Alert archive / Virginia / Loudoun County

Weather alerts in Loudoun County, Virginia, 2021

183 weather alerts in 2021, 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 2021. Tap one for its archive.

Alerts: 183
Warnings: 78
Watches: 40
Advisories: 30
Busiest month: August37 alerts
Busiest day: May 26, 202111 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 2021 had a tornado report inside them.

Loudoun County, 2021

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	1	1	0%	0
Severe thunderstorm warnings	55	39	29%	45	76%	21 min
Flash flood warnings	1	0	100%	0

Each office's whole area, 2021

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Baltimore/Washington: tornado warnings	49	10	80%	13	100%	11 min
NWS Baltimore/Washington: severe thunderstorm warnings	544	396	27%	1,446	83%	20 min
NWS Baltimore/Washington: flash flood warnings	76	32	58%	96	77%	60 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, 5:37 PM EST	Winter Weather Advisory	LWX	30 hr
Jan 25, 1:05 AM EST	Winter Weather Advisory	LWX	36 hr
Jan 26, 8:18 PM EST	Dense Fog Advisory	LWX	13 hr
Jan 29, 3:10 PM EST	Winter Storm Watch	LWX	23 hr
Jan 30, 9:02 AM EST	Winter Storm Warning	LWX	69 hr
Jan 31, 6:50 PM EST	Winter Weather Advisory	LWX	42 hr
Feb 5, 3:13 PM EST	Winter Storm Watch	LWX	12 hr
Feb 6, 3:22 AM EST	Winter Storm Warning	LWX	33 hr
Feb 10, 3:33 AM EST	Winter Weather Advisory	LWX	30 hr
Feb 12, 3:10 PM EST	Ice Storm Warning	LWX	30 hr
Feb 12, 3:10 PM EST	Winter Weather Advisory	LWX	43 hr
Feb 13, 10:02 AM EST	Mesoscale Discussion	SPC	6 hr
Feb 14, 10:00 AM EST	Winter Weather Advisory	LWX	44 hr
Feb 15, 4:24 AM EST	Winter Weather Advisory	LWX	25 hr
Feb 16, 4:56 AM EST	Winter Storm Watch	LWX	29 hr
Feb 17, 3:24 AM EST	Winter Storm Warning	LWX	57 hr
Feb 18, 10:23 AM EST	Mesoscale Discussion	SPC	3 hr
Feb 18, 1:05 PM EST	Winter Weather Advisory	LWX	23 hr
Feb 21, 3:17 PM EST	Winter Weather Advisory	LWX	24 hr
Feb 22, 8:22 PM EST	Wind Advisory	LWX	22 hr
Feb 28, 10:55 AM EST	River Flood Watch	LWX	21 days
Feb 28, 10:55 AM EST	River Flood Watch	LWX	21 days
Feb 28, 9:09 PM EST	Dense Fog Advisory	LWX	8 hr
Mar 1, 3:22 AM EST	River Flood Warning	LWX	42 hr
Mar 1, 5:26 AM EST	Wind Advisory	LWX	19 hr
Mar 1, 10:15 AM EST	River Flood Warning	LWX	52 hr
Mar 10, 3:43 PM EST	Fire Weather Watch	LWX	12 hr
Mar 11, 3:28 AM EST	Red Flag Warning	LWX	15 hr
Mar 13, 1:53 PM EST	Fire Weather Watch	LWX	13 hr
Mar 14, 4:01 AM EDT	Red Flag Warning	LWX	18 hr
Mar 24, 9:09 PM EDT	Dense Fog Advisory	LWX	14 hr
Mar 25, 2:41 PM EDT	Wind Advisory	LWX	27 hr
Mar 28, 4:16 AM EDT	Wind Advisory	LWX	23 hr
Mar 28, 4:30 PM EDT	Severe Thunderstorm Warning	LWX	45 min
Apr 11, 4:54 PM EDT	Mesoscale Discussion	SPC	2 hr
Apr 21, 4:08 AM EDT	Freeze Warning	LWX	29 hr
Apr 21, 2:47 PM EDT	Wind Advisory	LWX	5 hr
Apr 21, 9:06 PM EDT	Freeze Watch	LWX	15 hr
Apr 22, 12:03 PM EDT	Freeze Warning	LWX	20 hr
