Alert archive / Pennsylvania / Chester County

Weather alerts in Chester County, Pennsylvania, 2013

240 weather alerts in 2013, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Chester County and its neighbors

Each county as a circle sized by its count in 2013. Tap one for its archive.

Alerts: 240
Warnings: 59
Watches: 31
Advisories: 71
Busiest month: June66 alerts
Busiest day: January 31, 201312 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 1 tornado warnings covering Chester County in 2013 had a tornado report inside them.

Chester County, 2013

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	1	0	100%	0
Severe thunderstorm warnings	19	16	16%	11	64%	25 min
Flash flood warnings	7	4	43%	5	100%	122 min

Each office's whole area, 2013

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Philadelphia/Mount Holly: tornado warnings	5	1	80%	2	50%	1 min
NWS Philadelphia/Mount Holly: severe thunderstorm warnings	127	69	46%	212	73%	24 min
NWS Philadelphia/Mount Holly: flash flood warnings	70	38	46%	112	76%	71 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 12, 12:26 AM EST	Dense Fog Advisory	PHI	9 hr
Jan 12, 2:54 PM EST	Dense Fog Advisory	PHI	22 hr
Jan 13, 3:30 PM EST	Dense Fog Advisory	PHI	19 hr
Jan 15, 3:38 AM EST	Winter Weather Advisory	PHI	35 hr
Jan 24, 3:43 PM EST	Winter Weather Advisory	PHI	30 hr
Jan 27, 3:40 PM EST	Winter Weather Advisory	PHI	30 hr
Jan 29, 2:51 PM EST	Flash Flood Watch	PHI	39 hr
Jan 30, 4:02 AM EST	Dense Fog Advisory	PHI	8 hr
Jan 30, 4:02 AM EST	Wind Advisory	PHI	24 hr
Jan 30, 2:41 PM EST	Special Weather Statement	PHI	64 min
Jan 30, 3:33 PM EST	Special Weather Statement	PHI	117 min
Jan 30, 7:38 PM EST	Special Weather Statement	PHI	67 min
Jan 30, 8:15 PM EST	Special Weather Statement	PHI	60 min
Jan 30, 9:06 PM EST	Mesoscale Discussion	SPC	54 min
Jan 31, 12:34 AM EST	Special Weather Statement	PHI	116 min
Jan 31, 2:06 AM EST	Areal Flood Advisory	PHI	4 hr
Jan 31, 2:20 AM EST	Special Weather Statement	PHI	55 min
Jan 31, 2:56 AM EST	Areal Flood Advisory	PHI	4 hr
Jan 31, 4:00 AM EST	Areal Flood Warning	PHI	10 hr
Jan 31, 6:00 AM EST	Areal Flood Warning	PHI	6 hr
Jan 31, 6:01 AM EST	Wind Advisory	PHI	12 hr
Jan 31, 8:14 AM EST	River Flood Warning	PHI	12 hr
Jan 31, 1:21 PM EST	River Flood Warning	PHI	7 hr
Jan 31, 7:38 PM EST	Special Weather Statement	PHI	82 min
Feb 5, 11:46 PM EST	Freezing Rain Advisory	PHI	3 hr
Feb 7, 3:20 PM EST	Winter Storm Warning	PHI	36 hr
Feb 7, 3:20 PM EST	Winter Weather Advisory	PHI	36 hr
Feb 10, 3:14 PM EST	Freezing Rain Advisory	PHI	18 hr
Feb 13, 3:12 AM EST	Winter Weather Advisory	PHI	24 hr
Feb 22, 3:42 AM EST	Winter Weather Advisory	PHI	12 hr
Feb 22, 3:30 PM EST	Freezing Rain Advisory	PHI	20 hr
Mar 4, 2:51 PM EST	Winter Storm Watch	PHI	38 hr
Mar 5, 3:27 PM EST	Winter Storm Warning	PHI	25 hr
Mar 5, 3:27 PM EST	Winter Weather Advisory	PHI	32 hr
Mar 5, 3:30 PM EST	Wind Advisory	PHI	30 hr
