Alert archive / Illinois / Flash Flood Warnings
Flash Flood Warnings in Illinois, 2021
99 flash flood warnings in 2021. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of flash flood warnings reaches back to 1986.
Flash Flood Warnings by county
Each county as a circle sized by its count in 2021. Tap one for its archive.
- Flash Flood Warnings
- 99
- Busiest month
- July35 flash flood warnings
- Busiest day
- July 16, 202117 flash flood warnings
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
48 of 99 flash flood warnings covering Illinois in 2021 had a flash flood report inside them; 77 of 92 flash flood reports fell inside a warning, on average 92 minutes after it went out.
Illinois, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 99 | 48 | 52% | 92 | 84% | 92 min |
Each office's whole area, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS St. Louis, MO: flash flood warnings | 47 | 32 | 32% | 113 | 90% | 98 min |
| NWS Chicago, IL: flash flood warnings | 11 | 7 | 36% | 27 | 96% | 106 min |
| NWS Paducah, KY: flash flood warnings | 65 | 29 | 55% | 52 | 83% | 97 min |
| NWS Lincoln, IL: flash flood warnings | 37 | 14 | 62% | 32 | 84% | 93 min |
| NWS Indianapolis, IN: flash flood warnings | 27 | 14 | 48% | 23 | 78% | 102 min |
| NWS Quad Cities, IA: flash flood warnings | 20 | 10 | 50% | 24 | 79% | 70 min |
An office's figures cover every county it serves, including across state lines.
Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.
The alerts
Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 11, 4:52 PM CST | Flash Flood Warning | PAH | Jackson, Williamson | 3 hr |
| Apr 29, 2:27 AM CDT | Flash Flood Warning | LSX | Monroe | 4 hr |
| May 3, 8:53 PM CDT | Flash Flood Warning | ILX | Coles | 50 min |
| Jun 3, 8:10 AM CDT | Flash Flood Warning | PAH | Franklin, Hamilton, Saline, Williamson | 110 min |
| Jun 9, 9:35 PM CDT | Flash Flood Warning | DVN | Carroll | 3 hr |
| Jun 12, 6:21 PM CDT | Flash Flood Warning | ILX | Champaign, Vermilion | 78 min |
| Jun 12, 10:53 PM CDT | Flash Flood Warning | PAH | Gallatin, Hardin, White | 3 hr |
| Jun 19, 12:26 AM CDT | Flash Flood Warning | ILX | Clark | 6 hr |
| Jun 19, 12:28 AM CDT | Flash Flood Warning | ILX | Fulton, Knox | 5 hr |
| Jun 19, 1:53 AM CDT | Flash Flood Warning | ILX | Coles, Douglas, Edgar | 5 hr |
| Jun 19, 3:29 AM CDT | Flash Flood Warning | ILX | Champaign, Douglas, Edgar, Vermilion | 3 hr |
| Jun 19, 4:10 PM CDT | Flash Flood Warning | LSX | Calhoun | 6 hr |
| Jun 19, 4:35 PM CDT | Flash Flood Warning | LSX | Calhoun, Greene, Jersey | 6 hr |
| Jun 25, 1:42 AM CDT | Flash Flood Warning | ILX | Knox, Marshall, Stark | 6 hr |
| Jun 25, 1:44 AM CDT | Flash Flood Warning | DVN | Bureau, Henry | 6 hr |
| Jun 25, 7:32 PM CDT | Flash Flood Warning | LSX | Adams, Pike | 6 hr |
