Alert archive / Arizona / Severe Thunderstorm Warnings

Severe Thunderstorm Warnings in Arizona, 2009

141 severe thunderstorm warnings in 2009. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of severe thunderstorm warnings reaches back to 1986.

Severe Thunderstorm Warnings by county

Each county as a circle sized by its count in 2009. Tap one for its archive.

Severe Thunderstorm Warnings: 141
Busiest month: July89 severe thunderstorm warnings
Busiest day: July 20, 200921 severe thunderstorm warnings

Over time

By month

Warning verification

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

29 of 141 severe thunderstorm warnings covering Arizona in 2009 had a qualifying storm report inside them; 49 of 95 hail, wind and damage reports fell inside a warning, on average 16 minutes after it went out.

Arizona, 2009

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Severe thunderstorm warnings	141	29	79%	95	52%	16 min

Each office's whole area, 2009

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Las Vegas, NV: severe thunderstorm warnings	53	7	87%	39	26%	17 min
NWS Flagstaff, AZ: severe thunderstorm warnings	24	0	100%	3	0%
NWS Tucson, AZ: severe thunderstorm warnings	44	12	73%	38	55%	14 min
NWS Phoenix, AZ: severe thunderstorm warnings	54	12	78%	37	57%	17 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	Counties	Lasted
Feb 9, 11:47 AM MST	Severe Thunderstorm Warning	PSR	Maricopa	28 min
May 17, 7:13 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	38 min
May 18, 6:45 PM MST	Severe Thunderstorm Warning	TWC	Pima	15 min
May 18, 9:50 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	44 min
May 30, 11:42 AM MST	Severe Thunderstorm Warning	FGZ	Coconino	33 min
May 30, 1:30 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	30 min
May 30, 1:57 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	33 min
Jun 29, 5:24 PM MST	Severe Thunderstorm Warning	TWC	Cochise	51 min
Jun 29, 6:27 PM MST	Severe Thunderstorm Warning	TWC	Pima	33 min
Jun 30, 2:33 PM MST	Severe Thunderstorm Warning	TWC	Santa Cruz	27 min
Jun 30, 4:36 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	24 min
Jun 30, 6:42 PM MST	Severe Thunderstorm Warning	TWC	Pima	42 min
Jun 30, 7:39 PM MST	Severe Thunderstorm Warning	TWC	Pima	36 min
Jul 1, 6:54 PM MST	Severe Thunderstorm Warning	PSR	Gila	36 min
Jul 2, 5:13 PM MST	Severe Thunderstorm Warning	VEF	Mohave	32 min
Jul 3, 2:22 AM MST	Severe Thunderstorm Warning	VEF	Mohave	38 min
Jul 3, 3:00 AM MST	Severe Thunderstorm Warning	VEF	Mohave	60 min
Jul 3, 1:28 PM MST	Severe Thunderstorm Warning	VEF	Mohave	47 min
Jul 3, 1:48 PM MST	Severe Thunderstorm Warning	PSR	La Paz	27 min
Jul 3, 2:13 PM MST	Severe Thunderstorm Warning	PSR	La Paz	24 min
Jul 3, 2:28 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	35 min
Jul 3, 4:07 PM MST	Severe Thunderstorm Warning	VEF	Mohave	23 min
Jul 3, 4:27 PM MST	Severe Thunderstorm Warning	VEF	Mohave	33 min
Jul 3, 5:11 PM MST	Severe Thunderstorm Warning	VEF	Mohave	49 min
Jul 3, 6:44 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	61 min
Jul 3, 7:33 PM MST	Severe Thunderstorm Warning	TWC	Pima	42 min
Jul 3, 7:38 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	52 min
Jul 7, 12:52 PM MST	Severe Thunderstorm Warning	TWC	Cochise, Santa Cruz	38 min
Jul 7, 2:42 PM MST	Severe Thunderstorm Warning	TWC	Pima, Santa Cruz	21 min
Jul 7, 5:29 PM MST	Severe Thunderstorm Warning	TWC	Pima	31 min
Jul 7, 5:59 PM MST	Severe Thunderstorm Warning	TWC	Pima	31 min
Jul 8, 4:53 PM MST	Severe Thunderstorm Warning	TWC	Pima	37 min
Jul 8, 5:29 PM MST	Severe Thunderstorm Warning	TWC	Cochise, Graham, Pima	31 min
Jul 8, 6:20 PM MST	Severe Thunderstorm Warning	TWC	Graham	25 min
Jul 8, 6:37 PM MST	Severe Thunderstorm Warning	TWC	Pinal	38 min
Jul 8, 6:43 PM MST	Severe Thunderstorm Warning	TWC	Graham	47 min
