Alert archive / New Jersey / Mercer County

Weather alerts in Mercer County, New Jersey, 2020

195 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Mercer County and its neighbors

Each county as a circle sized by its count in 2020. Tap one for its archive.

Alerts: 195
Warnings: 56
Watches: 28
Advisories: 65
Busiest month: July46 alerts
Busiest day: June 27, 20209 alerts

Over time

By month

Warning verification

How often warnings here had a storm report inside them, and how much warning the reports had.

Mercer County, 2020

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	0			0
Severe thunderstorm warnings	37	31	16%	27	89%	33 min
Flash flood warnings	4	4	0%	0

Each office's whole area, 2020

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Philadelphia/Mount Holly: tornado warnings	36	9	75%	27	59%	12 min
NWS Philadelphia/Mount Holly: severe thunderstorm warnings	308	233	24%	1,626	89%	26 min
NWS Philadelphia/Mount Holly: flash flood warnings	65	45	31%	286	94%	96 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 4, 8:33 AM EST	Dense Fog Advisory	PHI	4 hr
Jan 7, 2:27 PM EST	Wind Advisory	PHI	28 hr
Jan 11, 1:12 PM EST	Wind Advisory	PHI	24 hr
Jan 12, 6:29 AM EST	Special Weather Statement	PHI	46 min
Jan 15, 1:18 PM EST	Wind Advisory	PHI	30 hr
Jan 17, 3:37 AM EST	Winter Weather Advisory	PHI	41 hr
Feb 1, 2:02 AM EST	Dense Fog Advisory	PHI	9 hr
Feb 5, 2:56 PM EST	Flood Watch	PHI	29 hr
Feb 6, 2:55 PM EST	Wind Advisory	PHI	27 hr
Feb 7, 8:03 AM EST	Coastal Flood Advisory	PHI	11 hr
Feb 7, 10:14 AM EST	Severe Thunderstorm Warning	PHI	61 min
Feb 27, 9:10 AM EST	Wind Advisory	PHI	9 hr
Mar 3, 6:50 PM EST	Mesoscale Discussion	SPC	2 hr
Mar 3, 9:09 PM EST	Severe Thunderstorm Warning	PHI	51 min
Mar 3, 10:52 PM EST	Mesoscale Discussion	SPC	113 min
Mar 20, 2:32 AM EDT	Dense Fog Advisory	PHI	6 hr
Mar 30, 4:31 PM EDT	Special Weather Statement	PHI	44 min
Apr 3, 2:36 PM EDT	Coastal Flood Advisory	PHI	23 hr
Apr 8, 3:13 AM EDT	Special Weather Statement	PHI	32 min
Apr 8, 7:19 PM EDT	Wind Advisory	PHI	24 hr
Apr 9, 11:09 AM EDT	Mesoscale Discussion	SPC	66 min
Apr 9, 12:01 PM EDT	Severe Thunderstorm Watch	SPC	4 hr
Apr 9, 1:00 PM EDT	Severe Thunderstorm Warning	PHI	45 min
Apr 9, 1:23 PM EDT	Severe Thunderstorm Warning	PHI	52 min
Apr 9, 1:33 PM EDT	Severe Thunderstorm Warning	PHI	42 min
Apr 9, 3:32 PM EDT	Wind Advisory	PHI	27 hr
Apr 10, 3:29 PM EDT	Freeze Warning	PHI	18 hr
Apr 10, 3:43 PM EDT	Fire Weather Watch	PHI	12 hr
Apr 11, 4:01 AM EDT	Red Flag Warning	PHI	15 hr
Apr 11, 3:32 PM EDT	High Wind Watch	PHI	21 hr
Apr 12, 12:25 PM EDT	High Wind Warning	PHI	29 hr
Apr 13, 8:03 AM EDT	Areal Flood Advisory	PHI	4 hr
Apr 13, 11:33 AM EDT	Tornado Watch	SPC	5 hr
Apr 13, 1:20 PM EDT	Mesoscale Discussion	SPC	85 min
Apr 13, 2:37 PM EDT	Areal Flood Advisory	PHI	2 hr
Apr 14, 3:34 PM EDT	Frost Advisory	PHI	39 hr
Apr 15, 2:52 AM EDT	Freeze Watch	PHI	36 hr
Apr 16, 3:19 PM EDT	Freeze Warning	PHI	18 hr
Apr 18, 3:07 AM EDT	Frost Advisory	PHI	29 hr
Apr 21, 3:34 AM EDT	Freeze Warning	PHI	28 hr
