RSS Mesoscale Discussions from Storm Prediction Center
SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0743 PM CDT Tue May 19 2026
Valid 200100Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS AND FROM THE OHIO VALLEY INTO THE LOWER GREAT
LAKES...
...SUMMARY...
Isolated to scattered severe thunderstorms will be possible this
evening from the southern Plains northeastward into mid Mississippi
Valley and Lower Great Lakes. A greater threat for large hail will
exist across parts of west-central Texas.
...Southern Plains...
Southwest flow aloft is evident on water vapor imagery over the
southern Plains. At the surface, an east-to-west oriented cold front
is located across west and central Texas. Several strong
thunderstorms are ongoing along the front. To the south of the
front, surface dewpoints near 70 F are contributing to strong
instability over the southern third of Texas, with the RAP showing
MLCAPE in the 3000 to 4500 J/kg range. In addition, the RAP has
steep mid-level lapse rates and moderate deep-layer shear analyzed
across much of central and south Texas. This will be favorable for
organized storms this evening capable of hail and severe wind gusts.
Large hail will be most likely with any supercell that can develop.
The severe threat is expected to move southward into south-central
Texas by late evening. MCS development appears to be underway. As
the convective coverage continues to increase, a transition to
severe wind gusts as the primary threat is expected...see MCD 795.
...Mid Mississippi and Ohio Valleys/Lower Great Lakes...
At mid-levels, a shortwave trough is evident on water vapor imagery
over the Ohio Valley. A cold front is located from southern Indiana
northeastward across central Ohio into the lower Great Lakes. A line
of strong thunderstorms is ongoing near the front. Ahead of the
front, surface dewpoints are in the 60s F which is enough for
sufficient instability to support severe storm development. The RAP
suggests that 0-3 km level lapse rates are still in the 7 to 7.5
C/km ahead of the front from Ohio into northwest Pennsylvania. This
could support isolated damaging wind gusts with the stronger cells
embedded in the line...see MCD 797.
..Broyles.. 05/20/2026
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