Mar 11, 5:14 AM EDT	Dense Fog Advisory	PHI	5 hr
Mar 17, 3:44 PM EDT	Winter Weather Advisory	PHI	42 hr
Mar 24, 3:44 PM EDT	Winter Weather Advisory	PHI	29 hr
Mar 25, 5:31 AM EDT	Mesoscale Discussion	SPC	6 hr
Apr 2, 3:33 PM EDT	Fire Weather Watch	PHI	12 hr
Apr 3, 3:44 AM EDT	Red Flag Warning	PHI	18 hr
Apr 10, 7:41 PM EDT	Special Weather Statement	PHI	64 min
Apr 10, 7:44 PM EDT	Severe Thunderstorm Warning	PHI	46 min
Apr 10, 8:28 PM EDT	Mesoscale Discussion	SPC	2 hr
Apr 10, 9:36 PM EDT	Special Weather Statement	PHI	84 min
Apr 10, 10:10 PM EDT	Special Weather Statement	PHI	2 hr
Apr 12, 7:37 AM EDT	Special Weather Statement	PHI	53 min
Apr 12, 8:33 AM EDT	Special Weather Statement	PHI	57 min
Apr 19, 1:27 PM EDT	Mesoscale Discussion	SPC	63 min
Apr 19, 3:36 PM EDT	Mesoscale Discussion	SPC	54 min
Apr 19, 3:55 PM EDT	Tornado Watch	SPC	6 hr
Apr 19, 6:02 PM EDT	Mesoscale Discussion	SPC	58 min
Apr 19, 6:20 PM EDT	Special Weather Statement	PHI	3 hr
Apr 20, 6:09 PM EDT	Frost Advisory	PHI	12 hr
Apr 21, 3:19 PM EDT	Frost Advisory	PHI	17 hr
Apr 24, 4:55 PM EDT	Severe Thunderstorm Watch	SPC	3 hr
Apr 24, 5:57 PM EDT	Special Weather Statement	PHI	2 hr
Apr 24, 6:59 PM EDT	Mesoscale Discussion	SPC	2 hr
Apr 26, 3:40 PM EDT	Frost Advisory	PHI	12 hr
May 11, 1:44 PM EDT	Mesoscale Discussion	SPC	91 min
May 11, 2:03 PM EDT	Areal Flood Advisory	PHI	117 min
May 13, 3:08 PM EDT	Frost Advisory	PHI	17 hr
May 20, 2:20 AM EDT	Dense Fog Advisory	PHI	6 hr
May 23, 3:37 PM EDT	Mesoscale Discussion	SPC	53 min
May 29, 3:23 AM EDT	Dense Fog Advisory	PHI	5 hr
Jun 2, 3:18 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 6, 3:10 PM EDT	Flash Flood Watch	PHI	36 hr
Jun 7, 6:51 AM EDT	Areal Flood Advisory	PHI	4 hr
Jun 7, 10:02 AM EDT	Areal Flood Advisory	PHI	4 hr
Jun 7, 1:40 PM EDT	Areal Flood Advisory	PHI	6 hr
Jun 7, 1:51 PM EDT	Areal Flood Warning	PHI	16 hr
Jun 7, 2:49 PM EDT	River Flood Warning	PHI	11 hr
Jun 7, 9:48 PM EDT	River Flood Warning	PHI	6 hr
Jun 10, 3:30 AM EDT	Flood Watch	PHI	24 hr
Jun 10, 5:14 AM EDT	Areal Flood Advisory	PHI	4 hr
Jun 10, 5:53 AM EDT	Areal Flood Advisory	PHI	4 hr
Jun 10, 6:07 AM EDT	Flash Flood Warning	PHI	4 hr
Jun 10, 9:04 AM EDT	River Flood Warning	PHI	5 hr
Jun 10, 2:02 PM EDT	Tornado Watch	SPC	10 hr
Jun 10, 4:02 PM EDT	Areal Flood Advisory	PHI	4 hr
Jun 10, 4:10 PM EDT	Special Weather Statement	PHI	65 min
Jun 10, 4:38 PM EDT	Mesoscale Discussion	SPC	97 min
Jun 10, 4:42 PM EDT	River Flood Warning	PHI	12 hr
Jun 10, 5:06 PM EDT	Areal Flood Warning	PHI	12 hr
Jun 10, 10:08 PM EDT	Special Weather Statement	PHI	52 min
Jun 12, 3:58 AM EDT	Flood Watch	PHI	36 hr
Jun 13, 2:40 AM EDT	Mesoscale Discussion	SPC	2 hr
Jun 13, 5:27 AM EDT	Mesoscale Discussion	SPC	2 hr
Jun 13, 7:30 AM EDT	Severe Thunderstorm Watch	SPC	4 hr
Jun 13, 8:10 AM EDT	Special Weather Statement	PHI	50 min
Jun 13, 8:10 AM EDT	Mesoscale Discussion	SPC	95 min
