Alert archive / California / Severe Thunderstorm Warnings
Severe Thunderstorm Warnings in California, 2019
91 severe thunderstorm warnings in 2019. 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 2019. Tap one for its archive.
- Severe Thunderstorm Warnings
- 91
- Busiest month
- May22 severe thunderstorm warnings
- Busiest day
- May 25, 20198 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 91 severe thunderstorm warnings covering California in 2019 had a qualifying storm report inside them; 28 of 60 hail, wind and damage reports fell inside a warning, on average 18 minutes after it went out.
California, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Severe thunderstorm warnings | 91 | 16 | 82% | 60 | 47% | 18 min |
Each office's whole area, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sacramento, CA: severe thunderstorm warnings | 17 | 6 | 65% | 24 | 54% | 16 min |
| NWS Hanford, CA: severe thunderstorm warnings | 33 | 1 | 97% | 7 | 14% | 42 min |
| NWS Phoenix, AZ: severe thunderstorm warnings | 80 | 24 | 70% | 73 | 68% | 16 min |
| NWS San Francisco Bay Area, CA: severe thunderstorm warnings | 1 | 0 | 100% | 1 | 0% | |
| NWS Los Angeles, CA: severe thunderstorm warnings | 5 | 0 | 100% | 0 | ||
| NWS Eureka, CA: severe thunderstorm warnings | 0 | 4 | 0% | |||
| NWS Medford, OR: severe thunderstorm warnings | 17 | 1 | 94% | 2 | 50% | 27 min |
| NWS Las Vegas, NV: severe thunderstorm warnings | 22 | 5 | 77% | 34 | 32% | 20 min |
| NWS San Diego, CA: severe thunderstorm warnings | 16 | 5 | 69% | 18 | 67% | 16 min |
| NWS Reno, NV: severe thunderstorm warnings | 7 | 0 | 100% | 3 | 0% |
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 |
|---|---|---|---|---|
| Feb 2, 3:05 PM PST | Severe Thunderstorm Warning | SGX | San Diego | 55 min |
| Feb 2, 3:13 PM PST | Severe Thunderstorm Warning | HNX | Madera, Mariposa, Merced | 32 min |
| Feb 2, 3:28 PM PST | Severe Thunderstorm Warning | HNX | Fresno, Madera | 32 min |
| Feb 2, 3:39 PM PST | Severe Thunderstorm Warning | STO | Colusa, Sutter | 36 min |
| Feb 17, 4:23 PM PST | Severe Thunderstorm Warning | HNX | Kern | 37 min |
| Mar 6, 1:55 PM PST | Severe Thunderstorm Warning | STO | Tuolumne | 35 min |
| Mar 6, 2:02 PM PST | Severe Thunderstorm Warning | HNX | Fresno, Madera | 43 min |
| Mar 6, 2:45 PM PST | Severe Thunderstorm Warning | HNX | Fresno, Madera | 30 min |
| Mar 6, 3:02 PM PST | Severe Thunderstorm Warning | HNX | Mariposa, Merced, Tuolumne | 28 min |
| Mar 6, 3:32 PM PST | Severe Thunderstorm Warning | HNX | Mariposa, Merced, Tuolumne | 28 min |
| Mar 6, 4:03 PM PST | Severe Thunderstorm Warning | HNX | Mariposa, Tuolumne | 27 min |
| Mar 27, 3:38 PM PDT | Severe Thunderstorm Warning | STO | Shasta | 20 min |
| Mar 27, 4:05 PM PDT | Severe Thunderstorm Warning | HNX | Mariposa, Merced, Tuolumne | 25 min |
| Mar 27, 5:08 PM PDT | Severe Thunderstorm Warning | HNX | Mariposa, Merced | 37 min |
| Mar 27, 5:14 PM PDT | Severe Thunderstorm Warning | HNX | Madera, Mariposa, Merced | 21 min |
| Mar 27, 6:49 PM PDT | Severe Thunderstorm Warning | HNX | Madera, Mariposa, Merced | 26 min |
| Apr 29, 5:16 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 44 min |
| May 9, 7:19 PM PDT | Severe Thunderstorm Warning | HNX | Fresno, Madera, Mariposa | 26 min |
| May 9, 7:47 PM PDT | Severe Thunderstorm Warning | HNX | Fresno, Madera | 28 min |
