Alert archive / Colorado / Arapahoe County

Weather alerts in Arapahoe County, Colorado, 2015

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

Alerts: 177
Warnings: 67
Watches: 27
Advisories: 37
Busiest month: June63 alerts
Busiest day: June 5, 201515 alerts

Over time

By month

Warning verification

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

2 of 12 tornado warnings covering Arapahoe County in 2015 had a tornado report inside them.

Arapahoe County, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	12	2	83%	0
Severe thunderstorm warnings	29	11	62%	23	74%	14 min
Flash flood warnings	6	3	50%	1	100%	17 min

Each office's whole area, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Denver/Boulder, CO: tornado warnings	59	12	80%	29	52%	13 min
NWS Denver/Boulder, CO: severe thunderstorm warnings	193	70	64%	208	67%	15 min
NWS Denver/Boulder, CO: flash flood warnings	33	5	85%	9	100%	37 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 1, 6:16 PM MST	Winter Weather Advisory	BOU	5 hr
Jan 2, 3:37 PM MST	Winter Weather Advisory	BOU	29 hr
Jan 7, 12:38 AM MST	Dense Fog Advisory	BOU	8 hr
Jan 7, 3:25 AM MST	Winter Weather Advisory	BOU	6 hr
Jan 8, 3:08 PM MST	Winter Weather Advisory	BOU	17 hr
Jan 21, 2:28 AM MST	Winter Weather Advisory	BOU	18 hr
Jan 31, 10:49 PM MST	Winter Weather Advisory	BOU	8 hr
Feb 15, 3:56 AM MST	Winter Weather Advisory	BOU	40 hr
Feb 19, 2:26 PM MST	Winter Storm Watch	BOU	22 hr
Feb 20, 4:25 AM MST	Winter Storm Warning	BOU	67 hr
Feb 20, 12:53 PM MST	Winter Weather Advisory	BOU	58 hr
Feb 21, 12:38 PM MST	Mesoscale Discussion	SPC	5 hr
Feb 25, 4:18 AM MST	Winter Weather Advisory	BOU	24 hr
Mar 3, 4:27 AM MST	Winter Weather Advisory	BOU	25 hr
Mar 16, 3:39 AM MDT	Red Flag Warning	BOU	14 hr
Mar 22, 2:56 PM MDT	Fire Weather Watch	BOU	24 hr
Mar 23, 2:40 PM MDT	Red Flag Warning	BOU	27 hr
Apr 6, 4:58 AM MDT	Red Flag Warning	BOU	13 hr
Apr 6, 1:34 PM MDT	Fire Weather Watch	BOU	15 hr
Apr 7, 4:36 AM MDT	Fire Weather Watch	BOU	15 hr
Apr 7, 4:36 AM MDT	Red Flag Warning	BOU	15 hr
Apr 7, 7:15 PM MDT	Red Flag Warning	BOU	25 hr
Apr 13, 5:25 AM MDT	Fire Weather Watch	BOU	9 hr
Apr 13, 2:45 PM MDT	Red Flag Warning	BOU	29 hr
Apr 15, 5:24 PM MDT	Special Weather Statement	BOU	66 min
Apr 16, 3:00 PM MDT	Winter Weather Advisory	BOU	21 hr
Apr 26, 4:29 AM MDT	Areal Flood Advisory	BOU	3 hr
May 1, 12:31 PM MDT	Mesoscale Discussion	SPC	2 hr
May 5, 4:21 AM MDT	Flash Flood Watch	BOU	13 hr
May 7, 5:14 PM MDT	Mesoscale Discussion	SPC	2 hr
May 8, 11:08 AM MDT	Areal Flood Advisory	BOU	60 hr
May 9, 5:10 AM MDT	Flash Flood Watch	BOU	15 hr
May 9, 5:15 AM MDT	Winter Storm Warning	BOU	25 hr
May 9, 5:51 AM MDT	Areal Flood Advisory	BOU	3 hr
