Alert archive / Virginia / Loudoun County

Weather alerts in Loudoun County, Virginia, 2015

165 weather alerts in 2015, 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 2015. Tap one for its archive.

Alerts: 165
Warnings: 59
Watches: 25
Advisories: 50
Busiest month: June44 alerts
Busiest day: June 20, 201511 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 Loudoun County in 2015 had a tornado report inside them.

Loudoun County, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	2	1	50%	0
Severe thunderstorm warnings	37	29	22%	27	74%	18 min
Flash flood warnings	3	2	33%	3	0%

Each office's whole area, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Baltimore/Washington: tornado warnings	17	2	88%	4	50%	5 min
NWS Baltimore/Washington: severe thunderstorm warnings	235	153	35%	526	75%	16 min
NWS Baltimore/Washington: flash flood warnings	89	47	47%	138	74%	64 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 2, 2:06 PM EST	Winter Weather Advisory	LWX	25 hr
Jan 5, 1:59 PM EST	Winter Weather Advisory	LWX	53 hr
Jan 6, 7:01 AM EST	Winter Storm Warning	LWX	12 hr
Jan 6, 2:58 PM EST	Wind Chill Advisory	LWX	50 hr
Jan 8, 8:18 AM EST	Wind Chill Advisory	LWX	42 min
Jan 11, 3:03 PM EST	Freezing Rain Advisory	LWX	22 hr
Jan 11, 8:50 PM EST	Mesoscale Discussion	SPC	6 hr
Jan 13, 4:59 PM EST	Winter Weather Advisory	LWX	22 hr
Jan 20, 2:55 PM EST	Winter Weather Advisory	LWX	26 hr
Jan 21, 6:32 PM EST	Winter Weather Advisory	LWX	15 hr
Jan 21, 10:56 PM EST	Dense Fog Advisory	LWX	12 hr
Jan 23, 4:19 AM EST	Winter Weather Advisory	LWX	32 hr
Jan 24, 2:49 PM EST	Winter Storm Watch	LWX	19 hr
Jan 25, 9:38 AM EST	Winter Weather Advisory	LWX	47 hr
Jan 29, 3:56 AM EST	Winter Weather Advisory	LWX	32 hr
Jan 29, 9:44 PM EST	Wind Advisory	LWX	26 hr
Jan 31, 8:04 PM EST	Winter Weather Advisory	LWX	47 hr
Feb 1, 10:39 PM EST	Wind Advisory	LWX	23 hr
Feb 9, 8:47 AM EST	Winter Weather Advisory	LWX	26 hr
Feb 12, 3:33 AM EST	Wind Advisory	LWX	21 hr
Feb 12, 3:48 AM EST	Wind Chill Advisory	LWX	32 hr
Feb 13, 3:25 AM EST	High Wind Watch	LWX	24 hr
Feb 13, 3:48 AM EST	Wind Chill Watch	LWX	24 hr
Feb 13, 2:56 PM EST	Winter Weather Advisory	LWX	33 hr
Feb 14, 3:17 AM EST	High Wind Warning	LWX	32 hr
Feb 14, 3:17 AM EST	Wind Advisory	LWX	36 hr
Feb 14, 3:44 AM EST	Wind Chill Warning	LWX	54 hr
Feb 14, 3:44 AM EST	Wind Chill Advisory	LWX	16 hr
Feb 14, 7:23 PM EST	Wind Chill Advisory	LWX	38 hr
Feb 15, 3:12 PM EST	Winter Storm Watch	LWX	13 hr
Feb 15, 9:53 PM EST	Winter Storm Warning	LWX	33 hr
Feb 17, 8:45 PM EST	Winter Weather Advisory	LWX	28 hr