Jun 13, 8:40 AM EDT	Severe Thunderstorm Warning	PHI	50 min
Jun 13, 9:18 AM EDT	Severe Thunderstorm Warning	PHI	57 min
Jun 17, 4:06 PM EDT	Severe Thunderstorm Warning	PHI	69 min
Jun 18, 12:14 PM EDT	Areal Flood Advisory	PHI	3 hr
Jun 18, 12:51 PM EDT	Flash Flood Warning	PHI	3 hr
Jun 18, 2:53 PM EDT	Areal Flood Warning	PHI	3 hr
Jun 24, 1:22 PM EDT	Severe Thunderstorm Warning	PHI	53 min
Jun 24, 1:48 PM EDT	Mesoscale Discussion	SPC	57 min
Jun 24, 2:07 PM EDT	Areal Flood Advisory	PHI	3 hr
Jun 24, 2:32 PM EDT	Special Weather Statement	PHI	58 min
Jun 24, 2:44 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 24, 4:43 PM EDT	Mesoscale Discussion	SPC	62 min
Jun 24, 6:25 PM EDT	Special Weather Statement	PHI	50 min
Jun 25, 3:26 PM EDT	Heat Advisory	PHI	20 hr
Jun 25, 3:45 PM EDT	Special Weather Statement	PHI	60 min
Jun 25, 8:22 PM EDT	Mesoscale Discussion	SPC	83 min
Jun 25, 8:46 PM EDT	Severe Thunderstorm Watch	SPC	4 hr
Jun 25, 10:07 PM EDT	Severe Thunderstorm Warning	PHI	53 min
Jun 26, 1:19 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 26, 2:55 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 26, 4:38 PM EDT	Mesoscale Discussion	SPC	97 min
Jun 26, 6:26 PM EDT	Special Weather Statement	PHI	64 min
Jun 26, 8:11 PM EDT	Severe Thunderstorm Warning	PHI	64 min
Jun 27, 1:04 PM EDT	Mesoscale Discussion	SPC	116 min
Jun 27, 1:58 PM EDT	Tornado Watch	SPC	7 hr
Jun 27, 3:57 PM EDT	Mesoscale Discussion	SPC	93 min
Jun 27, 4:32 PM EDT	Special Weather Statement	PHI	118 min
Jun 27, 5:18 PM EDT	Areal Flood Advisory	PHI	4 hr
Jun 27, 6:27 PM EDT	Areal Flood Advisory	PHI	4 hr
Jun 27, 6:52 PM EDT	Areal Flood Warning	PHI	9 hr
Jun 27, 10:04 PM EDT	River Flood Warning	PHI	6 hr
Jun 28, 1:02 PM EDT	Mesoscale Discussion	SPC	118 min
Jun 28, 2:08 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 28, 3:19 PM EDT	Severe Thunderstorm Warning	PHI	41 min
Jun 28, 3:30 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 28, 3:33 PM EDT	Areal Flood Advisory	PHI	117 min
Jun 29, 3:34 PM EDT	Flash Flood Watch	PHI	3 days
Jun 30, 11:18 AM EDT	Areal Flood Advisory	PHI	117 min
Jun 30, 11:45 AM EDT	Flash Flood Warning	PHI	5 hr
Jun 30, 11:48 AM EDT	Mesoscale Discussion	SPC	2 hr
Jul 1, 5:55 AM EDT	Areal Flood Advisory	PHI	3 hr
Jul 1, 6:58 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 1, 8:38 AM EDT	Areal Flood Warning	PHI	6 hr
Jul 1, 11:57 AM EDT	River Flood Warning	PHI	2 hr
Jul 2, 1:37 AM EDT	Areal Flood Advisory	PHI	113 min
Jul 5, 3:46 AM EDT	Excessive Heat Watch	PHI	11 hr
Jul 5, 3:04 PM EDT	Excessive Heat Warning	PHI	53 hr
Jul 5, 3:04 PM EDT	Heat Advisory	PHI	53 hr
Jul 7, 3:19 PM EDT	Mesoscale Discussion	SPC	116 min
Jul 7, 4:41 PM EDT	Special Weather Statement	PHI	2 hr
Jul 7, 4:45 PM EDT	Severe Thunderstorm Watch	SPC	5 hr
Jul 7, 6:09 PM EDT	Mesoscale Discussion	SPC	66 min
Jul 7, 6:20 PM EDT	Special Weather Statement	PHI	40 min
Jul 7, 6:29 PM EDT	Severe Thunderstorm Warning	PHI	61 min