| Jun 25, 8:54 PM CDT | Flash Flood Warning | ILX | DeWitt, Logan, McLean, Mason, Tazewell | 6 hr |
| Jun 25, 9:29 PM CDT | Flash Flood Warning | LSX | Calhoun, Greene, Jersey | 6 hr |
| Jun 25, 9:47 PM CDT | Flash Flood Warning | ILX | Morgan, Scott | 6 hr |
| Jun 25, 9:59 PM CDT | Flash Flood Warning | ILX | DeWitt, McLean, Piatt | 5 hr |
| Jun 26, 12:18 PM CDT | Flash Flood Warning | LOT | Cook, DuPage, Will | 6 hr |
| Jun 26, 3:25 PM CDT | Flash Flood Warning | ILX | DeWitt, Logan, McLean, Macon, Mason, Menard and 3 more | 4 hr |
| Jun 26, 3:50 PM CDT | Flash Flood Warning | LOT | Cook, Grundy, Kankakee, Will | 6 hr |
| Jun 26, 3:57 PM CDT | Flash Flood Warning | LOT | Ford, Grundy, Iroquois, Kankakee, Livingston | 6 hr |
| Jun 28, 12:20 PM CDT | Flash Flood Warning | DVN | Hancock | 5 hr |
| Jun 30, 5:20 PM CDT | Flash Flood Warning | LSX | Adams | 2 hr |
| Jul 10, 6:18 PM CDT | Flash Flood Warning | ILX | Clay | 3 hr |
| Jul 10, 10:29 PM CDT | Flash Flood Warning | PAH | Alexander, Hardin, Johnson, Massac, Pope, Pulaski and 1 more | 6 hr |
| Jul 10, 11:02 PM CDT | Flash Flood Warning | PAH | Alexander | 5 hr |
| Jul 11, 11:54 AM CDT | Flash Flood Warning | DVN | Hancock | 6 hr |
| Jul 11, 2:35 PM CDT | Flash Flood Warning | DVN | Hancock, McDonough | 3 hr |
| Jul 11, 3:31 PM CDT | Flash Flood Warning | ILX | Schuyler | 3 hr |
| Jul 11, 5:07 PM CDT | Flash Flood Warning | ILX | Logan, Mason, Menard | 6 hr |
| Jul 11, 6:00 PM CDT | Flash Flood Warning | ILX | Logan | 5 hr |
| Jul 11, 8:35 PM CDT | Flash Flood Warning | ILX | Sangamon | 3 hr |
| Jul 11, 9:31 PM CDT | Flash Flood Warning | ILX | Vermilion | 3 hr |
| Jul 12, 6:50 PM CDT | Flash Flood Warning | LSX | Montgomery | 4 hr |
| Jul 12, 8:42 PM CDT | Flash Flood Warning | LOT | Grundy, LaSalle | 5 hr |
| Jul 12, 11:35 PM CDT | Flash Flood Warning | ILX | Marshall, Peoria | 5 hr |
| Jul 12, 11:56 PM CDT | Flash Flood Warning | LOT | Grundy, Livingston, Will | 4 hr |
| Jul 15, 4:52 AM CDT | Flash Flood Warning | ILX | Marshall, Peoria, Stark, Woodford | 5 hr |
| Jul 15, 5:01 PM CDT | Flash Flood Warning | ILX | DeWitt, McLean | 3 hr |
| Jul 15, 7:35 PM CDT | Flash Flood Warning | ILX | Coles | 4 hr |
| Jul 15, 11:22 PM CDT | Flash Flood Warning | LSX | Randolph | 5 hr |
| Jul 15, 11:28 PM CDT | Flash Flood Warning | PAH | Perry | 3 hr |
| Jul 16, 1:09 AM CDT | Flash Flood Warning | PAH | Franklin, Jefferson | 6 hr |
| Jul 16, 2:19 AM CDT | Flash Flood Warning | PAH | Perry | 6 hr |
| Jul 16, 6:23 AM CDT | Flash Flood Warning | PAH | Jefferson | 6 hr |
| Jul 16, 7:04 AM CDT | Flash Flood Warning | ILX | McLean | 4 hr |
| Jul 16, 9:41 AM CDT | Flash Flood Warning | ILX | McLean | 4 hr |
| Jul 16, 1:21 PM CDT | Flash Flood Warning | PAH | Franklin, Hamilton, Jefferson | 114 min |
