Alert archive / Illinois / Grundy County
Weather alerts in Grundy County, Illinois, 2009
135 weather alerts in 2009, 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 2009. Tap one for its archive.
- Alerts
- 135
- Warnings
- 36
- Watches
- 27
- Advisories
- 51
- Busiest month
- June26 alerts
- Busiest day
- June 19, 200911 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
0 of 1 tornado warnings covering Grundy County in 2009 had a tornado report inside them.
Grundy County, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 14 | 5 | 64% | 2 | 100% | 9 min |
| Flash flood warnings | 2 | 1 | 50% | 0 |
Each office's whole area, 2009
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Chicago, IL: tornado warnings | 12 | 3 | 75% | 11 | 73% | 11 min |
| NWS Chicago, IL: severe thunderstorm warnings | 97 | 47 | 52% | 183 | 68% | 26 min |
| NWS Chicago, IL: flash flood warnings | 25 | 10 | 60% | 31 | 87% | 80 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 3, 9:25 PM CST | Dense Fog Advisory | LOT | 8 hr |
| Jan 8, 2:53 PM CST | Winter Weather Advisory | LOT | 51 hr |
| Jan 9, 10:05 AM CST | Areal Flood Advisory | LOT | 294 days |
| Jan 11, 10:49 AM CST | Areal Flood Advisory | LOT | 292 days |
| Jan 12, 4:21 AM CST | Blizzard Watch | LOT | 7 hr |
| Jan 12, 4:21 AM CST | Winter Weather Advisory | LOT | 28 hr |
| Jan 12, 11:49 AM CST | Blizzard Warning | LOT | 16 hr |
| Jan 12, 3:40 PM CST | Blizzard Watch | LOT | 19 hr |
| Jan 13, 2:07 PM CST | Wind Chill Watch | LOT | 13 hr |
| Jan 13, 3:02 PM CST | Winter Weather Advisory | LOT | 33 hr |
| Jan 13, 11:38 PM CST | Mesoscale Discussion | SPC | 4 hr |
| Jan 14, 3:23 AM CST | Wind Chill Warning | LOT | 57 hr |
| Jan 14, 6:52 AM CST | Winter Storm Warning | LOT | 17 hr |
| Jan 15, 9:49 AM CST | River Flood Advisory | LOT | 4 days |
| Jan 16, 3:08 PM CST | Wind Chill Advisory | LOT | 9 hr |
| Jan 19, 8:43 AM CST | River Flood Advisory | LOT | 12 hr |
| Jan 22, 8:28 PM CST | River Flood Advisory | LOT | 16 hr |
| Feb 10, 4:00 AM CST | Flood Watch | LOT | 41 hr |
| Feb 11, 1:31 AM CST | Dense Fog Advisory | LOT | 7 hr |
| Feb 11, 11:43 AM CST | River Flood Warning | LOT | 34 hr |
| Feb 13, 4:16 AM CST | River Flood Advisory | LOT | 23 hr |
| Feb 19, 1:38 PM CST | Winter Storm Watch | LOT | 14 hr |
| Feb 20, 3:41 AM CST | Winter Storm Warning | LOT | 34 hr |
| Feb 20, 3:41 AM CST | Winter Weather Advisory | LOT | 41 hr |
| Feb 26, 3:50 AM CST | Dense Fog Advisory | LOT | 11 hr |
| Feb 26, 7:02 PM CST | Areal Flood Advisory | LOT | 110 days |
| Feb 27, 7:09 AM CST | Areal Flood Warning | LOT | 30 hr |
| Feb 27, 11:03 AM CST | River Flood Warning | LOT | 24 hr |
| Mar 6, 3:28 PM CST | Flash Flood Watch | LOT | 48 hr |
| Mar 8, 4:03 AM CDT | Areal Flood Warning | LOT | 30 hr |
| Mar 8, 7:11 AM CDT | Severe Thunderstorm Warning | LOT | 64 min |
| Mar 8, 8:16 AM CDT | Severe Thunderstorm Warning | LOT | 26 min |
| Mar 8, 9:13 AM CDT | Wind Advisory | LOT | 12 hr |
| Mar 8, 10:14 AM CDT | River Flood Warning | LOT | 6 days |
| Mar 8, 12:13 PM CDT | River Flood Warning | LOT | 7 days |
