Alert archive / Colorado / Arapahoe County

Weather alerts in Arapahoe County, Colorado, 2018

190 weather alerts in 2018, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Arapahoe County and its neighbors

Each county as a circle sized by its count in 2018. Tap one for its archive.

Alerts: 190
Warnings: 81
Watches: 27
Advisories: 33
Busiest month: July43 alerts
Busiest day: August 7, 201812 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 5 tornado warnings covering Arapahoe County in 2018 had a tornado report inside them; 0 of 1 tornado reports fell inside a warning.

Arapahoe County, 2018

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	5	1	80%	1	0%
Severe thunderstorm warnings	49	12	76%	27	85%	25 min
Flash flood warnings	1	1	0%	6	100%	27 min

Each office's whole area, 2018

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Denver/Boulder, CO: tornado warnings	52	11	79%	36	53%	12 min
NWS Denver/Boulder, CO: severe thunderstorm warnings	322	114	65%	369	75%	20 min
NWS Denver/Boulder, CO: flash flood warnings	13	3	77%	14	79%	32 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, Mountain Time. Each opens its own page with the text, the map, the radar and the sounding.

Issued	Product	Office	Lasted
Jan 15, 6:46 AM MST	Winter Weather Advisory	BOU	6 hr
Jan 19, 1:54 PM MST	Winter Storm Watch	BOU	16 hr
Jan 20, 5:24 AM MST	Winter Storm Warning	BOU	36 hr
Feb 9, 5:37 PM MST	Dense Fog Advisory	BOU	3 hr
Feb 17, 4:04 AM MST	Fire Weather Watch	BOU	11 hr
Feb 17, 3:15 PM MST	Red Flag Warning	BOU	26 hr
Feb 18, 2:01 PM MST	Winter Weather Advisory	BOU	34 hr
Feb 27, 11:04 AM MST	Red Flag Warning	BOU	5 min
Feb 27, 11:09 AM MST	Red Flag Warning	BOU	3 hr
Mar 1, 3:13 PM MST	Fire Weather Watch	BOU	23 hr
Mar 2, 3:51 AM MST	Red Flag Warning	BOU	14 hr
Mar 2, 2:30 PM MST	Red Flag Warning	BOU	28 hr
Mar 2, 6:04 PM MST	Fire Weather Watch	BOU	21 hr
Mar 3, 3:17 PM MST	Fire Weather Watch	BOU	5 hr
Mar 3, 3:17 PM MST	Fire Weather Watch	BOU	19 hr
Mar 3, 3:17 PM MST	Red Flag Warning	BOU	28 hr
Mar 4, 5:22 AM MST	High Wind Watch	BOU	9 hr
Mar 4, 5:22 AM MST	High Wind Warning	BOU	36 hr
Mar 4, 9:49 AM MST	Red Flag Warning	BOU	32 hr
Mar 17, 2:40 PM MDT	Winter Weather Advisory	BOU	37 hr
Mar 23, 11:40 AM MDT	Special Weather Statement	BOU	50 min
Mar 25, 4:16 AM MDT	Red Flag Warning	BOU	14 hr
Mar 25, 7:31 PM MDT	Dense Fog Advisory	BOU	13 hr
Mar 26, 4:27 AM MDT	Winter Weather Advisory	BOU	24 hr
Apr 2, 1:25 PM MDT	Red Flag Warning	BOU	29 hr
Apr 10, 3:44 AM MDT	Red Flag Warning	BOU	39 hr
Apr 10, 3:44 AM MDT	Red Flag Warning	BOU	65 hr
Apr 11, 2:59 PM MDT	High Wind Watch	BOU	19 hr
Apr 12, 9:49 AM MDT	High Wind Warning	BOU	53 hr
Apr 15, 1:57 PM MDT	Fire Weather Watch	BOU	14 hr
Apr 16, 3:45 AM MDT	Red Flag Warning	BOU	42 hr
Apr 16, 2:16 PM MDT	High Wind Watch	BOU	18 hr
Apr 17, 4:58 AM MDT	High Wind Warning	BOU	16 hr
Apr 18, 8:27 PM MDT	Red Flag Warning	BOU	24 hr
Apr 29, 2:53 PM MDT	Red Flag Warning	BOU	28 hr
May 1, 1:01 PM MDT	Mesoscale Discussion	SPC	119 min
May 11, 10:58 PM MDT	Dense Fog Advisory	BOU	10 hr
