Alert archive / California / Severe Thunderstorm Warnings
Severe Thunderstorm Warnings in California, 2010
101 severe thunderstorm warnings in 2010. 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 2010. Tap one for its archive.
- Severe Thunderstorm Warnings
- 101
- Busiest month
- July31 severe thunderstorm warnings
- Busiest day
- October 20, 201017 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.
16 of 101 severe thunderstorm warnings covering California in 2010 had a qualifying storm report inside them; 25 of 97 hail, wind and damage reports fell inside a warning, on average 25 minutes after it went out.
California, 2010
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Severe thunderstorm warnings | 101 | 16 | 84% | 97 | 26% | 25 min |
Each office's whole area, 2010
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Phoenix, AZ: severe thunderstorm warnings | 82 | 36 | 56% | 113 | 69% | 19 min |
| NWS Sacramento, CA: severe thunderstorm warnings | 4 | 0 | 100% | 1 | 0% | |
| NWS San Diego, CA: severe thunderstorm warnings | 15 | 4 | 73% | 18 | 33% | 29 min |
| NWS Las Vegas, NV: severe thunderstorm warnings | 66 | 6 | 91% | 43 | 35% | 15 min |
| NWS San Francisco Bay Area, CA: severe thunderstorm warnings | 6 | 0 | 100% | 9 | 0% | |
| NWS Los Angeles, CA: severe thunderstorm warnings | 16 | 3 | 81% | 35 | 14% | 42 min |
| NWS Hanford, CA: severe thunderstorm warnings | 6 | 0 | 100% | 12 | 0% | |
| NWS Medford, OR: severe thunderstorm warnings | 23 | 10 | 57% | 17 | 82% | 15 min |
| NWS Reno, NV: severe thunderstorm warnings | 26 | 2 | 92% | 8 | 38% | 18 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, Pacific Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 18, 11:02 AM PST | Severe Thunderstorm Warning | MTR | Santa Clara, Santa Cruz | 43 min |
| Jan 18, 12:28 PM PST | Severe Thunderstorm Warning | HNX | Fresno, Kern, Kings, Tulare | 47 min |
| Jan 19, 2:00 PM PST | Severe Thunderstorm Warning | SGX | Riverside, San Bernardino | 45 min |
| Jan 19, 2:24 PM PST | Severe Thunderstorm Warning | SGX | Orange, Riverside, San Diego | 51 min |
| Jan 19, 3:08 PM PST | Severe Thunderstorm Warning | STO | Solano, Yolo | 38 min |
| Jan 19, 6:55 PM PST | Severe Thunderstorm Warning | MTR | Monterey | 18 min |
| Jan 20, 5:37 AM PST | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara | 83 min |
| Jan 20, 9:08 AM PST | Severe Thunderstorm Warning | MTR | San Mateo | 22 min |
| Jan 20, 9:29 AM PST | Severe Thunderstorm Warning | MTR | Monterey | 22 min |
| Jan 20, 2:21 PM PST | Severe Thunderstorm Warning | MTR | Monterey | 24 min |
| Jan 20, 2:42 PM PST | Severe Thunderstorm Warning | MTR | Monterey | 33 min |
| Jan 20, 4:56 PM PST | Severe Thunderstorm Warning | SGX | San Diego | 34 min |
| Jan 20, 5:07 PM PST | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara, Ventura | 38 min |
| Jan 20, 5:26 PM PST | Severe Thunderstorm Warning | SGX | San Diego | 34 min |
| Jan 21, 11:34 AM PST | Severe Thunderstorm Warning | LOX | Santa Barbara | 26 min |
| Jan 21, 11:34 AM PST | Severe Thunderstorm Warning | SGX | San Diego | 64 min |
| Jan 21, 12:18 PM PST | Severe Thunderstorm Warning | SGX | San Diego | 22 min |
| Jan 21, 3:31 PM PST | Severe Thunderstorm Warning | PSR | Imperial, Riverside | 59 min |
| Jan 21, 3:47 PM PST | Severe Thunderstorm Warning | PSR | Imperial | 45 min |
| Jan 21, 6:01 PM PST | Severe Thunderstorm Warning | LOX | Ventura | 44 min |
| Jan 21, 6:06 PM PST | Severe Thunderstorm Warning | LOX | Los Angeles, Ventura | 39 min |
| Jan 21, 6:46 PM PST | Severe Thunderstorm Warning | LOX | Los Angeles | 44 min |
| Jan 21, 7:42 PM PST | Severe Thunderstorm Warning | LOX | Los Angeles | 18 min |
| Feb 27, 8:47 AM PST | Severe Thunderstorm Warning | LOX | San Luis Obispo | 28 min |
| Apr 12, 2:56 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 19 min |
| Apr 27, 1:18 PM PDT | Severe Thunderstorm Warning | STO | Shasta | 27 min |
| Jul 7, 5:51 PM PDT | Severe Thunderstorm Warning | STO | Plumas, Shasta, Tehama | 40 min |
| Jul 9, 2:20 PM PDT | Severe Thunderstorm Warning | REV | Nevada, Sierra | 40 min |
| Jul 9, 6:22 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas | 38 min |
| Jul 15, 2:44 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 31 min |
| Jul 15, 5:09 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 39 min |
| Jul 15, 7:22 PM PDT | Severe Thunderstorm Warning | REV | Mono | 23 min |
| Jul 24, 6:28 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas, Sierra | 32 min |
| Jul 25, 12:50 PM PDT | Severe Thunderstorm Warning | REV | Plumas | 40 min |
| Jul 25, 2:57 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 19 min |
| Jul 25, 3:03 PM PDT | Severe Thunderstorm Warning | MFR | Modoc | 27 min |
| Jul 25, 4:01 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 29 min |
| Jul 25, 4:10 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 35 min |
| Jul 25, 4:21 PM PDT | Severe Thunderstorm Warning | STO | Lassen, Shasta | 24 min |
| Jul 25, 4:43 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 17 min |
| Jul 25, 5:22 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 23 min |
| Jul 25, 5:59 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas | 46 min |
| Jul 25, 6:01 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 14 min |
| Jul 25, 6:58 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 32 min |