| Mar 8, 1:06 PM CDT | Severe Thunderstorm Warning | LOT | 39 min |
| Mar 9, 3:39 AM CDT | Flash Flood Watch | LOT | 24 hr |
| Mar 10, 2:03 AM CDT | Areal Flood Warning | LOT | 36 hr |
| Mar 10, 3:37 AM CDT | Wind Advisory | LOT | 27 hr |
| Mar 24, 4:08 AM CDT | Wind Advisory | LOT | 16 hr |
| Mar 24, 10:28 PM CDT | Mesoscale Discussion | SPC | 92 min |
| Mar 27, 12:58 PM CDT | Winter Storm Watch | LOT | 19 hr |
| Mar 28, 3:40 AM CDT | Winter Weather Advisory | LOT | 24 hr |
| Apr 5, 10:50 AM CDT | Mesoscale Discussion | SPC | 115 min |
| Apr 6, 10:31 AM CDT | River Flood Advisory | LOT | 53 hr |
| Apr 24, 2:16 AM CDT | Dense Fog Advisory | LOT | 6 hr |
| Apr 25, 5:32 PM CDT | Mesoscale Discussion | SPC | 73 min |
| Apr 26, 2:01 PM CDT | Areal Flood Advisory | LOT | 57 days |
| Apr 27, 9:38 PM CDT | River Flood Warning | LOT | 14 hr |
| Apr 28, 12:44 AM CDT | Areal Flood Advisory | LOT | 55 days |
| Apr 28, 8:44 PM CDT | River Flood Advisory | LOT | 4 days |
| Apr 29, 3:10 PM CDT | Flash Flood Watch | LOT | 20 hr |
| May 7, 4:06 PM CDT | Severe Thunderstorm Warning | LOT | 37 min |
| May 8, 8:35 PM CDT | Mesoscale Discussion | SPC | 85 min |
| May 13, 11:21 AM CDT | River Flood Advisory | LOT | 48 hr |
| May 13, 5:47 PM CDT | Mesoscale Discussion | SPC | 88 min |
| May 13, 5:54 PM CDT | Severe Thunderstorm Warning | LOT | 34 min |
| May 13, 6:02 PM CDT | Tornado Watch | SPC | 5 hr |
| May 13, 8:35 PM CDT | Mesoscale Discussion | SPC | 85 min |
| May 13, 10:17 PM CDT | Mesoscale Discussion | SPC | 58 min |
| May 13, 10:35 PM CDT | Severe Thunderstorm Warning | LOT | 40 min |
| May 13, 10:51 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| May 14, 3:03 PM CDT | River Flood Warning | LOT | 60 hr |
| May 14, 3:34 PM CDT | Flash Flood Watch | LOT | 30 hr |
| May 14, 9:17 PM CDT | River Flood Warning | LOT | 3 days |
| May 15, 2:48 PM CDT | Areal Flood Advisory | LOT | 57 days |
| May 15, 5:46 PM CDT | Flash Flood Warning | LOT | 6 hr |
| May 15, 11:16 PM CDT | Areal Flood Warning | LOT | 12 hr |
| May 16, 11:27 AM CDT | Areal Flood Warning | LOT | 24 hr |
| Jun 1, 1:31 PM CDT | Mesoscale Discussion | SPC | 59 min |
| Jun 1, 2:37 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 1, 6:34 PM CDT | Mesoscale Discussion | SPC | 86 min |
| Jun 8, 11:54 AM CDT | Mesoscale Discussion | SPC | 96 min |
| Jun 8, 1:23 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 8, 3:53 PM CDT | Mesoscale Discussion | SPC | 67 min |
| Jun 11, 5:00 AM CDT | Flash Flood Warning | LOT | 10 hr |
| Jun 18, 10:11 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 18, 11:07 PM CDT | Mesoscale Discussion | SPC | 53 min |
| Jun 18, 11:30 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 19, 2:38 AM CDT | Mesoscale Discussion | SPC | 97 min |
| Jun 19, 7:14 AM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 19, 1:08 PM CDT | Flash Flood Watch | LOT | 8 hr |
| Jun 19, 1:54 PM CDT | Mesoscale Discussion | SPC | 96 min |
| Jun 19, 2:24 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 19, 5:37 PM CDT | Mesoscale Discussion | SPC | 53 min |
