Alert archive / Illinois / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 136, NWS St. Louis, MO

May 4, 2026Clinton County, Saint Clair County, Washington County, Illinois

NWS St. Louis, MO issued this severe thunderstorm warning at May 4, 2026, 2:48 PM CDT for Clinton County, Saint Clair County, Washington County, Illinois. It was in force for 42 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 4, 2026, 2:48 PM CDT (19:48 UTC)
Expired: May 4, 2026, 3:30 PM CDT
In force: 42 min
Issued by: NWS St. Louis, MO
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Clinton County, IL, Saint Clair County, IL, Washington County, IL

The radar

The St Louis radar (KLSX), 98 km from the middle of the area, began a volume at 19:48 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 7.8 hours before the alert went out and 205 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1708 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 231 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS St. Louis, MO wrote its last area forecast discussion before this severe thunderstorm warning went out at May 4, 12:55 PM CDT, 1 hour 53 minutes earlier.

Area forecast discussion, May 4, 12:55 PM CDT, 1 hour 53 minutes before

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Hazardous weather outlook, May 4, 5:55 AM CDT, 8 hours 53 minutes before

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In the hours before

Local storm report, May 4, 12:04 PM CDT, 2 hours 44 minutes before

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Local storm report, May 4, 12:40 PM CDT, 2 hours 8 minutes before

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Local storm report, May 4, 12:45 PM CDT, 2 hours 3 minutes before

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Local storm report, May 4, 12:55 PM CDT, 1 hour 53 minutes before

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The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 3, 9:38 PM CDT	Severe Thunderstorm Warning	LSX	Lincoln, Montgomery, Warren	30 min
May 3, 10:15 PM CDT	Severe Thunderstorm Warning	LSX	Lincoln, Saint Charles	30 min
May 3, 10:38 PM CDT	Severe Thunderstorm Warning	LSX	Saint Charles	45 min
May 4, 12:01 AM CDT	Severe Thunderstorm Warning	LSX	Macoupin	18 min
May 4, 6:08 PM CDT	Severe Thunderstorm Warning	LSX	Macoupin, Madison	52 min
May 4, 6:37 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LSX	Bond, Montgomery	38 min
May 4, 6:59 PM CDT	Severe Thunderstorm Warning	LSX	Fayette	46 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2026 Every severe thunderstorm warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.