Feb 18, 4:13 AM EST	Wind Chill Advisory	LWX	56 hr
Feb 19, 5:57 PM EST	Winter Storm Watch	LWX	22 hr
Feb 20, 3:37 PM EST	Winter Storm Warning	LWX	41 hr
Feb 20, 3:37 PM EST	Winter Weather Advisory	LWX	41 hr
Feb 21, 6:24 PM EST	Mesoscale Discussion	SPC	4 hr
Feb 25, 4:03 AM EST	Winter Weather Advisory	LWX	32 hr
Feb 28, 2:53 PM EST	Winter Weather Advisory	LWX	38 hr
Mar 1, 3:42 AM EST	Winter Storm Warning	LWX	18 hr
Mar 2, 4:51 AM EST	Dense Fog Advisory	LWX	4 hr
Mar 2, 3:37 PM EST	Winter Weather Advisory	LWX	30 hr
Mar 3, 2:50 PM EST	Winter Storm Watch	LWX	23 hr
Mar 4, 4:51 AM EST	Winter Storm Warning	LWX	39 hr
Mar 5, 7:58 AM EST	Mesoscale Discussion	SPC	5 hr
Mar 5, 11:55 AM EST	Mesoscale Discussion	SPC	6 hr
Mar 5, 2:13 PM EST	Wind Chill Advisory	LWX	18 hr
Mar 10, 5:23 PM EDT	Dense Fog Advisory	LWX	13 hr
Mar 19, 4:23 AM EDT	Winter Weather Advisory	LWX	34 hr
Mar 25, 3:03 AM EDT	Freezing Rain Advisory	LWX	8 hr
Mar 26, 6:12 PM EDT	Mesoscale Discussion	SPC	2 hr
Mar 31, 11:47 AM EDT	Wind Advisory	LWX	10 hr
Apr 11, 1:54 PM EDT	Frost Advisory	LWX	19 hr
Apr 19, 4:10 AM EDT	Flood Watch	LWX	26 hr
Apr 20, 1:54 PM EDT	Mesoscale Discussion	SPC	3 hr
Apr 20, 3:08 PM EDT	Tornado Watch	SPC	9 hr
Apr 20, 5:01 PM EDT	Mesoscale Discussion	SPC	119 min
Apr 22, 4:10 AM EDT	Wind Advisory	LWX	15 hr
Apr 22, 12:19 PM EDT	Severe Thunderstorm Warning	LWX	25 min
Apr 22, 12:32 PM EDT	Mesoscale Discussion	SPC	118 min
Apr 23, 2:07 PM EDT	Freeze Warning	LWX	17 hr
Apr 24, 3:23 AM EDT	Freeze Watch	LWX	11 hr
Apr 24, 2:35 PM EDT	Frost Advisory	LWX	18 hr
Apr 24, 2:35 PM EDT	Freeze Warning	LWX	18 hr
May 6, 3:21 PM EDT	Mesoscale Discussion	SPC	114 min
May 6, 4:41 PM EDT	Severe Thunderstorm Warning	LWX	34 min
May 11, 6:55 AM EDT	Dense Fog Advisory	LWX	2 hr
May 16, 1:35 PM EDT	Mesoscale Discussion	SPC	2 hr
May 16, 4:09 PM EDT	Severe Thunderstorm Warning	LWX	36 min
May 16, 4:14 PM EDT	Severe Thunderstorm Warning	LWX	31 min
May 16, 4:31 PM EDT	Severe Thunderstorm Warning	LWX	29 min
May 16, 5:02 PM EDT	Severe Thunderstorm Warning	LWX	43 min
May 27, 12:21 PM EDT	Mesoscale Discussion	SPC	54 min
May 27, 12:54 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
May 27, 2:59 PM EDT	Mesoscale Discussion	SPC	2 hr
May 31, 10:06 PM EDT	Severe Thunderstorm Warning	LWX	24 min
Jun 1, 4:22 AM EDT	Flash Flood Watch	LWX	23 hr
Jun 1, 6:20 PM EDT	Severe Thunderstorm Warning	LWX	25 min
Jun 1, 6:41 PM EDT	Severe Thunderstorm Warning	LWX	34 min
Jun 8, 2:34 PM EDT	Tornado Watch	SPC	5 hr
Jun 8, 4:46 PM EDT	Mesoscale Discussion	SPC	59 min
Jun 8, 6:17 PM EDT	Severe Thunderstorm Warning	LWX	28 min
