Alert archive / Colorado / Arapahoe County

Weather alerts in Arapahoe County, Colorado, 2011

184 weather alerts in 2011, 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 2011. Tap one for its archive.

Alerts: 184
Warnings: 75
Watches: 34
Advisories: 33
Busiest month: July61 alerts
Busiest day: July 14, 201116 alerts

Over time

By month

Warning verification

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

Arapahoe County, 2011

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	0			0
Severe thunderstorm warnings	34	15	56%	14	57%	24 min
Flash flood warnings	5	2	60%	0

Each office's whole area, 2011

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Denver/Boulder, CO: tornado warnings	35	6	83%	11	73%	12 min
NWS Denver/Boulder, CO: severe thunderstorm warnings	212	85	60%	251	65%	19 min
NWS Denver/Boulder, CO: flash flood warnings	36	6	83%	7	86%	68 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 7, 2:53 PM MST	Winter Storm Watch	BOU	25 hr
Jan 8, 3:52 PM MST	Winter Weather Advisory	BOU	41 hr
Jan 30, 3:13 PM MST	Winter Weather Advisory	BOU	33 hr
Jan 31, 4:10 PM MST	Wind Chill Warning	BOU	44 hr
Feb 1, 3:25 PM MST	Wind Chill Advisory	BOU	18 hr
Feb 5, 2:33 PM MST	Winter Weather Advisory	BOU	5 hr
Feb 6, 3:57 AM MST	Winter Weather Advisory	BOU	12 hr
Feb 6, 3:52 PM MST	Winter Weather Advisory	BOU	44 hr
Feb 28, 11:20 AM MST	Red Flag Warning	BOU	6 hr
Mar 10, 4:37 AM MST	Fire Weather Watch	BOU	11 hr
Mar 10, 3:39 PM MST	Red Flag Warning	BOU	26 hr
Mar 15, 2:43 PM MDT	Fire Weather Watch	BOU	34 hr
Mar 15, 2:43 PM MDT	Red Flag Warning	BOU	29 hr
Mar 15, 2:43 PM MDT	Red Flag Warning	BOU	52 hr
Mar 19, 4:16 AM MDT	Red Flag Warning	BOU	15 hr
Mar 20, 3:57 AM MDT	Fire Weather Watch	BOU	9 hr
Mar 20, 12:41 PM MDT	Red Flag Warning	BOU	33 hr
Mar 21, 4:31 AM MDT	Fire Weather Watch	BOU	10 hr
Mar 21, 2:45 PM MDT	Red Flag Warning	BOU	31 hr
Mar 23, 3:43 PM MDT	Fire Weather Watch	BOU	11 hr
Mar 24, 2:38 AM MDT	Red Flag Warning	BOU	17 hr
Mar 25, 9:50 AM MDT	Red Flag Warning	BOU	10 hr
Mar 30, 4:03 PM MDT	Red Flag Warning	BOU	26 hr
Apr 1, 4:20 AM MDT	Fire Weather Watch	BOU	11 hr
Apr 1, 3:34 PM MDT	Red Flag Warning	BOU	44 hr
Apr 4, 3:51 PM MDT	Red Flag Warning	BOU	28 hr
Apr 6, 2:28 PM MDT	Fire Weather Watch	BOU	24 hr
Apr 7, 2:47 PM MDT	Fire Weather Watch	BOU	23 hr
Apr 7, 2:47 PM MDT	Red Flag Warning	BOU	29 hr
Apr 7, 3:56 PM MDT	Special Weather Statement	BOU	34 min
Apr 7, 4:37 PM MDT	Special Weather Statement	BOU	23 min
Apr 8, 2:01 PM MDT	Red Flag Warning	BOU	31 hr
May 6, 2:02 PM MDT	Fire Weather Watch	BOU	31 hr
May 7, 8:51 PM MDT	Red Flag Warning	BOU	23 hr
May 8, 4:02 PM MDT	Red Flag Warning	BOU	28 hr
May 11, 6:23 PM MDT	Winter Weather Advisory	BOU	12 hr
May 12, 8:16 AM MDT	Winter Weather Advisory	BOU	4 hr
May 23, 2:17 PM MDT	Mesoscale Discussion	SPC	88 min
