SPC AC 130731

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0231 AM CDT Wed May 13 2020

   Valid 151200Z - 161200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE NORTHEAST AND SOUTHERN PLAINS/OZARK PLATEAU...

   ...SUMMARY...
   Isolated strong to severe thunderstorms are possible across portions
   of the Northeast States as well as the southern Plains and Ozark
   Plateau Friday.

   ...Northeast...
   A northern-stream shortwave trough is forecast to move quickly
   eastward from its position early Friday over Upper Great Lakes
   through the Northeast States. Surface low associated with this
   system will likely begin the period over southwestern Ontario before
   then moving quickly eastward across NY. Cold front attendant to this
   low will move eastward through the Upper OH Valley and NY/northern
   Mid-Atlantic. Temperatures and dewpoints ahead of this front are
   forecast to reach the mid 70s and upper 50s/low 60s, respectively,
   resulting in a modest instability. Consequently, thunderstorm
   development is anticipated along the front during the afternoon.
   Strong mid-level flow will support fast-moving bowing line segments
   capable of damaging wind gusts. Isolated hail and a brief tornado
   are also possible.

   ...Southern/Central Plains into the Ozarks...
   Showers and thunderstorms will likely be ongoing early Friday
   morning in the vicinity of the KS/OK border, supported by a strong
   nocturnal low-level jet from southwest TX into western OK. Evolution
   of these storms will have a large influence on convective potential
   for the remainder of the day. Outflow from these storms could result
   in an enhancement of the severe weather potential during the
   afternoon/evening, providing the boundary needed for convective
   initiation. However, predicting the location and strength of this
   cold pool is difficult at this forecast range.
    
   A well-defined EML will be in place across the region, resulting in
   strong instability in areas where the low-level moisture is
   unaffected by convective outflow. Vertical shear will be weak, but
   the overall environment will support severe thunderstorms where
   convective initiation occurs. Uncertainty precludes higher severe
   probabilities with this outlook, but higher probabilities may be
   needed in subsequent outlooks if the convective evolution becomes
   more certain.

   Additionally, a broad and weak southern-stream shortwave trough will
   move out of northern Mexico into TX Friday afternoon/evening. This
   shortwave may augment ascent over the region, contributing to
   convective initiation along the dryline from western OK through
   southwest TX. Vertical shear will be weak, but strong instability
   will still support updrafts strong enough to produce severe
   hail/wind. Uncertainty regarding severe thunderstorm coverage
   currently precludes higher probabilities.

   ..Mosier.. 05/13/2020

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z