ACUS02 KWNS 230526
SWODY2
SPC AC 230524

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 AM CDT Tue Jul 23 2024

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF NORTHERN OHIO AND PENNSYLVANIA INTO NEW YORK...

...SUMMARY...
Isolated strong to severe thunderstorms may produce damaging gusts
across parts of northern Ohio and Pennsylvania into New York
Wednesday afternoon and evening.

...Synopsis...

An upper shortwave trough over the upper Great Lakes will develop
eastward toward the upper Ohio Valley/lower Great Lakes vicinity on
Wednesday. At the same time, the sub-tropical high over the western
Atlantic will scoot westward toward the Mid-Atlantic and Southeast.
This will result in an increasing/tightening height gradient across
the Northeast as the upper trough develops east, and southwesterly
mid/upper flow will increase from the Ohio Valley into the
Mid-Atlantic and Northeast. Further west, an upper shortwave trough
will develop east/southeast over the Pacific Northwest and northern
Rockies, while an upper anticyclone persists over the Southwest. As
the Pacific Northwest trough moves east, an upper ridge will
overspread the central Rockies to the northern Plains.

At the surface, a weak low will track northeast from the Lake Huron
vicinity into southern Quebec. A trailing cold front will sag
south/southeast across northern IL/IN/OH/PA and western NY during
the afternoon and into the overnight hours. Meanwhile, a surface
trough will extend southwest across the Chesapeake Bay vicinity into
central NC. A moist airmass will be in place ahead of the surface
cold front and near the surface trough, aiding in at least weak to
moderate destabilization. These boundaries also will focus
thunderstorm potential during the afternoon and evening hours.
Further west, a baroclinic zone will exist over the northern Plains
as a surface low deepens over the Canadian Prairies and high
pressure builds over the upper Great Lakes. South/southeasterly
low-level flow will allow for 60s F dewpoints across central/eastern
portions of the Dakotas. However, capping within the amplifying
upper ridge will likely preclude thunderstorm development.

...Northern OH/PA into NY...

Increasing mid/upper-level southwesterly flow will support around
30-35 kt effective shear magnitudes by afternoon. Midlevel lapse
rates will remain modest, but heating into the 80s and dewpoints in
the mid/upper 60s F will allow for MLCAPE as high as 1500 J/kg.
Stronger height falls will likely not occur until around/after 00z,
somewhat misaligned with peak heating. Nevertheless, increasing
vertical shear and modest large-scale ascent, coupled with the
approaching cold front should support at least isolated to scattered
thunderstorm development during the afternoon. Elongated hodographs
and modest vertically veering wind profiles suggest organized cells,
with perhaps transient supercell characteristics, will be possible.
Steepening low-level lapse rates will support sporadic
strong/locally damaging gusts. A couple of the strongest cells may
produce marginal hail.

...Southeast VA into central/eastern NC...

Thunderstorms are expected to develop within a very moist and
unstable airmass Wednesday afternoon. While midlevel flow will
gradually increase, vertical shear will remain marginal for
organized convection, especially until after 00z. Given the high
PW/moderately unstable airmass, a wet microburst or two will be
possible. However, modest vertical shear and poor midlevel lapse
rates preclude severe probabilities at this time.

..Leitman.. 07/23/2024

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