Alert archive / Illinois / Stephenson County
Weather alerts in Stephenson County, Illinois, 2011
100 weather alerts in 2011, 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 2011. Tap one for its archive.
- Alerts
- 100
- Warnings
- 20
- Watches
- 16
- Advisories
- 23
- Busiest month
- July26 alerts
- Busiest day
- July 28, 20119 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 2 tornado warnings covering Stephenson County in 2011 had a tornado report inside them; 1 of 1 tornado reports fell inside a warning, on average 4 minutes after it went out.
Stephenson County, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 2 | 1 | 50% | 1 | 100% | 4 min |
| Severe thunderstorm warnings | 10 | 7 | 30% | 14 | 50% | 25 min |
| Flash flood warnings | 2 | 2 | 0% | 8 | 88% | 103 min |
Each office's whole area, 2011
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Quad Cities, IA: tornado warnings | 15 | 7 | 53% | 14 | 71% | 15 min |
| NWS Quad Cities, IA: severe thunderstorm warnings | 157 | 110 | 30% | 411 | 81% | 27 min |
| NWS Quad Cities, IA: flash flood warnings | 30 | 23 | 23% | 69 | 77% | 164 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 16, 3:50 PM CST | Winter Weather Advisory | DVN | 28 hr |
| Jan 20, 3:02 AM CST | Wind Chill Advisory | DVN | 31 hr |
| Jan 30, 3:40 AM CST | Winter Storm Watch | DVN | 37 hr |
| Jan 30, 3:55 PM CST | Winter Weather Advisory | DVN | 24 hr |
| Jan 31, 4:12 PM CST | Blizzard Warning | DVN | 44 hr |
| Feb 1, 3:36 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Feb 2, 3:38 PM CST | Wind Chill Advisory | DVN | 19 hr |
| Feb 7, 3:31 PM CST | Wind Chill Advisory | DVN | 20 hr |
| Feb 8, 3:37 PM CST | Wind Chill Advisory | DVN | 18 hr |
| Feb 9, 2:41 PM CST | Wind Chill Advisory | DVN | 19 hr |
| Feb 16, 5:00 AM CST | Dense Fog Advisory | DVN | 8 hr |
| Feb 16, 8:25 PM CST | Dense Fog Advisory | DVN | 6 hr |
| Feb 19, 4:07 PM CST | Winter Weather Advisory | DVN | 17 hr |
| Feb 20, 4:35 AM CST | Mesoscale Discussion | SPC | 6 hr |
| Feb 27, 8:49 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Mar 20, 2:06 PM CDT | Severe Thunderstorm Warning | DVN | 23 min |
| Mar 22, 10:59 PM CDT | Special Weather Statement | DVN | 61 min |
| Apr 3, 4:49 PM CDT | Mesoscale Discussion | SPC | 56 min |
| Apr 3, 5:57 PM CDT | Tornado Watch | SPC | 6 hr |
| Apr 3, 7:44 PM CDT | Mesoscale Discussion | SPC | 61 min |
| Apr 3, 8:07 PM CDT | Severe Thunderstorm Warning | DVN | 29 min |
| Apr 3, 10:23 PM CDT | Mesoscale Discussion | SPC | 67 min |
| Apr 10, 3:55 AM CDT | Wind Advisory | DVN | 12 hr |
| Apr 10, 1:30 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 10, 6:05 PM CDT | Tornado Watch | SPC | 7 hr |
| Apr 10, 8:50 PM CDT | Severe Thunderstorm Warning | DVN | 55 min |
| Apr 15, 4:30 AM CDT | Wind Advisory | DVN | 15 hr |
| Apr 19, 4:29 PM CDT | Special Weather Statement | DVN | 61 min |
| Apr 28, 3:27 AM CDT | Frost Advisory | DVN | 29 hr |
| May 2, 3:33 PM CDT | Frost Advisory | DVN | 15 hr |
| May 3, 3:15 PM CDT | Freeze Warning | DVN | 16 hr |
| May 11, 12:55 PM CDT | Mesoscale Discussion | SPC | 65 min |
| May 11, 1:23 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 11, 3:38 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 16, 2:57 PM CDT | Frost Advisory | DVN | 16 hr |
| May 22, 4:41 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 22, 10:53 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 22, 12:51 PM CDT | Tornado Watch | SPC | 10 hr |
| May 22, 5:28 PM CDT | Severe Thunderstorm Warning | DVN | 62 min |
| May 22, 5:47 PM CDT | Mesoscale Discussion | SPC | 88 min |
| May 22, 6:12 PM CDT | Severe Thunderstorm Warning | DVN | 63 min |
| May 29, 5:05 AM CDT | Dense Fog Advisory | DVN | 4 hr |
