Alert archive / Illinois / Stephenson County
Weather alerts in Stephenson County, Illinois, 2021
100 weather alerts in 2021, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Stephenson County and its neighbors
Each county as a circle sized by its count in 2021. Tap one for its archive.
- Alerts
- 100
- Warnings
- 20
- Watches
- 12
- Advisories
- 39
- Busiest month
- August18 alerts
- Busiest day
- July 14, 20217 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Stephenson County, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 11 | 8 | 27% | 4 | 100% | 19 min |
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2021
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Quad Cities, IA: tornado warnings | 30 | 13 | 57% | 29 | 76% | 17 min |
| NWS Quad Cities, IA: severe thunderstorm warnings | 122 | 70 | 43% | 202 | 83% | 23 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 | Lasted |
|---|---|---|---|
| Jan 2, 2:49 PM CST | Dense Fog Advisory | DVN | 21 hr |
| Jan 3, 2:22 PM CST | Dense Fog Advisory | DVN | 28 hr |
| Jan 5, 3:41 PM CST | Dense Fog Advisory | DVN | 18 hr |
| Jan 6, 2:37 PM CST | Dense Fog Advisory | DVN | 13 hr |
| Jan 13, 2:53 PM CST | Winter Weather Advisory | DVN | 44 hr |
| Jan 16, 8:33 PM CST | Winter Weather Advisory | DVN | 15 hr |
| Jan 19, 5:03 PM CST | Winter Weather Advisory | DVN | 4 hr |
| Jan 23, 3:44 PM CST | Winter Storm Watch | DVN | 23 hr |
| Jan 24, 2:43 PM CST | Winter Storm Warning | DVN | 45 hr |
| Jan 29, 2:11 AM CST | Winter Storm Watch | DVN | 12 hr |
| Jan 29, 2:29 PM CST | Winter Storm Warning | DVN | 46 hr |
| Jan 29, 2:29 PM CST | Winter Weather Advisory | DVN | 52 hr |
| Feb 3, 1:04 AM CST | Dense Fog Advisory | DVN | 10 hr |
| Feb 3, 4:01 AM CST | Winter Storm Watch | DVN | 11 hr |
| Feb 3, 4:01 AM CST | Winter Weather Advisory | DVN | 56 hr |
| Feb 3, 2:56 PM CST | Winter Storm Warning | DVN | 36 hr |
| Feb 6, 12:51 AM CST | Wind Chill Advisory | DVN | 9 hr |
| Feb 6, 3:47 AM CST | Wind Chill Warning | DVN | 32 hr |
| Feb 8, 2:48 PM CST | Wind Chill Advisory | DVN | 19 hr |
| Feb 10, 2:30 PM CST | Wind Chill Advisory | DVN | 20 hr |
| Feb 11, 5:07 PM CST | Wind Chill Advisory | DVN | 43 hr |
| Feb 13, 3:37 AM CST | Wind Chill Warning | DVN | 56 hr |
| Feb 15, 12:29 AM CST | Wind Chill Advisory | DVN | 12 hr |
| Feb 20, 2:35 PM CST | Winter Weather Advisory | DVN | 30 hr |
| Feb 28, 6:13 AM CST | Dense Fog Advisory | DVN | 6 hr |
| Mar 10, 2:52 AM CST | Wind Advisory | DVN | 17 hr |
| Mar 14, 3:53 AM CDT | Winter Weather Advisory | DVN | 39 hr |
| Mar 17, 2:28 PM CDT | Wind Advisory | DVN | 29 hr |
| Mar 28, 2:41 PM CDT | Wind Advisory | DVN | 29 hr |
| Mar 28, 2:55 PM CDT | Red Flag Warning | DVN | 29 hr |
| Apr 19, 3:41 AM CDT | Freeze Watch | DVN | 10 hr |
| Apr 19, 2:07 PM CDT | Freeze Warning | DVN | 43 hr |
| Apr 19, 11:47 PM CDT | Frost Advisory | DVN | 8 hr |
| Apr 21, 3:07 AM CDT | Freeze Warning | DVN | 30 hr |
| Apr 24, 2:25 PM CDT | Frost Advisory | DVN | 18 hr |
| Apr 29, 4:58 PM CDT | Special Weather Statement | DVN | 32 min |
| May 1, 3:26 AM CDT | Wind Advisory | DVN | 16 hr |
| May 7, 1:48 PM CDT | Frost Advisory | DVN | 18 hr |
| May 10, 2:28 PM CDT | Frost Advisory | DVN | 18 hr |
| May 11, 2:26 PM CDT | Frost Advisory | DVN | 17 hr |
| May 28, 3:30 AM CDT | Frost Advisory | DVN | 28 hr |
| Jun 11, 2:38 PM CDT | Special Weather Statement | DVN | 52 min |
| Jun 18, 2:21 AM CDT | Special Weather Statement | DVN | 24 min |
| Jun 20, 8:10 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 20, 8:53 PM CDT | Severe Thunderstorm Warning | DVN | 67 min |
| Jun 20, 9:54 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Jun 25, 2:34 PM CDT | Special Weather Statement | DVN | 41 min |
| Jun 28, 3:19 AM CDT | Flash Flood Watch | DVN | 38 hr |
| Jul 14, 7:02 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 11:45 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 1:13 PM CDT | Special Weather Statement | DVN | 32 min |