May 9, 6:53 AM MDT	Areal Flood Advisory	BOU	3 hr
May 9, 7:51 AM MDT	Flash Flood Warning	BOU	3 hr
May 9, 8:50 AM MDT	Areal Flood Warning	BOU	12 hr
May 9, 9:09 AM MDT	Winter Storm Watch	BOU	4 hr
May 9, 10:52 AM MDT	Areal Flood Warning	BOU	9 hr
May 9, 7:49 PM MDT	Areal Flood Warning	BOU	18 hr
May 10, 5:26 AM MDT	Frost Advisory	BOU	26 hr
May 10, 5:56 AM MDT	Winter Storm Warning	BOU	3 hr
May 10, 1:04 PM MDT	Areal Flood Warning	BOU	24 hr
May 15, 12:49 PM MDT	Severe Thunderstorm Warning	BOU	41 min
May 15, 1:21 PM MDT	Severe Thunderstorm Warning	BOU	27 min
May 19, 6:52 AM MDT	Areal Flood Advisory	BOU	8 hr
May 23, 5:41 AM MDT	Flash Flood Watch	BOU	18 hr
May 23, 12:27 PM MDT	Mesoscale Discussion	SPC	2 hr
May 23, 12:54 PM MDT	Tornado Watch	SPC	6 hr
May 23, 2:36 PM MDT	Severe Thunderstorm Warning	BOU	24 min
May 23, 4:11 PM MDT	Mesoscale Discussion	SPC	2 hr
May 24, 4:44 AM MDT	Flash Flood Watch	BOU	14 hr
May 24, 11:57 AM MDT	Flash Flood Warning	BOU	3 hr
May 24, 12:08 PM MDT	Special Weather Statement	BOU	37 min
May 24, 12:15 PM MDT	Tornado Warning	BOU	15 min
May 24, 12:33 PM MDT	Tornado Warning	BOU	27 min
May 24, 1:00 PM MDT	Tornado Warning	BOU	18 min
May 24, 1:23 PM MDT	Areal Flood Advisory	BOU	3 hr
May 28, 1:18 PM MDT	Severe Thunderstorm Watch	SPC	7 hr
May 28, 7:50 PM MDT	Severe Thunderstorm Warning	BOU	25 min
May 31, 2:50 PM MDT	Mesoscale Discussion	SPC	115 min
Jun 3, 12:34 PM MDT	Mesoscale Discussion	SPC	86 min
Jun 3, 2:03 PM MDT	Tornado Watch	SPC	7 hr
Jun 3, 4:59 PM MDT	Severe Thunderstorm Warning	BOU	30 min
Jun 3, 5:24 PM MDT	Severe Thunderstorm Warning	BOU	38 min
Jun 3, 6:02 PM MDT	Severe Thunderstorm Warning	BOU	43 min
Jun 3, 7:14 PM MDT	Mesoscale Discussion	SPC	61 min
Jun 3, 7:45 PM MDT	Severe Thunderstorm Warning	BOU	45 min
Jun 3, 8:29 PM MDT	Severe Thunderstorm Warning	BOU	61 min
Jun 3, 8:33 PM MDT	Areal Flood Advisory	BOU	117 min
Jun 3, 8:59 PM MDT	Severe Thunderstorm Watch	SPC	5 hr
Jun 3, 9:15 PM MDT	Severe Thunderstorm Warning	BOU	34 min
Jun 4, 1:53 PM MDT	Mesoscale Discussion	SPC	97 min
Jun 4, 2:20 PM MDT	Tornado Watch	SPC	8 hr
Jun 4, 5:22 PM MDT	Mesoscale Discussion	SPC	113 min
Jun 4, 8:20 PM MDT	Mesoscale Discussion	SPC	115 min
Jun 4, 9:19 PM MDT	Severe Thunderstorm Warning	BOU	26 min
Jun 5, 12:42 AM MDT	Severe Thunderstorm Warning	BOU	33 min
Jun 5, 2:21 AM MDT	Areal Flood Advisory	BOU	3 hr
Jun 5, 4:27 AM MDT	Flash Flood Watch	BOU	18 hr
Jun 5, 12:49 PM MDT	Mesoscale Discussion	SPC	86 min
Jun 5, 12:52 PM MDT	Tornado Warning	BOU	23 min
Jun 5, 1:08 PM MDT	Tornado Warning	BOU	37 min
Jun 5, 1:09 PM MDT	Tornado Watch	SPC	6 hr
Jun 5, 1:25 PM MDT	Areal Flood Advisory	BOU	3 hr
Jun 5, 1:48 PM MDT	Tornado Warning	BOU	42 min