May 24, 9:37 AM MDT	Mesoscale Discussion	SPC	83 min
May 29, 3:35 PM MDT	High Wind Watch	BOU	14 hr
Jun 1, 4:12 PM MDT	Red Flag Warning	BOU	28 hr
Jun 8, 2:51 PM MDT	Mesoscale Discussion	SPC	84 min
Jun 11, 3:04 PM MDT	Mesoscale Discussion	SPC	86 min
Jun 11, 3:35 PM MDT	Severe Thunderstorm Watch	SPC	6 hr
Jun 11, 4:30 PM MDT	Severe Thunderstorm Warning	BOU	60 min
Jun 11, 5:12 PM MDT	Severe Thunderstorm Warning	BOU	36 min
Jun 13, 8:47 PM MDT	Severe Thunderstorm Warning	BOU	29 min
Jun 13, 11:14 PM MDT	Special Weather Statement	BOU	31 min
Jun 14, 4:58 AM MDT	Severe Thunderstorm Warning	BOU	32 min
Jun 14, 5:33 AM MDT	Special Weather Statement	BOU	27 min
Jun 14, 5:38 AM MDT	Severe Thunderstorm Warning	BOU	37 min
Jun 15, 6:50 PM MDT	Red Flag Warning	BOU	25 hr
Jun 16, 3:05 PM MDT	Special Weather Statement	BOU	25 min
Jun 16, 5:03 PM MDT	Severe Thunderstorm Warning	BOU	23 min
Jun 16, 5:24 PM MDT	Severe Thunderstorm Warning	BOU	66 min
Jun 16, 7:29 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Jun 16, 8:33 PM MDT	Special Weather Statement	BOU	42 min
Jun 16, 9:19 PM MDT	Special Weather Statement	BOU	56 min
Jun 17, 12:17 PM MDT	Mesoscale Discussion	SPC	88 min
Jun 17, 12:35 PM MDT	Special Weather Statement	BOU	25 min
Jun 17, 12:52 PM MDT	Special Weather Statement	BOU	23 min
Jun 17, 12:58 PM MDT	Severe Thunderstorm Watch	SPC	9 hr
Jun 17, 1:36 PM MDT	Special Weather Statement	BOU	24 min
Jun 17, 1:51 PM MDT	Severe Thunderstorm Warning	BOU	39 min
Jun 17, 2:27 PM MDT	Severe Thunderstorm Warning	BOU	48 min
Jun 18, 11:45 AM MDT	Mesoscale Discussion	SPC	2 hr
Jun 18, 12:32 PM MDT	Severe Thunderstorm Warning	BOU	43 min
Jun 18, 12:57 PM MDT	Severe Thunderstorm Warning	BOU	48 min
Jun 18, 1:20 PM MDT	Severe Thunderstorm Warning	BOU	40 min
Jun 19, 2:04 PM MDT	Tornado Watch	SPC	7 hr
Jun 19, 7:59 PM MDT	Severe Thunderstorm Warning	BOU	21 min
Jun 19, 11:15 PM MDT	Special Weather Statement	BOU	30 min
Jun 28, 2:29 PM MDT	Mesoscale Discussion	SPC	91 min
Jun 28, 2:59 PM MDT	Fire Weather Watch	BOU	25 hr
Jun 29, 3:48 PM MDT	Red Flag Warning	BOU	28 hr
Jun 30, 12:04 PM MDT	Severe Thunderstorm Warning	BOU	31 min
Jun 30, 12:18 PM MDT	Severe Thunderstorm Watch	SPC	9 hr
Jun 30, 1:49 PM MDT	Mesoscale Discussion	SPC	116 min
Jun 30, 4:17 PM MDT	Mesoscale Discussion	SPC	118 min
Jun 30, 7:25 PM MDT	Mesoscale Discussion	SPC	2 hr
Jun 30, 10:10 PM MDT	Severe Thunderstorm Warning	BOU	16 min
Jul 2, 12:47 PM MDT	Mesoscale Discussion	SPC	58 min
Jul 2, 3:20 PM MDT	Severe Thunderstorm Watch	SPC	9 hr
Jul 2, 5:26 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 2, 7:40 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 5, 3:15 AM MDT	Flash Flood Watch	BOU	23 hr
Jul 5, 5:19 PM MDT	Mesoscale Discussion	SPC	56 min
Jul 6, 2:38 PM MDT	Mesoscale Discussion	SPC	67 min
Jul 6, 2:56 PM MDT	Severe Thunderstorm Watch	SPC	8 hr
