Alert archive / Virginia / Loudoun County
Weather alerts in Loudoun County, Virginia, 2024
173 weather alerts in 2024, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Loudoun County and its neighbors
Each county as a circle sized by its count in 2024. Tap one for its archive.
- Alerts
- 173
- Warnings
- 55
- Watches
- 42
- Advisories
- 44
- Busiest month
- August39 alerts
- Busiest day
- August 9, 202410 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
3 of 5 tornado warnings covering Loudoun County in 2024 had a tornado report inside them; 3 of 3 tornado reports fell inside a warning, on average 10 minutes after it went out.
Loudoun County, 2024
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 5 | 3 | 40% | 3 | 100% | 10 min |
| Severe thunderstorm warnings | 33 | 28 | 15% | 46 | 91% | 16 min |
| Flash flood warnings | 2 | 1 | 50% | 0 |
Each office's whole area, 2024
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Baltimore/Washington: tornado warnings | 50 | 12 | 76% | 35 | 69% | 19 min |
| NWS Baltimore/Washington: severe thunderstorm warnings | 306 | 203 | 34% | 536 | 85% | 19 min |
| NWS Baltimore/Washington: flash flood warnings | 59 | 26 | 56% | 60 | 82% | 97 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 |
|---|---|---|---|
| Jan 4, 2:21 PM EST | Winter Storm Watch | LWX | 19 hr |
| Jan 5, 4:49 AM EST | Winter Weather Advisory | LWX | 68 hr |
| Jan 6, 11:47 AM EST | Mesoscale Discussion | SPC | 5 hr |
| Jan 8, 1:57 AM EST | Flood Watch | LWX | 44 hr |
| Jan 8, 3:48 AM EST | Wind Advisory | LWX | 41 hr |
| Jan 9, 10:16 AM EST | River Flood Watch | LWX | 18 hr |
| Jan 9, 10:16 AM EST | River Flood Watch | LWX | 20 hr |
| Jan 9, 2:40 PM EST | Wind Advisory | LWX | 25 hr |
| Jan 9, 3:29 PM EST | Areal Flood Warning | LWX | 30 hr |
| Jan 9, 5:29 PM EST | River Flood Watch | LWX | 5 hr |
| Jan 9, 7:27 PM EST | Areal Flood Warning | LWX | 13 hr |
| Jan 10, 2:47 AM EST | River Flood Warning | LWX | 8 hr |
| Jan 10, 9:30 PM EST | River Flood Watch | LWX | 6 hr |
| Jan 11, 3:22 AM EST | River Flood Warning | LWX | 8 hr |
| Jan 11, 2:06 PM EST | Flood Watch | LWX | 33 hr |
| Jan 12, 2:24 AM EST | Wind Advisory | LWX | 39 hr |
| Jan 14, 2:09 AM EST | Wind Advisory | LWX | 15 hr |
| Jan 14, 10:18 AM EST | Special Weather Statement | LWX | 57 min |
| Jan 14, 10:45 AM EST | Special Weather Statement | LWX | 60 min |
| Jan 14, 2:35 PM EST | Winter Weather Advisory | LWX | 43 hr |
| Jan 15, 10:11 AM EST | Winter Storm Warning | LWX | 24 hr |
| Jan 18, 3:08 AM EST | Winter Storm Warning | LWX | 64 hr |
| Jan 18, 8:26 AM EST | Winter Weather Advisory | LWX | 33 hr |
| Jan 20, 1:40 AM EST | Special Weather Statement | LWX | 65 min |
| Jan 24, 6:19 PM EST | Dense Fog Advisory | LWX | 41 hr |
| Jan 27, 1:40 PM EST | Flood Watch | LWX | 18 hr |
| Jan 28, 9:19 AM EST | River Flood Watch | LWX | 32 hr |
| Jan 28, 9:19 AM EST | River Flood Watch | LWX | 24 hr |
| Feb 12, 4:07 AM EST | Winter Weather Advisory | LWX | 31 hr |
| Feb 15, 9:46 AM EST | Winter Storm Watch | LWX | 24 hr |
| Feb 16, 3:24 AM EST | Winter Storm Warning | LWX | 28 hr |
| Feb 16, 3:24 AM EST | Winter Weather Advisory | LWX | 25 hr |