| Jul 16, 1:41 PM CDT | Flash Flood Warning | LSX | Washington | 6 hr |
| Jul 16, 2:04 PM CDT | Flash Flood Warning | PAH | Hamilton, Wayne, White | 116 min |
| Jul 16, 2:17 PM CDT | Flash Flood Warning | PAH | Edwards, Wabash, White | 118 min |
| Jul 16, 3:25 PM CDT | Flash Flood Warning | PAH | Franklin, Jackson, Jefferson, Perry | 3 hr |
| Jul 16, 4:04 PM CDT | Flash Flood Warning | PAH | Perry | 2 hr |
| Jul 16, 4:28 PM CDT | Flash Flood Warning | PAH | Franklin, Hamilton, Wayne | 3 hr |
| Jul 16, 4:59 PM CDT | Flash Flood Warning | PAH | Edwards, Wabash, White | 3 hr |
| Jul 16, 5:47 PM CDT | Flash Flood Warning | ILX | Clay, Crawford, Effingham, Jasper, Lawrence, Richland | 4 hr |
| Jul 25, 8:28 AM CDT | Flash Flood Warning | LSX | Saint Clair, Washington | 3 hr |
| Jul 31, 8:34 AM CDT | Flash Flood Warning | LSX | Bond, Calhoun, Greene, Jersey, Macoupin, Montgomery and 1 more | 4 hr |
| Aug 8, 5:35 PM CDT | Flash Flood Warning | ILX | McLean | 3 hr |
| Aug 9, 4:56 AM CDT | Flash Flood Warning | PAH | Wayne | 3 hr |
| Aug 9, 5:28 AM CDT | Flash Flood Warning | PAH | Edwards, Wabash | 3 hr |
| Aug 9, 8:19 AM CDT | Flash Flood Warning | PAH | Edwards, Wayne | 2 hr |
| Aug 9, 8:02 PM CDT | Flash Flood Warning | DVN | Bureau | 2 hr |
| Aug 11, 6:59 AM CDT | Flash Flood Warning | DVN | Hancock, Henderson | 3 hr |
| Aug 12, 9:59 AM CDT | Flash Flood Warning | LOT | Ford | 5 hr |
| Aug 12, 10:04 AM CDT | Flash Flood Warning | ILX | Champaign, McLean | 5 hr |
| Aug 12, 11:17 AM CDT | Flash Flood Warning | ILX | Champaign, DeWitt, Piatt | 3 hr |
| Aug 12, 2:16 PM CDT | Flash Flood Warning | ILX | Champaign, DeWitt, Piatt | 119 min |
| Aug 12, 4:15 PM CDT | Flash Flood Warning | ILX | Douglas, Moultrie, Shelby | 3 hr |
| Aug 12, 7:40 PM CDT | Flash Flood Warning | LSX | Bond, Madison | 4 hr |
| Aug 21, 6:54 AM CDT | Flash Flood Warning | PAH | Massac, Pope | 5 hr |
| Aug 24, 5:40 PM CDT | Flash Flood Warning | LOT | Boone, McHenry | 4 hr |
| Aug 24, 6:36 PM CDT | Flash Flood Warning | LOT | Cook, DuPage, Lake | 3 hr |
| Aug 25, 7:21 PM CDT | Flash Flood Warning | LOT | Cook, DuPage | 3 hr |
| Aug 25, 9:06 PM CDT | Flash Flood Warning | LOT | DuPage, Kane, Kendall, Will | 5 hr |
| Aug 25, 9:15 PM CDT | Flash Flood Warning | LOT | Cook, Kankakee, Will | 4 hr |
| Aug 26, 2:20 PM CDT | Flash Flood Warning | ILX | Coles, Cumberland, Moultrie, Shelby | 3 hr |
| Aug 26, 2:45 PM CDT | Flash Flood Warning | LSX | Montgomery | 4 hr |
| Aug 26, 2:56 PM CDT | Flash Flood Warning | ILX | Champaign, Douglas, Moultrie, Piatt | 3 hr |
| Aug 27, 6:48 PM CDT | Flash Flood Warning | PAH | Edwards | 61 min |
| Aug 30, 11:37 AM CDT | Flash Flood Warning | ILX | Clay, Richland | 3 hr |
| Aug 30, 2:54 PM CDT | Flash Flood Warning | LSX | Madison, Saint Clair | 3 hr |
| Aug 30, 5:22 PM CDT | Flash Flood Warning | PAH | Perry | 2 hr |