| May 29, 8:39 AM CDT | Mesoscale Discussion | SPC | 66 min |
| May 29, 8:53 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 8, 9:15 AM CDT | Special Weather Statement | DVN | 60 min |
| Jun 8, 3:36 PM CDT | Mesoscale Discussion | SPC | 84 min |
| Jun 8, 4:49 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 8, 8:43 PM CDT | Mesoscale Discussion | SPC | 92 min |
| Jun 8, 9:06 PM CDT | Severe Thunderstorm Warning | DVN | 39 min |
| Jun 8, 9:32 PM CDT | Severe Thunderstorm Warning | DVN | 43 min |
| Jun 9, 1:44 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 9, 3:12 AM CDT | Flash Flood Watch | DVN | 28 hr |
| Jun 19, 10:20 AM CDT | Special Weather Statement | DVN | 70 min |
| Jun 21, 11:45 AM CDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 21, 5:42 PM CDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Jun 29, 3:18 PM CDT | Excessive Heat Watch | DVN | 13 hr |
| Jun 30, 3:55 AM CDT | Heat Advisory | DVN | 44 hr |
| Jul 6, 5:15 PM CDT | Special Weather Statement | DVN | 105 min |
| Jul 10, 2:45 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 11, 3:30 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 11, 5:07 AM CDT | Mesoscale Discussion | SPC | 113 min |
| Jul 11, 6:11 AM CDT | Severe Thunderstorm Warning | DVN | 64 min |
| Jul 11, 7:10 AM CDT | Mesoscale Discussion | SPC | 95 min |
| Jul 14, 3:40 PM CDT | Excessive Heat Watch | DVN | 24 hr |
| Jul 15, 3:42 PM CDT | Excessive Heat Warning | DVN | 9 days |
| Jul 18, 6:30 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 19, 1:04 PM CDT | Mesoscale Discussion | SPC | 86 min |
| Jul 22, 3:59 PM CDT | Heat Advisory | DVN | 23 hr |
| Jul 22, 7:38 PM CDT | Mesoscale Discussion | SPC | 97 min |
| Jul 23, 2:32 PM CDT | Flash Flood Watch | DVN | 14 hr |
| Jul 24, 5:21 AM CDT | Special Weather Statement | DVN | 54 min |
| Jul 27, 3:42 PM CDT | Flash Flood Watch | DVN | 31 hr |
| Jul 27, 6:54 PM CDT | Mesoscale Discussion | SPC | 66 min |
| Jul 27, 7:43 PM CDT | Tornado Watch | SPC | 5 hr |
| Jul 27, 7:51 PM CDT | Tornado Warning | DVN | 39 min |
| Jul 27, 8:40 PM CDT | Flash Flood Warning | DVN | 8 hr |
| Jul 27, 9:43 PM CDT | Mesoscale Discussion | SPC | 62 min |
| Jul 28, 12:36 AM CDT | Mesoscale Discussion | SPC | 84 min |
| Jul 28, 12:50 AM CDT | Special Weather Statement | DVN | 55 min |
| Jul 28, 4:10 AM CDT | Areal Flood Warning | DVN | 12 hr |
| Jul 28, 10:15 AM CDT | River Flood Warning | DVN | 43 hr |
| Jul 28, 3:39 PM CDT | Areal Flood Warning | DVN | 6 hr |
| Jul 31, 3:54 AM CDT | Heat Advisory | DVN | 66 hr |
| Aug 2, 12:57 PM CDT | Mesoscale Discussion | SPC | 93 min |
| Aug 8, 1:06 PM CDT | Mesoscale Discussion | SPC | 84 min |
| Aug 8, 6:01 PM CDT | Areal Flood Advisory | DVN | 4 hr |
| Aug 12, 4:43 PM CDT | Special Weather Statement | DVN | 62 min |
| Aug 12, 5:23 PM CDT | Severe Thunderstorm Warning | DVN | 22 min |
| Aug 12, 5:24 PM CDT | Flash Flood Warning | DVN | 2 hr |
| Aug 12, 5:39 PM CDT | Tornado Warning | DVN | 26 min |
| Aug 17, 3:44 PM CDT | Mesoscale Discussion | SPC | 91 min |
| Aug 23, 6:25 AM CDT | Special Weather Statement | DVN | 65 min |
| Aug 23, 7:20 AM CDT | Special Weather Statement | DVN | 25 min |
| Sep 2, 2:41 PM CDT | Mesoscale Discussion | SPC | 94 min |
| Sep 2, 11:56 PM CDT | Mesoscale Discussion | SPC | 94 min |
| Sep 3, 12:48 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Sep 28, 3:57 PM CDT | Wind Advisory | DVN | 27 hr |
| Sep 30, 3:48 AM CDT | Frost Advisory | DVN | 28 hr |
| Oct 1, 2:47 PM CDT | Frost Advisory | DVN | 17 hr |
| Oct 20, 3:20 AM CDT | Freeze Warning | DVN | 30 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 archive20102012
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.