Alert archive / Maryland / Frederick County
Weather alerts in Frederick County, Maryland, 2023
117 weather alerts in 2023, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Frederick County and its neighbors
Each county as a circle sized by its count in 2023. Tap one for its archive.
- Alerts
- 117
- Warnings
- 40
- Watches
- 23
- Advisories
- 20
- Busiest month
- July38 alerts
- Busiest day
- August 7, 202312 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Frederick County, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 34 | 32 | 6% | 37 | 78% | 21 min |
| Flash flood warnings | 0 | 0 |
Each office's whole area, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Baltimore/Washington: tornado warnings | 15 | 1 | 93% | 2 | 50% | 0 min |
| NWS Baltimore/Washington: severe thunderstorm warnings | 370 | 286 | 23% | 992 | 89% | 21 min |
| NWS Baltimore/Washington: flash flood warnings | 48 | 23 | 52% | 47 | 98% | 48 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, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Dec 31, 11:10 PM EST | Dense Fog Advisory | LWX | 10 hr |
| Jan 20, 2:13 AM EST | Dense Fog Advisory | LWX | 4 hr |
| Jan 24, 12:03 PM EST | Winter Weather Advisory | LWX | 30 hr |
| Feb 17, 3:21 PM EST | Wind Advisory | LWX | 4 hr |
| Feb 21, 3:58 AM EST | Wind Advisory | LWX | 13 hr |
| Feb 21, 2:22 PM EST | Mesoscale Discussion | SPC | 53 min |
| Mar 3, 12:33 PM EST | Wind Advisory | LWX | 26 hr |
| Mar 13, 2:38 PM EDT | Wind Advisory | LWX | 33 hr |
| Mar 15, 10:38 AM EDT | Wind Advisory | LWX | 2 hr |
| Mar 23, 11:24 PM EDT | Severe Thunderstorm Warning | LWX | 36 min |
| Mar 25, 11:17 PM EDT | Dense Fog Advisory | LWX | 5 hr |
| Mar 30, 3:40 AM EDT | High Wind Watch | LWX | 35 hr |
| Mar 31, 2:29 PM EDT | High Wind Warning | LWX | 35 hr |
| Apr 1, 6:00 PM EDT | Severe Thunderstorm Warning | LWX | 45 min |
| Apr 2, 1:13 PM EDT | Frost Advisory | LWX | 20 hr |
| Apr 7, 11:21 AM EDT | Freeze Watch | LWX | 16 hr |
| Apr 8, 3:21 AM EDT | Freeze Warning | LWX | 30 hr |
| Apr 9, 9:08 AM EDT | Freeze Warning | LWX | 24 hr |
| Apr 11, 3:46 PM EDT | Fire Weather Watch | LWX | 17 hr |
| Apr 12, 9:01 AM EDT | Red Flag Warning | LWX | 11 hr |
| Apr 15, 12:10 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Apr 15, 12:54 PM EDT | Severe Thunderstorm Warning | LWX | 22 min |
| Apr 17, 12:25 PM EDT | Fire Weather Watch | LWX | 15 hr |
| Apr 20, 11:22 AM EDT | Fire Weather Watch | LWX | 15 hr |
| Apr 22, 9:34 AM EDT | Mesoscale Discussion | SPC | 116 min |
| Apr 22, 10:07 AM EDT | Severe Thunderstorm Watch | SPC | 10 hr |
| Apr 22, 1:20 PM EDT | Severe Thunderstorm Warning | LWX | 40 min |
| Apr 22, 2:02 PM EDT | Severe Thunderstorm Warning | LWX | 43 min |
| Apr 22, 2:12 PM EDT | Mesoscale Discussion | SPC | 93 min |
| Apr 24, 3:08 AM EDT | Freeze Watch | LWX | 11 hr |
| Apr 24, 2:32 PM EDT | Freeze Warning | LWX | 17 hr |
| May 17, 12:45 PM EDT | Frost Advisory | LWX | 17 hr |
| Jun 3, 1:27 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 16, 4:13 PM EDT | Mesoscale Discussion | SPC | 92 min |
| Jun 19, 4:56 PM EDT | Severe Thunderstorm Warning | LWX | 33 min |
| Jun 26, 12:36 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 26, 2:20 PM EDT | Severe Thunderstorm Watch | SPC | 9 hr |
| Jun 26, 4:30 PM EDT | Mesoscale Discussion | SPC | 90 min |
| Jun 26, 6:27 PM EDT | Severe Thunderstorm Warning | LWX | 48 min |
| Jun 26, 8:03 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jul 1, 1:37 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jul 2, 2:06 PM EDT | Mesoscale Discussion | SPC | 114 min |
| Jul 2, 4:31 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 3, 2:55 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 3, 4:49 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jul 7, 11:26 AM EDT | Flood Watch | LWX | 8 hr |
| Jul 8, 3:23 PM EDT | Flood Watch | LWX | 25 hr |
| Jul 9, 10:28 AM EDT | Mesoscale Discussion | SPC | 92 min |
| Jul 9, 12:55 PM EDT | Mesoscale Discussion | SPC | 65 min |
| Jul 9, 1:19 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 9, 1:28 PM EDT | Severe Thunderstorm Warning | LWX | 26 min |
| Jul 13, 2:36 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 2:02 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 4:30 PM EDT | Severe Thunderstorm Warning | LWX | 45 min |
| Jul 15, 3:50 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 6:38 PM EDT | Flood Watch | LWX | 23 hr |