Apr 29, 3:59 AM EDT	High Wind Watch	LWX	16 hr
Apr 29, 8:18 PM EDT	High Wind Warning	LWX	25 hr
Apr 29, 8:18 PM EDT	Wind Advisory	LWX	30 hr
Apr 30, 4:31 PM EDT	Severe Thunderstorm Warning	LWX	29 min
Apr 30, 4:39 PM EDT	Severe Thunderstorm Warning	LWX	36 min
May 3, 6:26 PM EDT	Tornado Warning	LWX	34 min
May 4, 1:51 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
May 4, 3:50 PM EDT	Mesoscale Discussion	SPC	115 min
May 4, 4:01 PM EDT	Severe Thunderstorm Warning	LWX	44 min
May 4, 4:26 PM EDT	Severe Thunderstorm Warning	LWX	49 min
May 17, 2:51 AM EDT	Dense Fog Advisory	LWX	7 hr
May 26, 1:21 PM EDT	Mesoscale Discussion	SPC	84 min
May 26, 2:48 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
May 26, 2:51 PM EDT	Severe Thunderstorm Warning	LWX	39 min
May 26, 3:21 PM EDT	Severe Thunderstorm Warning	LWX	39 min
May 26, 3:40 PM EDT	Severe Thunderstorm Warning	LWX	28 min
May 26, 3:59 PM EDT	Severe Thunderstorm Warning	LWX	9 min
May 26, 4:05 PM EDT	Severe Thunderstorm Warning	LWX	40 min
May 26, 6:34 PM EDT	Mesoscale Discussion	SPC	116 min
May 26, 6:51 PM EDT	Severe Thunderstorm Warning	LWX	39 min
May 26, 7:27 PM EDT	Severe Thunderstorm Warning	LWX	48 min
May 26, 7:50 PM EDT	Severe Thunderstorm Warning	LWX	40 min
Jun 3, 1:46 PM EDT	Mesoscale Discussion	SPC	119 min
Jun 3, 2:48 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 3, 3:14 PM EDT	Severe Thunderstorm Warning	LWX	46 min
Jun 3, 3:50 PM EDT	Severe Thunderstorm Warning	LWX	40 min
Jun 3, 4:08 PM EDT	Severe Thunderstorm Warning	LWX	52 min
Jun 3, 4:47 PM EDT	Mesoscale Discussion	SPC	88 min
Jun 3, 4:54 PM EDT	Severe Thunderstorm Warning	LWX	36 min
Jun 10, 2:53 AM EDT	Flash Flood Watch	LWX	43 hr
Jun 10, 5:05 PM EDT	Flash Flood Warning Considerable damage threat	LWX	114 min
Jun 11, 11:51 AM EDT	Areal Flood Warning	LWX	9 hr
Jun 11, 1:10 PM EDT	Areal Flood Warning	LWX	6 hr
Jun 11, 1:41 PM EDT	Areal Flood Warning	LWX	6 hr
Jun 13, 12:32 PM EDT	Mesoscale Discussion	SPC	118 min
Jun 14, 3:55 PM EDT	Mesoscale Discussion	SPC	65 min
Jun 14, 6:41 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 14, 7:29 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 14, 8:26 PM EDT	Severe Thunderstorm Warning	LWX	37 min
Jun 14, 9:55 PM EDT	Severe Thunderstorm Warning	LWX	50 min
Jun 14, 10:11 PM EDT	Severe Thunderstorm Warning	LWX	49 min
Jun 21, 1:51 PM EDT	Mesoscale Discussion	SPC	114 min
Jun 21, 2:20 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 21, 4:26 PM EDT	Severe Thunderstorm Warning	LWX	49 min
Jun 21, 4:43 PM EDT	Severe Thunderstorm Warning	LWX	32 min
Jun 21, 4:47 PM EDT	Severe Thunderstorm Warning	LWX	28 min
Jun 21, 5:02 PM EDT	Severe Thunderstorm Warning	LWX	43 min
Jun 21, 5:14 PM EDT	Severe Thunderstorm Warning	LWX	31 min
Jun 30, 2:23 PM EDT	Flash Flood Watch	LWX	42 hr
Jun 30, 6:58 PM EDT	Mesoscale Discussion	SPC	92 min
Jul 1, 11:45 AM EDT	Mesoscale Discussion	SPC	2 hr