| Jun 19, 5:49 PM CDT | Severe Thunderstorm Warning | LOT | 41 min |
| Jun 19, 6:23 PM CDT | Severe Thunderstorm Warning | LOT | 52 min |
| Jun 19, 6:38 PM CDT | Severe Thunderstorm Warning | LOT | 67 min |
| Jun 19, 7:22 PM CDT | Severe Thunderstorm Warning | LOT | 38 min |
| Jun 22, 3:15 PM CDT | Heat Advisory | LOT | 52 hr |
| Jun 25, 10:18 AM CDT | Heat Advisory | LOT | 9 hr |
| Jun 25, 3:57 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 27, 2:41 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 27, 6:22 PM CDT | Mesoscale Discussion | SPC | 113 min |
| Jun 27, 7:12 PM CDT | Severe Thunderstorm Warning | LOT | 32 min |
| Jul 5, 3:58 AM CDT | Dense Fog Advisory | LOT | 5 hr |
| Jul 24, 11:16 PM CDT | Severe Thunderstorm Warning | LOT | 59 min |
| Jul 24, 11:28 PM CDT | Areal Flood Advisory | LOT | 6 hr |
| Jul 27, 11:40 PM CDT | Special Weather Statement | LOT | 95 min |
| Jul 28, 6:21 PM CDT | Special Weather Statement | LOT | 54 min |
| Aug 4, 4:29 AM CDT | Dense Fog Advisory | LOT | 4 hr |
| Aug 8, 4:07 AM CDT | Heat Advisory | LOT | 38 hr |
| Aug 19, 12:49 PM CDT | Tornado Watch | SPC | 6 hr |
| Aug 19, 3:19 PM CDT | Mesoscale Discussion | SPC | 86 min |
| Aug 19, 4:01 PM CDT | Severe Thunderstorm Warning | LOT | 55 min |
| Aug 19, 4:35 PM CDT | Tornado Warning | LOT | 25 min |
| Aug 19, 4:37 PM CDT | Severe Thunderstorm Warning | LOT | 53 min |
| Aug 19, 5:40 PM CDT | Areal Flood Advisory | LOT | 5 hr |
| Aug 26, 1:59 PM CDT | Flash Flood Watch | LOT | 37 hr |
| Aug 27, 8:46 PM CDT | Areal Flood Advisory | LOT | 6 hr |
| Sep 5, 8:08 AM CDT | Dense Fog Advisory | LOT | 3 hr |
| Sep 9, 9:19 PM CDT | Dense Fog Advisory | LOT | 12 hr |
| Sep 12, 4:08 AM CDT | Dense Fog Advisory | LOT | 5 hr |
| Sep 12, 9:43 PM CDT | Dense Fog Advisory | LOT | 11 hr |
| Sep 27, 5:55 AM CDT | Dense Fog Advisory | LOT | 4 hr |
| Sep 27, 5:32 PM CDT | Mesoscale Discussion | SPC | 88 min |
| Sep 27, 8:22 PM CDT | Tornado Watch | SPC | 3 hr |
| Oct 6, 9:09 PM CDT | Wind Advisory | LOT | 5 hr |
| Oct 9, 4:37 AM CDT | Frost Advisory | LOT | 24 hr |
| Oct 9, 4:00 PM CDT | Freeze Warning | LOT | 41 hr |
| Oct 29, 3:13 PM CDT | Flood Watch | LOT | 24 hr |
| Oct 29, 9:29 PM CDT | River Flood Advisory | LOT | 25 hr |
| Oct 30, 10:03 PM CDT | River Flood Warning | LOT | 41 hr |
| Nov 1, 1:43 PM CST | River Flood Advisory | LOT | 31 hr |
| Nov 20, 9:38 PM CST | Dense Fog Advisory | LOT | 10 hr |
| Nov 23, 7:07 AM CST | Dense Fog Advisory | LOT | 3 hr |
| Nov 23, 9:40 PM CST | Dense Fog Advisory | LOT | 11 hr |
| Dec 7, 9:35 PM CST | Winter Weather Advisory | LOT | 50 hr |
| Dec 9, 4:47 AM CST | Wind Advisory | LOT | 13 hr |
| Dec 22, 11:31 AM CST | Winter Storm Watch | LOT | 17 hr |
| Dec 22, 3:35 PM CST | Winter Weather Advisory | LOT | 29 hr |
| Dec 23, 3:45 AM CST | Flood Watch | LOT | 55 hr |
| Dec 24, 12:37 PM CST | River Flood Warning | LOT | 24 hr |
| Dec 25, 2:29 PM CST | River Flood Advisory | LOT | 58 hr |
| Dec 26, 9:33 AM CST | Winter Weather Advisory | LOT | 11 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 archive20082010
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.