| Feb 27, 2:58 PM EST | Wind Advisory | LWX | 36 hr |
| Mar 6, 4:36 AM EST | Dense Fog Advisory | LWX | 7 hr |
| Mar 9, 3:15 AM EST | Wind Advisory | LWX | 61 hr |
| Mar 9, 9:23 AM EST | River Flood Watch | LWX | 24 hr |
| Mar 9, 9:23 AM EST | River Flood Watch | LWX | 18 hr |
| Mar 18, 2:33 PM EDT | Fire Weather Watch | LWX | 36 hr |
| Mar 19, 12:02 PM EDT | Wind Advisory | LWX | 32 hr |
| Mar 19, 2:50 PM EDT | Red Flag Warning | LWX | 29 hr |
| Mar 21, 2:10 PM EDT | Flood Watch | LWX | 47 hr |
| Mar 31, 1:41 PM EDT | Flood Watch | LWX | 3 days |
| Apr 2, 10:05 AM EDT | River Flood Watch | LWX | 24 hr |
| Apr 2, 10:05 AM EDT | River Flood Watch | LWX | 45 hr |
| Apr 3, 10:19 AM EDT | River Flood Warning | LWX | 54 hr |
| Apr 4, 6:56 AM EDT | River Flood Warning | LWX | 13 hr |
| Apr 12, 3:29 AM EDT | Wind Advisory | LWX | 37 hr |
| Apr 15, 11:01 AM EDT | Mesoscale Discussion | SPC | 89 min |
| Apr 15, 1:03 PM EDT | Mesoscale Discussion | SPC | 117 min |
| Apr 15, 1:36 PM EDT | Severe Thunderstorm Warning | LWX | 24 min |
| Apr 15, 1:44 PM EDT | Severe Thunderstorm Warning | LWX | 20 min |
| Apr 15, 1:50 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Apr 15, 2:36 PM EDT | Severe Thunderstorm Warning | LWX | 24 min |
| Apr 21, 12:42 PM EDT | Frost Advisory | LWX | 19 hr |
| Apr 22, 10:45 AM EDT | Frost Advisory | LWX | 22 hr |
| Apr 28, 6:23 AM EDT | Dense Fog Advisory | LWX | 4 hr |
| May 6, 3:27 AM EDT | Dense Fog Advisory | LWX | 7 hr |
| May 20, 5:04 AM EDT | Dense Fog Advisory | LWX | 5 hr |
| May 22, 3:00 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| May 22, 4:39 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| May 23, 6:20 PM EDT | Severe Thunderstorm Warning | LWX | 25 min |
| May 26, 8:44 PM EDT | Severe Thunderstorm Watch | SPC | 3 hr |
| May 26, 9:05 PM EDT | Severe Thunderstorm Warning | LWX | 55 min |
| May 26, 9:50 PM EDT | Severe Thunderstorm Warning | LWX | 28 min |
| May 26, 9:56 PM EDT | Severe Thunderstorm Warning | LWX | 49 min |
| May 26, 10:18 PM EDT | Mesoscale Discussion | SPC | 87 min |
| May 26, 10:38 PM EDT | Severe Thunderstorm Warning | LWX | 37 min |
| May 27, 11:53 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| May 27, 3:39 PM EDT | Tornado Watch | SPC | 7 hr |
| May 27, 6:51 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| Jun 5, 4:04 AM EDT | Flood Watch | LWX | 18 hr |
| Jun 5, 6:33 PM EDT | Tornado Warning | LWX | 27 min |
| Jun 5, 6:53 PM EDT | Tornado Warning | LWX | 37 min |
| Jun 20, 4:59 PM EDT | Excessive Heat Watch | LWX | 19 hr |
| Jun 21, 12:27 PM EDT | Heat Advisory | LWX | 32 hr |
| Jun 22, 12:12 PM EDT | Heat Advisory | LWX | 30 hr |
| Jun 26, 6:43 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 26, 8:33 PM EDT | Severe Thunderstorm Warning | LWX | 27 min |
| Jun 26, 8:51 PM EDT | Severe Thunderstorm Watch | SPC | 3 hr |
| Jun 26, 9:10 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Jun 29, 3:30 PM EDT | Mesoscale Discussion | SPC | 90 min |
| Jun 30, 12:11 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 30, 3:21 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 4, 3:52 AM EDT | Heat Advisory | LWX | 40 hr |