Jul 6, 3:28 PM MDT	Severe Thunderstorm Warning	BOU	47 min
Jul 7, 4:46 PM MDT	Areal Flood Advisory	BOU	3 hr
Jul 7, 5:08 PM MDT	Severe Thunderstorm Warning	BOU	52 min
Jul 7, 5:14 PM MDT	Flash Flood Warning	BOU	5 hr
Jul 7, 7:38 PM MDT	Areal Flood Advisory	BOU	2 hr
Jul 7, 10:05 PM MDT	Areal Flood Advisory	BOU	4 hr
Jul 8, 1:43 PM MDT	Mesoscale Discussion	SPC	92 min
Jul 8, 2:07 PM MDT	Severe Thunderstorm Warning	BOU	34 min
Jul 8, 3:29 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 9, 2:13 PM MDT	Severe Thunderstorm Watch	SPC	8 hr
Jul 9, 4:56 PM MDT	Mesoscale Discussion	SPC	94 min
Jul 10, 3:14 PM MDT	Special Weather Statement	BOU	61 min
Jul 10, 3:28 PM MDT	Severe Thunderstorm Warning	BOU	51 min
Jul 10, 4:58 PM MDT	Severe Thunderstorm Warning	BOU	53 min
Jul 10, 5:29 PM MDT	Severe Thunderstorm Warning	BOU	54 min
Jul 12, 3:49 AM MDT	Flash Flood Watch	BOU	25 hr
Jul 12, 2:07 PM MDT	Mesoscale Discussion	SPC	53 min
Jul 12, 4:16 PM MDT	Special Weather Statement	BOU	59 min
Jul 12, 5:18 PM MDT	Areal Flood Advisory	BOU	23 min
Jul 12, 5:31 PM MDT	Special Weather Statement	BOU	44 min
Jul 12, 6:34 PM MDT	Flash Flood Warning	BOU	2 hr
Jul 12, 6:39 PM MDT	Severe Thunderstorm Warning	BOU	51 min
Jul 12, 7:19 PM MDT	Flash Flood Warning	BOU	91 min
Jul 12, 8:33 PM MDT	Flash Flood Warning	BOU	3 hr
Jul 12, 9:15 PM MDT	Areal Flood Advisory	BOU	90 min
Jul 12, 9:30 PM MDT	Severe Thunderstorm Warning	BOU	44 min
Jul 12, 11:19 PM MDT	Areal Flood Warning	BOU	6 hr
Jul 13, 2:23 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 13, 5:13 PM MDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 13, 5:56 PM MDT	Severe Thunderstorm Warning	BOU	49 min
Jul 13, 6:32 PM MDT	Areal Flood Advisory	BOU	43 min
Jul 13, 6:40 PM MDT	Severe Thunderstorm Warning	BOU	19 min
Jul 13, 8:12 PM MDT	Mesoscale Discussion	SPC	63 min
Jul 13, 9:05 PM MDT	Severe Thunderstorm Warning	BOU	55 min
Jul 13, 9:28 PM MDT	Areal Flood Advisory	BOU	77 min
Jul 13, 10:58 PM MDT	Areal Flood Advisory	BOU	92 min
Jul 14, 12:35 AM MDT	Areal Flood Advisory	BOU	81 min
Jul 14, 5:25 AM MDT	Flash Flood Watch	BOU	16 hr
Jul 14, 1:14 PM MDT	Mesoscale Discussion	SPC	2 hr
Jul 14, 2:40 PM MDT	Severe Thunderstorm Warning	BOU	50 min
Jul 14, 2:43 PM MDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 14, 3:02 PM MDT	Areal Flood Advisory	BOU	26 min
Jul 14, 3:22 PM MDT	Flash Flood Warning	BOU	2 hr
Jul 14, 3:28 PM MDT	Severe Thunderstorm Warning	BOU	47 min
Jul 14, 4:00 PM MDT	Severe Thunderstorm Warning	BOU	22 min
Jul 14, 4:16 PM MDT	Areal Flood Advisory	BOU	89 min
Jul 16, 3:47 PM MDT	Mesoscale Discussion	SPC	58 min
Jul 24, 3:48 PM MDT	Severe Thunderstorm Warning	BOU	27 min
Jul 24, 4:31 PM MDT	Severe Thunderstorm Warning	BOU	21 min
Jul 25, 1:32 PM MDT	Mesoscale Discussion	SPC	88 min
Jul 26, 5:53 PM MDT	Severe Thunderstorm Warning	BOU	37 min
Aug 2, 4:17 AM MDT	Flash Flood Watch	BOU	16 hr