Jun 8, 6:27 PM EDT	Severe Thunderstorm Warning	LWX	33 min
Jun 8, 6:43 PM EDT	Severe Thunderstorm Warning	LWX	32 min
Jun 8, 7:07 PM EDT	Mesoscale Discussion	SPC	53 min
Jun 8, 7:12 PM EDT	Severe Thunderstorm Warning	LWX	48 min
Jun 8, 7:24 PM EDT	Severe Thunderstorm Watch	SPC	2 hr
Jun 12, 2:03 PM EDT	Mesoscale Discussion	SPC	87 min
Jun 14, 2:06 PM EDT	Mesoscale Discussion	SPC	84 min
Jun 16, 12:15 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 18, 4:00 PM EDT	Severe Thunderstorm Warning	LWX	30 min
Jun 18, 4:30 PM EDT	Severe Thunderstorm Warning	LWX	30 min
Jun 18, 4:48 PM EDT	Severe Thunderstorm Warning	LWX	42 min
Jun 19, 12:50 AM EDT	Severe Thunderstorm Warning	LWX	28 min
Jun 19, 3:11 PM EDT	Flash Flood Watch	LWX	38 hr
Jun 20, 1:36 PM EDT	Mesoscale Discussion	SPC	114 min
Jun 20, 2:23 PM EDT	Severe Thunderstorm Watch	SPC	9 hr
Jun 20, 6:24 PM EDT	Mesoscale Discussion	SPC	96 min
Jun 20, 6:30 PM EDT	Severe Thunderstorm Warning	LWX	30 min
Jun 20, 7:00 PM EDT	Severe Thunderstorm Warning	LWX	30 min
Jun 20, 7:05 PM EDT	Tornado Warning	LWX	25 min
Jun 20, 7:21 PM EDT	Severe Thunderstorm Warning	LWX	39 min
Jun 20, 7:35 PM EDT	Tornado Warning	LWX	25 min
Jun 20, 7:40 PM EDT	Severe Thunderstorm Warning	LWX	35 min
Jun 20, 7:48 PM EDT	Severe Thunderstorm Warning	LWX	27 min
Jun 20, 7:59 PM EDT	Flash Flood Warning	LWX	4 hr
Jun 23, 1:45 PM EDT	Mesoscale Discussion	SPC	3 hr
Jun 23, 4:09 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 23, 4:54 PM EDT	Severe Thunderstorm Warning	LWX	36 min
Jun 23, 5:22 PM EDT	Severe Thunderstorm Warning	LWX	38 min
Jun 23, 5:47 PM EDT	Mesoscale Discussion	SPC	88 min
Jun 23, 6:01 PM EDT	Severe Thunderstorm Warning	LWX	29 min
Jun 23, 6:27 PM EDT	Severe Thunderstorm Warning	LWX	48 min
Jun 23, 6:35 PM EDT	Severe Thunderstorm Warning	LWX	25 min
Jun 23, 6:46 PM EDT	Severe Thunderstorm Warning	LWX	29 min
Jun 23, 7:41 PM EDT	Mesoscale Discussion	SPC	94 min
Jun 26, 4:20 AM EDT	Flash Flood Watch	LWX	40 hr
Jun 27, 2:38 PM EDT	Flash Flood Warning	LWX	3 hr
Jun 30, 2:22 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 30, 9:37 PM EDT	Severe Thunderstorm Warning	LWX	38 min
Jun 30, 11:36 PM EDT	Severe Thunderstorm Warning	LWX	24 min
Jun 30, 11:55 PM EDT	Severe Thunderstorm Warning	LWX	35 min
Jul 4, 9:53 PM EDT	Dense Fog Advisory	LWX	12 hr
Jul 6, 1:01 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 9, 12:59 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 9, 3:09 PM EDT	Mesoscale Discussion	SPC	96 min
Jul 14, 5:05 AM EDT	Flash Flood Watch	LWX	16 hr
Jul 14, 5:50 PM EDT	Severe Thunderstorm Warning	LWX	25 min
