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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1233 AM CDT Thu May 26 2022

Valid 261200Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
PACIFIC NORTHWEST...GEORGIA INTO THE WESTERN CAROLINAS...AND THE
UPPER OHIO RIVER VALLEY...

...SUMMARY...
Isolated to widely scattered severe thunderstorms may occur Thursday
over Ohio/eastern Kentucky, northeastern Georgia into the far
western Carolinas, and parts of northeastern Oregon, southeastern
Washington, and Idaho. Severe wind gusts and large hail should be
the primary hazards.

...Synopsis...
An upper-level low over the central CONUS is evident in
early-morning water vapor imagery. This feature will continue to
drift east into the southern/central Appalachians over the next 24
hours. As this occurs, a diffuse surface low and attendant cold
front will shift into the OH River Valley and southeastern U.S.
respectively. 00 UTC RAOBs from across these regions sampled modest
mid-level lapse rates (generally between 6-7 C/km), but a broad
swath of boundary-layer mean mixing ratios between 10-13 g/kg across
the region coupled with diurnal warming will support adequate
buoyancy for convection by early afternoon. To the west, an
upper-level wave off the West Coast will move onshore later today.
Height falls across the Pacific Northwest and the approach of a
mid-level cold front will support thunderstorm development late in
the afternoon/evening.

...Southeast...
A cold front currently moving across the lower MS River Valley is
expected to continue eastward into the Southeast today.
Thunderstorms will likely be ongoing at the start of the period
along the Gulf Coast, but will increase in coverage along the front
through the late morning and early afternoon across AL into GA.
Although moist profiles and modest mid-level lapse rates will limit
buoyancy to a degree, MLCAPE should be adequate for increasingly
robust updrafts by early afternoon. Increasing deep-layer shear off
the boundary, as well as strengthening 850-700 mb flow, will support
the potential for a few cells and/or organized segments along the
front. A Slight risk is introduced for portions of central GA into
the western Carolinas where the potential for such organized
segments (and an attendant damaging wind threat) appears greatest.  


A diffuse wedge front, noted in early-morning observations across
the Carolinas, is expected to lift north as a warm frontal zone
through the day in response to increasing southerly flow.
Thunderstorms may develop along this boundary during the afternoon.
A few stronger, more organized cells are possible, but storm motions
along the boundary and the possibility of destructive storm
interference may limit this potential.

...Upper OH River Valley...
Broad ascent ahead of the upper low overlaid with a mid-level
convergence zone will support isolated to widely scattered
thunderstorms from IL into the upper OH River Valley. Modest low to
mid-level lapse rates will limit buoyancy despite 55-65 F dewpoints
already in place. However, forecast soundings show adequate CAPE
profiles to utilize the stronger flow aloft with 35-45 knots of
effective bulk shear likely across this region. The isolated to
scattered nature of convection should allow for at least a few
organized cells and/or linear segments. Narrow CAPE profiles may
limit the overall hail potential to a degree, but 30-40 knot flow
within the lowest 1 km will support a damaging-wind potential.
Recent guidance continues to suggest that the greatest convective
coverage (and hence increased wind threat) will reside across
northeast KY into OH and far western WV near the exit region of the
upper jet.

...Pacific Northwest...
00 UTC soundings from across the Pacific Northwest have shown a
general increase in mid-level moisture over the past 12 hours as
deep-layer onshore flow increases. Additionally, mid-level lapse
rates have steepened as broad, but weak, ascent overspreads the
region ahead of the upper-level wave. This trend will continue
through the day and, when coupled with daytime heating, should
support around 500 J/kg MLCAPE by late afternoon. While buoyancy may
be somewhat limited, straight hodographs off an initiating cold
front will promote discrete cells, including the potential for a few
supercells, from northeast OR into northern ID. Large hail appears
probable with these cells, and steep low-level lapse rates with a
1-2 km dry sub-cloud layer will support the potential for severe
wind gusts.

..Moore/Darrow.. 05/26/2022