SPC AC 141741

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1241 PM CDT Thu May 14 2020

   Valid 151200Z - 161200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION
   OF THE NORTHEAST STATES...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE CENTRAL AND SOUTHERN PLAINS...

   ...SUMMARY...
   Severe thunderstorms are forecast across portions of the Northeast
   States Friday afternoon as well as the central High Plains and
   southern Plains and Ozark Plateau Friday afternoon into Friday
   night.

   ...Northeast States and Ohio Valley regions...

   Shortwave trough now situated over ND near the international border
   will continue into the Great Lakes Friday, reaching the northeast
   states later Friday afternoon and evening. A low amplitude impulse
   may precede this feature. By late afternoon the accompanying cold
   front should extend from a surface low in upstate NY southwest into
   the lower Great Lakes and OH Valley. Warm front will extend from the
   surface low through southern New England. Modest low-level moisture
   with upper 50s to around 60 F dewpoints will advect through the
   pre-frontal warm sector and contribute to 1000-1500 J/kg MLCAPE as
   the surface layer warms during the afternoon. Thunderstorms are
   expected to redevelop along and ahead of the front by early to mid
   afternoon within the weakly capped, destabilizing warm sector. A
   mid-level jet within the base of the approaching shortwave trough
   will contribute to 35-45 kt effective bulk shear over the northeast
   U.S. supporting organized storms including a few supercells and
   bowing segments with damaging wind the main threat. The low-level
   jet is forecast to strengthen by late afternoon into early evening
   across the northeast U.S. with 0-1 km hodographs becoming sufficient
   for isolated tornadoes, especially with any storms interacting with
   the warm front across southern New England. Farther west across OH,
   deep-layer shear will be weaker, but wind profiles with 40-45 kt
   flow in the 700-500 mb layer will be supportive of a few damaging
   wind gusts as the boundary layer destabilizes during the afternoon. 


   ...Southern Plains and Ozark Plateau...

   An MCS will likely be ongoing from southeast KS through northeast OK
   early Friday, and this activity might pose an ongoing threat for a
   few strong to damaging wind gusts. Rich low-level moisture will
   return northward through the Southern Plains beneath steep lapse
   rates contributing to very unstable conditions Friday afternoon with
   3000-4000 J/kg MLCAPE likely. Storms will likely redevelop along
   dryline across west TX into southwest OK near the dryline/outflow
   boundary intersection by mid to late afternoon. Vertical shear will
   remain weak and supportive of multicells, but the thermodynamic
   environment will favor large hail and damaging wind. Storms are
   expected to congeal into line segments during by evening and
   continue eastward through TX. A southern-stream shortwave trough
   will move through southwest TX and northern Mexico during the
   evening and may contribute to a more persistent organized MCS in
   that region. Storms may reach southern TX toward the end of the
   period. An upgrade to enhanced may be needed for a portion of this
   region in later updates. 

   ...Central High Plains...

   Modest low-level moisture will return northward through the central
   High Plains beneath steep lapse rates contributing to modest
   instability with 500-1000 J/kg MLCAPE. Storms are expected to
   develop over the higher terrain and along lee trough and spread
   eastward into the High Plains during the afternoon. Winds aloft
   accompanying a low-amplitude shortwave trough will contribute to
   sufficient vertical shear (35-40 kt) for some supercell structures,
   possibly evolving into a linear MCS during the evening. Damaging
   wind and large hail will be the primary threats.

   ..Dial.. 05/14/2020

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