Alert archive / Illinois / Grundy County
Weather alerts in Grundy County, Illinois, 2018
110 weather alerts in 2018, 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 2018. Tap one for its archive.
- Alerts
- 110
- Warnings
- 16
- Watches
- 17
- Advisories
- 47
- Busiest month
- February21 alerts
- Busiest day
- February 20, 20186 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, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 1 | 0 | 100% | 0 | ||
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Chicago, IL: tornado warnings | 3 | 1 | 67% | 9 | 33% | 0 min |
| NWS Chicago, IL: severe thunderstorm warnings | 74 | 38 | 49% | 157 | 60% | 22 min |
| NWS Chicago, IL: flash flood warnings | 12 | 8 | 33% | 32 | 69% | 74 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, 2:10 PM CST | Wind Chill Warning | LOT | 22 hr |
| Jan 3, 2:57 AM CST | Wind Chill Advisory | LOT | 33 hr |
| Jan 4, 2:48 PM CST | Wind Chill Advisory | LOT | 19 hr |
| Jan 5, 2:46 PM CST | Wind Chill Advisory | LOT | 19 hr |
| Jan 7, 2:53 AM CST | Winter Weather Advisory | LOT | 27 hr |
| Jan 7, 1:49 PM CST | Mesoscale Discussion | SPC | 4 hr |
| Jan 7, 2:00 PM CST | Mesoscale Discussion | SPC | 4 hr |
| Jan 7, 6:16 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Jan 8, 9:53 PM CST | Dense Fog Advisory | LOT | 14 hr |
| Jan 10, 8:56 AM CST | Dense Fog Advisory | LOT | 10 hr |
| Jan 11, 3:58 AM CST | Winter Weather Advisory | LOT | 32 hr |
| Jan 14, 1:45 PM CST | Winter Weather Advisory | LOT | 25 hr |
| Jan 21, 3:52 AM CST | Dense Fog Advisory | LOT | 26 hr |
| Jan 22, 4:14 AM CST | Areal Flood Advisory | LOT | 5 hr |
| Jan 24, 4:49 AM CST | Winter Weather Advisory | LOT | 7 hr |
| Feb 4, 2:44 PM CST | Winter Weather Advisory | LOT | 33 hr |
| Feb 5, 4:57 PM CST | Mesoscale Discussion | SPC | 4 hr |
| Feb 7, 3:32 AM CST | Winter Storm Watch | LOT | 23 hr |
| Feb 8, 2:54 AM CST | Winter Storm Warning | LOT | 42 hr |
| Feb 9, 2:27 AM CST | Winter Weather Advisory | LOT | 10 hr |
| Feb 10, 2:37 PM CST | Winter Weather Advisory | LOT | 21 hr |
| Feb 14, 5:14 PM CST | Dense Fog Advisory | LOT | 25 hr |
| Feb 18, 3:36 AM CST | Dense Fog Advisory | LOT | 6 hr |
| Feb 18, 8:00 PM CST | Flood Watch | LOT | 55 hr |
| Feb 18, 9:41 PM CST | River Flood Watch | LOT | 6 days |
| Feb 19, 10:40 AM CST | River Flood Watch | LOT | 6 days |
| Feb 19, 11:30 AM CST | River Flood Warning | LOT | 8 days |
| Feb 19, 10:21 PM CST | River Flood Warning | LOT | 8 days |
| Feb 19, 10:44 PM CST | Areal Flood Warning | LOT | 12 hr |
| Feb 20, 3:17 AM CST | River Flood Advisory | LOT | 36 hr |
| Feb 20, 10:45 AM CST | Areal Flood Warning | LOT | 24 hr |
| Feb 20, 12:44 PM CST | River Flood Warning | LOT | 47 hr |
| Feb 20, 3:31 PM CST | Winter Weather Advisory | LOT | 15 hr |
| Feb 20, 9:18 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Feb 28, 10:37 AM CST | River Flood Advisory | LOT | 4 days |
| Feb 28, 11:37 AM CST | River Flood Advisory | LOT | 6 days |
| Mar 16, 3:07 AM CDT | Winter Weather Advisory | LOT | 29 hr |
| Mar 22, 4:00 AM CDT | Winter Storm Watch | LOT | 34 hr |
| Mar 23, 3:43 AM CDT | Winter Storm Warning | LOT | 41 hr |
| Mar 31, 5:38 AM CDT | Wind Advisory | LOT | 11 hr |
| Apr 29, 8:55 PM CDT | Red Flag Warning | LOT | 23 hr |
| Apr 30, 4:35 PM CDT | Red Flag Warning | LOT | 26 hr |
| May 2, 1:33 PM CDT | Mesoscale Discussion | SPC | 117 min |
| May 2, 3:56 PM CDT | Severe Thunderstorm Watch | SPC | 9 hr |
| May 2, 7:21 PM CDT | Mesoscale Discussion | SPC | 84 min |
| May 2, 8:51 PM CDT | Flash Flood Watch | LOT | 11 hr |
| May 2, 10:01 PM CDT | Mesoscale Discussion | SPC | 89 min |
| May 2, 10:51 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| May 3, 1:57 AM CDT | Mesoscale Discussion | SPC | 93 min |
| May 9, 3:50 PM CDT | Mesoscale Discussion | SPC | 85 min |