Jul 1, 12:46 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 1, 1:03 PM EDT	Severe Thunderstorm Warning	LWX	42 min
Jul 1, 1:53 PM EDT	Severe Thunderstorm Warning	LWX	52 min
Jul 1, 2:11 PM EDT	Severe Thunderstorm Warning	LWX	49 min
Jul 1, 2:28 PM EDT	Severe Thunderstorm Warning	LWX	47 min
Jul 1, 8:26 PM EDT	Severe Thunderstorm Warning	LWX	37 min
Jul 12, 1:32 PM EDT	Mesoscale Discussion	SPC	88 min
Jul 12, 3:15 PM EDT	Severe Thunderstorm Warning	LWX	22 min
Jul 12, 3:34 PM EDT	Severe Thunderstorm Watch	SPC	5 hr
Jul 14, 3:24 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 14, 4:01 PM EDT	Severe Thunderstorm Warning	LWX	44 min
Jul 17, 12:00 PM EDT	Mesoscale Discussion	SPC	3 hr
Jul 17, 1:13 PM EDT	Severe Thunderstorm Watch	SPC	10 hr
Jul 17, 2:58 PM EDT	Severe Thunderstorm Warning	LWX	28 min
Jul 17, 3:09 PM EDT	Severe Thunderstorm Warning	LWX	39 min
Jul 17, 3:30 PM EDT	Severe Thunderstorm Warning	LWX	45 min
Jul 17, 4:38 PM EDT	Mesoscale Discussion	SPC	97 min
Jul 17, 6:35 PM EDT	Severe Thunderstorm Warning	LWX	40 min
Jul 17, 6:54 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 21, 11:56 AM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 21, 1:59 PM EDT	Severe Thunderstorm Warning	LWX	23 min
Jul 28, 6:27 PM EDT	Severe Thunderstorm Warning	LWX	14 min
Jul 29, 1:21 PM EDT	Mesoscale Discussion	SPC	114 min
Jul 29, 3:00 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 10, 1:33 PM EDT	Excessive Heat Watch	LWX	37 hr
Aug 10, 1:33 PM EDT	Heat Advisory	LWX	29 hr
Aug 10, 2:30 PM EDT	Mesoscale Discussion	SPC	3 hr
Aug 10, 4:34 PM EDT	Severe Thunderstorm Warning	LWX	41 min
Aug 10, 5:16 PM EDT	Severe Thunderstorm Warning	LWX	44 min
Aug 10, 5:41 PM EDT	Severe Thunderstorm Warning Considerable damage threat	LWX	35 min
Aug 11, 1:01 PM EDT	Mesoscale Discussion	SPC	89 min
Aug 11, 2:02 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 11, 2:49 PM EDT	Severe Thunderstorm Warning Considerable damage threat	LWX	41 min
Aug 11, 2:59 PM EDT	Severe Thunderstorm Warning	LWX	46 min
Aug 11, 3:18 PM EDT	Severe Thunderstorm Warning	LWX	42 min
Aug 11, 3:42 PM EDT	Severe Thunderstorm Warning	LWX	48 min
Aug 11, 3:47 PM EDT	Mesoscale Discussion	SPC	88 min
Aug 12, 2:15 AM EDT	Heat Advisory	LWX	18 hr
Aug 12, 6:04 PM EDT	Heat Advisory	LWX	25 hr
Aug 13, 12:33 PM EDT	Mesoscale Discussion	SPC	87 min
Aug 13, 1:11 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 13, 4:05 PM EDT	Severe Thunderstorm Warning	LWX	40 min
Aug 13, 4:46 PM EDT	Severe Thunderstorm Warning	LWX	29 min
Aug 14, 6:14 PM EDT	Flash Flood Watch	LWX	10 hr
Aug 17, 12:09 AM EDT	Areal Flood Warning	LWX	4 hr
Aug 17, 1:54 PM EDT	Flash Flood Watch	LWX	27 hr
Aug 18, 8:46 AM EDT	Mesoscale Discussion	SPC	119 min
Aug 18, 10:58 AM EDT	Mesoscale Discussion	SPC	92 min
Aug 18, 11:37 AM EDT	Tornado Watch	SPC	11 hr
Aug 18, 3:29 PM EDT	Mesoscale Discussion	SPC	91 min
