Alert archive / Illinois / Grundy County
Weather alerts in Grundy County, Illinois, 2024
128 weather alerts in 2024, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Grundy County and its neighbors
Each county as a circle sized by its count in 2024. Tap one for its archive.
- Alerts
- 128
- Warnings
- 23
- Watches
- 24
- Advisories
- 36
- Busiest month
- January26 alerts
- Busiest day
- July 15, 202410 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
1 of 1 tornado warnings covering Grundy County in 2024 had a tornado report inside them; 1 of 1 tornado reports fell inside a warning, on average 1 minutes after it went out.
Grundy County, 2024
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 1 | 0% | 1 | 100% | 1 min |
| Severe thunderstorm warnings | 8 | 6 | 25% | 7 | 86% | 28 min |
| Flash flood warnings | 2 | 0 | 100% | 0 |
Each office's whole area, 2024
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Chicago, IL: tornado warnings | 34 | 20 | 41% | 58 | 69% | 17 min |
| NWS Chicago, IL: severe thunderstorm warnings | 155 | 88 | 43% | 549 | 79% | 30 min |
| NWS Chicago, IL: flash flood warnings | 22 | 6 | 73% | 72 | 72% | 85 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 | Lasted |
|---|---|---|---|
| Jan 8, 3:00 AM CST | Winter Weather Advisory | LOT | 47 hr |
| Jan 10, 2:18 PM CST | Winter Storm Watch | LOT | 24 hr |
| Jan 11, 2:22 PM CST | Winter Storm Warning | LOT | 37 hr |
| Jan 11, 2:22 PM CST | Winter Weather Advisory | LOT | 46 hr |
| Jan 12, 4:23 AM CST | Mesoscale Discussion | SPC | 4 hr |
| Jan 12, 9:31 AM CST | Winter Weather Advisory | LOT | 26 hr |
| Jan 13, 3:29 AM CST | Wind Chill Advisory | LOT | 4 days |
| Jan 13, 2:17 PM CST | Wind Chill Warning | LOT | 70 hr |
| Jan 13, 2:17 PM CST | Winter Weather Advisory | LOT | 20 hr |
| Jan 15, 1:44 PM CST | Areal Flood Warning | LOT | 7 days |
| Jan 16, 12:17 PM CST | Flash Flood Watch | LOT | 72 hr |
| Jan 18, 3:41 AM CST | Winter Weather Advisory | LOT | 26 hr |
| Jan 19, 3:28 AM CST | Wind Chill Advisory | LOT | 30 hr |
| Jan 20, 2:44 AM CST | Wind Chill Advisory | LOT | 31 hr |
| Jan 21, 2:42 PM CST | Winter Weather Advisory | LOT | 42 hr |
| Jan 22, 9:17 AM CST | Mesoscale Discussion | SPC | 4 hr |
| Jan 22, 1:05 PM CST | Areal Flood Warning | LOT | 5 days |
| Jan 23, 1:57 PM CST | Dense Fog Advisory | LOT | 22 hr |
| Jan 23, 2:04 PM CST | Flood Watch | LOT | 4 days |
| Jan 24, 2:57 PM CST | Dense Fog Advisory | LOT | 30 hr |
| Jan 25, 9:29 AM CST | Flash Flood Warning | LOT | 39 hr |
| Jan 26, 8:39 AM CST | Dense Fog Advisory | LOT | 5 hr |
| Jan 26, 12:03 PM CST | River Flood Warning | LOT | 72 hr |
| Jan 26, 1:22 PM CST | Dense Fog Advisory | LOT | 33 hr |
| Jan 26, 8:15 PM CST | Flash Flood Warning | LOT | 4 hr |
| Jan 28, 10:57 AM CST | River Flood Warning | LOT | 34 hr |
| Feb 6, 1:34 AM CST | Dense Fog Advisory | LOT | 10 hr |
| Feb 6, 9:08 PM CST | Dense Fog Advisory | LOT | 12 hr |
| Feb 26, 3:05 AM CST | Red Flag Warning | LOT | 15 hr |
| Feb 27, 2:35 PM CST | Wind Advisory | LOT | 15 hr |