May 13, 12:22 AM MDT	Dense Fog Advisory	BOU	9 hr
May 13, 4:00 PM MDT	Special Weather Statement	BOU	30 min
May 13, 4:10 PM MDT	Severe Thunderstorm Warning	BOU	35 min
May 13, 4:19 PM MDT	Mesoscale Discussion	SPC	2 hr
May 13, 4:40 PM MDT	Severe Thunderstorm Warning	BOU	20 min
May 13, 7:30 PM MDT	Severe Thunderstorm Warning	BOU	30 min
May 13, 7:40 PM MDT	Severe Thunderstorm Warning	BOU	35 min
May 13, 8:07 PM MDT	Severe Thunderstorm Warning	BOU	23 min
May 14, 12:38 PM MDT	Mesoscale Discussion	SPC	2 hr
May 14, 12:54 PM MDT	Areal Flood Advisory	BOU	38 min
May 14, 1:18 PM MDT	Special Weather Statement	BOU	42 min
May 14, 1:45 PM MDT	Severe Thunderstorm Warning	BOU	30 min
May 14, 2:06 PM MDT	Severe Thunderstorm Warning	BOU	39 min
May 14, 2:07 PM MDT	Severe Thunderstorm Warning	BOU	38 min
May 14, 2:41 PM MDT	Severe Thunderstorm Warning	BOU	49 min
May 15, 1:32 PM MDT	Mesoscale Discussion	SPC	118 min
May 15, 5:14 PM MDT	Severe Thunderstorm Warning	BOU	34 min
May 17, 4:19 PM MDT	Mesoscale Discussion	SPC	116 min
May 18, 11:02 AM MDT	Flash Flood Watch	BOU	30 hr
May 18, 3:06 PM MDT	Mesoscale Discussion	SPC	114 min
May 18, 6:27 PM MDT	Special Weather Statement	BOU	33 min
May 21, 3:00 PM MDT	Mesoscale Discussion	SPC	2 hr
May 27, 1:13 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
May 27, 4:30 PM MDT	Mesoscale Discussion	SPC	2 hr
May 28, 1:39 PM MDT	Mesoscale Discussion	SPC	96 min
May 28, 2:01 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
May 28, 4:13 PM MDT	Severe Thunderstorm Warning	BOU	47 min
May 28, 4:40 PM MDT	Severe Thunderstorm Warning	BOU	50 min
May 28, 6:08 PM MDT	Mesoscale Discussion	SPC	97 min
May 30, 1:25 PM MDT	Mesoscale Discussion	SPC	2 hr
Jun 4, 4:08 PM MDT	Special Weather Statement	BOU	22 min
Jun 6, 7:55 PM MDT	Severe Thunderstorm Warning	BOU	35 min
Jun 7, 3:26 PM MDT	Special Weather Statement	BOU	34 min
Jun 8, 3:17 PM MDT	Fire Weather Watch	BOU	18 hr
Jun 9, 9:00 AM MDT	Red Flag Warning	BOU	37 hr
Jun 13, 1:42 PM MDT	Mesoscale Discussion	SPC	2 hr
Jun 14, 3:27 AM MDT	Red Flag Warning	BOU	17 hr
Jun 15, 2:46 PM MDT	Severe Thunderstorm Warning	BOU	29 min
Jun 15, 4:18 PM MDT	Severe Thunderstorm Warning	BOU	27 min
Jun 15, 4:47 PM MDT	Mesoscale Discussion	SPC	88 min
Jun 17, 3:52 PM MDT	Severe Thunderstorm Warning	BOU	38 min
Jun 17, 4:20 PM MDT	Severe Thunderstorm Warning	BOU	25 min
Jun 18, 3:06 PM MDT	Mesoscale Discussion	SPC	114 min
Jun 18, 6:37 PM MDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 18, 8:31 PM MDT	Mesoscale Discussion	SPC	119 min
Jun 19, 11:48 AM MDT	Mesoscale Discussion	SPC	117 min
Jun 19, 12:25 PM MDT	Tornado Watch	SPC	7 hr
Jun 19, 12:53 PM MDT	Severe Thunderstorm Warning	BOU	52 min
Jun 19, 1:29 PM MDT	Severe Thunderstorm Warning	BOU	46 min
Jun 19, 1:54 PM MDT	Mesoscale Discussion	SPC	2 hr
Jun 19, 2:15 PM MDT	Severe Thunderstorm Warning	BOU	45 min
Jun 19, 2:57 PM MDT	Tornado Warning	BOU	33 min
Jun 19, 3:30 PM MDT	Severe Thunderstorm Warning	BOU	45 min
Jun 19, 6:21 PM MDT	Mesoscale Discussion	SPC	54 min
