Alert archive / Virginia / Loudoun County
Weather alerts in Loudoun County, Virginia, 2018
211 weather alerts in 2018, 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 2018. Tap one for its archive.
- Alerts
- 211
- Warnings
- 84
- Watches
- 59
- Advisories
- 37
- Busiest month
- May48 alerts
- Busiest day
- May 14, 20189 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 2 tornado warnings covering Loudoun County in 2018 had a tornado report inside them.
Loudoun County, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 2 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 22 | 15 | 32% | 18 | 67% | 24 min |
| Flash flood warnings | 2 | 1 | 50% | 2 | 0% |
Each office's whole area, 2018
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Baltimore/Washington: tornado warnings | 19 | 1 | 95% | 4 | 25% | 1 min |
| NWS Baltimore/Washington: severe thunderstorm warnings | 312 | 208 | 33% | 690 | 70% | 20 min |
| NWS Baltimore/Washington: flash flood warnings | 87 | 38 | 56% | 129 | 89% | 103 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 3, 3:34 AM EST | Winter Weather Advisory | LWX | 35 hr |
| Jan 4, 3:36 AM EST | Wind Chill Advisory | LWX | 32 hr |
| Jan 4, 12:47 PM EST | Wind Advisory | LWX | 5 hr |
| Jan 5, 3:45 AM EST | Wind Chill Advisory | LWX | 54 hr |
| Jan 6, 3:55 AM EST | Wind Chill Advisory | LWX | 26 hr |
| Jan 7, 2:46 PM EST | Winter Weather Advisory | LWX | 33 hr |
| Jan 9, 4:32 AM EST | Dense Fog Advisory | LWX | 4 hr |
| Jan 15, 1:47 PM EST | Winter Weather Advisory | LWX | 46 hr |
| Feb 3, 3:00 PM EST | Winter Weather Advisory | LWX | 28 hr |
| Feb 6, 4:02 AM EST | Winter Weather Advisory | LWX | 38 hr |
| Feb 10, 3:38 AM EST | Flood Watch | LWX | 36 hr |
| Feb 16, 9:12 PM EST | Winter Weather Advisory | LWX | 31 hr |
| Feb 23, 8:30 PM EST | Dense Fog Advisory | LWX | 15 hr |
| Feb 25, 10:46 PM EST | Dense Fog Advisory | LWX | 6 hr |
| Feb 28, 2:52 PM EST | High Wind Watch | LWX | 21 hr |
| Mar 1, 4:06 AM EST | High Wind Warning | LWX | 45 hr |
| Mar 1, 10:37 PM EST | Special Weather Statement | LWX | 7 hr |
| Mar 2, 7:57 PM EST | Wind Advisory | LWX | 10 hr |
| Mar 19, 12:06 PM EDT | Winter Storm Watch | LWX | 25 hr |
| Mar 19, 3:42 PM EDT | Winter Storm Warning | LWX | 52 hr |
| Mar 19, 3:42 PM EDT | Winter Weather Advisory | LWX | 28 hr |
| Mar 20, 10:00 AM EDT | Special Weather Statement | LWX | 15 min |
| Mar 20, 12:47 PM EDT | Winter Storm Warning | LWX | 31 hr |
| Mar 29, 4:23 AM EDT | Dense Fog Advisory | LWX | 6 hr |
| Apr 1, 4:01 AM EDT | Winter Weather Advisory | LWX | 27 hr |
| Apr 3, 5:33 PM EDT | Wind Advisory | LWX | 25 hr |
| Apr 11, 1:34 PM EDT | Fire Weather Watch | LWX | 14 hr |
| Apr 12, 3:42 AM EDT | Red Flag Warning | LWX | 16 hr |
| Apr 16, 10:27 PM EDT | River Flood Watch | LWX | 11 hr |
| Apr 17, 4:08 AM EDT | Freeze Watch | LWX | 9 hr |
| Apr 17, 1:24 PM EDT | Freeze Warning | LWX | 19 hr |
| Apr 18, 6:17 AM EDT | River Flood Warning | LWX | 8 hr |