| May 12, 12:34 PM CDT | Flash Flood Watch | LOT | 15 hr |
| May 14, 2:37 PM CDT | Mesoscale Discussion | SPC | 53 min |
| May 14, 2:54 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 14, 6:36 PM CDT | Mesoscale Discussion | SPC | 84 min |
| May 14, 10:07 PM CDT | Special Weather Statement | LOT | 23 min |
| May 21, 9:52 PM CDT | Dense Fog Advisory | LOT | 12 hr |
| May 30, 3:47 PM CDT | Areal Flood Warning | LOT | 3 hr |
| May 31, 2:42 PM CDT | Special Weather Statement | LOT | 33 min |
| Jun 2, 6:55 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 10, 2:35 AM CDT | Areal Flood Advisory | LOT | 3 hr |
| Jun 10, 9:30 AM CDT | River Flood Advisory | LOT | 37 hr |
| Jun 16, 9:21 AM CDT | Heat Advisory | LOT | 58 hr |
| Jun 19, 4:50 PM CDT | Severe Thunderstorm Warning | LOT | 25 min |
| Jun 21, 3:28 AM CDT | Flash Flood Watch | LOT | 34 hr |
| Jun 21, 7:46 AM CDT | Areal Flood Advisory | LOT | 4 hr |
| Jun 21, 10:20 AM CDT | River Flood Advisory | LOT | 48 hr |
| Jun 21, 6:19 PM CDT | Areal Flood Advisory | LOT | 3 hr |
| Jun 21, 10:05 PM CDT | River Flood Advisory | LOT | 60 hr |
| Jun 22, 1:04 AM CDT | Areal Flood Advisory | LOT | 6 hr |
| Jun 26, 5:45 PM CDT | Special Weather Statement | LOT | 60 min |
| Jun 27, 3:09 PM CDT | Excessive Heat Watch | LOT | 36 hr |
| Jun 28, 2:44 PM CDT | Excessive Heat Warning | LOT | 3 days |
| Jul 1, 12:23 PM CDT | Mesoscale Discussion | SPC | 97 min |
| Jul 1, 12:58 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 1, 3:37 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Jul 3, 2:38 PM CDT | Heat Advisory | LOT | 49 hr |
| Aug 19, 4:21 AM CDT | Dense Fog Advisory | LOT | 5 hr |
| Aug 20, 4:46 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Aug 25, 5:15 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 26, 3:07 AM CDT | Dense Fog Advisory | LOT | 6 hr |
| Aug 26, 3:07 AM CDT | Heat Advisory | LOT | 16 hr |
| Aug 26, 2:56 PM CDT | Heat Advisory | LOT | 28 hr |
| Aug 28, 3:42 PM CDT | Mesoscale Discussion | SPC | 93 min |
| Aug 28, 7:05 PM CDT | Mesoscale Discussion | SPC | 55 min |
| Aug 28, 7:37 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Aug 28, 8:04 PM CDT | Flash Flood Watch | LOT | 8 hr |
| Aug 28, 8:39 PM CDT | Special Weather Statement | LOT | 66 min |
| Aug 28, 9:54 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Aug 29, 5:56 AM CDT | Special Weather Statement | LOT | 64 min |
| Aug 31, 6:35 PM CDT | Areal Flood Advisory | LOT | 3 hr |
| Sep 3, 1:20 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 3, 3:07 PM CDT | Special Weather Statement | LOT | 38 min |
| Sep 11, 4:36 AM CDT | Dense Fog Advisory | LOT | 4 hr |
| Sep 25, 1:36 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 25, 3:39 PM CDT | Mesoscale Discussion | SPC | 96 min |
| Sep 25, 5:35 PM CDT | Special Weather Statement | LOT | 55 min |
| Oct 11, 3:23 AM CDT | Frost Advisory | LOT | 28 hr |
| Oct 12, 2:37 PM CDT | Frost Advisory | LOT | 18 hr |
| Oct 15, 1:14 PM CDT | Freeze Warning | LOT | 19 hr |
| Oct 20, 9:47 AM CDT | Wind Advisory | LOT | 8 hr |
| Oct 27, 2:36 PM CDT | Wind Advisory | LOT | 27 hr |
| Nov 23, 2:16 PM CST | Winter Storm Watch | LOT | 23 hr |
| Nov 24, 1:44 PM CST | Winter Storm Warning | LOT | 43 hr |
| Nov 25, 11:37 AM CST | Blizzard Warning | LOT | 18 hr |
| Nov 25, 6:54 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Dec 4, 7:49 PM CST | Winter Weather Advisory | LOT | 7 hr |
| Dec 9, 9:45 PM CST | Dense Fog Advisory | LOT | 16 hr |
| Dec 14, 4:10 PM CST | Dense Fog Advisory | LOT | 18 hr |
| Dec 16, 12:54 AM CST | Dense Fog Advisory | LOT | 9 hr |
| Dec 27, 12:22 PM CST | Wind Advisory | LOT | 4 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 archive20172019
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.