SPC AC 310548

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1248 AM CDT Sat Jul 31 2021

   Valid 011200Z - 021200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN NORTH
   CAROLINA AND SOUTHEAST VIRGINIA...

   ...SUMMARY...
   Several severe storms will be possible Sunday over eastern North
   Carolina and southeast Virginia. Isolated severe storms will be
   possible over parts of Pennsylvania and New York.

   ...Synopsis...
   Cyclonic flow aloft will persist over the Great Lakes and Northeast,
   with an upper speed max moving across the OH Valley and into the
   Northeast. This feature will provide large-scale lift as well as
   increasing deep-layer shear. Meanwhile, a leading speed max will
   move off the East Coast with the right-entrance region of the upper
   jet sweeping across the Mid Atlantic.

   At the surface, a steadily deepening low will move across Lake Erie
   and Ontario during the day, with a lee trough over eastern VA and
   NC. A cold front will extend southwestward from the Mid Atlantic
   across the Deep South and into northern TX, with ample moisture and
   MUCAPE to 3000 J/kg ahead of the front.

   Weaker instability is expected near the northern low and cold front
   in the 500-1000 J/kg MUCAPE range as dewpoints only average 55-60 F.
   This front is forecast to move into western and central NY and PA
   prior to 00Z.

   Elsewhere, an upper high will be centered over the Four Corners
   states with ridge extending north into Alberta, with scattered
   daytime storms over the West.

   ...Mid Atlantic...
   Rain and thunderstorms may be ongoing across parts of eastern VA
   into the Delmarva Sunday morning, in a region of low-level
   warm/moist advection. Behind this activity, dewpoints are expected
   to rise into the lower 70s F into VA, with mid to upper 70s F over
   the eastern Carolinas. A plume of steep lapse rates will develop
   across the Carolinas, with MUCAPE over 3000 J/kg expected. While
   low-level winds will be relatively weak, they will veer with height,
   becoming westerly at around 40 kt in the midlevels. This should
   create hodographs favorable for a supercell or two, although storm
   interference appears likely given CAM trends. Effective SRH over 100
   m2/s2 is expected. Diurnal storms are expected to form between
   18-21Z over central NC, with upscale growth possible as they
   progress east. Damaging winds appear likely, along with marginal
   hail and perhaps a tornado. Less storm coverage is anticipated
   farther south into SC, but robust instability may favor a few
   damaging gusts there.

   ...NY and PA...
   Storms will initially develop over southwest Ontario, and are likely
   to cross into the USA after 18Z, from northeast OH into western NY.
   Heating ahead of this frontal activity should allow for a steady
   ramp up of low-topped convection, with damaging gusts the primary
   concern as cells merge along the front. Marginal hail may occur
   before storm mode becomes linear. Weak instability and low-level
   winds suggest any gusts over 50 kt will be isolated.

   ..Jewell.. 07/31/2021

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z