SPC AC 211731

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1231 PM CDT Thu Sep 21 2023

   Valid 221200Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   NORTHERN NE AND SD AS WELL AS OVER THE COASTAL MID-ATLANTIC...

   ...SUMMARY...
   Severe thunderstorms will be possible across parts of the central
   and northern Plains, mainly Friday afternoon into Friday night. A
   few tornadoes are also possible along the Mid-Atlantic Coast early
   Saturday morning.

   ...Synopsis...
   A mid/upper cyclone will likely be centered near the OR/ID/NV border
   intersection early Friday morning, before then gradually shifting
   eastward throughout the day. This cyclone is forecast to be centered
   over eastern WY by early Saturday morning. Enhanced mid-level flow
   will accompany this cyclone, spreading across the Great Basin and
   into the central Plains as the cyclone progresses eastward. Surface
   lee troughing across the High Plains will likely deepen ahead of
   this system, and cyclogenesis along this troughing may lead to the
   development of a pair of surface lows, one over the central Plains
   and the other farther north across southeast MT.  

   Elevated showers and thunderstorms will likely be ongoing at the
   beginning on the period from the Mid MO Valley into eastern OK and
   northeast TX. Evolution of these storms and their attendant cloud
   cover and outflow will influence the surface pattern across the
   Plains. General expectation is that the resulting combination of
   cloud cover and storm outflow will lead to a sharpening of the warm
   front across central and southern Plains. Strong heating is
   anticipated west of this warm front across the warm sector, but the
   warm temperatures aloft will likely keep most of OK and KS capped
   throughout during the afternoon and evening. The only exception is
   across southwest TX, where the combination of heating and low-level
   moisture could erode all the convective inhibition. A conditional
   risk for storms capable of strong gusts and large hail exists in
   this area. 

   Higher thunderstorm chances are expected farther north across NE and
   SD during the evening and overnight. Much of this activity will
   likely be elevated, fostered by a strengthening low-level jet over
   the warm front and aided by increasing large-scale ascent attendant
   to the approaching cyclone. Environmental conditions support the
   potential for some stronger storms capable of large hail and a
   strong gust or two. There is a low-probability chance that
   development occurs close enough to the warm to support a
   surface-based (or at least near-surface-based) storm, with limited
   tornado potential. Additional development is possible early Saturday
   morning closer to the low, with some severe potential with this
   activity as well.  

   ...Mid-Atlantic Coast...
   A developing tropical cyclone, recently deeded Potential Tropical
   Cyclone 16 by NHC, is forecast to track northeastward. Wind fields
   are expected to strengthening considerably, elongating hodographs
   over the Mid-Atlantic states. Highest tornado potential is
   anticipated closer to the center of this system, where the best
   low-level moisture and resulting instability will exist. Based on
   the current forecast, this appears it will occur over coastal NC
   around 06Z to 12Z.

   ..Mosier.. 09/21/2023

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