| Apr 19, 4:27 AM EDT | Freeze Watch | LWX | 10 hr |
| Apr 19, 2:22 PM EDT | Freeze Warning | LWX | 18 hr |
| Apr 20, 2:28 PM EDT | Freeze Warning | LWX | 19 hr |
| Apr 28, 5:21 AM EDT | Dense Fog Advisory | LWX | 5 hr |
| Apr 29, 3:15 PM EDT | Frost Advisory | LWX | 17 hr |
| Apr 29, 3:18 PM EDT | Fire Weather Watch | LWX | 12 hr |
| Apr 30, 3:32 AM EDT | Red Flag Warning | LWX | 16 hr |
| May 10, 12:36 PM EDT | Mesoscale Discussion | SPC | 114 min |
| May 10, 1:14 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| May 10, 3:53 PM EDT | Severe Thunderstorm Warning | LWX | 37 min |
| May 10, 3:58 PM EDT | Severe Thunderstorm Warning | LWX | 33 min |
| May 10, 4:10 PM EDT | Severe Thunderstorm Warning | LWX | 28 min |
| May 10, 4:53 PM EDT | Mesoscale Discussion | SPC | 67 min |
| May 12, 2:47 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| May 12, 5:05 PM EDT | Mesoscale Discussion | SPC | 115 min |
| May 13, 1:56 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| May 13, 4:28 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| May 13, 7:00 PM EDT | Mesoscale Discussion | SPC | 60 min |
| May 14, 5:32 AM EDT | Dense Fog Advisory | LWX | 4 hr |
| May 14, 11:56 AM EDT | Mesoscale Discussion | SPC | 64 min |
| May 14, 12:29 PM EDT | Severe Thunderstorm Watch | SPC | 9 hr |
| May 14, 3:26 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| May 14, 5:29 PM EDT | Severe Thunderstorm Warning | LWX | 61 min |
| May 14, 5:35 PM EDT | Severe Thunderstorm Warning | LWX | 55 min |
| May 14, 5:49 PM EDT | Tornado Warning | LWX | 26 min |
| May 14, 6:07 PM EDT | Severe Thunderstorm Warning | LWX | 53 min |
| May 14, 6:12 PM EDT | Tornado Warning | LWX | 33 min |
| May 15, 4:33 AM EDT | Flash Flood Watch | LWX | 20 hr |
| May 15, 5:43 PM EDT | Mesoscale Discussion | SPC | 92 min |
| May 15, 5:54 PM EDT | Severe Thunderstorm Watch | SPC | 4 hr |
| May 15, 7:18 PM EDT | Severe Thunderstorm Warning | LWX | 42 min |
| May 15, 7:54 PM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| May 15, 8:41 PM EDT | Mesoscale Discussion | SPC | 94 min |
| May 15, 8:52 PM EDT | Areal Flood Warning | LWX | 3 hr |
| May 15, 8:52 PM EDT | Areal Flood Warning | LWX | 13 hr |
| May 15, 10:10 PM EDT | Areal Flood Warning | LWX | 8 hr |
| May 15, 10:32 PM EDT | Areal Flood Warning | LWX | 11 hr |
| May 16, 6:05 AM EDT | Areal Flood Warning | LWX | 4 hr |
| May 16, 1:40 PM EDT | Flood Watch | LWX | 3 days |
| May 16, 11:58 PM EDT | Areal Flood Warning | LWX | 14 hr |
| May 17, 7:13 AM EDT | Areal Flood Warning | LWX | 8 hr |
| May 17, 3:28 PM EDT | River Flood Warning | LWX | 18 hr |
| May 17, 3:43 PM EDT | River Flood Warning | LWX | 4 days |
| May 17, 3:44 PM EDT | River Flood Warning | LWX | 4 days |
| May 17, 3:44 PM EDT | River Flood Warning | LWX | 3 days |
| May 19, 1:59 AM EDT | Areal Flood Warning | LWX | 27 hr |
| May 22, 1:52 PM EDT | Mesoscale Discussion | SPC | 113 min |
