SPC AC 060529

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1229 AM CDT Thu Jul 06 2017

   Valid 071200Z - 081200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE OHIO VALLEY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MIDDLE
   MISSISSIPPI VALLEY INTO A PORTION OF THE NORTHEAST STATES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL
   HIGH PLAINS...

   ...SUMMARY...
   Strong to severe storms are expected to develop Friday afternoon
   over the Ohio Valley and possibly into a portion of the Northeast
   States. A few other strong to severe storms are possible over the
   central High Plains later Friday afternoon and evening.

   ...Synopsis...

   The eastern U.S. upper trough will undergo further amplification,
   while a ridge persists in the west. A cold front will move through
   the northeast U.S. and OH Valley in association with the amplifying
   trough. Western extension of this boundary will stall across OK/KS.

   ...Ohio Valley area...

   A moist pre-frontal warm sector with upper 60s to 70F dewpoints will
   reside across the OH Valley into a portion of the Northeast States.
   Destabilization of the boundary layer will result in moderate
   instability in the presence of 6.5-7 C/km mid-level lapse rates. At
   least a modest increase in deep-layer winds is expected with 30-40
   kt unidirectional westerly flow between 2-6 km. A significant
   mid-level speed max will move southeast into the Great Lakes and
   Ohio Valley region, but this feature will remain post frontal.
   Nevertheless...storms should redevelop within the weakly capped warm
   sector and along the southeast-advancing cold front during the
   afternoon. Vertical shear from 25-35 kt will support primarily
   multicells with storms evolving into clusters and line segments.
   Strong to damaging wind gusts may accompany the stronger storms
   during the afternoon into early evening.

   ...Central High Plains area...

   Winds will shift to southeasterly over the central High Plains
   region east of a lee trough. A cold front will settle southward into
   KS where it will likely stall. The southeasterly low-level winds
   will maintain dewpoints in the 40s to near 50F beneath steep
   mid-level lapse rates, contributing to a corridor of modest
   /500-1000 J/kg/ MLCAPE during the afternoon. Isolated to widely
   scattered storms should develop over the higher terrain and spread
   southeast into the High Plains where they will pose some risk for
   mainly isolated downburst winds through early evening. Trends will
   continue to be monitored for a possible slight risk over a portion
   of this region.

   ..Dial.. 07/06/2017

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