Weather outlook, discussion

[WeatherWheeler35]

  SPC AC 161602
  Day 1 Convective Outlook NWS Storm Prediction Center Norman OK  1102 AM CDT Tue May 16 2023
  Valid 161630Z - 171200Z
  ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS  OF SOUTHEAST KENTUCKY...NORTHEAST TENNESSEE...EXTREME SOUTHERN WEST  VIRGINIA...WESTERN VIRGINIA...AND FAR NORTHWEST NORTH CAROLINA...
  ...SUMMARY...  Strong to severe thunderstorms, associated with wind damage,  isolated large hail and a few tornadoes are expected to develop  across parts of the southern and central Appalachians this afternoon  into early evening.
  ...KY/TN to VA/NC Vicinity...
  A shortwave mid/upper trough will move across the Ohio Valley and  Central Appalachians today, and into the Mid-Atlantic by this  evening. This feature will allow midlevel flow to increase through  the day, with a belt of 40-50 kt westerly flow overspreading western  KY/TN to coastal VA/NC. 
  At the surface, a weak low was analyzed over western KY at 15z. A  composite warm front/outflow boundary extended eastward from the low  across northern/central KY. This will likely demarcate the northern  extent of greater severe potential/coverage. A weak surface lee  trough is also evident across the VA/NC Piedmont. The surface low  should track roughly east/northeast through the day with a trailing  cold front spreading across the region this afternoon/evening.  Dewpoints in the upper 60s to near 70 F (low/mid 60s with eastward  extent to the lee of the Appalachians), and strong heating south of  the warm front where mostly clear skies exist, will allow for weak  to moderate destabilization. 
  Low-level flow will remain somewhat weak through 1-2 km, but  increasing speed with height will result in effective shear  magnitudes around 35-45 kt, supporting organized convection. Initial  semi-discrete cells are expected, posing a risk for hail and  damaging gusts. Steep low-level lapse rates will support strong  outflow and convection will likely transition toward bows as storms  shift east across the spine of the Appalachians. A swath of strong  gusts may persist east of the Appalachians in a moist and unstable  downstream environment. While low-level flow will remain weak,  modestly enlarged forecast hodographs and some increase in effective  SRH suggest a few spin-ups along the eastward-advancing gust front  will be possible given a favorable low-level thermodynamic  environment. For short term severe potential across KY/TN vicinity,  see MCD 800.
  More than one round of strong/severe thunderstorm activity may be  possible across the VA/NC Piedmont. Initial activity associated with  the lee trough may pose a hail/wind risk, while any emerging bow/MCS  by late afternoon/early evening may also result in a damaging wind  risk.
  ...Northern MS/AL/GA into Upstate SC...
  This area will remain south of strong midlevel flow, with mainly  modestly, mostly unidirectional westerly deep-layer flow forecast.  Effective shear around 20-25 kt amid moderate instability will allow  for some transient/loosely organized cells. Steep low-level lapse  rates will foster strong outflows and a few locally strong/damaging  gusts are possible. 
  ...High Plains...
  A shortwave trough currently over SD will track southward today into  the high plains of eastern WY/CO and western NE/KS. Strong heating  over this region, coupled with dewpoints in the 40s to lower 50s,  will result in a deeply mixed boundary layer and CAPE values of  1000-1500 J/kg. Widely scattered diurnal thunderstorms are  expected, with sufficient deep-layer shear for high-based supercell  structures capable of gusty winds and hail.
  ..Leitman/Moore.. 05/16/2023
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  NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z