| May 22, 2:33 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| May 22, 3:25 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| May 22, 4:50 PM EDT | Mesoscale Discussion | SPC | 115 min |
| May 27, 4:25 AM EDT | Flash Flood Watch | LWX | 16 hr |
| May 27, 1:29 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| May 31, 4:06 AM EDT | Flash Flood Watch | LWX | 17 hr |
| May 31, 4:44 PM EDT | Areal Flood Warning | LWX | 2 hr |
| May 31, 5:16 PM EDT | Flash Flood Warning | LWX | 92 min |
| Jun 1, 9:12 PM EDT | Areal Flood Warning | LWX | 3 hr |
| Jun 2, 3:13 AM EDT | Flash Flood Watch | LWX | 25 hr |
| Jun 2, 3:25 AM EDT | River Flood Watch | LWX | 33 hr |
| Jun 2, 3:26 AM EDT | River Flood Watch | LWX | 33 hr |
| Jun 2, 3:27 AM EDT | River Flood Watch | LWX | 36 hr |
| Jun 3, 4:11 AM EDT | Flood Watch | LWX | 14 hr |
| Jun 3, 12:20 PM EDT | River Flood Warning | LWX | 54 hr |
| Jun 3, 12:27 PM EDT | River Flood Warning | LWX | 66 hr |
| Jun 3, 3:48 PM EDT | River Flood Warning | LWX | 53 hr |
| Jun 9, 1:34 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 9, 7:16 PM EDT | Severe Thunderstorm Warning | LWX | 29 min |
| Jun 10, 3:47 AM EDT | Flash Flood Watch | LWX | 24 hr |
| Jun 19, 12:04 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jun 19, 2:08 PM EDT | Severe Thunderstorm Warning | LWX | 52 min |
| Jun 19, 2:32 PM EDT | Severe Thunderstorm Warning | LWX | 28 min |
| Jun 20, 6:08 PM EDT | Severe Thunderstorm Warning | LWX | 30 min |
| Jun 23, 12:09 AM EDT | Areal Flood Warning | LWX | 4 hr |
| Jun 24, 2:22 AM EDT | River Flood Warning | LWX | 14 hr |
| Jun 24, 2:04 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jun 24, 2:32 PM EDT | Severe Thunderstorm Warning | LWX | 43 min |
| Jun 27, 7:37 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 30, 2:14 PM EDT | Heat Advisory | LWX | 27 hr |
| Jul 1, 2:10 PM EDT | Heat Advisory | LWX | 30 hr |
| Jul 2, 1:40 PM EDT | Heat Advisory | LWX | 30 hr |
| Jul 5, 9:56 AM EDT | Flash Flood Watch | LWX | 17 hr |
| Jul 21, 5:05 AM EDT | Flash Flood Watch | LWX | 21 hr |
| Jul 21, 4:41 PM EDT | Areal Flood Warning | LWX | 27 hr |
| Jul 21, 6:30 PM EDT | Areal Flood Warning | LWX | 38 hr |
| Jul 21, 9:29 PM EDT | Flash Flood Warning | LWX | 3 hr |
| Jul 22, 11:35 AM EDT | Flash Flood Watch | LWX | 17 hr |
| Jul 23, 4:59 AM EDT | Flash Flood Watch | LWX | 68 hr |
| Jul 23, 10:48 AM EDT | River Flood Watch | LWX | 23 hr |
| Jul 23, 2:40 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Jul 24, 6:14 AM EDT | Areal Flood Warning | LWX | 8 hr |
| Jul 25, 4:41 PM EDT | Areal Flood Warning | LWX | 21 hr |
| Jul 26, 1:47 AM EDT | Dense Fog Advisory | LWX | 7 hr |
| Jul 27, 4:06 AM EDT | Flash Flood Watch | LWX | 17 hr |
| Jul 27, 1:28 PM EDT | Mesoscale Discussion | SPC | 62 min |
| Jul 27, 1:52 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 27, 4:31 PM EDT | Severe Thunderstorm Warning | LWX | 59 min |
