SPC AC 020542

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1242 AM CDT Sun Aug 02 2020

   Valid 021200Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE NORTHEAST...

   ...SUMMARY...
   Scattered strong storms, a few possibly severe, will be noted across
   the Northeast later today. Damaging winds are the primary threat.

   ...Northeast...

   Weak mid-level disturbance will eject across the lower Great Lakes
   ahead of the main upper trough positioned farther west over the MS
   Valley. This lead feature should encourage a weak surface low to
   track from southern ON into southwest QC by mid evening. Any
   appreciable mid-level height falls will remain north of the
   international border, along with the primary large-scale mass
   response.

   Early in the day1 period, deep convection will likely be ongoing
   within a corridor of low-level warm advection, along the nose of a
   pronounced LLJ. This LLJ will shift north across upstate NY into
   southern ON/QC during the afternoon hours as a surface warm front
   advances north of the border. At this time it appears the primary
   focus for sustained, organized deep convection will be noted
   immediately ahead of the surface low. Latest model guidance suggests
   strong boundary-layer heating will occur ahead of the surface low
   across western NY where temperatures should warm rapidly through the
   mid 80s. Renewed surface-based convection should evolve in the lee
   of Lake Ontario then track northeast. If the surface warm front were
   to be delayed advancing north into QC, low-level shear would be
   improved markedly across northern NY which would prove more
   supportive for supercells and tornadoes. Additionally, there is also
   some concern for strong convection along the trailing warm front
   that extends southeast across the Hudson Valley. While
   boundary-layer warming may not be as strong/focused as farther
   north, sustained warm advection and high PW-airmass should result in
   scattered strong convection. Forecast wind profiles favor some
   supercell threat, though clustering is also possible. Damaging winds
   should be the primary concern. 

   Farther south, a belt of seasonally strong mid-level flow will
   extend from the base of the trough over the southern Appalachians
   into the northern Middle Atlantic. While neutral/weak height rises
   are expected across this region, boundary-layer heating and
   orographic influences should encourage at least isolated
   thunderstorms. While poor lapse rates will limit convective updraft
   strength with this activity, modest cloud-layer flow should allow
   for some organization, along with a threat for localized wind
   damage.


   ...Central/Southern Rockies Region...

   Modest 500mb flow along the front side of the southwestern US ridge
   will continue across the central/southern Rockies through the day1
   period. Scattered convection has developed regularly during the
   afternoon hours across the higher terrain, and this will occur again
   later this afternoon. Isolated damaging winds remain the greatest
   risk with this diurnally driven convection.

   ..Darrow/Wendt.. 08/02/2020

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z