Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0758 AM CDT Tue May 19 2026

Valid 191300Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
PLAINS INTO THE LOWER MISSISSIPPI VALLEY/MID-SOUTH...OHIO
VALLEY...AND LOWER GREAT LAKES...

...SUMMARY...
Scattered severe thunderstorms will be possible today from the
southern Plains into the lower Mississippi Valley/Mid-South, Ohio
Valley, and lower Great Lakes. Damaging winds and hail will be the
primary threats. A greater threat for large to very large hail
should exist across parts of west-central Texas.

...Southern Plains into the Lower Mississippi Valley...
Numerous thunderstorms are ongoing this morning across
central/eastern OK into northwest AR and southern MO. Most of this
activity is occurring along and north of a southward-moving cold
front, and should therefore pose a limited severe risk in the short
term. Eventual regeneration along the cold front and/or
strengthening of ongoing activity should occur later today across TX
into the lower MS Valley/Mid-South. Mid-level flow is forecast to
remain fairly modest, and deep-layer shear for most areas will tend
to be marginal. Still, filtered daytime heating of a moist low-level
airmass will support moderate to strong instability along/ahead of
the front by early afternoon. Scattered severe/damaging winds should
be the main threat with loosely organized clusters and bowing line
segments. This wind threat may continue to the TX/LA Coast this
evening/overnight. Some potential for supercells should also exist
across parts of west-central TX and vicinity, where steeper
mid-level lapse rates and greater instability is forecast to be in
place. Large hail appears possible with any supercells that can be
sustained, and isolated 2+ inch diameter hail may occur. With time
this evening, this convection may also grow upscale into a bowing
cluster and pose a greater severe wind risk.

...Ohio Valley into the Lower Great Lakes and Northeast...
Modestly enhanced mid-level southwesterly flow will be present today
over the OH Valley and lower Great Lakes regions, as a positively
tilted mid/upper-level trough moves from the Upper Midwest into
eastern Canada. Isolated to scattered thunderstorms should develop
along/ahead of a surface cold front this afternoon as the
pre-frontal airmass gradually destabilizes. Stronger instability
should be present this afternoon across the OH Valley, but greater
deep-layer shear may tend to remain mostly displaced farther north.
Even so, some thunderstorm organization should occur, with
multicells and bowing line segments possible. Scattered
severe/damaging winds should be the main threat, although isolated
hail could occur with the strongest cores. This convection should
spread into the lower Great Lakes by mid to late evening, before
eventually weakening across the Northeast late tonight. A separate
area of convection may develop this afternoon across parts of New
England, and also pose a threat for mainly occasional damaging
winds.

..Gleason/Marsh.. 05/19/2026