Jul 7, 7:27 PM EDT	Severe Thunderstorm Warning	PHI	48 min
Jul 8, 3:31 PM EDT	Special Weather Statement	PHI	59 min
Jul 12, 4:08 AM EDT	Flash Flood Watch	PHI	17 hr
Jul 12, 9:13 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 12, 10:49 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 12, 4:04 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 12, 4:47 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 12, 8:31 PM EDT	Special Weather Statement	PHI	59 min
Jul 13, 3:16 PM EDT	Excessive Heat Watch	PHI	13 hr
Jul 14, 4:16 AM EDT	Excessive Heat Watch	PHI	11 hr
Jul 14, 4:16 AM EDT	Excessive Heat Warning	PHI	7 days
Jul 14, 3:38 PM EDT	Heat Advisory	PHI	28 hr
Jul 17, 3:27 PM EDT	Heat Advisory	PHI	3 days
Jul 19, 6:09 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 19, 7:21 PM EDT	Special Weather Statement	PHI	24 min
Jul 19, 9:01 PM EDT	Special Weather Statement	PHI	29 min
Jul 20, 1:36 PM EDT	Mesoscale Discussion	SPC	54 min
Jul 22, 1:18 PM EDT	Mesoscale Discussion	SPC	87 min
Jul 22, 1:40 PM EDT	Areal Flood Advisory	PHI	3 hr
Jul 22, 11:09 PM EDT	Areal Flood Advisory	PHI	3 hr
Jul 23, 12:11 AM EDT	Special Weather Statement	PHI	94 min
Jul 23, 12:25 AM EDT	Flash Flood Warning	PHI	4 hr
Jul 23, 3:49 AM EDT	Flash Flood Watch	PHI	11 hr
Jul 28, 2:51 PM EDT	Areal Flood Advisory	PHI	114 min
Jul 28, 6:56 PM EDT	Special Weather Statement	PHI	49 min
Jul 28, 8:39 PM EDT	Areal Flood Warning	PHI	4 hr
Jul 28, 11:46 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 28, 11:54 PM EDT	Severe Thunderstorm Warning	PHI	51 min
Jul 29, 12:24 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 29, 12:39 AM EDT	Special Weather Statement	PHI	66 min
Aug 1, 3:42 AM EDT	Flash Flood Watch	PHI	14 hr
Aug 1, 10:50 AM EDT	Areal Flood Advisory	PHI	3 hr
Aug 9, 3:17 PM EDT	Mesoscale Discussion	SPC	58 min
Aug 13, 2:45 AM EDT	Flash Flood Watch	PHI	9 hr
Aug 13, 5:15 AM EDT	Areal Flood Advisory	PHI	4 hr
Aug 13, 5:47 AM EDT	Flash Flood Warning	PHI	4 hr
Aug 13, 6:07 AM EDT	Severe Thunderstorm Warning	PHI	53 min
Aug 13, 6:23 AM EDT	Severe Thunderstorm Warning	PHI	67 min
Aug 13, 6:32 AM EDT	Tornado Warning	PHI	43 min
Aug 13, 6:36 AM EDT	Flash Flood Warning	PHI	8 hr
Aug 13, 8:07 AM EDT	River Flood Warning	PHI	9 hr
Aug 13, 9:50 AM EDT	Flash Flood Warning	PHI	4 hr
Aug 13, 11:22 AM EDT	River Flood Warning	PHI	16 hr
Aug 13, 2:18 PM EDT	Areal Flood Warning	PHI	9 hr
Sep 2, 7:59 PM EDT	Special Weather Statement	PHI	46 min
Sep 2, 8:17 PM EDT	Special Weather Statement	PHI	58 min
Sep 2, 8:56 PM EDT	Special Weather Statement	PHI	49 min
Sep 2, 8:58 PM EDT	Special Weather Statement	PHI	47 min
Sep 12, 2:50 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Sep 12, 4:24 PM EDT	Mesoscale Discussion	SPC	66 min
Sep 12, 5:47 PM EDT	Severe Thunderstorm Warning	PHI	58 min
Oct 7, 8:10 AM EDT	Mesoscale Discussion	SPC	2 hr
Oct 7, 8:56 AM EDT	Tornado Watch	SPC	8 hr
Oct 7, 10:36 AM EDT	Mesoscale Discussion	SPC	114 min
