Mar 14, 2019 0600 UTC Day 1 Convective Outlook

Day 1 Convective Outlook  

   NWS Storm Prediction Center Norman OK
   1259 AM CDT Thu Mar 14 2019

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
   OF THE TENNESSEE AND OHIO VALLEYS...

   ...SUMMARY...
   Strong to severe thunderstorms are possible from a portion of the
   Southeast U.S. into the Ohio Valley and southern Great Lakes.
   Damaging wind and a few tornadoes will be possible along with some
   hail.

   ...Synopsis...

   A very strong upper jet will rotate through the base of a potent
   synoptic upper trough and into the middle MS Valley, Ohio Valley and
   upper Great Lakes. Surface low within the exit region of this jet
   will develop northeastward and occlude over WI this afternoon. The
   trailing cold front will stretch from a surface low in IA early in
   the day southward through the lower MS Valley. This front will
   advance east reaching the lower Great Lakes southwest into the
   middle Gulf coast by the end of this period.

   ...Southeast U.S. through Ohio Valley and Great Lakes...

   Initial band of convection developing along warm conveyor belt from
   the TN Valley into the OH Valley will shift northeast and weaken
   early Thursday. However, ageostropic forcing accompanying an
   upstream jet exit region is already spreading through the Southern
   Plains, contributing to thunderstorms development along the front
   over northeast TX. This zone of ascent will continue to spread
   northeast during the early part of the day, and most models develop
   a secondary band of showers and thunderstorms over the middle MS
   Valley that shifts into the OH Valley by mid day. The timing and
   evolution of this early convection and areas of clouds complicate
   the forecast to some degree. Nevertheless, a corridor of mid-upper
   50s dewpoints will advect north into the OH Valley along a strong
   low-level jet, with mid-upper 60s farther south across the Southeast
   States. MLCAPE should range from 1000+ J/kg over the Southeast
   States, where more diabatic heating is possible and higher dewpoints
   will reside, to around 500 J/kg farther north into the OH Valley and
   southern Great Lakes. Current indications are that additional
   thunderstorms will gradually intensify along and just ahead of the
   progressive front from the OH Valley southward into the TN Valley
   from late morning into the afternoon. The stronger forcing will
   exist along and north of the upper jet exit region over the OH
   Valley where instability will be more limited, while farther south
   weaker forcing will exist, but a destabilizing boundary layer and
   low-level convergence should be sufficient to initiate storms. Wind
   profiles will be very favorable for organized severe storms with 50+
   kt effective bulk shear and 300-500 m2/s2 0-1 km storm relative
   helicity. Both discrete supercells and line segments are possible
   with damaging wind and a few tornadoes the main threats, mainly from
   late morning through early evening.