Alert archive / Virginia / Loudoun County
Weather alerts in Loudoun County, Virginia, 2013
105 weather alerts in 2013, 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 2013. Tap one for its archive.
- Alerts
- 105
- Warnings
- 37
- Watches
- 19
- Advisories
- 0
- Busiest month
- June44 alerts
- Busiest day
- June 13, 201313 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 1 tornado warnings covering Loudoun County in 2013 had a tornado report inside them.
Loudoun County, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 1 | 1 | 0% | 0 | ||
| Severe thunderstorm warnings | 23 | 10 | 57% | 30 | 73% | 26 min |
| Flash flood warnings | 4 | 4 | 0% | 12 | 75% | 83 min |
Each office's whole area, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Baltimore/Washington: tornado warnings | 22 | 9 | 59% | 21 | 62% | 11 min |
| NWS Baltimore/Washington: severe thunderstorm warnings | 210 | 141 | 33% | 495 | 74% | 21 min |
| NWS Baltimore/Washington: flash flood warnings | 81 | 51 | 37% | 124 | 78% | 74 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 30, 10:19 AM EST | Mesoscale Discussion | SPC | 86 min |
| Jan 30, 12:54 PM EST | Mesoscale Discussion | SPC | 96 min |
| Jan 30, 1:49 PM EST | Special Weather Statement | LWX | 26 min |
| Jan 30, 2:15 PM EST | Special Weather Statement | LWX | 45 min |
| Jan 30, 3:12 PM EST | River Flood Watch | LWX | 18 hr |
| Jan 30, 5:25 PM EST | Special Weather Statement | LWX | 80 min |
| Jan 30, 5:39 PM EST | Flash Flood Warning | LWX | 4 hr |
| Jan 30, 6:31 PM EST | Tornado Watch | SPC | 8 hr |
| Jan 30, 9:38 PM EST | Mesoscale Discussion | SPC | 67 min |
| Jan 30, 9:39 PM EST | Areal Flood Warning | LWX | 6 hr |
| Jan 30, 9:42 PM EST | River Flood Warning | LWX | 31 hr |
| Jan 30, 10:30 PM EST | Flash Flood Warning | LWX | 6 hr |
| Jan 31, 5:36 AM EST | Areal Flood Warning | LWX | 7 hr |
| Jan 31, 9:36 AM EST | River Flood Warning | LWX | 34 hr |
| Mar 5, 10:52 PM EST | Mesoscale Discussion | SPC | 6 hr |
| Mar 6, 3:25 AM EST | Mesoscale Discussion | SPC | 4 hr |
| Mar 25, 5:31 AM EDT | Mesoscale Discussion | SPC | 6 hr |
| Apr 19, 1:27 PM EDT | Mesoscale Discussion | SPC | 63 min |
| Apr 19, 2:31 PM EDT | Tornado Watch | SPC | 7 hr |
| Apr 19, 4:36 PM EDT | Mesoscale Discussion | SPC | 114 min |
| Apr 19, 5:33 PM EDT | Special Weather Statement | LWX | 57 min |
| Apr 24, 6:59 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| May 8, 11:04 AM EDT | River Flood Watch | LWX | 23 hr |
| May 8, 2:16 PM EDT | Special Weather Statement | LWX | 29 min |
| May 9, 10:15 AM EDT | River Flood Warning | LWX | 12 hr |
| May 10, 7:32 PM EDT | Severe Thunderstorm Warning | LWX | 43 min |
| May 10, 8:22 PM EDT | Special Weather Statement | LWX | 23 min |
| May 11, 1:44 PM EDT | Mesoscale Discussion | SPC | 91 min |
| May 22, 3:53 PM EDT | Mesoscale Discussion | SPC | 67 min |
| May 22, 6:23 PM EDT | Severe Thunderstorm Warning | LWX | 37 min |
| May 22, 8:33 PM EDT | Severe Thunderstorm Warning | LWX | 42 min |
| May 23, 3:06 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| May 23, 3:37 PM EDT | Mesoscale Discussion | SPC | 53 min |
| May 28, 4:01 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 2, 3:18 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 2, 3:31 PM EDT | Severe Thunderstorm Warning | LWX | 44 min |
| Jun 2, 4:18 PM EDT | Special Weather Statement | LWX | 27 min |
| Jun 10, 12:56 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 10, 2:02 PM EDT | Tornado Watch | SPC | 10 hr |
| Jun 10, 4:38 PM EDT | Mesoscale Discussion | SPC | 97 min |
| Jun 10, 5:22 PM EDT | Severe Thunderstorm Warning | LWX | 23 min |
| Jun 10, 5:42 PM EDT | Severe Thunderstorm Warning | LWX | 48 min |
| Jun 10, 6:38 PM EDT | Areal Flood Warning | LWX | 13 hr |
