGS ACROSS THIS REGION SUGGEST CONVECTIVE
   TEMPERATURES ARE BREACHED BY 19Z.  GIVEN THE STRONG SHEAR CONVECTIVE
   UPDRAFTS COULD STRUGGLE INITIALLY BEFORE ORGANIZED UPDRAFTS EVOLVE
   INTO SUPERCELL STRUCTURES.  ONCE THIS OCCURS ACTIVITY SHOULD SPREAD
   QUICKLY NEWD INTO WRN IND AND LOWER MI.  IF CONVECTION REMAINS
   DISCRETE...TORNADO THREAT WILL REMAIN ENHANCED.  HOWEVER...ANY
   LINEAR EVOLUTION COULD RESULT IN VERY DAMAGING BOW ECHO STRUCTURES
   GIVEN EXPECTED STORM MOTIONS IN EXCESS OF 50KT.  THESE FAST STORM
   MOTIONS COULD LEAD TO A FEW LONG-TRACK SUPERCELLS/TORNADOES.

   FARTHER SOUTH...A MORE COMPLEX AND NEBULOUS EVOLUTION IS EXPECTED
   ACROSS THE TN VALLEY INTO THE CENTRAL GULF STATES.  WIDESPREAD
   CLOUDINESS WILL TEND TO SUPPRESS DIURNAL HEATING AND MAINTAIN
   MARGINAL LAPSE RATE ENVIRONMENT.  HOWEVER...CONVECTIVE UPDRAFTS WILL
   RESIDE WITHIN A BROAD WARM ADVECTION REGIME WHERE STORM ROTATION
   WILL LEAD TO AT LEAST LOW PROBABILITIES FOR TORNADOES AND DAMAGING
   WINDS.  AS STRONGER FLOW SPREADS INTO THE NWRN PORTIONS OF THE GULF
   STATES LATER TONIGHT VERTICAL SHEAR PROFILES AND STORM MOTIONS WILL
   INCREASE.  FASTER MOVING STORMS SHOULD EVOLVE DURING THE OVERNIGHT
   HOURS...ALONG WITH A POSSIBLE INCREASE IN TORNADIC ACTIVITY.

   ..DARROW/JEWELL.. 10/18/2007

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
   CURRENT UTC TIME: 1741Z (1:41PM), RELOAD THIS PAGE TO UPDATE THE TIME

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