Apr 21, 12:23 PM EDT	Mesoscale Discussion	SPC	2 hr
Apr 21, 1:27 PM EDT	Severe Thunderstorm Watch	SPC	3 hr
Apr 21, 1:28 PM EDT	Severe Thunderstorm Warning	PHI	32 min
Apr 21, 1:59 PM EDT	Severe Thunderstorm Warning	PHI	61 min
Apr 22, 3:03 PM EDT	Freeze Warning	PHI	16 hr
Apr 25, 3:20 AM EDT	Dense Fog Advisory	PHI	3 hr
Apr 29, 3:14 AM EDT	Flood Watch	PHI	48 hr
Apr 29, 3:15 PM EDT	Wind Advisory	PHI	29 hr
May 8, 11:39 PM EDT	Special Weather Statement	PHI	36 min
May 12, 2:25 PM EDT	Frost Advisory	PHI	18 hr
May 13, 2:20 PM EDT	Frost Advisory	PHI	18 hr
May 25, 9:01 PM EDT	Dense Fog Advisory	PHI	12 hr
May 26, 3:21 PM EDT	Dense Fog Advisory	PHI	17 hr
May 29, 8:01 PM EDT	Mesoscale Discussion	SPC	119 min
Jun 3, 10:08 AM EDT	Severe Thunderstorm Watch	SPC	4 hr
Jun 3, 11:34 AM EDT	Mesoscale Discussion	SPC	86 min
Jun 3, 11:59 AM EDT	Severe Thunderstorm Warning	PHI	46 min
Jun 3, 12:35 PM EDT	Severe Thunderstorm Warning	PHI	55 min
Jun 3, 6:58 PM EDT	Mesoscale Discussion	SPC	92 min
Jun 4, 6:06 AM EDT	Coastal Flood Advisory	PHI	22 hr
Jun 5, 9:47 AM EDT	Flash Flood Watch	PHI	12 hr
Jun 5, 3:24 PM EDT	Special Weather Statement	PHI	36 min
Jun 5, 3:57 PM EDT	Special Weather Statement	PHI	33 min
Jun 5, 5:01 PM EDT	Areal Flood Advisory	PHI	4 hr
Jun 10, 3:16 AM EDT	Heat Advisory	PHI	15 hr
Jun 11, 1:59 PM EDT	Areal Flood Advisory	PHI	4 hr
Jun 19, 7:56 PM EDT	Areal Flood Advisory	PHI	3 hr
Jun 21, 4:14 AM EDT	Dense Fog Advisory	PHI	5 hr
Jun 22, 8:48 PM EDT	Special Weather Statement	PHI	42 min
Jun 22, 9:18 PM EDT	Areal Flood Advisory	PHI	3 hr
Jun 27, 12:34 PM EDT	Mesoscale Discussion	SPC	2 hr
Jun 27, 3:16 PM EDT	Severe Thunderstorm Watch	SPC	5 hr
Jun 27, 3:37 PM EDT	Severe Thunderstorm Warning	PHI	53 min
Jun 27, 4:15 PM EDT	Mesoscale Discussion	SPC	90 min
Jun 27, 4:17 PM EDT	Severe Thunderstorm Warning	PHI	58 min
Jun 27, 4:51 PM EDT	Special Weather Statement	PHI	24 min
Jun 27, 5:12 PM EDT	Areal Flood Advisory	PHI	2 hr
Jun 27, 5:12 PM EDT	Severe Thunderstorm Warning	PHI	48 min
Jun 27, 5:47 PM EDT	Special Weather Statement	PHI	13 min
Jun 28, 8:34 PM EDT	Severe Thunderstorm Warning	PHI	41 min
Jul 3, 8:08 PM EDT	Special Weather Statement	PHI	37 min
Jul 3, 8:13 PM EDT	Severe Thunderstorm Warning	PHI	24 min
Jul 3, 8:44 PM EDT	Special Weather Statement	PHI	31 min
Jul 3, 9:03 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 6, 3:16 AM EDT	Heat Advisory	PHI	12 hr
Jul 6, 12:33 PM EDT	Mesoscale Discussion	SPC	3 hr
Jul 6, 12:52 PM EDT	Flash Flood Watch	PHI	8 hr
Jul 6, 1:15 PM EDT	Severe Thunderstorm Warning	PHI	60 min
Jul 6, 1:38 PM EDT	Severe Thunderstorm Watch	SPC	9 hr
Jul 6, 2:00 PM EDT	Severe Thunderstorm Warning	PHI	75 min
Jul 6, 2:02 PM EDT	Areal Flood Advisory	PHI	118 min
Jul 6, 2:41 PM EDT	Severe Thunderstorm Warning	PHI	49 min
Jul 6, 4:33 PM EDT	Mesoscale Discussion	SPC	117 min
Jul 9, 3:00 PM EDT	Flash Flood Watch	PHI	30 hr
Jul 10, 11:08 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 10, 12:35 PM EDT	Areal Flood Advisory	PHI	3 hr
Jul 10, 12:49 PM EDT	Flash Flood Warning	PHI	4 hr
