SPC AC 221951

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0251 PM CDT Wed Jun 22 2022

   Valid 222000Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MIDDLE AND UPPER
   OHIO VALLEY AND MID-ATLANTIC STATES...

   ...SUMMARY...
   Scattered damaging winds are most probable across the middle and
   upper Ohio Valley and Mid-Atlantic States this afternoon through
   about dusk.

   ...Discussion...
   Only substantial change this outlook update is to include parts of
   northern KY and southwest OH in the 15-percent wind probability
   (categorical change from marginal to slight risk).  A very unstable
   airmass will lead to pulse-like thunderstorms capable of strong to
   locally severe gusts (50-65 mph) and the potential for wind damage.

   ..Smith.. 06/22/2022

   .PREV DISCUSSION... /ISSUED 1121 AM CDT Wed Jun 22 2022/

   ...Upper OH Valley to the Mid-Atlantic...
   A closed low off the southern New England coast will retrograde
   westward, while a separate shortwave impulse in the westerlies moves
   across the Great Lakes. A northeast/southwest-oriented cold front
   will move southeast across the Lower Great Lakes and OH Valley,
   eventually merging with a north/south-oriented backdoor cold front
   drifting west in central PA to western NY. 12Z observed soundings
   were unimpressive in terms of mean-mixing ratios and mid-level lapse
   rates. While strong boundary-layer heating and evapotranspiration
   will yield a plume of moderate to large buoyancy, guidance such as
   the 12Z NAM appears far too moist with mean-mixing ratios peaking
   around 20 g/kg and extreme MLCAPE in excess of 5000 J/kg. MLCAPE of
   2000-3000 J/kg will probably be more common between the two fronts
   across the Upper OH Valley to western PA. 

   Northwesterly to northerly mid-level flow on the west side of the
   closed low will favor southeast to southward-moving clusters later
   this afternoon from central/western PA into northern WV and
   northwest VA, along and west of the stalled north-south front. A
   cooler marine layer to the east of this front will result in severe
   potential decreasing rapidly with eastern extent in eastern PA to
   the Chesapeake. Slightly longer hodographs will be present along the
   north-south front, where there will be some potential for a few
   transient supercell structures. However, multicell clusters should
   be the dominant storm mode, with a primary threat of scattered
   damaging winds from strong to localized severe gusts. This threat
   will gradually diminish during the evening as clusters spread
   southward into an environment with weaker buoyancy but residual
   steeper low-level lapse rates across southern VA into NC.

   Multicell storm clusters are also expected along the cold front
   farther southwest across the OH Valley by mid-late afternoon.
   Vertical shear will be weaker, but large CAPE/DCAPE will favor
   localized damaging outflow gusts with multicell clusters into early
   evening.

   ...Southern KS and far northern OK...
   A surface cold front has stalled near the OK/KS border. Isolated to
   scattered thunderstorms should develop towards early evening along
   and north of this boundary as strong surface heating and deep mixing
   impinges on the front. Despite some weak enhancement to the
   hodographs on the cool side of the boundary, vertical shear will
   largely remain weak, with multicell clusters the expected convective
   mode. A confined corridor of MLCAPE from 2000-2500 J/kg and DCAPE in
   excess of 1000 J/kg will support isolated strong/damaging outflow
   gusts, and marginally severe hail for a few hours this evening.

   ...Southern/central CA...
   A plume of richer moisture centered around 700-mb and ascent tied to
   a mid-level closed low just off the coast has yielded regenerative
   scattered thunderstorms across southern into central CA this
   morning. Pockets of stronger surface heating/mixing in cloud breaks
   to the south of this morning's activity will contribute to deepening
   inverted-v profiles. Weak surface-based buoyancy with MLCAPE of
   250-750 J/kg should be sufficient to realize some downburst
   potential in an environment of steep low-level lapse rates and DCAPE
   greater than 1000 J/kg. Isolated damaging gusts will be possible,
   mainly during the late afternoon to early evening from the higher
   terrain of southern CA northward into the San Joaquin Valley.

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