Jun 5, 2:17 PM MDT	Tornado Warning	BOU	43 min
Jun 5, 3:04 PM MDT	Tornado Warning	BOU	26 min
Jun 5, 3:27 PM MDT	Tornado Warning	BOU	33 min
Jun 5, 4:31 PM MDT	Severe Thunderstorm Warning	BOU	29 min
Jun 5, 9:11 PM MDT	Areal Flood Advisory	BOU	94 min
Jun 6, 2:14 PM MDT	Mesoscale Discussion	SPC	91 min
Jun 6, 4:25 PM MDT	Severe Thunderstorm Watch	SPC	5 hr
Jun 6, 6:55 PM MDT	Mesoscale Discussion	SPC	95 min
Jun 6, 9:33 PM MDT	Mesoscale Discussion	SPC	57 min
Jun 7, 1:36 PM MDT	Mesoscale Discussion	SPC	114 min
Jun 7, 8:16 PM MDT	Special Weather Statement	BOU	29 min
Jun 7, 8:24 PM MDT	Severe Thunderstorm Warning	BOU	36 min
Jun 10, 11:41 AM MDT	Flash Flood Watch	BOU	39 hr
Jun 11, 11:56 AM MDT	Mesoscale Discussion	SPC	94 min
Jun 11, 5:15 PM MDT	Flash Flood Warning	BOU	3 hr
Jun 11, 6:43 PM MDT	Areal Flood Advisory	BOU	3 hr
Jun 11, 8:42 PM MDT	Areal Flood Warning	BOU	4 hr
Jun 11, 8:55 PM MDT	Areal Flood Warning	BOU	6 hr
Jun 12, 6:23 AM MDT	Areal Flood Advisory	BOU	6 hr
Jun 16, 4:53 PM MDT	Mesoscale Discussion	SPC	97 min
Jun 16, 7:29 PM MDT	Severe Thunderstorm Warning	BOU	46 min
Jun 16, 9:28 PM MDT	Mesoscale Discussion	SPC	62 min
Jun 17, 5:29 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Jun 17, 5:48 PM MDT	Severe Thunderstorm Warning	BOU	27 min
Jun 23, 4:09 PM MDT	Mesoscale Discussion	SPC	96 min
Jun 24, 2:34 PM MDT	Mesoscale Discussion	SPC	86 min
Jun 24, 4:45 PM MDT	Severe Thunderstorm Warning	BOU	45 min
Jun 24, 5:00 PM MDT	Tornado Warning	BOU	19 min
Jun 24, 5:08 PM MDT	Areal Flood Advisory	BOU	52 min
Jun 24, 5:22 PM MDT	Flash Flood Warning	BOU	113 min
Jun 24, 7:19 PM MDT	Flash Flood Warning	BOU	3 hr
Jun 25, 2:30 PM MDT	Severe Thunderstorm Watch	SPC	8 hr
Jun 25, 4:25 PM MDT	Mesoscale Discussion	SPC	95 min
Jun 25, 4:56 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Jun 25, 6:34 PM MDT	Severe Thunderstorm Warning	BOU	41 min
Jun 25, 6:39 PM MDT	Areal Flood Advisory	BOU	111 min
Jun 25, 9:30 PM MDT	Mesoscale Discussion	SPC	30 min
Jun 28, 7:24 PM MDT	Severe Thunderstorm Warning	BOU	36 min
Jul 1, 2:43 PM MDT	Mesoscale Discussion	SPC	3 hr
Jul 8, 4:53 PM MDT	Areal Flood Advisory	BOU	3 hr
Jul 15, 5:54 PM MDT	Special Weather Statement	BOU	36 min
Jul 18, 4:34 PM MDT	Special Weather Statement	BOU	41 min
Jul 19, 6:06 PM MDT	Mesoscale Discussion	SPC	114 min
Jul 21, 12:46 PM MDT	Mesoscale Discussion	SPC	119 min
Jul 21, 1:45 PM MDT	Areal Flood Advisory	BOU	3 hr
Jul 21, 3:50 PM MDT	Flash Flood Watch	BOU	4 hr
Jul 21, 4:11 PM MDT	Severe Thunderstorm Warning	BOU	34 min
Jul 26, 1:07 PM MDT	Severe Thunderstorm Watch	SPC	9 hr
Aug 7, 2:12 PM MDT	Mesoscale Discussion	SPC	3 hr
Aug 7, 3:05 PM MDT	Severe Thunderstorm Watch	SPC	8 hr