Jul 10, 1:41 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 10, 4:30 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 10, 5:39 PM EDT	Areal Flood Advisory	PHI	4 hr
Jul 16, 3:43 PM EDT	Excessive Heat Watch	PHI	36 hr
Jul 18, 3:55 AM EDT	Excessive Heat Warning	PHI	64 hr
Jul 20, 7:57 PM EDT	Heat Advisory	PHI	48 hr
Jul 22, 1:45 PM EDT	Mesoscale Discussion	SPC	2 hr
Jul 22, 2:57 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 22, 4:55 PM EDT	Mesoscale Discussion	SPC	95 min
Jul 22, 5:40 PM EDT	Severe Thunderstorm Warning	PHI	65 min
Jul 22, 6:17 PM EDT	Severe Thunderstorm Warning	PHI	52 min
Jul 22, 7:01 PM EDT	Mesoscale Discussion	SPC	119 min
Jul 23, 9:32 AM EDT	Special Weather Statement	PHI	28 min
Jul 23, 6:30 PM EDT	Special Weather Statement	PHI	30 min
Jul 23, 6:53 PM EDT	Special Weather Statement	PHI	37 min
Jul 23, 7:00 PM EDT	Severe Thunderstorm Warning	PHI	30 min
Jul 24, 12:23 AM EDT	Severe Thunderstorm Warning	PHI	52 min
Jul 24, 12:31 AM EDT	Areal Flood Advisory	PHI	119 min
Jul 24, 1:13 AM EDT	Severe Thunderstorm Warning	PHI	62 min
Jul 24, 1:28 AM EDT	Flash Flood Warning	PHI	4 hr
Jul 24, 1:43 PM EDT	Areal Flood Advisory	PHI	3 hr
Jul 27, 3:06 PM EDT	Heat Advisory	PHI	29 hr
Jul 30, 1:20 PM EDT	Mesoscale Discussion	SPC	115 min
Jul 30, 11:35 PM EDT	Severe Thunderstorm Warning	PHI	40 min
Jul 30, 11:51 PM EDT	Severe Thunderstorm Warning	PHI	54 min
Jul 31, 12:10 AM EDT	Severe Thunderstorm Warning	PHI	50 min
Jul 31, 12:21 AM EDT	Areal Flood Advisory	PHI	4 hr
Jul 31, 12:33 AM EDT	Severe Thunderstorm Warning	PHI	42 min
Jul 31, 12:54 AM EDT	Areal Flood Advisory	PHI	4 hr
Aug 1, 3:20 PM EDT	Heat Advisory	PHI	29 hr
Aug 2, 3:33 PM EDT	Flash Flood Watch	PHI	48 hr
Aug 2, 5:04 PM EDT	Tropical Storm Watch	PHI	18 hr
Aug 3, 5:08 AM EDT	Tropical Storm Warning	PHI	39 hr
Aug 3, 7:20 PM EDT	Severe Thunderstorm Warning	PHI	40 min
Aug 3, 7:56 PM EDT	Severe Thunderstorm Warning	PHI	52 min
Aug 4, 5:17 AM EDT	Areal Flood Advisory	PHI	4 hr
Aug 4, 6:45 AM EDT	Mesoscale Discussion	SPC	3 hr
Aug 4, 7:23 AM EDT	Tornado Watch	SPC	9 hr
Aug 4, 8:59 AM EDT	Mesoscale Discussion	SPC	91 min
Aug 4, 11:01 AM EDT	Flash Flood Warning	PHI	4 hr
Aug 4, 11:13 AM EDT	Mesoscale Discussion	SPC	92 min
Aug 4, 2:47 PM EDT	Areal Flood Warning	PHI	9 hr
Aug 6, 3:37 AM EDT	Flash Flood Watch	PHI	44 hr
Aug 7, 6:16 PM EDT	Areal Flood Advisory	PHI	2 hr
Aug 7, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	27 min
Aug 11, 3:48 PM EDT	Flash Flood Watch	PHI	28 hr
Aug 12, 12:43 PM EDT	Areal Flood Advisory	PHI	3 hr
Aug 12, 1:15 PM EDT	Mesoscale Discussion	SPC	2 hr
Aug 13, 3:02 AM EDT	Flash Flood Watch	PHI	17 hr
Aug 13, 7:47 AM EDT	Areal Flood Advisory	PHI	118 min
Aug 13, 8:37 AM EDT	Flash Flood Warning	PHI	3 hr
Aug 25, 3:10 PM EDT	Mesoscale Discussion	SPC	95 min
Aug 25, 3:34 PM EDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 25, 8:33 PM EDT	Severe Thunderstorm Warning	PHI	27 min
Aug 27, 6:35 PM EDT	Mesoscale Discussion	SPC	115 min
Aug 27, 8:29 PM EDT	Severe Thunderstorm Warning	PHI	46 min