Jul 14, 6:10 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 14, 6:28 PM EDT	Severe Thunderstorm Warning	LWX	32 min
Jul 14, 6:44 PM EDT	Severe Thunderstorm Watch	SPC	4 hr
Jul 14, 6:58 PM EDT	Severe Thunderstorm Warning	LWX	21 min
Jul 18, 3:11 PM EDT	Heat Advisory	LWX	29 hr
Jul 20, 3:41 AM EDT	Heat Advisory	LWX	16 hr
Aug 4, 3:29 AM EDT	Mesoscale Discussion	SPC	3 hr
Aug 4, 3:44 AM EDT	Severe Thunderstorm Warning	LWX	46 min
Aug 4, 4:14 AM EDT	Severe Thunderstorm Warning	LWX	46 min
Aug 4, 4:22 AM EDT	Severe Thunderstorm Warning	LWX	53 min
Aug 11, 1:30 PM EDT	Mesoscale Discussion	SPC	3 hr
Aug 20, 11:49 AM EDT	Mesoscale Discussion	SPC	2 hr
Aug 20, 3:45 PM EDT	Mesoscale Discussion	SPC	3 hr
Sep 2, 3:35 PM EDT	Mesoscale Discussion	SPC	85 min
Sep 29, 4:20 AM EDT	Flash Flood Watch	LWX	23 hr
Sep 29, 8:56 PM EDT	Areal Flood Warning	LWX	3 hr
Sep 29, 9:08 PM EDT	Flash Flood Warning	LWX	3 hr
Sep 29, 10:26 PM EDT	Areal Flood Warning	LWX	6 hr
Sep 29, 10:55 PM EDT	Areal Flood Warning	LWX	7 hr
Sep 29, 11:01 PM EDT	Areal Flood Warning	LWX	3 hr
Sep 29, 11:45 PM EDT	River Flood Warning	LWX	15 hr
Sep 30, 1:09 AM EDT	Areal Flood Warning	LWX	6 hr
Oct 1, 4:19 AM EDT	Flash Flood Watch	LWX	50 hr
Oct 16, 3:57 AM EDT	Freeze Watch	LWX	24 hr
Oct 17, 3:34 AM EDT	Freeze Watch	LWX	31 hr
Oct 17, 3:34 AM EDT	Freeze Warning	LWX	29 hr
Oct 18, 10:38 AM EDT	Freeze Warning	LWX	22 hr
Nov 12, 8:34 AM EST	Wind Advisory	LWX	43 hr
Dec 1, 10:47 PM EST	Dense Fog Advisory	LWX	17 hr
Dec 6, 9:28 PM EST	Dense Fog Advisory	LWX	6 hr
Dec 9, 6:14 AM EST	Dense Fog Advisory	LWX	7 hr
Dec 10, 3:16 AM EST	Dense Fog Advisory	LWX	8 hr
Dec 17, 9:57 PM EST	Dense Fog Advisory	LWX	5 hr
Dec 25, 4:14 AM EST	Dense Fog Advisory	LWX	9 hr
Dec 25, 1:19 PM EST	Flash Flood Watch	LWX	6 hr
Dec 30, 12:08 AM EST	Dense Fog Advisory	LWX	11 hr
Dec 31, 1:18 AM EST	Dense Fog Advisory	LWX	9 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	37
Tornado Warning	2
Severe Thunderstorm Watch	6
Tornado Watch	2
Mesoscale Discussion	31
Flooding
Areal Flood Warning	5
Flash Flood Warning	3
River Flood Warning	1
Flash Flood Watch	7
Flood Watch	1
Winter
Winter Storm Warning	5
Winter Storm Watch	4
Freezing Rain Advisory	2
Winter Weather Advisory	17
Heat
Heat Advisory	2
Cold
Freeze Warning	4
Wind Chill Warning	1
Freeze Watch	3
Wind Chill Watch	1
Frost Advisory	2
Wind Chill Advisory	7
Wind and dust
High Wind Warning	1
High Wind Watch	1
Wind Advisory	7
Fog and smoke
Dense Fog Advisory	13

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2014 2016

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.