| Feb 27, 2:50 PM CST | Mesoscale Discussion | SPC | 115 min |
| Feb 27, 3:53 PM CST | Tornado Watch | SPC | 6 hr |
| Feb 27, 5:59 PM CST | Mesoscale Discussion | SPC | 91 min |
| Mar 3, 2:13 PM CST | Wind Advisory | LOT | 4 hr |
| Mar 4, 1:25 PM CST | Mesoscale Discussion | SPC | 2 hr |
| Mar 5, 1:38 AM CST | Areal Flood Advisory | LOT | 4 hr |
| Mar 14, 1:39 AM CDT | Special Weather Statement | LOT | 51 min |
| Mar 14, 3:15 AM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Mar 29, 8:52 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Apr 1, 5:41 PM CDT | Special Weather Statement | LOT | 19 min |
| Apr 1, 6:29 PM CDT | Areal Flood Advisory | LOT | 3 hr |
| Apr 1, 9:11 PM CDT | River Flood Watch | LOT | 25 hr |
| Apr 16, 3:40 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Apr 16, 6:32 PM CDT | Special Weather Statement | LOT | 13 min |
| Apr 20, 2:41 PM CDT | Freeze Warning | LOT | 17 hr |
| Apr 21, 2:29 PM CDT | Frost Advisory | LOT | 18 hr |
| Apr 24, 2:58 PM CDT | Frost Advisory | LOT | 17 hr |
| Apr 27, 7:58 PM CDT | Mesoscale Discussion | SPC | 62 min |
| May 2, 3:07 PM CDT | Mesoscale Discussion | SPC | 113 min |
| May 2, 8:31 PM CDT | Special Weather Statement | LOT | 14 min |
| May 4, 1:56 PM CDT | Mesoscale Discussion | SPC | 94 min |
| May 4, 6:13 PM CDT | Special Weather Statement | LOT | 32 min |
| May 7, 7:32 AM CDT | Special Weather Statement | LOT | 43 min |
| May 7, 12:14 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 7, 1:22 PM CDT | Severe Thunderstorm Warning | LOT | 38 min |
| May 7, 1:28 PM CDT | Tornado Watch | SPC | 12 hr |
| May 7, 7:57 PM CDT | Special Weather Statement | LOT | 33 min |
| May 9, 5:41 AM CDT | Special Weather Statement | LOT | 64 min |
| May 13, 1:01 PM CDT | Special Weather Statement | LOT | 44 min |
| May 13, 1:47 PM CDT | Areal Flood Advisory | LOT | 43 min |
| May 13, 2:29 PM CDT | Areal Flood Advisory | LOT | 109 min |
| May 13, 6:06 PM CDT | Areal Flood Advisory | LOT | 3 hr |
| May 17, 2:42 AM CDT | Dense Fog Advisory | LOT | 6 hr |
| May 20, 10:13 AM CDT | Mesoscale Discussion | SPC | 92 min |
| May 20, 6:41 PM CDT | Special Weather Statement | LOT | 34 min |
| May 21, 10:20 PM CDT | Wind Advisory | LOT | 6 hr |
| May 24, 6:07 AM CDT | Severe Thunderstorm Watch | SPC | 9 hr |
| May 24, 11:09 AM CDT | Severe Thunderstorm Warning | LOT | 51 min |
| May 24, 11:31 AM CDT | Severe Thunderstorm Warning | LOT | 59 min |
| May 24, 4:46 PM CDT | Mesoscale Discussion | SPC | 119 min |
| May 27, 5:10 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 5, 1:02 AM CDT | Areal Flood Advisory | LOT | 4 hr |
| Jun 13, 1:02 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Jun 13, 1:50 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 13, 4:46 PM CDT | Mesoscale Discussion | SPC | 89 min |
| Jun 13, 9:33 PM CDT | Special Weather Statement | LOT | 27 min |
| Jun 16, 2:15 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 16, 3:42 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 16, 4:39 PM CDT | Dust Storm Advisory | LOT | 66 min |
