031
ACUS02 KWNS 201731
SWODY2
SPC AC 201730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Mon Jul 20 2026

Valid 211200Z - 221200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE UPPER OHIO VALLEY INTO THE MID-ATLANTIC...

...SUMMARY...
Numerous severe thunderstorms are expected across a broad region
from the Ohio Valley into the Mid-Atlantic and Northeast on Tuesday.
All severe hazards are possible, but swaths of damaging wind gusts
should be the primary severe risk Tuesday afternoon into the
nighttime hours.

...Synopsis...
High amplitude ridging will build across the western US with
continued progressive troughing across the east on Tuesday. Multiple
short-wave impulses will rotate through the eastern US trough, with
a belt of enhanced northwesterly flow traversing the Midwest into
the Ohio Valley. At the surface, a cold front will shift south and
east through the period, with a surface low across southern
Ontario/Quebec. A pre-frontal surface trough will also be in place
across western/central NY into the Mid-Atlantic vicinity. Widely
scattered thunderstorm activity is expected through the period.

...Mid-Atlantic and Northeast...
Thunderstorm activity is expected to increase along the pre-frontal
trough from western/central New York into the Northeast/Mid-Atlantic
late Tuesday morning into the afternoon. Though there may be
potential for early morning cloud cover, it does appear that
sufficient heating/moistening will occur for at least moderate
instability to develop across the region through the afternoon.
Mid-level flow will increase through the day along with forcing for
ascent. It appears widely scattered thunderstorm activity with
several clusters/embedded supercells will be ongoing by the
afternoon. Highest confidence in transient embedded supercell modes
would be closer to the surface low and near the front across western
NY into eastern PA. Here, there may be potential for both damaging
wind, large hail, and perhaps a couple of tornadoes. Guidance
suggests the best signal for damaging wind will be across the
Mid-Atlantic, where several damaging clusters could occur. As such,
the Enhanced was expanded eastward into portions of the
Mid-Atlantic.

...Ohio Valley...
Evolution of overnight convection will play a large role in
development/maintenance of thunderstorm activity across the Ohio
Valley Tuesday. It appears that remnant convection will be ongoing
at the start of the period near/just ahead of the surface front
across northern Kentucky/southern Indiana/Ohio. This will likely
re-intensify and continue to expand south and east during the
morning as daytime heating begins. Strong daytime heating and moist
profiles should support moderate to strong instability developing
though the afternoon. Storm mode appears to be generally linear,
with the greatest threat being for damaging wind given more linear
forcing/initially boundary parallel shear along residual southward
moving outflow. As such, the primary hazard will be damaging wind.

Additional thunderstorm development is likely along and ahead of the
front through the afternoon with increasing forcing for ascent with
approaching shortwaves. Strong deep layer shear may become more
boundary perpendicular supporting a supercell or two as the front
sags south, with potential for large hail and perhaps a tornado.
Confidence in this scenario is on the lower end and the primary
hazard is expected to be a secondary wave of damaging wind
potential. Should storms be able to cluster and establish a more
organized cold pool, potential for some corridor of significant wind
may be possible. Overall, no significant wind areas were included
given low confidence in exact morning storm evolution and concerns
over generally poor lapse rates.

..Thornton.. 07/20/2026

$$