Oct 7, 11:31 AM EDT	Special Weather Statement	PHI	59 min
Oct 7, 12:20 PM EDT	Mesoscale Discussion	SPC	115 min
Oct 7, 12:41 PM EDT	Special Weather Statement	PHI	64 min
Oct 7, 12:49 PM EDT	Severe Thunderstorm Warning	PHI	41 min
Oct 7, 1:05 PM EDT	Severe Thunderstorm Warning	PHI	25 min
Oct 11, 12:19 AM EDT	Special Weather Statement	PHI	86 min
Oct 11, 3:15 AM EDT	Areal Flood Advisory	PHI	9 hr
Oct 11, 5:08 AM EDT	Special Weather Statement	PHI	3 hr
Oct 11, 8:32 AM EDT	River Flood Warning	PHI	6 hr
Oct 11, 12:00 PM EDT	River Flood Warning	PHI	16 hr
Oct 23, 4:07 AM EDT	Frost Advisory	PHI	29 hr
Oct 24, 2:55 PM EDT	Frost Advisory	PHI	18 hr
Oct 25, 3:47 AM EDT	Freeze Watch	PHI	10 hr
Oct 25, 1:32 PM EDT	Freeze Warning	PHI	19 hr
Oct 31, 1:34 AM EDT	Dense Fog Advisory	PHI	7 hr
Nov 1, 3:14 AM EDT	Wind Advisory	PHI	9 hr
Nov 1, 5:41 AM EDT	Mesoscale Discussion	SPC	94 min
Nov 1, 6:25 AM EDT	Severe Thunderstorm Watch	SPC	5 hr
Nov 1, 7:53 AM EDT	Severe Thunderstorm Warning	PHI	67 min
Nov 1, 8:34 AM EDT	Mesoscale Discussion	SPC	86 min
Nov 1, 8:37 AM EDT	Severe Thunderstorm Warning	PHI	68 min
Nov 18, 1:07 AM EST	Severe Thunderstorm Watch	SPC	5 hr
Nov 18, 2:28 AM EST	Severe Thunderstorm Warning	PHI	62 min
Nov 18, 2:31 AM EST	Mesoscale Discussion	SPC	89 min
Nov 23, 3:43 PM EST	Red Flag Warning	PHI	26 hr
Nov 26, 3:43 PM EST	Flood Watch	PHI	19 hr
Nov 27, 3:46 AM EST	Areal Flood Advisory	PHI	6 hr
Nov 27, 6:08 AM EST	River Flood Warning	PHI	4 hr
Dec 5, 6:36 AM EST	Dense Fog Advisory	PHI	3 hr
Dec 5, 8:37 PM EST	Dense Fog Advisory	PHI	7 hr
Dec 7, 4:03 PM EST	Winter Weather Advisory	PHI	45 hr
Dec 8, 12:41 PM EST	Winter Storm Warning	PHI	8 hr
Dec 8, 2:30 PM EST	Mesoscale Discussion	SPC	2 hr
Dec 9, 3:48 PM EST	Winter Storm Warning	PHI	22 hr
Dec 9, 3:48 PM EST	Winter Weather Advisory	PHI	22 hr
Dec 10, 7:23 AM EST	Special Weather Statement	PHI	112 min
Dec 10, 7:28 AM EST	Mesoscale Discussion	SPC	5 hr
Dec 13, 3:33 AM EST	Winter Storm Watch	PHI	12 hr
Dec 13, 3:24 PM EST	Winter Storm Warning	PHI	38 hr
Dec 13, 3:24 PM EST	Winter Weather Advisory	PHI	36 hr
Dec 16, 2:56 PM EST	Winter Weather Advisory	PHI	27 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	19
Tornado Warning	1
Severe Thunderstorm Watch	10
Tornado Watch	4
Mesoscale Discussion	39
Special Weather Statement	40
Flooding
Areal Flood Warning	9
Flash Flood Warning	7
River Flood Warning	13
Flash Flood Watch	7
Flood Watch	3
Areal Flood Advisory	31
Winter
Winter Storm Warning	5
Winter Storm Watch	2
Freezing Rain Advisory	3
Winter Weather Advisory	13
Heat
Excessive Heat Warning	2
Excessive Heat Watch	3
Heat Advisory	4
Cold
Freeze Warning	1
Freeze Watch	1
Frost Advisory	6
Wind and dust
Wind Advisory	4
Fire
Red Flag Warning	2
Fire Weather Watch	1
Fog and smoke
Dense Fog Advisory	10

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2012 2014

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.