SPC AC 251710

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1210 PM CDT Wed Apr 25 2018

   Valid 261200Z - 271200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHEAST...

   ...SUMMARY...
   Isolated severe thunderstorms are expected across parts of the
   Southeast Thursday.

   ...Southeast...

   Upper low over the central Plains is expected to dig southeast into
   northern AL by 18z Thursday before deamplifying during the overnight
   hours and ejecting into NC. Notable drying will surge into AL by mid
   day as this feature progresses across the northern Gulf States.
   Latest guidance suggests convection will be ongoing at the beginning
   of the period along the cold front and this boundary should remain
   convectively active as it progresses into the Carolinas. Air mass
   will not be particularly unstable early in the period but partial
   breaks in cloud cover will allow for some boundary-layer heating
   beneath a cooling mid-level profile. With 500mb temperatures <-20C
   beneath the upper low, it appears a corridor of instability will
   evolve from portions of northern AL into SC during the day. Forecast
   soundings suggest robust updrafts may develop immediately ahead of
   the upper low and shear profiles will favor sustained rotating
   updrafts. For these reasons have introduced 5% severe probs to
   account for isolated supercell development possibly as early as mid
   day over AL. This activity should spread into the Carolinas during
   the evening hours. Hail and perhaps locally damaging winds are the
   primary threats.

   ...Elsewhere...

   Weak convection may produce a few lightning strikes across parts of
   the southern Plains during the latter half of the period ahead of
   digging short-wave trough.

   Isolated thunderstorms are also expected to develop across portions
   of the western US from the Sierra Nevada into western OR. It appears
   instability will be a bit too weak to warrant severe probs across
   these regions.

   ..Darrow.. 04/25/2018

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