Aug 18, 4:57 PM EDT	Mesoscale Discussion	SPC	93 min
Aug 19, 2:11 PM EDT	Flash Flood Watch	LWX	28 hr
Aug 25, 5:41 PM EDT	Severe Thunderstorm Warning	LWX	49 min
Aug 25, 6:29 PM EDT	Severe Thunderstorm Warning	LWX	46 min
Aug 25, 7:23 PM EDT	Severe Thunderstorm Warning	LWX	21 min
Aug 27, 1:41 PM EDT	Mesoscale Discussion	SPC	3 hr
Aug 28, 1:05 PM EDT	Mesoscale Discussion	SPC	115 min
Aug 28, 6:55 PM EDT	Severe Thunderstorm Warning	LWX	33 min
Aug 28, 7:18 PM EDT	Severe Thunderstorm Warning	LWX	42 min
Aug 30, 4:54 AM EDT	Flash Flood Watch	LWX	62 hr
Aug 30, 11:48 AM EDT	Flash Flood Watch	LWX	6 hr
Aug 31, 9:44 PM EDT	River Flood Watch	LWX	25 hr
Aug 31, 9:44 PM EDT	River Flood Watch	LWX	48 hr
Sep 1, 12:19 AM EDT	Mesoscale Discussion	SPC	86 min
Sep 1, 12:56 AM EDT	Tornado Watch	SPC	6 hr
Sep 1, 2:25 AM EDT	Areal Flood Warning	LWX	11 hr
Sep 1, 4:34 AM EDT	Areal Flood Warning	LWX	6 hr
Sep 1, 11:03 AM EDT	Mesoscale Discussion	SPC	2 hr
Sep 1, 11:46 AM EDT	Tornado Watch	SPC	9 hr
Sep 1, 1:30 PM EDT	Areal Flood Warning	LWX	27 hr
Sep 2, 11:26 AM EDT	River Flood Watch	LWX	33 hr
Sep 2, 9:36 PM EDT	River Flood Warning	LWX	15 hr
Sep 8, 6:11 PM EDT	Flash Flood Watch	LWX	10 hr
Sep 8, 8:29 PM EDT	Severe Thunderstorm Watch	SPC	4 hr
Sep 8, 9:11 PM EDT	Severe Thunderstorm Warning	LWX	64 min
Sep 8, 10:42 PM EDT	Mesoscale Discussion	SPC	2 hr
Sep 16, 2:44 PM EDT	Flash Flood Watch	LWX	6 hr
Sep 21, 3:04 AM EDT	Flash Flood Watch	LWX	57 hr
Oct 4, 4:44 PM EDT	Mesoscale Discussion	SPC	2 hr
Oct 13, 3:53 AM EDT	Dense Fog Advisory	LWX	7 hr
Oct 14, 2:36 AM EDT	Dense Fog Advisory	LWX	7 hr
Oct 25, 5:25 PM EDT	Severe Thunderstorm Warning	LWX	35 min
Oct 25, 5:44 PM EDT	Severe Thunderstorm Warning	LWX	46 min
Oct 25, 6:41 PM EDT	Mesoscale Discussion	SPC	2 hr
Oct 26, 2:55 AM EDT	Wind Advisory	LWX	21 hr
Oct 29, 12:34 PM EDT	Areal Flood Warning	LWX	9 hr
Nov 1, 3:03 AM EDT	Freeze Watch	LWX	24 hr
Nov 2, 3:22 AM EDT	Frost Advisory	LWX	30 hr
Nov 2, 3:22 AM EDT	Freeze Warning	LWX	30 hr
Nov 26, 1:48 PM EST	Wind Advisory	LWX	3 hr
Dec 6, 11:09 AM EST	Wind Advisory	LWX	14 hr
Dec 10, 10:48 AM EST	Wind Advisory	LWX	38 hr
Dec 30, 10:18 PM EST	Dense Fog Advisory	LWX	14 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	55
Tornado Warning	1
Severe Thunderstorm Watch	13
Tornado Watch	3
Mesoscale Discussion	35
Flooding
Areal Flood Warning	8
Flash Flood Warning	1
River Flood Warning	3
Flash Flood Watch	10
River Flood Watch	5
Winter
Ice Storm Warning	1
Winter Storm Warning	3
Winter Storm Watch	3
Winter Weather Advisory	9
Heat
Excessive Heat Watch	1
Heat Advisory	3
Cold
Freeze Warning	3
Freeze Watch	2
Frost Advisory	1
Wind and dust
High Wind Warning	1
High Wind Watch	1
Wind Advisory	10
Fire
Red Flag Warning	2
Fire Weather Watch	2
Fog and smoke
Dense Fog Advisory	7

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2020 2022

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.