| Jul 14, 2:01 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Jul 14, 2:03 PM CDT | Special Weather Statement | DVN | 42 min |
| Jul 14, 5:42 PM CDT | Mesoscale Discussion | SPC | 63 min |
| Jul 14, 6:13 PM CDT | Tornado Watch | SPC | 6 hr |
| Jul 14, 9:15 PM CDT | Mesoscale Discussion | SPC | 90 min |
| Jul 14, 11:17 PM CDT | Mesoscale Discussion | SPC | 58 min |
| Jul 14, 11:41 PM CDT | Severe Thunderstorm Warning | DVN | 34 min |
| Jul 15, 12:05 AM CDT | Severe Thunderstorm Warning | DVN | 25 min |
| Jul 27, 3:12 AM CDT | Heat Advisory | DVN | 64 hr |
| Jul 28, 3:17 AM CDT | Special Weather Statement | DVN | 43 min |
| Jul 29, 12:32 AM CDT | Mesoscale Discussion | SPC | 88 min |
| Jul 29, 1:00 AM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 29, 1:30 AM CDT | Severe Thunderstorm Warning | DVN | 60 min |
| Jul 29, 2:35 AM CDT | Special Weather Statement | DVN | 55 min |
| Aug 8, 2:24 PM CDT | Heat Advisory | DVN | 53 hr |
| Aug 9, 4:59 AM CDT | Special Weather Statement | DVN | 31 min |
| Aug 9, 7:08 AM CDT | Special Weather Statement | DVN | 22 min |
| Aug 9, 7:38 AM CDT | Special Weather Statement | DVN | 22 min |
| Aug 10, 2:28 PM CDT | Heat Advisory | DVN | 29 hr |
| Aug 10, 3:10 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 10, 3:47 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 10, 5:24 PM CDT | Severe Thunderstorm Warning | DVN | 51 min |
| Aug 10, 5:49 PM CDT | Severe Thunderstorm Warning | DVN | 41 min |
| Aug 10, 5:51 PM CDT | Mesoscale Discussion | SPC | 84 min |
| Aug 10, 6:16 PM CDT | Severe Thunderstorm Warning | DVN | 13 min |
| Aug 11, 5:40 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Aug 11, 7:35 PM CDT | Mesoscale Discussion | SPC | 85 min |
| Aug 24, 1:52 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Aug 24, 3:09 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Aug 24, 4:17 PM CDT | Severe Thunderstorm Warning | DVN | 58 min |
| Aug 24, 5:01 PM CDT | Severe Thunderstorm Warning | DVN | 59 min |
| Aug 24, 5:10 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 7, 12:25 PM CDT | Mesoscale Discussion | SPC | 65 min |
| Oct 8, 3:52 AM CDT | Dense Fog Advisory | DVN | 5 hr |
| Oct 8, 9:43 PM CDT | Dense Fog Advisory | DVN | 10 hr |
| Oct 11, 12:37 PM CDT | Mesoscale Discussion | SPC | 113 min |
| Oct 20, 4:54 PM CDT | Special Weather Statement | DVN | 36 min |
| Oct 22, 2:22 PM CDT | Frost Advisory | DVN | 19 hr |
| Nov 27, 8:16 AM CST | Winter Weather Advisory | DVN | 2 hr |
| Dec 5, 3:06 AM CST | Wind Advisory | DVN | 33 hr |
| Dec 13, 2:36 PM CST | High Wind Watch | DVN | 24 hr |
| Dec 14, 2:33 PM CST | High Wind Warning | DVN | 39 hr |
| Dec 15, 5:30 PM CST | Tornado Watch | SPC | 6 hr |
| Dec 15, 9:45 PM CST | Severe Thunderstorm Warning | DVN | 60 min |
| Dec 15, 10:17 PM CST | Severe Thunderstorm Warning | DVN | 31 min |
| Dec 27, 2:57 PM CST | Winter Weather Advisory | DVN | 27 hr |
| Dec 28, 8:59 AM CST | Mesoscale Discussion | SPC | 5 hr |
| Dec 30, 7:17 PM CST | Dense Fog Advisory | DVN | 23 hr |
| Dec 31, 11:01 AM CST | Winter Weather Advisory | DVN | 10 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 | 11 |
| Severe Thunderstorm Watch | 4 |
| Tornado Watch | 2 |
| Mesoscale Discussion | 17 |
| Special Weather Statement | 12 |
| Flooding | |
| Flash Flood Watch | 1 |
| Winter | |
| Winter Storm Warning | 3 |
| Winter Storm Watch | 3 |
| Winter Weather Advisory | 10 |
| Heat | |
| Heat Advisory | 3 |
| Cold | |
| Freeze Warning | 2 |
| Wind Chill Warning | 2 |
| Freeze Watch | 1 |
| Frost Advisory | 7 |
| Wind Chill Advisory | 5 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Wind Advisory | 5 |
| Fire | |
| Red Flag Warning | 1 |
| Fog and smoke | |
| Dense Fog Advisory | 9 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe 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.