| Jul 27, 4:50 PM EDT | Mesoscale Discussion | SPC | 55 min |
| Jul 27, 5:02 PM EDT | Severe Thunderstorm Warning | LWX | 23 min |
| Aug 1, 4:10 AM EDT | Flash Flood Watch | LWX | 3 days |
| Aug 1, 3:15 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 1, 11:05 PM EDT | Areal Flood Warning | LWX | 4 hr |
| Aug 1, 11:05 PM EDT | Severe Thunderstorm Warning | LWX | 25 min |
| Aug 3, 11:54 PM EDT | Areal Flood Warning | LWX | 6 hr |
| Aug 11, 10:50 AM EDT | Flash Flood Watch | LWX | 10 hr |
| Aug 12, 12:23 PM EDT | Flash Flood Watch | LWX | 9 hr |
| Aug 13, 4:21 AM EDT | Flash Flood Watch | LWX | 18 hr |
| Aug 13, 1:57 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 13, 4:22 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Aug 17, 3:10 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 17, 4:41 PM EDT | Severe Thunderstorm Warning | LWX | 49 min |
| Aug 21, 2:41 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Aug 21, 4:56 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 21, 6:59 PM EDT | Severe Thunderstorm Warning | LWX | 46 min |
| Aug 21, 7:06 PM EDT | Mesoscale Discussion | SPC | 84 min |
| Aug 21, 8:25 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Aug 21, 10:39 PM EDT | Areal Flood Warning | LWX | 6 hr |
| Aug 21, 11:16 PM EDT | Areal Flood Warning | LWX | 6 hr |
| Aug 31, 9:49 PM EDT | Areal Flood Warning | LWX | 2 hr |
| Sep 1, 7:00 PM EDT | Areal Flood Warning | LWX | 3 hr |
| Sep 4, 2:17 AM EDT | Heat Advisory | LWX | 17 hr |
| Sep 7, 3:29 AM EDT | Flash Flood Watch | LWX | 19 hr |
| Sep 8, 2:46 PM EDT | Flood Watch | LWX | 39 hr |
| Sep 9, 12:56 PM EDT | River Flood Watch | LWX | 5 days |
| Sep 9, 12:56 PM EDT | River Flood Watch | LWX | 5 days |
| Sep 9, 12:57 PM EDT | River Flood Watch | LWX | 5 days |
| Sep 9, 6:06 PM EDT | River Flood Warning | LWX | 59 hr |
| Sep 9, 6:10 PM EDT | River Flood Warning | LWX | 69 hr |
| Sep 10, 4:47 AM EDT | River Flood Warning | LWX | 49 hr |
| Sep 11, 5:24 AM EDT | Dense Fog Advisory | LWX | 4 hr |
| Sep 16, 3:11 PM EDT | Flash Flood Watch | LWX | 52 hr |
| Sep 16, 9:24 PM EDT | River Flood Watch | LWX | 24 hr |
| Sep 16, 9:28 PM EDT | River Flood Watch | LWX | 42 hr |
| Sep 16, 9:31 PM EDT | River Flood Watch | LWX | 24 hr |
| Sep 26, 3:40 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 26, 5:02 PM EDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Sep 27, 12:08 AM EDT | River Flood Warning | LWX | 13 hr |
| Sep 27, 2:39 AM EDT | Flood Watch | LWX | 27 hr |
| Sep 27, 4:53 PM EDT | River Flood Watch | LWX | 5 hr |
| Sep 27, 9:31 PM EDT | River Flood Warning | LWX | 3 days |
| Sep 27, 9:34 PM EDT | River Flood Watch | LWX | 62 hr |
| Sep 28, 12:09 AM EDT | Areal Flood Warning | LWX | 22 hr |
| Sep 28, 1:09 AM EDT | Areal Flood Warning | LWX | 11 hr |
| Sep 28, 3:46 AM EDT | River Flood Warning | LWX | 56 hr |
| Sep 28, 3:49 AM EDT | River Flood Warning | LWX | 56 hr |
| Sep 28, 7:13 AM EDT | River Flood Warning | LWX | 11 hr |