| Jul 19, 4:48 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jul 21, 1:15 AM EDT | Severe Thunderstorm Warning | LWX | 45 min |
| Jul 26, 9:01 AM EDT | Heat Advisory | LWX | 35 hr |
| Jul 26, 1:57 PM EDT | Excessive Heat Watch | LWX | 24 hr |
| Jul 27, 11:40 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 27, 1:48 PM EDT | Heat Advisory | LWX | 29 hr |
| Jul 27, 3:18 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 27, 3:36 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| Jul 27, 4:22 PM EDT | Severe Thunderstorm Warning | LWX | 53 min |
| Jul 27, 4:46 PM EDT | Mesoscale Discussion | SPC | 89 min |
| Jul 28, 8:33 AM EDT | Heat Advisory | LWX | 34 hr |
| Jul 28, 1:54 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 28, 4:48 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 28, 5:31 PM EDT | Severe Thunderstorm Warning | LWX | 44 min |
| Jul 28, 5:43 PM EDT | Severe Thunderstorm Warning | LWX | 47 min |
| Jul 28, 6:09 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Jul 28, 6:22 PM EDT | Severe Thunderstorm Warning | LWX | 53 min |
| Jul 28, 6:33 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jul 29, 1:56 PM EDT | Mesoscale Discussion | SPC | 64 min |
| Jul 29, 2:48 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 29, 3:40 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Jul 29, 4:45 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 4, 6:51 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| Aug 4, 7:58 PM EDT | Severe Thunderstorm Warning | LWX | 36 min |
| Aug 5, 5:42 AM EDT | Dense Fog Advisory | LWX | 3 hr |
| Aug 7, 8:18 AM EDT | Mesoscale Discussion | SPC | 117 min |
| Aug 7, 12:14 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 7, 1:20 PM EDT | Tornado Watch | SPC | 11 hr |
| Aug 7, 1:56 PM EDT | Severe Thunderstorm Warning | LWX | 49 min |
| Aug 7, 3:07 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Aug 7, 3:17 PM EDT | Severe Thunderstorm Warning | LWX | 23 min |
| Aug 7, 3:17 PM EDT | Mesoscale Discussion | SPC | 88 min |
| Aug 7, 3:34 PM EDT | Severe Thunderstorm Warning | LWX | 56 min |
| Aug 7, 3:49 PM EDT | Severe Thunderstorm Warning | LWX | 41 min |
| Aug 7, 4:25 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Aug 7, 4:38 PM EDT | Severe Thunderstorm Warning | LWX | 37 min |
| Aug 7, 4:40 PM EDT | Mesoscale Discussion | SPC | 95 min |
| Sep 5, 12:36 AM EDT | Heat Advisory | LWX | 18 hr |
| Sep 6, 3:11 AM EDT | Heat Advisory | LWX | 16 hr |
| Sep 7, 11:58 AM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 7, 1:14 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 7, 1:55 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Sep 7, 2:09 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Sep 7, 2:31 PM EDT | Severe Thunderstorm Warning | LWX | 44 min |
| Sep 7, 3:06 PM EDT | Mesoscale Discussion | SPC | 84 min |
| Sep 7, 3:14 PM EDT | Severe Thunderstorm Warning | LWX | 46 min |
| Sep 8, 2:46 PM EDT | Mesoscale Discussion | SPC | 119 min |
| Sep 8, 3:11 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 8, 6:34 PM EDT | Mesoscale Discussion | SPC | 86 min |
| Sep 9, 2:08 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 9, 3:56 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Sep 9, 4:02 PM EDT | Severe Thunderstorm Warning | LWX | 43 min |
| Sep 9, 4:23 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Sep 9, 4:33 PM EDT | Severe Thunderstorm Warning | LWX | 16 min |
| Sep 9, 6:06 PM EDT | Mesoscale Discussion | SPC | 114 min |
| Sep 9, 8:08 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Oct 23, 9:52 AM EDT | Frost Advisory | LWX | 24 hr |
| Oct 31, 3:48 AM EDT | Freeze Watch | LWX | 23 hr |
| Nov 1, 2:26 AM EDT | Freeze Warning | LWX | 32 hr |
| Dec 9, 3:07 AM EST | Dense Fog Advisory | LWX | 8 hr |
| Dec 17, 3:51 AM EST | Wind Advisory | LWX | 34 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 | 34 |
| Severe Thunderstorm Watch | 11 |
| Tornado Watch | 1 |
| Mesoscale Discussion | 34 |
| Flooding | |
| Flood Watch | 3 |
| Winter | |
| Winter Weather Advisory | 1 |
| Heat | |
| Excessive Heat Watch | 1 |
| Heat Advisory | 5 |
| Cold | |
| Freeze Warning | 4 |
| Freeze Watch | 3 |
| Frost Advisory | 3 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Wind Advisory | 6 |
| Fire | |
| Red Flag Warning | 1 |
| Fire Weather Watch | 3 |
| Fog and smoke | |
| Dense Fog Advisory | 5 |
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.