Jun 19, 7:14 PM MDT	Special Weather Statement	BOU	46 min
Jun 22, 10:51 AM MDT	Severe Thunderstorm Warning	BOU	39 min
Jun 22, 4:17 PM MDT	Special Weather Statement	BOU	58 min
Jun 24, 12:51 PM MDT	Mesoscale Discussion	SPC	84 min
Jun 27, 7:01 PM MDT	Special Weather Statement	BOU	29 min
Jun 30, 2:03 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
Jun 30, 4:40 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 4, 1:51 PM MDT	Mesoscale Discussion	SPC	54 min
Jul 4, 5:07 PM MDT	Severe Thunderstorm Warning	BOU	23 min
Jul 4, 5:33 PM MDT	Severe Thunderstorm Warning	BOU	42 min
Jul 4, 6:11 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Jul 5, 1:27 AM MDT	Special Weather Statement	BOU	63 min
Jul 15, 4:14 AM MDT	Flash Flood Watch	BOU	16 hr
Jul 16, 3:36 AM MDT	Dense Fog Advisory	BOU	3 hr
Jul 16, 6:44 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Jul 16, 7:45 PM MDT	Areal Flood Advisory	BOU	55 min
Jul 17, 5:39 PM MDT	Special Weather Statement	BOU	66 min
Jul 23, 1:00 PM MDT	Mesoscale Discussion	SPC	90 min
Jul 23, 4:07 PM MDT	Areal Flood Advisory	BOU	83 min
Jul 23, 4:16 PM MDT	Areal Flood Advisory	BOU	89 min
Jul 23, 5:32 PM MDT	Areal Flood Advisory	BOU	38 min
Jul 23, 5:47 PM MDT	Areal Flood Advisory	BOU	55 min
Jul 23, 7:42 PM MDT	Areal Flood Advisory	BOU	80 min
Jul 24, 3:44 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 24, 5:56 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Jul 24, 6:13 PM MDT	Areal Flood Advisory	BOU	32 min
Jul 24, 6:28 PM MDT	Severe Thunderstorm Warning	BOU	46 min
Jul 24, 6:41 PM MDT	Flash Flood Warning	BOU	2 hr
Jul 25, 10:41 AM MDT	Flash Flood Watch	BOU	11 hr
Jul 25, 12:48 PM MDT	Mesoscale Discussion	SPC	57 min
Jul 25, 1:22 PM MDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 25, 5:08 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 25, 6:52 PM MDT	Areal Flood Advisory	BOU	78 min
Jul 25, 7:25 PM MDT	Severe Thunderstorm Warning	BOU	16 min
Jul 25, 7:30 PM MDT	Areal Flood Advisory	BOU	66 min
Jul 25, 7:46 PM MDT	Areal Flood Advisory	BOU	45 min
Jul 26, 12:49 PM MDT	Mesoscale Discussion	SPC	56 min
Jul 26, 1:49 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
Jul 26, 6:07 PM MDT	Mesoscale Discussion	SPC	113 min
Jul 26, 9:45 PM MDT	Severe Thunderstorm Warning	BOU	30 min
Jul 27, 1:04 PM MDT	Tornado Watch	SPC	8 hr
Jul 27, 3:47 PM MDT	Severe Thunderstorm Warning	BOU	43 min
Jul 27, 4:08 PM MDT	Severe Thunderstorm Warning	BOU	41 min
Jul 27, 4:10 PM MDT	Tornado Warning	BOU	35 min
Jul 27, 4:28 PM MDT	Tornado Warning Tornado observed	BOU	32 min
Jul 29, 12:46 PM MDT	Mesoscale Discussion	SPC	59 min
Jul 29, 1:07 PM MDT	Tornado Watch	SPC	8 hr
Jul 29, 5:23 PM MDT	Mesoscale Discussion	SPC	67 min
Jul 29, 7:59 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Jul 29, 8:27 PM MDT	Severe Thunderstorm Warning	BOU	33 min
Aug 3, 8:39 PM MDT	Severe Thunderstorm Warning	BOU	51 min
Aug 6, 2:37 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 6, 5:24 PM MDT	Mesoscale Discussion	SPC	66 min
