Alert archive / Illinois / Grundy County
Weather alerts in Grundy County, Illinois, 2023
109 weather alerts in 2023, 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 2023. Tap one for its archive.
- Alerts
- 109
- Warnings
- 22
- Watches
- 17
- Advisories
- 39
- Busiest month
- April22 alerts
- Busiest day
- May 8, 20238 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Grundy County, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 13 | 9 | 31% | 11 | 82% | 20 min |
| Flash flood warnings | 1 | 0 | 100% | 0 |
Each office's whole area, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Chicago, IL: tornado warnings | 32 | 17 | 47% | 68 | 56% | 11 min |
| NWS Chicago, IL: severe thunderstorm warnings | 164 | 106 | 35% | 544 | 84% | 27 min |
| NWS Chicago, IL: flash flood warnings | 19 | 10 | 47% | 42 | 90% | 75 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 1, 5:52 AM CST | Dense Fog Advisory | LOT | 6 hr |
| Jan 1, 5:16 PM CST | Dense Fog Advisory | LOT | 16 hr |
| Jan 2, 9:04 AM CST | Dense Fog Advisory | LOT | 19 hr |
| Jan 3, 9:35 AM CST | Dense Fog Advisory | LOT | 16 hr |
| Jan 19, 8:26 AM CST | Dense Fog Advisory | LOT | 2 hr |
| Jan 24, 1:57 AM CST | Winter Weather Advisory | LOT | 52 hr |
| Jan 27, 2:28 PM CST | Winter Weather Advisory | LOT | 40 hr |
| Jan 30, 12:03 AM CST | Winter Weather Advisory | LOT | 8 hr |
| Feb 2, 2:53 AM CST | Wind Chill Advisory | LOT | 31 hr |
| Feb 8, 2:01 PM CST | Wind Advisory | LOT | 28 hr |
| Feb 14, 4:03 AM CST | Wind Advisory | LOT | 34 hr |
| Feb 15, 3:35 AM CST | Winter Weather Advisory | LOT | 53 hr |
| Feb 22, 1:27 PM CST | Areal Flood Advisory | LOT | 11 hr |
| Feb 23, 4:19 AM CST | Dense Fog Advisory | LOT | 5 hr |
| Feb 27, 9:14 AM CST | Wind Advisory | LOT | 3 hr |
| Feb 27, 9:22 AM CST | Special Weather Statement | LOT | 38 min |
| Feb 27, 9:55 AM CST | Areal Flood Advisory | LOT | 4 hr |
| Mar 2, 2:39 AM CST | Winter Storm Watch | LOT | 18 hr |
| Mar 2, 11:46 AM CST | River Flood Watch | LOT | 21 days |
| Mar 2, 8:38 PM CST | Winter Weather Advisory | LOT | 22 hr |
| Mar 4, 10:24 PM CST | Dense Fog Advisory | LOT | 11 hr |
| Mar 26, 1:41 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Mar 26, 3:23 PM CDT | Severe Thunderstorm Warning | LOT | 52 min |
| Mar 31, 3:06 AM CDT | Wind Advisory | LOT | 37 hr |
| Mar 31, 2:07 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Mar 31, 2:36 PM CDT | Tornado Watch | SPC | 7 hr |
| Mar 31, 3:46 PM CDT | Severe Thunderstorm Warning | LOT | 44 min |
| Mar 31, 3:50 PM CDT | Mesoscale Discussion | SPC | 55 min |
| Mar 31, 4:37 PM CDT | Severe Thunderstorm Warning | LOT | 38 min |
| Mar 31, 6:20 PM CDT | Mesoscale Discussion | SPC | 115 min |
| Mar 31, 7:43 PM CDT | Severe Thunderstorm Warning | LOT | 47 min |
| Mar 31, 7:54 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 4, 10:36 AM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Apr 4, 3:42 PM CDT | Wind Advisory | LOT | 24 hr |
| Apr 5, 3:27 AM CDT | Mesoscale Discussion | SPC | 93 min |
| Apr 5, 3:57 AM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Apr 11, 3:19 AM CDT | Fire Weather Watch | LOT | 23 hr |
| Apr 12, 2:40 AM CDT | Red Flag Warning | LOT | 16 hr |
| Apr 17, 2:43 PM CDT | Freeze Warning | LOT | 17 hr |
| Apr 19, 2:42 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 19, 4:52 PM CDT | Severe Thunderstorm Warning | LOT | 38 min |
| Apr 19, 5:28 PM CDT | Severe Thunderstorm Warning | LOT | 32 min |
| Apr 20, 3:47 AM CDT | Special Weather Statement | LOT | 28 min |
| Apr 20, 1:50 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Apr 20, 2:06 PM CDT | Tornado Watch | SPC | 6 hr |
| Apr 20, 3:41 PM CDT | Mesoscale Discussion | SPC | 94 min |
| Apr 20, 5:23 PM CDT | Mesoscale Discussion | SPC | 97 min |
| Apr 20, 6:06 PM CDT | Severe Thunderstorm Warning | LOT | 54 min |
| Apr 22, 1:56 PM CDT | Freeze Watch | LOT | 13 hr |
| Apr 23, 2:56 AM CDT | Freeze Warning | LOT | 29 hr |
| Apr 25, 1:41 PM CDT | Freeze Warning | LOT | 18 hr |
| Apr 26, 2:28 PM CDT | Frost Advisory | LOT | 17 hr |
| May 7, 6:36 PM CDT | Flood Watch | LOT | 8 hr |
| May 7, 6:40 PM CDT | Mesoscale Discussion | SPC | 65 min |
| May 7, 6:54 PM CDT | Severe Thunderstorm Warning | LOT | 66 min |