Jul 10, 3:54 PM MST	Severe Thunderstorm Warning	TWC	Pinal	36 min
Jul 10, 6:52 PM MST	Severe Thunderstorm Warning	TWC	Pima	38 min
Jul 14, 6:26 PM MST	Severe Thunderstorm Warning	TWC	Santa Cruz	34 min
Jul 15, 10:07 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	30 min
Jul 16, 2:06 PM MST	Severe Thunderstorm Warning	VEF	Mohave	21 min
Jul 16, 4:22 PM MST	Severe Thunderstorm Warning	FGZ	Gila	23 min
Jul 16, 6:04 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa, Pinal	26 min
Jul 17, 2:59 PM MST	Severe Thunderstorm Warning	TWC	Greenlee	46 min
Jul 17, 4:03 PM MST	Severe Thunderstorm Warning	TWC	Graham, Greenlee	42 min
Jul 17, 4:06 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa, Pinal	39 min
Jul 17, 4:13 PM MST	Severe Thunderstorm Warning	TWC	Graham, Pinal	47 min
Jul 17, 4:43 PM MST	Severe Thunderstorm Warning	TWC	Graham, Greenlee	32 min
Jul 17, 4:57 PM MST	Severe Thunderstorm Warning	TWC	Pinal	48 min
Jul 17, 5:12 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	48 min
Jul 17, 5:46 PM MST	Severe Thunderstorm Warning	TWC	Pima, Pinal	44 min
Jul 17, 6:19 PM MST	Severe Thunderstorm Warning	TWC	Pima	56 min
Jul 17, 6:42 PM MST	Severe Thunderstorm Warning	TWC	Pima	48 min
Jul 17, 7:08 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	31 min
Jul 18, 1:56 PM MST	Severe Thunderstorm Warning	TWC	Pima	49 min
Jul 18, 3:40 PM MST	Severe Thunderstorm Warning	PSR	Yuma	80 min
Jul 18, 5:09 PM MST	Severe Thunderstorm Warning	VEF	Mohave	36 min
Jul 18, 5:26 PM MST	Severe Thunderstorm Warning	PSR	Pinal	64 min
Jul 18, 6:08 PM MST	Severe Thunderstorm Warning	PSR	Gila, Pinal	52 min
Jul 19, 4:28 PM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Jul 19, 4:55 PM MST	Severe Thunderstorm Warning	TWC	Pima	65 min
Jul 19, 5:20 PM MST	Severe Thunderstorm Warning	PSR	La Paz	55 min
Jul 19, 5:23 PM MST	Severe Thunderstorm Warning	TWC	Pima	52 min
Jul 19, 6:06 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	54 min
Jul 19, 6:06 PM MST	Severe Thunderstorm Warning	TWC	Pima	39 min
Jul 19, 6:20 PM MST	Severe Thunderstorm Warning	PSR	La Paz	55 min
Jul 19, 7:09 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	66 min
Jul 19, 7:20 PM MST	Severe Thunderstorm Warning	PSR	La Paz	70 min
Jul 19, 8:04 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	56 min
Jul 19, 10:03 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	57 min
Jul 19, 11:25 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa	65 min
Jul 20, 10:45 AM MST	Severe Thunderstorm Warning	VEF	Mohave	45 min
Jul 20, 11:00 AM MST	Severe Thunderstorm Warning	FGZ	Coconino	30 min
Jul 20, 11:14 AM MST	Severe Thunderstorm Warning	FGZ	Coconino	31 min
Jul 20, 11:20 AM MST	Severe Thunderstorm Warning	VEF	Mohave	40 min
Jul 20, 11:33 AM MST	Severe Thunderstorm Warning	VEF	Mohave	42 min
Jul 20, 11:58 AM MST	Severe Thunderstorm Warning	FGZ	Coconino	32 min
Jul 20, 1:21 PM MST	Severe Thunderstorm Warning	VEF	Mohave	39 min
Jul 20, 1:41 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	49 min
Jul 20, 1:59 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	31 min
Jul 20, 4:25 PM MST	Severe Thunderstorm Warning	TWC	Pima	65 min
Jul 20, 4:48 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Maricopa	42 min
Jul 20, 5:19 PM MST	Severe Thunderstorm Warning	TWC	Pima	41 min
Jul 20, 5:31 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Maricopa	44 min
Jul 20, 6:16 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Maricopa	44 min
Jul 20, 6:29 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	31 min
Jul 20, 6:29 PM MST	Severe Thunderstorm Warning	TWC	Pima	46 min
Jul 20, 6:32 PM MST	Severe Thunderstorm Warning	PSR	Pinal	32 min
Jul 20, 6:57 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	20 min
Jul 21, 8:19 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	41 min