| Jun 16, 5:04 PM CDT | Severe Thunderstorm Warning | LOT | 41 min |
| Jun 22, 6:55 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 22, 7:36 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 22, 7:37 PM CDT | Flood Watch | LOT | 5 hr |
| Jun 22, 10:43 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 24, 11:52 PM CDT | Severe Thunderstorm Warning | LOT | 53 min |
| Jun 25, 5:00 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 25, 6:28 AM CDT | Mesoscale Discussion | SPC | 92 min |
| Jun 25, 8:29 AM CDT | Special Weather Statement | LOT | 31 min |
| Jun 25, 4:52 PM CDT | Flood Watch | LOT | 4 hr |
| Jul 9, 2:20 AM CDT | Flood Watch | LOT | 30 hr |
| Jul 10, 7:28 PM CDT | Areal Flood Advisory | LOT | 3 hr |
| Jul 14, 7:55 AM CDT | Special Weather Statement | LOT | 50 min |
| Jul 14, 3:03 PM CDT | Flood Watch | LOT | 11 hr |
| Jul 14, 3:15 PM CDT | Mesoscale Discussion | SPC | 90 min |
| Jul 14, 5:55 PM CDT | Severe Thunderstorm Watch | SPC | 9 hr |
| Jul 14, 7:51 PM CDT | Mesoscale Discussion | SPC | 84 min |
| Jul 14, 10:52 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Jul 14, 11:10 PM CDT | Severe Thunderstorm Warning | LOT | 80 min |
| Jul 15, 12:28 AM CDT | Severe Thunderstorm Warning | LOT | 48 min |
| Jul 15, 12:54 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 4:07 AM CDT | Heat Advisory | LOT | 15 hr |
| Jul 15, 12:52 PM CDT | Flood Watch | LOT | 14 hr |
| Jul 15, 1:59 PM CDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 15, 6:06 PM CDT | Mesoscale Discussion | SPC | 114 min |
| Jul 15, 6:53 PM CDT | Tornado Watch | SPC | 6 hr |
| Jul 15, 8:26 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 8:43 PM CDT | Severe Thunderstorm Warning | LOT | 62 min |
| Jul 15, 9:13 PM CDT | Tornado Warning | LOT | 47 min |
| Aug 5, 5:09 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Aug 5, 5:52 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Aug 16, 12:33 AM CDT | Special Weather Statement | LOT | 42 min |
| Aug 16, 1:19 AM CDT | Mesoscale Discussion | SPC | 116 min |
| Aug 24, 2:32 PM CDT | Excessive Heat Watch | LOT | 48 hr |
| Aug 25, 3:35 AM CDT | Heat Advisory | LOT | 40 hr |
| Aug 25, 2:13 PM CDT | Excessive Heat Warning | LOT | 54 hr |
| Aug 27, 4:47 PM CDT | Mesoscale Discussion | SPC | 88 min |
| Aug 27, 5:09 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 27, 9:39 PM CDT | Mesoscale Discussion | SPC | 96 min |
| Oct 14, 1:24 PM CDT | Freeze Watch | LOT | 14 hr |
| Oct 15, 3:29 AM CDT | Freeze Warning | LOT | 30 hr |
| Oct 16, 1:54 PM CDT | Freeze Warning | LOT | 19 hr |
| Oct 28, 1:59 PM CDT | Fire Weather Watch | LOT | 13 hr |
| Oct 29, 2:43 AM CDT | Red Flag Warning | LOT | 18 hr |
| Nov 4, 1:57 PM CST | Wind Advisory | LOT | 22 hr |
| Nov 21, 3:59 AM CST | Wind Advisory | LOT | 10 hr |
| Dec 4, 2:19 AM CST | Wind Advisory | LOT | 22 hr |
| Dec 15, 2:48 AM CST | Dense Fog Advisory | LOT | 9 hr |
| Dec 15, 3:12 PM CST | Dense Fog Advisory | LOT | 20 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20232025
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.