Aug 6, 7:14 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Aug 6, 7:41 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Aug 6, 7:48 PM MDT	Tornado Warning	BOU	27 min
Aug 6, 8:00 PM MDT	Severe Thunderstorm Warning	BOU	45 min
Aug 6, 8:06 PM MDT	Mesoscale Discussion	SPC	54 min
Aug 6, 8:25 PM MDT	Severe Thunderstorm Warning	BOU	35 min
Aug 6, 8:28 PM MDT	Severe Thunderstorm Warning	BOU	17 min
Aug 6, 9:00 PM MDT	Severe Thunderstorm Warning	BOU	11 min
Aug 6, 10:13 PM MDT	Special Weather Statement	BOU	32 min
Aug 7, 12:59 PM MDT	Mesoscale Discussion	SPC	2 hr
Aug 7, 5:09 PM MDT	Severe Thunderstorm Warning	BOU	34 min
Aug 7, 5:42 PM MDT	Areal Flood Advisory	BOU	46 min
Aug 7, 7:24 PM MDT	Severe Thunderstorm Warning	BOU	19 min
Aug 7, 7:57 PM MDT	Mesoscale Discussion	SPC	2 hr
Aug 14, 5:31 PM MDT	Mesoscale Discussion	SPC	119 min
Aug 14, 5:39 PM MDT	Severe Thunderstorm Warning	BOU	51 min
Aug 14, 6:13 PM MDT	Severe Thunderstorm Warning	BOU	47 min
Aug 14, 6:59 PM MDT	Special Weather Statement	BOU	61 min
Aug 14, 7:09 PM MDT	Areal Flood Advisory	BOU	96 min
Aug 14, 7:29 PM MDT	Severe Thunderstorm Warning	BOU	46 min
Aug 14, 8:01 PM MDT	Tornado Warning	BOU	29 min
Aug 17, 2:39 PM MDT	Areal Flood Advisory	BOU	96 min
Aug 17, 2:56 PM MDT	Mesoscale Discussion	SPC	2 hr
Aug 26, 3:58 AM MDT	Fire Weather Watch	BOU	12 hr
Aug 26, 3:30 PM MDT	Special Weather Statement	BOU	45 min
Aug 26, 3:35 PM MDT	Red Flag Warning	BOU	26 hr
Sep 1, 2:54 PM MDT	Severe Thunderstorm Warning	BOU	37 min
Sep 5, 3:57 AM MDT	Areal Flood Advisory	BOU	93 min
Sep 5, 3:14 PM MDT	Areal Flood Advisory	BOU	61 min
Sep 7, 4:04 AM MDT	Dense Fog Advisory	BOU	5 hr
Sep 19, 5:49 PM MDT	Areal Flood Advisory	BOU	75 min
Sep 19, 7:58 PM MDT	Severe Thunderstorm Warning	BOU	47 min
Oct 7, 2:30 PM MDT	Freeze Watch	BOU	25 hr
Oct 8, 3:01 PM MDT	Freeze Warning	BOU	13 hr
Oct 9, 4:25 AM MDT	Freeze Warning	BOU	30 hr
Oct 10, 2:27 PM MDT	Freeze Warning	BOU	19 hr
Oct 12, 2:20 PM MDT	Winter Weather Advisory	BOU	49 hr
Oct 29, 3:56 AM MDT	Winter Weather Advisory	BOU	50 hr
Nov 2, 10:35 PM MDT	Severe Thunderstorm Warning	BOU	33 min
Nov 10, 4:18 AM MST	Winter Weather Advisory	BOU	44 hr
Nov 16, 10:36 AM MST	Winter Weather Advisory	BOU	34 hr
Nov 22, 3:49 PM MST	Winter Weather Advisory	BOU	61 hr
Nov 24, 5:39 AM MST	High Wind Warning	BOU	19 hr
Dec 17, 3:32 PM MST	High Wind Watch	BOU	18 hr
Dec 18, 9:57 AM MST	High Wind Warning	BOU	31 hr
Dec 30, 1:56 PM MST	Winter Weather Advisory	BOU	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	49
Tornado Warning	5
Severe Thunderstorm Watch	7
Tornado Watch	3
Mesoscale Discussion	35
Special Weather Statement	14
Flooding
Flash Flood Warning	1
Flash Flood Watch	3
Areal Flood Advisory	17
Winter
Winter Storm Warning	1
Winter Storm Watch	1
Winter Weather Advisory	10
Cold
Freeze Warning	3
Freeze Watch	1
Wind and dust
High Wind Warning	5
High Wind Watch	4
Fire
Red Flag Warning	17
Fire Weather Watch	8
Fog and smoke
Dense Fog Advisory	6

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2017 2019

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.