Flash Flooding in Illinois, May 12, 2002

Name: Flash Flooding in Illinois, May 12, 2002
Start: 2002-05-12T05:00
End: 2002-05-12T09:30
Location: Illinois

May 12, 2002 · NWS LSX · 4 events in 4 counties and zones

Rainfall of 3 to 6 inches caused widespread flash flooding across the area. In Greene County, highways 67 and 267 were closed due to flooding.

Where it happened

Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 4

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS LSX wrote it up.

Rainfall of 3 to 6 inches caused widespread flash flooding across the area. In Greene County, highways 67 and 267 were closed due to flooding. In Jersey County, street flooding was reported through much of Jerseyville. In Macoupin County, up to 4 inches of rain brought creeks and small streams out of their banks flooding area roads.

What forecasters said that day

The local office's own words before the first event, 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 the first event at May 12, 2:48 AM CST, 2 hours 12 minutes earlier.

Area forecast discussion, May 12, 2:48 AM CST, 2 hours 12 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
240 PM CDT SAT MAY 11 2002

MAIN CONCERNS CONT TO BE HVY PCPN WI ISOLD SVR TSTMS.

GETTING LOTS OF RAIN NORTH...IRK HAD OVR 4 INCHES PAST 6 HRS AND
NEARLY 8 INCHES STORM TOTAL PAST 24 HRS OR SO. PCPBL H20 CONT TO RUN
HIGH AND RAIN FALLING QUICKLY. WL ISSUE THESE FCSTS HURRIDLY TO CONT
TO MONITER FOR MORE PCPN PROBLEMS IN CWA ALG NEW LIN THAT HAS JUST
FORMED.

LOOK FOR S/W RIDING INTO AREA TNGT TO KEEP LN THAT FORMED DURING
AFTN/EVE STNRY FOR A FEW HRS AND THIS WILL RESULT IN A MAJOR FLASH
FLOOD PROB SOMEWHERE NR OR JUST SOUTH OF I-44/I-70 THIS EVE. THEN
AS S/W APPROACHES IT SHOULD EVOLVE IN A MORE NORTH/SOUTH LN WHICH
WILL PROB BECOME SEVERE BUT LIMIT TRAINING SO MUCH.

LONGER RANGE LOOKS WETTER AGAIN FOR LATTER HALF OF WEEK SO WILL
TWEAK EXTENDED TO COME MORE IN LINE WITH MRF EXTENSION.

.STL...FLASH FLOOD WATCH CONTINUES...
            FOR TODAY NORTH THIRD CWA
            FOR TODAY AND TONIGHT FOR CNTRL THIRD NORTH OF A LINE
              FROM LAKE OF THE OZARKS TO 40S KSTL TO 25 SW OF
              EFFINGHAM IL
            FOR TNGT/MON FOR SRN CWA S OF LN FROM LAKE OF THE OZARKS
              TO 40S KSTL TO 25 SW OF EFFINGHAM IL.

PEDIGO

The radar

The St Louis radar (KLSX), 52 km away, was scanning. The volume nearest the first event began at 11:01 UTC.

Open the radar archive at this moment

Event by event

4 flash flood. Local standard time, as filed.

Flash Flood, Calhoun

When: May 12, 5:00 AM CST to 9:30 AM CST
Where: Calhoun County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 39.169, -90.667 (the zone’s center; the record gives no point)

Flash Flood, Greene

When: May 12, 5:00 AM CST to 9:30 AM CST
Where: Greene County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 39.356, -90.390 (the zone’s center; the record gives no point)

Flash Flood, Jersey

When: May 12, 5:00 AM CST to 9:30 AM CST
Where: Jersey County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 39.086, -90.357 (the zone’s center; the record gives no point)

Flash Flood, Macoupin

When: May 12, 5:00 AM CST to 9:30 AM CST
Where: Macoupin County, Countywide
Reported by: LAW ENFORCEMENT
Coordinates: 39.261, -89.924 (the zone’s center; the record gives no point)

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Illinois in 2002 Every state in 2002 This day in weather history Warnings in Illinois, May 2002

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5291599, 5291600, 5291601, 5291602.