SPC 2000Z Day 1 Outlook
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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