Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Wed Apr 17 2024
Valid 171200Z - 181200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY AND LOWER GREAT LAKES...AND IN PARTS OF NORTHEAST
KANSAS AND WESTERN MISSOURI...
...SUMMARY...
Scattered thunderstorms, capable of wind damage, isolated large hail
and a tornado threat, are expected to develop across parts of the
Ohio Valley and Lower Great Lakes this afternoon. Storms with large
hail are expected tonight in parts of the central Plains and Ozarks.
...Ohio and Tennessee Valleys/Central Gulf Coast States...
A negatively tilted upper-level trough, and an associated surface
low, will move into the Great Lakes today. A corridor of maximized
surface dewpoints will move eastward across the Ohio Valley today,
as a cold front approaches from the west. Scattered thunderstorms
will likely develop during the late morning, as low-level
convergence and instability increases. These storms, in the form of
clusters or short line segments, will move eastward across the Ohio
Valley and Lower Great Lakes region during the afternoon.
RAP forecast soundings across far eastern Indiana and western Ohio
during the early afternoon show a favorable environment for severe
storms, with MLCAPE near 1500 J/kg and 0-6 km shear around 50 knots.
This should support an isolated large hail threat with the more
discrete rotating storms. A wind-damage threat will also be
possible, especially with the more organized line segments. Forecast
soundings suggest that low-level shear will become more favorable in
the late afternoon, with 0-3 km storm-relative helicity increasing
into the 225 to 250 m2/s2 range. For this reason, the tornado threat
is expected to be greater a bit further east from central and
eastern Ohio into far western Pennsylvania.
Further south into the Tennessee Valley and central Gulf Coast
states, isolated thunderstorms are expected to develop ahead of a
cold front, and near a moist axis with surface dewpoints in the 60s
F. MLCAPE in the 750 to 1000 J/kg range, along with 0-6 km shear
from 40 to 50 knots will be sufficient for an isolated severe
threat. Marginally severe wind gusts and hail will be the primary
threats.
...Central Plains/Ozarks...
An upper-level trough will move through the north-central U.S.
tonight, as a 70 to 80 knot mid-level jet passes through the trough.
In response, a 40 to 50 knot low-level jet will develop further
south across the central Plains. Thunderstorms are expected to
initiate near the northern edge of the low-level jet late this
evening from central Kansas into far southeast Nebraska. These
storms are expected to move eastward across northeast Kansas and
into western Missouri. Forecast soundings in northeast Kansas around
06Z have MUCAPE near 2500 J/kg, with effective shear around 45
knots. This, combined with 700-500 mb lapse rates around 7.5 C/km,
should be favorable for elevated rotating storms with potential for
very large hail. The large hail threat is expected to be greatest in
the 04Z to 07Z time window, but may persist through late in the
period.
..Broyles/Lyons.. 04/17/2024
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