The SPC is forecasting ...Severe thunderstorms expected over parts of the Southeast States to the Ohio Valley region today and tonight....   Please read the latest public statement about this event.  View What is a Watch? clip.

   SPC AC 051629

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1129 AM CDT Wed Apr 05 2017

   Valid 051630Z - 061200Z

   ...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
   CENTRAL AND SOUTHERN GEORGIA INTO CENTRAL SOUTH CAROLINA...

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   HIGH FROM PORTIONS OF SOUTH CAROLINA TO GEORGIA AND ALABAMA AND THEN
   NORTHWARD INTO SOUTH-CENTRAL KENTUCKY...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE FROM PORTIONS OF THE OHIO VALLEY REGION TO THE SOUTHEAST
   STATES AND MID-ATLANTIC...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   ENHANCED FROM PORTIONS OF THE LOWER GREAT LAKES REGION TO THE
   SOUTHEAST STATES AND MID-ATLANTIC...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE EASTERN STATES...

   ...SUMMARY...
   An outbreak of severe thunderstorms is expected from portions of the
   Southeast States to the Ohio Valley region and eastward to the
   Mid-Atlantic. Significant tornadoes will be possible, especially
   from parts of central and southern Georgia into South Carolina, and
   also from parts of eastern Alabama into south-central Kentucky. In
   addition, very large hail, and damaging wind gusts are expected.

   ...Portions of the Southeast States to the Ohio Valley region and
   the Mid-Atlantic...
   Ongoing semi-discrete supercells and supercell clusters are
   developing northeastward from parts of the central/eastern Gulf
   Coast into southern GA. This activity resides well ahead of a
   shortwave trough across the South-Central States and is evolving
   within a broad, moistening open warm sector. With observational data
   suggesting dewpoints in the lower 70s developing northward ahead of
   this activity, supporting MLCAPE around 2000-3000 J/kg aided by
   warm-sector insolation steepening low-level lapse rates beneath a
   residual EML plume, and given the ongoing semi-discrete nature to
   rotating updrafts developing as far south as the central Gulf Coast
   vicinity, there is increasing confidence that long-track supercells
   will be likely. Furthermore, with maturing midlevel mesocyclones
   already evident, and low-level SRH around 200-300 m2/s2 aiding the
   development of low-level mesocyclones amid the increasing low-level
   theta-e, confidence has increased in higher coverage of tornado
   potential -- including significant tornado potential -- across the
   now-upgraded High Risk area. This activity will spread across the
   High Risk area into the evening hours, as vertical wind profiles
   further strengthen with the approaching midlevel trough and 700-mb
   flow increasing over 50 kt. Observational trends and previous model
   guidance are the primary supporters of this High Risk upgrade, as
   opposed to the most recent model guidance which suggests a dry bias
   in thermodynamic profiles -- Reference Mesoscale Discussion 440.
   Outflow from ongoing convection from north GA to western SC serves
   as a northern bound to the greatest severe potential.

   Furthermore, confidence has increased that substantial severe risk
   including tornado potential will develop through parts of the
   Mid-Atlantic region into the overnight hours amid strong low-level
   and deep shear, and a moistening boundary layer. As a result, severe
   probabilities have been increased across parts of the Mid-Atlantic.
   Also, severe storms are expected to spread across parts of the Gulf
   Coast vicinity into the evening/overnight hours -- affecting parts
   of north/central FL with tornado potential.

   Farther to the west, a somewhat separate area of severe storm
   development will be likely from parts of the Ohio Valley region to
   the Tennessee Valley and vicinity in association with the primary
   midlevel vorticity maximum and related low-level baroclinic zone
   this afternoon. Strong low-level SRH in the destabilizing warm
   sector -- enhanced near the surface low tracking from parts of IL
   into OH -- will support organized, rotating updrafts. All severe
   hazards -- including significant hail and tornadoes -- will be
   possible from this afternoon into the evening.

   ..Cohen.. 04/05/2017

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