SPC May 20, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... 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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SPC May 19, 2026 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Tue May 19 2026

Valid 192000Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
OHIO VALLEY INTO THE LOWER GREAT LAKES...AND PARTS OF CENTRAL/SOUTH
TEXAS...

...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.

...20Z Update...
The primary change to the forecast was to increase wind
probabilities in parts of South Texas. Convection within the Rolling
Plains should continue to develop this afternoon along a slowly
moving cold front. Given the moisture surge ahead of this activity,
it seems plausible that cold pool development will be robust enough
to support continued development southward into the overnight.
Recent HRRR guidance and the ECMWF support this possibility.
Elsewhere, only minor changes where made based on current
observations.

..Wendt.. 05/19/2026

.PREV DISCUSSION... /ISSUED 1119 AM CDT Tue May 19 2026/

...OH Valley and Lower Great Lakes...
Deep southwesterly flow is present today from southern IL into much
of the OH Valley and NY. Visible satellite imagery shows mostly
clear skies in the region, allowing strong destabilization and
steepening low-level lapse rates. The result will be a rather large
zone of favorable environment for strong/damaging wind gusts this
afternoon with any organized convection. Given the continued trend
in morning model guidance of scattered clusters of storms in this
corridor, the SLGT risk area has been maintained.

...South-central TX...
A warm/moist and unstable air mass will develop this afternoon
across parts of west-central TX. Scattered thunderstorm development
is expected along a cold front sagging into the region. with weak
supercells structures possible. These storms will track
southeastward through the late afternoon/evening with a large hail
threat. Eventual upscale growth into bowing structures may extend
the severe risk overnight into south-central TX.

...East TX/LA/AR...
Widespread overnight convection continues to build southeastward
across southeast OK and western AR. This activity will persist much
of the day and spread across much of AR/East TX/northern LA, in a
region of relatively weak vertical shear and poor lapse rates.
Storms may occasionally pose a risk of gusty/damaging winds, but the
overall threat appears marginal.


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SPC May 19, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1119 AM CDT Tue May 19 2026

Valid 191630Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
OVER PART OF THE OHIO VALLEY INTO NEW YORK...AND THROUGH TONIGHT
OVER PARTS OF TEXAS....

...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.

...OH Valley and Lower Great Lakes...
Deep southwesterly flow is present today from southern IL into much
of the OH Valley and NY. Visible satellite imagery shows mostly
clear skies in the region, allowing strong destabilization and
steepening low-level lapse rates. The result will be a rather large
zone of favorable environment for strong/damaging wind gusts this
afternoon with any organized convection. Given the continued trend
in morning model guidance of scattered clusters of storms in this
corridor, the SLGT risk area has been maintained.

...South-central TX...
A warm/moist and unstable air mass will develop this afternoon
across parts of west-central TX. Scattered thunderstorm development
is expected along a cold front sagging into the region. with weak
supercells structures possible. These storms will track
southeastward through the late afternoon/evening with a large hail
threat. Eventual upscale growth into bowing structures may extend
the severe risk overnight into south-central TX.

...East TX/LA/AR...
Widespread overnight convection continues to build southeastward
across southeast OK and western AR. This activity will persist much
of the day and spread across much of AR/East TX/northern LA, in a
region of relatively weak vertical shear and poor lapse rates.
Storms may occasionally pose a risk of gusty/damaging winds, but the
overall threat appears marginal.

..Hart/Halbert.. 05/19/2026


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SPC May 19, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


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


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