Aug 7, 5:50 PM MDT	Tornado Warning	BOU	40 min
Aug 7, 6:33 PM MDT	Severe Thunderstorm Warning	BOU	42 min
Aug 10, 2:33 PM MDT	Flash Flood Warning	BOU	3 hr
Aug 11, 3:55 PM MDT	Tornado Warning Tornado observed	BOU	35 min
Aug 11, 4:26 PM MDT	Severe Thunderstorm Warning	BOU	10 min
Aug 11, 4:40 PM MDT	Areal Flood Advisory	BOU	95 min
Aug 15, 7:16 PM MDT	Special Weather Statement	BOU	29 min
Aug 15, 7:22 PM MDT	Severe Thunderstorm Warning	BOU	24 min
Aug 16, 12:08 PM MDT	Mesoscale Discussion	SPC	3 hr
Aug 16, 2:53 PM MDT	Mesoscale Discussion	SPC	2 hr
Aug 17, 1:59 PM MDT	Mesoscale Discussion	SPC	2 hr
Aug 17, 2:32 PM MDT	Tornado Watch	SPC	7 hr
Aug 17, 3:47 PM MDT	Severe Thunderstorm Warning	BOU	43 min
Aug 17, 3:56 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Aug 17, 4:28 PM MDT	Severe Thunderstorm Warning	BOU	47 min
Aug 17, 4:41 PM MDT	Mesoscale Discussion	SPC	94 min
Aug 31, 5:34 PM MDT	Special Weather Statement	BOU	41 min
Sep 7, 4:46 PM MDT	Mesoscale Discussion	SPC	119 min
Sep 13, 2:44 PM MDT	Fire Weather Watch	BOU	25 hr
Sep 14, 3:47 PM MDT	Red Flag Warning	BOU	28 hr
Sep 29, 1:48 PM MDT	Mesoscale Discussion	SPC	117 min
Sep 29, 4:55 PM MDT	Severe Thunderstorm Warning	BOU	35 min
Oct 2, 2:09 PM MDT	Mesoscale Discussion	SPC	2 hr
Oct 6, 6:45 AM MDT	Dense Fog Advisory	BOU	3 hr
Oct 23, 3:54 AM MDT	Frost Advisory	BOU	28 hr
Oct 27, 3:13 AM MDT	Frost Advisory	BOU	29 hr
Nov 2, 3:42 PM MST	Red Flag Warning	BOU	25 hr
Nov 9, 3:05 PM MST	Blizzard Watch	BOU	14 hr
Nov 10, 5:05 AM MST	Blizzard Warning	BOU	30 hr
Nov 10, 5:05 AM MST	Winter Weather Advisory	BOU	30 hr
Nov 11, 1:27 AM MST	Mesoscale Discussion	SPC	6 hr
Nov 15, 3:36 PM MST	Blizzard Watch	BOU	14 hr
Nov 16, 5:57 AM MST	Blizzard Warning	BOU	32 hr
Nov 16, 8:05 PM MST	Mesoscale Discussion	SPC	4 hr
Nov 17, 4:32 AM MST	Mesoscale Discussion	SPC	4 hr
Nov 17, 9:27 AM MST	Mesoscale Discussion	SPC	4 hr
Nov 25, 10:25 AM MST	Winter Weather Advisory	BOU	42 hr
Dec 14, 3:45 AM MST	Winter Weather Advisory	BOU	37 hr
Dec 14, 3:12 PM MST	Winter Storm Warning	BOU	26 hr
Dec 15, 2:55 AM MST	Mesoscale Discussion	SPC	4 hr
Dec 23, 3:14 AM MST	Dense Fog Advisory	BOU	7 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	29
Tornado Warning	12
Severe Thunderstorm Watch	6
Tornado Watch	5
Mesoscale Discussion	39
Special Weather Statement	7
Flooding
Areal Flood Warning	6
Flash Flood Warning	6
Flash Flood Watch	7
Areal Flood Advisory	17
Winter
Blizzard Warning	2
Winter Storm Warning	4
Blizzard Watch	2
Winter Storm Watch	2
Winter Weather Advisory	14
Cold
Frost Advisory	3
Fire
Red Flag Warning	8
Fire Weather Watch	5
Fog and smoke
Dense Fog Advisory	3

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.