| Aug 31, 2:01 PM CDT | Flash Flood Warning | DVN | Henry, Mercer, Rock Island | 6 hr |
| Aug 31, 3:09 PM CDT | Flash Flood Warning | DVN | Henry, Rock Island | 2 hr |
| Aug 31, 3:49 PM CDT | Flash Flood Warning | DVN | Henry, Mercer | 4 hr |
| Aug 31, 11:37 PM CDT | Flash Flood Warning | LSX | Bond, Fayette, Montgomery | 6 hr |
| Oct 24, 4:58 AM CDT | Flash Flood Warning | LSX | Adams | 2 hr |
| Oct 24, 5:03 AM CDT | Flash Flood Warning | ILX | Morgan, Scott | 3 hr |
| Oct 24, 4:03 PM CDT | Flash Flood Warning | LSX | Adams, Brown | 4 hr |
| Oct 24, 5:00 PM CDT | Flash Flood Warning | ILX | Fulton, Schuyler | 3 hr |
| Oct 24, 5:14 PM CDT | Flash Flood Warning | LSX | Brown, Pike | 4 hr |
| Oct 24, 6:37 PM CDT | Flash Flood Warning | ILX | Cass, Morgan, Scott | 3 hr |
| Oct 24, 7:08 PM CDT | Flash Flood Warning | ILX | McLean, Tazewell, Woodford | 3 hr |
| Oct 24, 7:48 PM CDT | Flash Flood Warning | ILX | McLean, Tazewell | 3 hr |
| Oct 24, 11:34 PM CDT | Flash Flood Warning | PAH | Jackson | 6 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- McLean County10
- Champaign County6
- DeWitt County6
- Franklin County5
- Cook County5
- Will County5
- Perry County5
- Edwards County5
- Coles County4
- Hamilton County4
- White County4
- Douglas County4
- Calhoun County4
- Henry County4
- Adams County4
- Logan County4
- Tazewell County4
- Piatt County4
- DuPage County4
- Grundy County4
- Hancock County4
- Montgomery County4
- Jefferson County4
- Wayne County4
- Jackson County3
- Vermilion County3
- Greene County3
- Jersey County3
- Marshall County3
- Pike County3
- Mason County3
- Morgan County3
- Scott County3
- Woodford County3
- Kankakee County3
- Clay County3
- Wabash County3
- Bond County3
- Moultrie County3
- Williamson County2
50 more counties
- Hardin County2
- Fulton County2
- Knox County2
- Edgar County2
- Stark County2
- Bureau County2
- Menard County2
- Sangamon County2
- Ford County2
- Livingston County2
- Alexander County2
- Massac County2
- Pope County2
- Schuyler County2
- Peoria County2
- Washington County2
- Richland County2
- Saint Clair County2
- Shelby County2
- Madison County2
- Mercer County2
- Rock Island County2
- Brown County2
- Monroe County1
- Saline County1
- Carroll County1
- Gallatin County1
- Clark County1
- Macon County1
- Iroquois County1
- Johnson County1
- Pulaski County1
- Union County1
- McDonough County1
- LaSalle County1
- Randolph County1
- Crawford County1
- Effingham County1
- Jasper County1
- Lawrence County1
- Macoupin County1
- Henderson County1
- Boone County1
- McHenry County1
- Lake County1
- Kane County1
- Kendall County1
- Cumberland County1
- Fayette County1
- Cass County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20202022
Sources
National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.