| Jul 5, 11:48 PM EDT | Heat Advisory | LWX | 20 hr |
| Jul 7, 3:21 PM EDT | Heat Advisory | LWX | 29 hr |
| Jul 8, 2:25 PM EDT | Heat Advisory | LWX | 30 hr |
| Jul 9, 4:15 AM EDT | Heat Advisory | LWX | 39 hr |
| Jul 10, 12:52 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jul 10, 1:37 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 10, 4:22 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jul 13, 1:39 PM EDT | Excessive Heat Watch | LWX | 23 hr |
| Jul 14, 9:33 AM EDT | Excessive Heat Watch | LWX | 27 hr |
| Jul 14, 12:59 PM EDT | Heat Advisory | LWX | 31 hr |
| Jul 15, 12:55 PM EDT | Heat Advisory | LWX | 31 hr |
| Jul 15, 3:41 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 4:17 PM EDT | Severe Thunderstorm Warning | LWX | 28 min |
| Jul 15, 4:40 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Jul 15, 4:57 PM EDT | Severe Thunderstorm Warning | LWX | 33 min |
| Jul 15, 5:14 PM EDT | Severe Thunderstorm Warning | LWX | 46 min |
| Jul 16, 11:44 AM EDT | Heat Advisory | LWX | 32 hr |
| Jul 16, 2:35 PM EDT | Mesoscale Discussion | SPC | 115 min |
| Jul 16, 3:36 PM EDT | Severe Thunderstorm Watch | SPC | 9 hr |
| Jul 16, 6:20 PM EDT | Mesoscale Discussion | SPC | 115 min |
| Jul 16, 8:11 PM EDT | Severe Thunderstorm Warning | LWX | 34 min |
| Jul 16, 8:14 PM EDT | Severe Thunderstorm Warning | LWX | 31 min |
| Jul 16, 8:19 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jul 17, 2:11 PM EDT | Mesoscale Discussion | SPC | 79 min |
| Jul 17, 2:38 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 17, 4:14 PM EDT | Severe Thunderstorm Warning | LWX | 46 min |
| Jul 17, 4:26 PM EDT | Mesoscale Discussion | SPC | 94 min |
| Jul 25, 3:01 PM EDT | Mesoscale Discussion | SPC | 89 min |
| Jul 29, 5:01 PM EDT | Severe Thunderstorm Warning | LWX | 29 min |
| Jul 30, 12:39 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 30, 4:15 PM EDT | Severe Thunderstorm Warning | LWX | 30 min |
| Aug 1, 12:01 PM EDT | Heat Advisory | LWX | 32 hr |
| Aug 1, 2:53 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 3, 12:56 PM EDT | Mesoscale Discussion | SPC | 94 min |
| Aug 3, 1:20 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Aug 3, 2:39 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Aug 3, 3:11 PM EDT | Severe Thunderstorm Warning | LWX | 31 min |
| Aug 3, 4:39 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Aug 3, 5:02 PM EDT | Severe Thunderstorm Warning | LWX | 28 min |
| Aug 3, 5:19 PM EDT | Severe Thunderstorm Warning | LWX | 26 min |
| Aug 3, 5:20 PM EDT | Severe Thunderstorm Warning | LWX | 25 min |
| Aug 3, 5:39 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Aug 7, 2:43 PM EDT | Flood Watch | LWX | 45 hr |
| Aug 7, 10:35 PM EDT | Flash Flood Warning | LWX | 3 hr |
| Aug 8, 11:49 AM EDT | River Flood Watch | LWX | 40 hr |
| Aug 8, 11:49 AM EDT | River Flood Watch | LWX | 31 hr |
| Aug 8, 6:37 PM EDT | Tornado Watch | SPC | 12 hr |
| Aug 8, 8:38 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 8, 9:07 PM EDT | Flash Flood Warning | LWX | 6 hr |
| Aug 8, 9:07 PM EDT | Tornado Warning | LWX | 23 min |