Aug 14, 1:59 PM MDT	Mesoscale Discussion	SPC	91 min
Aug 16, 1:48 PM MDT	Mesoscale Discussion	SPC	117 min
Aug 28, 7:44 PM MDT	Areal Flood Advisory	BOU	91 min
Aug 28, 9:20 PM MDT	Areal Flood Advisory	BOU	115 min
Aug 29, 1:05 PM MDT	Mesoscale Discussion	SPC	85 min
Aug 29, 5:20 PM MDT	Severe Thunderstorm Warning	BOU	40 min
Sep 2, 5:10 PM MDT	Areal Flood Advisory	BOU	65 min
Sep 21, 4:00 PM MDT	Frost Advisory	BOU	16 hr
Sep 26, 10:45 AM MDT	Red Flag Warning	BOU	8 hr
Oct 4, 2:50 AM MDT	Red Flag Warning	BOU	15 hr
Oct 6, 2:48 AM MDT	High Wind Warning	BOU	16 hr
Oct 6, 4:27 AM MDT	Red Flag Warning	BOU	16 hr
Oct 8, 5:46 AM MDT	Freeze Watch	BOU	8 hr
Oct 8, 2:07 PM MDT	Freeze Warning	BOU	19 hr
Oct 9, 1:45 PM MDT	Frost Advisory	BOU	18 hr
Oct 12, 7:35 PM MDT	Frost Advisory	BOU	12 hr
Oct 17, 4:49 AM MDT	Freeze Warning	BOU	27 hr
Oct 18, 10:40 AM MDT	Freeze Warning	BOU	21 hr
Oct 23, 3:29 PM MDT	Winter Storm Watch	BOU	36 hr
Oct 25, 3:49 AM MDT	Winter Storm Warning	BOU	37 hr
Oct 31, 5:02 AM MDT	Winter Storm Watch	BOU	24 hr
Nov 1, 5:12 AM MDT	Blizzard Watch	BOU	6 hr
Nov 1, 5:12 AM MDT	Winter Weather Advisory	BOU	29 hr
Nov 1, 10:54 AM MDT	Blizzard Warning	BOU	25 hr
Nov 1, 10:54 AM MDT	Winter Storm Warning	BOU	25 hr
Nov 1, 7:13 PM MDT	Mesoscale Discussion	SPC	5 hr
Nov 7, 4:06 AM MST	Winter Weather Advisory	BOU	24 hr
Nov 14, 9:46 AM MST	Red Flag Warning	BOU	7 hr
Nov 18, 5:14 AM MST	High Wind Watch	BOU	10 hr
Nov 18, 3:28 PM MST	High Wind Warning	BOU	12 hr
Nov 25, 1:34 PM MST	Fire Weather Watch	BOU	14 hr
Nov 29, 12:14 PM MST	Winter Storm Watch	BOU	23 hr
Nov 30, 5:35 AM MST	Winter Storm Warning	BOU	33 hr
Nov 30, 11:27 AM MST	Winter Weather Advisory	BOU	27 hr
Dec 2, 7:57 PM MST	Winter Weather Advisory	BOU	18 hr
Dec 3, 3:20 PM MST	Winter Weather Advisory	BOU	32 hr
Dec 9, 3:48 AM MST	Dense Fog Advisory	BOU	5 hr
Dec 9, 7:20 PM MST	Dense Fog Advisory	BOU	8 hr
Dec 20, 2:00 PM MST	Winter Storm Watch	BOU	15 hr
Dec 21, 4:33 AM MST	Winter Storm Warning	BOU	30 hr
Dec 21, 4:33 AM MST	Winter Weather Advisory	BOU	30 hr
Dec 29, 3:03 PM MST	High Wind Watch	BOU	19 hr
Dec 30, 10:15 AM MST	High Wind Warning	BOU	31 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	34
Severe Thunderstorm Watch	8
Tornado Watch	1
Mesoscale Discussion	28
Special Weather Statement	14
Flooding
Areal Flood Warning	1
Flash Flood Warning	5
Flash Flood Watch	4
Areal Flood Advisory	14
Winter
Blizzard Warning	1
Winter Storm Warning	4
Blizzard Watch	1
Winter Storm Watch	5
Winter Weather Advisory	13
Cold
Freeze Warning	3
Wind Chill Warning	1
Freeze Watch	1
Frost Advisory	3
Wind Chill Advisory	1
Wind and dust
High Wind Warning	3
High Wind Watch	3
Fire
Red Flag Warning	23
Fire Weather Watch	11
Fog and smoke
Dense Fog Advisory	2

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2010 2012

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.