| Oct 8, 2:58 AM EDT | Dense Fog Advisory | LWX | 7 hr |
| Oct 11, 3:12 AM EDT | Wind Advisory | LWX | 29 hr |
| Oct 18, 2:57 PM EDT | Frost Advisory | LWX | 18 hr |
| Oct 20, 1:10 PM EDT | Wind Advisory | LWX | 18 hr |
| Oct 21, 4:05 AM EDT | Frost Advisory | LWX | 30 hr |
| Oct 21, 4:05 AM EDT | Freeze Warning | LWX | 30 hr |
| Nov 14, 3:54 PM EST | Winter Storm Warning | LWX | 36 hr |
| Nov 14, 3:54 PM EST | Winter Weather Advisory | LWX | 36 hr |
| Nov 15, 3:18 AM EST | Mesoscale Discussion | SPC | 6 hr |
| Nov 15, 9:56 AM EST | Mesoscale Discussion | SPC | 6 hr |
| Nov 23, 3:32 AM EST | Winter Weather Advisory | LWX | 36 hr |
| Nov 24, 6:24 PM EST | Areal Flood Warning | LWX | 11 hr |
| Nov 27, 2:03 PM EST | Wind Advisory | LWX | 24 hr |
| Dec 2, 6:32 PM EST | Dense Fog Advisory | LWX | 11 hr |
| Dec 13, 2:04 PM EST | Flood Watch | LWX | 63 hr |
| Dec 15, 9:47 AM EST | River Flood Watch | LWX | 6 hr |
| Dec 15, 9:49 AM EST | River Flood Watch | LWX | 6 hr |
| Dec 15, 1:38 PM EST | Areal Flood Warning | LWX | 33 hr |
| Dec 15, 3:13 PM EST | River Flood Warning | LWX | 63 hr |
| Dec 15, 3:15 PM EST | River Flood Warning | LWX | 3 days |
| Dec 15, 3:17 PM EST | River Flood Watch | LWX | 24 hr |
| Dec 15, 3:25 PM EST | River Flood Warning | LWX | 31 hr |
| Dec 15, 4:34 PM EST | Areal Flood Warning | LWX | 25 hr |
| Dec 16, 3:21 AM EST | River Flood Warning | LWX | 65 hr |
| Dec 19, 3:48 AM EST | Flood Watch | LWX | 59 hr |
| Dec 20, 5:13 PM EST | River Flood Watch | LWX | 24 hr |
| Dec 20, 5:16 PM EST | River Flood Watch | LWX | 24 hr |
| Dec 20, 5:18 PM EST | River Flood Watch | LWX | 24 hr |
| Dec 20, 5:44 PM EST | River Flood Watch | LWX | 10 hr |
| Dec 21, 2:33 PM EST | Mesoscale Discussion | SPC | 57 min |
| Dec 21, 4:00 PM EST | Severe Thunderstorm Warning | LWX | 45 min |
| Dec 21, 4:16 PM EST | Mesoscale Discussion | SPC | 59 min |
| Dec 22, 2:19 PM EST | River Flood Warning | LWX | 38 hr |
| Dec 27, 3:41 AM EST | Flood Watch | LWX | 39 hr |
| Dec 28, 7:45 PM EST | Dense Fog Advisory | LWX | 11 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 | 22 |
| Tornado Warning | 2 |
| Severe Thunderstorm Watch | 9 |
| Mesoscale Discussion | 29 |
| Special Weather Statement | 2 |
| Flooding | |
| Areal Flood Warning | 26 |
| Flash Flood Warning | 2 |
| River Flood Warning | 22 |
| Flash Flood Watch | 16 |
| Flood Watch | 8 |
| River Flood Watch | 20 |
| Winter | |
| Winter Storm Warning | 3 |
| Winter Storm Watch | 1 |
| Winter Weather Advisory | 10 |
| Heat | |
| Heat Advisory | 4 |
| Cold | |
| Freeze Warning | 4 |
| Freeze Watch | 2 |
| Frost Advisory | 3 |
| Wind Chill Advisory | 3 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Wind Advisory | 6 |
| Fire | |
| Red Flag Warning | 2 |
| Fire Weather Watch | 2 |
| Fog and smoke | |
| Dense Fog Advisory | 11 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20172019
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.