| Jul 26, 12:10 PM PDT | Severe Thunderstorm Warning | REV | Mono | 50 min |
| Jul 26, 1:08 PM PDT | Severe Thunderstorm Warning | REV | Alpine | 52 min |
| Jul 26, 1:22 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Sierra | 38 min |
| Jul 26, 1:53 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 52 min |
| Jul 26, 2:47 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas, Sierra | 43 min |
| Jul 26, 2:53 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 37 min |
| Jul 26, 3:19 PM PDT | Severe Thunderstorm Warning | VEF | Inyo | 41 min |
| Jul 26, 3:56 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 34 min |
| Jul 26, 4:11 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 34 min |
| Jul 26, 4:20 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 25 min |
| Jul 26, 4:43 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 32 min |
| Jul 26, 5:13 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 32 min |
| Jul 26, 8:07 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 23 min |
| Aug 7, 7:12 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 33 min |
| Aug 7, 7:45 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 45 min |
| Aug 8, 3:34 PM PDT | Severe Thunderstorm Warning | REV | Alpine, El Dorado | 41 min |
| Aug 8, 3:37 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas | 38 min |
| Aug 16, 4:55 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 35 min |
| Aug 26, 1:01 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 44 min |
| Aug 26, 2:33 PM PDT | Severe Thunderstorm Warning | LOX | Los Angeles | 57 min |
| Aug 26, 2:36 PM PDT | Severe Thunderstorm Warning | SGX | Riverside | 54 min |
| Aug 26, 2:47 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 43 min |
| Aug 26, 3:32 PM PDT | Severe Thunderstorm Warning | SGX | Riverside | 22 min |
| Aug 26, 3:51 PM PDT | Severe Thunderstorm Warning | SGX | San Bernardino | 54 min |
| Aug 26, 7:32 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 58 min |
| Aug 27, 4:02 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 59 min |
| Aug 27, 4:34 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 56 min |
| Aug 27, 8:38 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 52 min |
| Aug 27, 9:32 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 43 min |
| Oct 1, 2:38 PM PDT | Severe Thunderstorm Warning | SGX | San Bernardino | 37 min |
| Oct 2, 8:24 AM PDT | Severe Thunderstorm Warning | PSR | Imperial | 51 min |
| Oct 2, 1:06 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 32 min |
| Oct 2, 4:43 PM PDT | Severe Thunderstorm Warning | SGX | Riverside, San Bernardino | 51 min |
| Oct 3, 11:14 AM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 31 min |
| Oct 4, 4:49 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 26 min |
| Oct 19, 4:32 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 43 min |
| Oct 19, 5:09 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 51 min |
| Oct 19, 5:21 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 24 min |
| Oct 19, 5:31 PM PDT | Severe Thunderstorm Warning | LOX | Los Angeles, Ventura | 29 min |
| Oct 19, 5:32 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 43 min |
| Oct 19, 5:36 PM PDT | Severe Thunderstorm Warning | LOX | Los Angeles | 39 min |
| Oct 19, 5:56 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 34 min |
| Oct 19, 5:59 PM PDT | Severe Thunderstorm Warning | LOX | Ventura | 20 min |
| Oct 19, 6:44 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 31 min |
| Oct 19, 6:58 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 32 min |
| Oct 19, 7:29 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 31 min |
| Oct 19, 7:30 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 45 min |
| Oct 19, 7:56 PM PDT | Severe Thunderstorm Warning | LOX | Los Angeles | 49 min |
| Oct 19, 7:56 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 49 min |
| Oct 19, 8:16 PM PDT | Severe Thunderstorm Warning | LOX | Los Angeles | 29 min |
| Oct 19, 11:23 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 52 min |
| Oct 20, 12:09 AM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 51 min |
| Oct 20, 12:22 AM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 24 min |
| Nov 21, 12:29 AM PST | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara | 91 min |
| Nov 21, 2:33 AM PST | Severe Thunderstorm Warning | LOX | Santa Barbara | 57 min |
| Dec 22, 3:24 PM PST | Severe Thunderstorm Warning | VEF | San Bernardino | 51 min |
| Dec 22, 3:43 PM PST | Severe Thunderstorm Warning | SGX | Riverside, San Bernardino | 53 min |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- San Bernardino County22
- Lassen County17
- San Diego County8
- Los Angeles County8
- Riverside County7
- Plumas County7
- Siskiyou County7
- Imperial County6
- Kern County5
- Santa Barbara County5
- Ventura County5
- Monterey County4
- San Luis Obispo County4
- Sierra County4
- Shasta County3
- Tulare County2
- Mono County2
- Alpine County2
- Santa Clara County1
- Santa Cruz County1
- Fresno County1
- Kings County1
- Orange County1
- Solano County1
- Yolo County1
- San Mateo County1
- Tehama County1
- Nevada County1
- Modoc County1
- Inyo County1
- El Dorado County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20092011
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.