| Aug 8, 9:26 PM EDT | Tornado Warning | LWX | 19 min |
| Aug 8, 9:40 PM EDT | Tornado Warning | LWX | 35 min |
| Aug 8, 11:04 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Aug 9, 3:25 AM EDT | Areal Flood Warning | LWX | 10 hr |
| Aug 9, 4:38 AM EDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 9, 6:17 AM EDT | Tornado Watch | SPC | 8 hr |
| Aug 9, 6:22 PM EDT | River Flood Warning | LWX | 22 hr |
| Aug 18, 3:07 AM EDT | Flood Watch | LWX | 20 hr |
| Aug 18, 1:09 PM EDT | Mesoscale Discussion | SPC | 96 min |
| Aug 18, 2:02 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Aug 18, 4:30 PM EDT | Mesoscale Discussion | SPC | 90 min |
| Aug 27, 2:36 PM EDT | Heat Advisory | LWX | 28 hr |
| Aug 29, 10:59 AM EDT | Flood Watch | LWX | 12 hr |
| Aug 29, 1:20 PM EDT | Mesoscale Discussion | SPC | 115 min |
| Aug 29, 3:54 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 29, 4:11 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Aug 29, 4:37 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Aug 29, 5:16 PM EDT | Severe Thunderstorm Warning | LWX | 29 min |
| Aug 29, 5:40 PM EDT | Mesoscale Discussion | SPC | 95 min |
| Aug 29, 7:23 PM EDT | Severe Thunderstorm Warning | LWX | 26 min |
| Sep 14, 5:37 AM EDT | Dense Fog Advisory | LWX | 3 hr |
| Sep 21, 2:37 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 21, 7:39 PM EDT | Severe Thunderstorm Warning | LWX | 36 min |
| Sep 21, 8:10 PM EDT | Severe Thunderstorm Warning | LWX | 35 min |
| Oct 5, 2:51 AM EDT | Dense Fog Advisory | LWX | 6 hr |
| Oct 15, 1:34 PM EDT | Frost Advisory | LWX | 19 hr |
| Oct 16, 2:01 PM EDT | Frost Advisory | LWX | 19 hr |
| Oct 17, 1:54 PM EDT | Frost Advisory | LWX | 19 hr |
| Oct 18, 4:02 PM EDT | Frost Advisory | LWX | 17 hr |
| Oct 24, 2:05 PM EDT | Frost Advisory | LWX | 19 hr |
| Oct 26, 3:05 AM EDT | Freeze Watch | LWX | 24 hr |
| Oct 27, 3:06 AM EDT | Freeze Warning | LWX | 30 hr |
| Nov 1, 9:54 AM EDT | Red Flag Warning | LWX | 8 hr |
| Nov 7, 5:33 PM EST | Red Flag Warning | LWX | 24 hr |
| Nov 20, 1:59 AM EST | Wind Advisory | LWX | 23 hr |
| Dec 4, 4:22 AM EST | Wind Advisory | LWX | 44 hr |
| Dec 9, 9:31 PM EST | Dense Fog Advisory | LWX | 14 hr |
| Dec 10, 5:08 PM EST | Dense Fog Advisory | LWX | 13 hr |
| Dec 23, 3:00 AM EST | Winter Weather Advisory | LWX | 40 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 | 33 |
| Tornado Warning | 5 |
| Severe Thunderstorm Watch | 11 |
| Tornado Watch | 3 |
| Mesoscale Discussion | 29 |
| Special Weather Statement | 3 |
| Flooding | |
| Areal Flood Warning | 3 |
| Flash Flood Warning | 2 |
| River Flood Warning | 5 |
| Flood Watch | 9 |
| River Flood Watch | 12 |
| Winter | |
| Winter Storm Warning | 3 |
| Winter Storm Watch | 2 |
| Winter Weather Advisory | 6 |
| Heat | |
| Excessive Heat Watch | 3 |
| Heat Advisory | 12 |
| Cold | |
| Freeze Warning | 1 |
| Freeze Watch | 1 |
| Frost Advisory | 7 |
| Wind and dust | |
| Wind Advisory | 10 |
| Fire | |
| Red Flag Warning | 3 |
| Fire Weather Watch | 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 archive20232025
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.