Aug 27, 9:13 PM EDT	Special Weather Statement	PHI	47 min
Aug 27, 9:28 PM EDT	Severe Thunderstorm Warning	PHI	47 min
Aug 28, 4:29 PM EDT	Severe Thunderstorm Warning	PHI	61 min
Aug 28, 4:49 PM EDT	Severe Thunderstorm Warning	PHI	56 min
Aug 29, 3:56 PM EDT	Mesoscale Discussion	SPC	2 hr
Aug 29, 6:45 PM EDT	Mesoscale Discussion	SPC	2 hr
Sep 3, 7:16 PM EDT	Special Weather Statement	PHI	44 min
Sep 3, 8:02 PM EDT	Special Weather Statement	PHI	43 min
Sep 9, 5:08 PM EDT	Flash Flood Watch	PHI	29 hr
Sep 10, 7:31 PM EDT	Areal Flood Advisory	PHI	101 min
Sep 25, 8:01 AM EDT	Dense Fog Advisory	PHI	119 min
Sep 30, 1:56 AM EDT	Special Weather Statement	PHI	64 min
Sep 30, 2:37 AM EDT	Areal Flood Advisory	PHI	4 hr
Oct 17, 3:46 AM EDT	Frost Advisory	PHI	28 hr
Oct 20, 10:49 PM EDT	Dense Fog Advisory	PHI	11 hr
Oct 22, 12:25 AM EDT	Dense Fog Advisory	PHI	9 hr
Oct 23, 2:54 AM EDT	Dense Fog Advisory	PHI	6 hr
Oct 29, 3:21 PM EDT	Freeze Warning	PHI	42 hr
Nov 1, 3:10 AM EST	Wind Advisory	PHI	36 hr
Nov 11, 6:34 PM EST	Areal Flood Advisory	PHI	3 hr
Nov 11, 6:51 PM EST	Areal Flood Advisory	PHI	3 hr
Nov 15, 3:33 PM EST	Mesoscale Discussion	SPC	2 hr
Nov 15, 5:35 PM EST	Severe Thunderstorm Watch	SPC	5 hr
Nov 15, 6:52 PM EST	Mesoscale Discussion	SPC	113 min
Nov 15, 7:31 PM EST	Severe Thunderstorm Warning	PHI	74 min
Nov 15, 7:50 PM EST	Severe Thunderstorm Warning	PHI	70 min
Nov 30, 12:52 PM EST	Areal Flood Advisory	PHI	92 min
Nov 30, 1:07 PM EST	Tornado Watch	SPC	6 hr
Nov 30, 2:01 PM EST	Areal Flood Warning	PHI	9 hr
Nov 30, 3:02 PM EST	Mesoscale Discussion	SPC	88 min
Nov 30, 4:17 PM EST	Areal Flood Warning	PHI	10 hr
Nov 30, 4:37 PM EST	Mesoscale Discussion	SPC	53 min
Nov 30, 5:29 PM EST	Severe Thunderstorm Warning	PHI	46 min
Dec 1, 1:37 PM EST	Coastal Flood Advisory	PHI	2 hr
Dec 10, 3:53 PM EST	Freezing Fog Advisory	PHI	12 hr
Dec 13, 7:15 PM EST	Winter Storm Watch	PHI	44 hr
Dec 15, 3:18 AM EST	Winter Storm Warning	PHI	51 hr
Dec 22, 3:22 PM EST	Flood Watch	PHI	66 hr
Dec 23, 3:23 PM EST	Wind Advisory	PHI	38 hr
Dec 24, 11:48 PM EST	Areal Flood Warning	PHI	15 hr
Dec 25, 5:43 AM EST	Areal Flood Advisory	PHI	3 hr
Dec 26, 6:56 AM EST	River Flood Warning	PHI	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
Severe Thunderstorm Watch	8
Tornado Watch	3
Mesoscale Discussion	28
Special Weather Statement	18
Flooding
Areal Flood Warning	4
Flash Flood Warning	4
River Flood Warning	1
Flash Flood Watch	8
Flood Watch	3
Areal Flood Advisory	28
Winter
Winter Storm Warning	1
Winter Storm Watch	1
Winter Weather Advisory	1
Heat
Excessive Heat Warning	1
Excessive Heat Watch	1
Heat Advisory	5
Cold
Freeze Warning	5
Freeze Watch	1
Frost Advisory	5
Wind and dust
High Wind Warning	1
High Wind Watch	1
Wind Advisory	10
Fire
Red Flag Warning	1
Fire Weather Watch	1
Fog and smoke
Dense Fog Advisory	11
Freezing Fog Advisory	1
Tropical
Tropical Storm Warning	1
Tropical Storm Watch	1
Coast and beach
Coastal Flood Advisory	4

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2019 2021

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.