| May 7, 6:58 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| May 7, 7:23 PM CDT | Flash Flood Warning | LOT | 5 hr |
| May 7, 8:00 PM CDT | Special Weather Statement | LOT | 30 min |
| May 7, 8:29 PM CDT | Severe Thunderstorm Warning | LOT | 46 min |
| May 7, 8:42 PM CDT | Severe Thunderstorm Warning | LOT | 78 min |
| May 7, 8:45 PM CDT | Mesoscale Discussion | SPC | 90 min |
| May 7, 8:47 PM CDT | Dust Storm Warning | LOT | 58 min |
| May 7, 9:16 PM CDT | Severe Thunderstorm Warning | LOT | 89 min |
| May 7, 10:36 PM CDT | Wind Advisory | LOT | 2 hr |
| Jun 29, 3:08 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 29, 10:34 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 29, 12:41 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 29, 12:54 PM CDT | Severe Thunderstorm Warning | LOT | 44 min |
| Jun 30, 4:27 AM CDT | Dense Fog Advisory | LOT | 5 hr |
| Jul 1, 8:01 PM CDT | Special Weather Statement | LOT | 29 min |
| Jul 5, 12:49 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Jul 5, 5:32 PM CDT | Special Weather Statement | LOT | 28 min |
| Jul 5, 6:14 PM CDT | Special Weather Statement | LOT | 46 min |
| Jul 11, 2:41 PM CDT | Mesoscale Discussion | SPC | 94 min |
| Jul 12, 3:05 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Jul 12, 3:53 PM CDT | Tornado Watch | SPC | 5 hr |
| Jul 14, 2:38 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 3:52 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 14, 8:23 PM CDT | Mesoscale Discussion | SPC | 97 min |
| Jul 26, 3:50 AM CDT | Heat Advisory | LOT | 65 hr |
| Jul 27, 3:05 AM CDT | Excessive Heat Warning | LOT | 42 hr |
| Jul 27, 4:06 AM CDT | Dense Fog Advisory | LOT | 4 hr |
| Jul 28, 2:52 AM CDT | Mesoscale Discussion | SPC | 113 min |
| Jul 28, 7:21 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 28, 7:30 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 28, 7:36 PM CDT | Flood Watch | LOT | 5 hr |
| Jul 28, 10:39 PM CDT | Severe Thunderstorm Warning | LOT | 50 min |
| Aug 4, 5:17 AM CDT | Dense Fog Advisory | LOT | 3 hr |
| Aug 9, 3:46 AM CDT | Dense Fog Advisory | LOT | 4 hr |
| Aug 10, 1:04 AM CDT | Dense Fog Advisory | LOT | 8 hr |
| Aug 14, 11:13 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 14, 5:44 PM CDT | Special Weather Statement | LOT | 16 min |
| Aug 17, 4:41 AM CDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 17, 8:28 AM CDT | Special Weather Statement | LOT | 32 min |
| Aug 19, 2:47 AM CDT | Heat Advisory | LOT | 41 hr |
| Aug 20, 4:12 PM CDT | Heat Advisory | LOT | 52 hr |
| Aug 21, 2:47 AM CDT | Excessive Heat Watch | LOT | 48 hr |
| Aug 22, 2:59 AM CDT | Excessive Heat Warning | LOT | 65 hr |
| Sep 26, 1:20 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Sep 29, 1:34 AM CDT | Dense Fog Advisory | LOT | 7 hr |
| Oct 9, 2:04 PM CDT | Frost Advisory | LOT | 18 hr |
| Oct 10, 2:18 PM CDT | Frost Advisory | LOT | 18 hr |
| Oct 29, 3:24 AM CDT | Freeze Warning | LOT | 30 hr |
| Nov 5, 12:33 AM CDT | Dense Fog Advisory | LOT | 10 hr |
| Nov 25, 2:10 PM CST | Winter Weather Advisory | LOT | 22 hr |
| Dec 22, 11:35 PM CST | Dense Fog Advisory | LOT | 12 hr |
| Dec 23, 3:29 PM CST | Dense Fog Advisory | LOT | 21 hr |
| Dec 30, 6:56 AM CST | Dense Fog Advisory | LOT | 5 hr |
| Dec 30, 6:15 PM CST | Winter Weather Advisory | LOT | 17 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 13 |
| Severe Thunderstorm Watch | 7 |
| Tornado Watch | 3 |
| Mesoscale Discussion | 23 |
| Special Weather Statement | 8 |
| Flooding | |
| Flash Flood Warning | 1 |
| Flood Watch | 2 |
| River Flood Watch | 1 |
| Areal Flood Advisory | 2 |
| Winter | |
| Winter Storm Watch | 1 |
| Winter Weather Advisory | 7 |
| Heat | |
| Excessive Heat Warning | 2 |
| Excessive Heat Watch | 1 |
| Heat Advisory | 3 |
| Cold | |
| Freeze Warning | 4 |
| Freeze Watch | 1 |
| Frost Advisory | 3 |
| Wind Chill Advisory | 1 |
| Wind and dust | |
| Dust Storm Warning | 1 |
| Wind Advisory | 6 |
| Fire | |
| Red Flag Warning | 1 |
| Fire Weather Watch | 1 |
| Fog and smoke | |
| Dense Fog Advisory | 17 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20222024
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.