| Jun 13, 2:40 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 13, 3:58 AM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 13, 5:27 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 13, 7:52 AM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Jun 13, 8:10 AM EDT | Mesoscale Discussion | SPC | 95 min |
| Jun 13, 11:38 AM EDT | Mesoscale Discussion | SPC | 67 min |
| Jun 13, 12:19 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 13, 2:20 PM EDT | Mesoscale Discussion | SPC | 55 min |
| Jun 13, 2:56 PM EDT | Severe Thunderstorm Warning | LWX | 49 min |
| Jun 13, 3:16 PM EDT | Flash Flood Warning | LWX | 3 hr |
| Jun 13, 3:23 PM EDT | Tornado Warning | LWX | 37 min |
| Jun 13, 3:29 PM EDT | Severe Thunderstorm Warning | LWX | 61 min |
| Jun 13, 5:50 PM EDT | Areal Flood Warning | LWX | 4 hr |
| Jun 24, 1:48 PM EDT | Mesoscale Discussion | SPC | 57 min |
| Jun 24, 2:44 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jun 24, 3:06 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| Jun 24, 3:10 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Jun 24, 3:25 PM EDT | Severe Thunderstorm Warning | LWX | 50 min |
| Jun 24, 3:51 PM EDT | Severe Thunderstorm Warning | LWX | 39 min |
| Jun 25, 6:20 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 25, 9:37 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Jun 25, 10:06 PM EDT | Severe Thunderstorm Warning | LWX | 54 min |
| Jun 26, 1:19 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 26, 2:47 PM EDT | Severe Thunderstorm Warning | LWX | 43 min |
| Jun 26, 2:55 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 26, 4:38 PM EDT | Mesoscale Discussion | SPC | 97 min |
| Jun 27, 1:04 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jun 27, 1:58 PM EDT | Tornado Watch | SPC | 7 hr |
| Jun 28, 1:02 PM EDT | Mesoscale Discussion | SPC | 118 min |
| Jun 28, 1:09 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 28, 2:33 PM EDT | Severe Thunderstorm Warning | LWX | 42 min |
| Jun 28, 2:43 PM EDT | Severe Thunderstorm Warning | LWX | 32 min |
| Jun 28, 2:50 PM EDT | Severe Thunderstorm Warning | LWX | 40 min |
| Jun 28, 3:30 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 30, 11:48 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 7, 1:16 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 7, 3:19 PM EDT | Mesoscale Discussion | SPC | 116 min |
| Jul 7, 5:07 PM EDT | Severe Thunderstorm Warning | LWX | 38 min |
| Jul 11, 10:39 PM EDT | Flash Flood Warning | LWX | 3 hr |
| Jul 12, 1:44 AM EDT | Areal Flood Warning | LWX | 14 hr |
| Jul 17, 2:22 PM EDT | Mesoscale Discussion | SPC | 83 min |
| Jul 19, 6:09 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 20, 1:07 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 20, 8:15 PM EDT | Mesoscale Discussion | SPC | 60 min |
| Jul 22, 1:18 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jul 27, 5:25 PM EDT | Mesoscale Discussion | SPC | 95 min |
| Aug 22, 2:26 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 12, 1:29 PM EDT | Mesoscale Discussion | SPC | 91 min |
| Sep 12, 2:50 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Sep 12, 3:24 PM EDT | Severe Thunderstorm Warning | LWX | 36 min |
| Oct 7, 8:10 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Oct 7, 8:24 AM EDT | Severe Thunderstorm Warning | LWX | 51 min |
| Oct 7, 8:56 AM EDT | Tornado Watch | SPC | 8 hr |
| Oct 11, 5:20 PM EDT | Areal Flood Warning | LWX | 12 hr |
| Nov 1, 3:37 AM EDT | Mesoscale Discussion | SPC | 83 min |
| Nov 1, 4:17 AM EDT | Severe Thunderstorm Watch | SPC | 4 hr |
| Nov 17, 11:31 PM EST | Severe Thunderstorm Watch | SPC | 2 hr |
| Dec 8, 11:05 AM EST | Mesoscale Discussion | SPC | 3 hr |
| Dec 8, 2:30 PM EST | Mesoscale Discussion | SPC | 2 hr |
| Dec 10, 4:37 AM EST | Mesoscale Discussion | SPC | 4 hr |
| Dec 22, 3:37 AM EST | Severe Thunderstorm Watch | SPC | 5 hr |
| Dec 22, 6:14 AM EST | Mesoscale Discussion | SPC | 61 min |
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 archive20122014
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.