...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST
MISSOURI...SOUTHERN ILLINOIS/INDIANA...SOUTHWEST OHIO...AND PORTIONS
OF WESTERN TO NORTHERN KENTUCKY...
...SUMMARY...
Severe thunderstorms are expected across the Middle Mississippi and
Ohio Valley region Friday afternoon and evening. All-severe hazards
are possible with this activity. More isolated severe thunderstorms
will extend southwestward into northeast Texas, and northeast into
the Mid-Atlantic.
...Mid-South/Ohio Valley vicinity...
An upper trough over the southern High Plains will pivot quickly
east/northeast across the Midwest on Friday. As this occurs, strong
mid/upper southwesterly flow will overspread the region, with a 500
mb jet around 70-90 kt forecast. At the surface, A very moist
airmass will be in place from southern MO into southern IL and
northeast into OH. Increasing southerly low-level flow ahead of a
surface cold front will allow a warm front, roughly along the I-70
corridor at mid-morning, to lift north toward the northern IL/IN/OH
through the afternoon. Cooling aloft will result in steep midlevel
lapse rates atop the mid/upper 60s F dewpoint surface warm sector,
resulting in strong destabilization.
A low-level jet around 45-65 kt is forecast to overspread the region
from peak heating into the evening, coincident with increasing
large-scale ascent. Both the eastward-advancing cold front/dryline
across MO, and the warm front vicinity will be a focus for
convective initiation. One or more bowing clusters is possible, in
addition to more discrete supercells. Given vertically veering
supercells wind profiles, significant severe storms appear possible
-- with a risk for all hazards accompanying this activity, including
very large hail, tornadoes, and intense wind gusts. The southward
extent of highest severe potential is a bit uncertain given
orientation of surface boundaries and potential overnight convection
in the Day 2/Thursday time period impacting parts of the KY
vicinity.
Eventually, a northeast to southwest line of storms will likely
congeal during the late evening/nighttime hours and sag southward
across KY into the TN Valley, with a gradually lessening severe risk
with southward extent during the overnight hours.
...TX into OK/AR...
With southwest extent, severe potential is a bit more
uncertain/conditional. Some minor height rises may occur across TX
and the into AR during the late afternoon/evening. Large-scale
ascent will be weaker and any capping may be more difficult to
overcome. Nevertheless, a very moist and unstable airmass will be in
place amid supercell wind profiles. If storms can develop, very
large hail and strong gusts will be possible.
...Mid-Atlantic Vicinity...
Convection may be ongoing in a warm advection regime Friday morning
as a weak shortwave impulse moves across the region through
afternoon. Moderate mid/upper flow will support effective shear
magnitudes around 25-35 kt, and be sufficient for some organized
convection. Pockets of stronger heating downstream from morning
activity will allow for weak to moderate destabilization. Isolated
strong to severe storms producing hail and gusty winds will be
possible.
..Leitman.. 05/14/2025