Jul 21, 10:18 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	42 min
Jul 21, 10:20 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	40 min
Jul 22, 12:57 AM MST	Severe Thunderstorm Warning	VEF	Mohave	48 min
Jul 22, 3:36 PM MST	Severe Thunderstorm Warning	PSR	Gila	24 min
Jul 23, 9:14 PM MST	Severe Thunderstorm Warning	TWC	Pinal	31 min
Jul 24, 2:49 PM MST	Severe Thunderstorm Warning	PSR	Yuma	41 min
Jul 25, 4:59 PM MST	Severe Thunderstorm Warning	TWC	Pinal	46 min
Jul 25, 5:17 PM MST	Severe Thunderstorm Warning	PSR	Pinal	58 min
Jul 29, 2:27 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	33 min
Jul 30, 11:59 AM MST	Severe Thunderstorm Warning	FGZ	Apache, Navajo	46 min
Aug 4, 4:44 PM MST	Severe Thunderstorm Warning	TWC	Graham, Greenlee	46 min
Aug 4, 5:21 PM MST	Severe Thunderstorm Warning	PSR	Gila	44 min
Aug 20, 5:11 PM MST	Severe Thunderstorm Warning	TWC	Cochise	49 min
Aug 21, 2:36 PM MST	Severe Thunderstorm Warning	TWC	Pima	39 min
Aug 21, 6:53 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa	52 min
Aug 21, 7:59 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	61 min
Aug 21, 8:41 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	49 min
Aug 22, 1:38 PM MST	Severe Thunderstorm Warning	FGZ	Coconino, Navajo	37 min
Aug 23, 2:25 PM MST	Severe Thunderstorm Warning	PSR	La Paz	43 min
Aug 23, 3:33 PM MST	Severe Thunderstorm Warning	PSR	La Paz	42 min
Aug 23, 4:13 PM MST	Severe Thunderstorm Warning	VEF	Mohave	47 min
Aug 23, 4:57 PM MST	Severe Thunderstorm Warning	VEF	Mohave	34 min
Sep 4, 2:05 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	25 min
Sep 4, 2:18 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Yavapai	27 min
Sep 4, 3:24 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa	24 min
Sep 4, 4:07 PM MST	Severe Thunderstorm Warning	VEF	Mohave	53 min
Sep 4, 5:41 PM MST	Severe Thunderstorm Warning	VEF	Mohave	49 min
Sep 4, 6:26 PM MST	Severe Thunderstorm Warning	VEF	Mohave	34 min
Sep 4, 6:41 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Maricopa	34 min
Sep 4, 9:00 PM MST	Severe Thunderstorm Warning	VEF	Mohave	30 min
Sep 4, 10:29 PM MST	Severe Thunderstorm Warning	VEF	Mohave	31 min
Sep 4, 10:53 PM MST	Severe Thunderstorm Warning	VEF	Mohave	52 min
Sep 5, 11:30 AM MST	Severe Thunderstorm Warning	FGZ	Yavapai	30 min
Sep 5, 1:11 PM MST	Severe Thunderstorm Warning	PSR	Yuma	28 min
Sep 5, 1:43 PM MST	Severe Thunderstorm Warning	PSR	Yuma	29 min
Sep 5, 3:47 PM MST	Severe Thunderstorm Warning	FGZ	Coconino	43 min
Sep 5, 3:57 PM MST	Severe Thunderstorm Warning	PSR	Yuma	33 min
Sep 5, 4:43 PM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Sep 6, 4:49 PM MST	Severe Thunderstorm Warning	TWC	Santa Cruz	56 min
Sep 8, 1:12 PM MST	Severe Thunderstorm Warning	TWC	Santa Cruz	24 min
Sep 10, 3:17 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	43 min
Sep 12, 2:10 PM MST	Severe Thunderstorm Warning	FGZ	Yavapai	32 min
Sep 19, 11:38 AM MST	Severe Thunderstorm Warning	FGZ	Navajo	37 min
Sep 19, 12:38 PM MST	Severe Thunderstorm Warning	FGZ	Gila, Navajo	22 min
Oct 20, 1:53 PM MST	Severe Thunderstorm Warning	TWC	Cochise	30 min
Dec 7, 8:10 PM MST	Severe Thunderstorm Warning	PSR	La Paz	35 min
Dec 7, 11:06 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	39 min
Dec 7, 11:41 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa	64 min
Dec 7, 11:45 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	30 min
Dec 7, 11:50 PM MST	Severe Thunderstorm Warning	FGZ	Gila	25 min
Dec 8, 12:15 AM MST	Severe Thunderstorm Warning	FGZ	Gila	30 min

By county

Every county with at least one alert. A county page lists each alert that covered it.

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record The radar archive 2008 2010

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.