SPC AC 220100

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0800 PM CDT Sat Jul 21 2018

   Valid 220100Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHEAST AND NORTHERN HIGH PLAINS...

   ...SUMMARY...
   A few severe storms remain possible across parts of the Southeast
   and northern High Plains this evening. A strong storm or two will
   also be possible late tonight across the Mid-Atlantic and southern
   New England.

   ...Southeast...
   Scattered strong to severe thunderstorms are persisting within
   northwesterly flow along the southern fringe of a deep mid-level
   trough. Where prior convection has not overturned the low/mid-level
   air mass, clusters of multi/supercells will remain possible for a
   few more hours this evening into early tonight. The highest severe
   potential may be focused near the Georgia/Alabama border, where
   westerly deep-layer flow, sufficient effective shear, and
   moderate/strong buoyancy should maintain a southward-moving cluster
   of strong/severe cells. Large hail and damaging winds will continue
   to be the primary threat. Over time, this cluster should encounter
   an increasingly hostile thermodynamic environment, though, resulting
   in a gradual downturn in intensity.

   ...Northern Plains...
   The primary severe threat will exist ahead of a severe cluster of HP
   supercells progressing south/southeast over western North Dakota
   this evening. Although convective inhibition will increase with both
   time and southeastward extent, a rather mature cold pool should
   encourage new, robust updrafts into early tonight, considering the
   steep mid-level lapse rates noted in the 12Z UNR sounding. Farther
   south, isolated/widely scattered severe storms, capable of large
   hail and damaging winds as well, may also continue into at least
   late evening.

   ...Northeast...
   A strengthening low-level jet and surface destabilization associated
   with an approaching warm front are forecast to yield a conditional
   threat of a brief tornado across coastal areas late tonight. Enough
   low-level instability will be present to foster this threat (via
   stretching of near-surface vorticity), although warming/drying near
   700mb may limit deep updraft acceleration and dampen the threat
   some. Any potential tornado threat should maximize around 06-12Z.

   ..Picca.. 07/22/2018

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z