| May 11, 1:44 PM PDT | Severe Thunderstorm Warning | SGX | San Bernardino | 46 min |
| May 19, 4:01 PM PDT | Severe Thunderstorm Warning | HNX | Fresno, Kings, Tulare | 29 min |
| May 19, 4:27 PM PDT | Severe Thunderstorm Warning | HNX | Fresno, Kings, Tulare | 33 min |
| May 19, 4:53 PM PDT | Severe Thunderstorm Warning | HNX | Kern, Kings, Tulare | 22 min |
| May 19, 5:13 PM PDT | Severe Thunderstorm Warning | HNX | Kern, Kings, Tulare | 32 min |
| May 19, 5:45 PM PDT | Severe Thunderstorm Warning | HNX | Kern, Tulare | 45 min |
| May 19, 6:23 PM PDT | Severe Thunderstorm Warning | HNX | Kern, Tulare | 37 min |
| May 24, 6:46 PM PDT | Severe Thunderstorm Warning | STO | Shasta | 44 min |
| May 24, 7:45 PM PDT | Severe Thunderstorm Warning | STO | Shasta | 45 min |
| May 24, 9:43 PM PDT | Severe Thunderstorm Warning | STO | Butte, Plumas | 47 min |
| May 24, 10:29 PM PDT | Severe Thunderstorm Warning | STO | Butte, Sierra, Yuba | 40 min |
| May 25, 2:45 AM PDT | Severe Thunderstorm Warning | STO | Tehama | 45 min |
| May 25, 2:46 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 29 min |
| May 25, 3:27 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 63 min |
| May 25, 4:04 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 26 min |
| May 29, 3:15 PM PDT | Severe Thunderstorm Warning | STO | Plumas | 45 min |
| May 29, 3:35 PM PDT | Severe Thunderstorm Warning | STO | Plumas | 40 min |
| May 31, 3:41 PM PDT | Severe Thunderstorm Warning | HNX | Fresno | 64 min |
| May 31, 4:00 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 60 min |
| May 31, 4:46 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 44 min |
| May 31, 5:26 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 34 min |
| Jun 1, 3:02 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 32 min |
| Jun 1, 3:26 PM PDT | Severe Thunderstorm Warning | MTR | Santa Clara | 49 min |
| Jun 1, 4:23 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 22 min |
| Jun 1, 5:19 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 41 min |
| Jun 1, 7:43 PM PDT | Severe Thunderstorm Warning | STO | Nevada, Placer | 47 min |
| Jun 2, 2:22 PM PDT | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara | 23 min |
| Jun 2, 2:41 PM PDT | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara | 49 min |
| Jun 2, 3:28 PM PDT | Severe Thunderstorm Warning | LOX | San Luis Obispo, Santa Barbara | 62 min |
| Jun 2, 5:19 PM PDT | Severe Thunderstorm Warning | HNX | Kern | 26 min |
| Jun 2, 6:19 PM PDT | Severe Thunderstorm Warning | STO | Butte, Plumas | 44 min |
| Jun 3, 4:34 PM PDT | Severe Thunderstorm Warning | STO | Sierra | 41 min |
| Jun 5, 4:17 PM PDT | Severe Thunderstorm Warning | LOX | Santa Barbara | 28 min |
| Jun 5, 4:42 PM PDT | Severe Thunderstorm Warning | LOX | Santa Barbara | 44 min |
| Jun 17, 1:38 PM PDT | Severe Thunderstorm Warning | HNX | Tulare | 37 min |
| Jun 17, 4:26 PM PDT | Severe Thunderstorm Warning | STO | Nevada, Placer | 28 min |
| Jul 22, 2:28 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 34 min |
| Jul 22, 2:53 PM PDT | Severe Thunderstorm Warning | PSR | Riverside, San Bernardino | 37 min |
| Jul 23, 3:56 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 22 min |
| Jul 23, 5:03 PM PDT | Severe Thunderstorm Warning | SGX | Riverside | 57 min |
| Jul 23, 5:58 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 32 min |
| Jul 24, 12:47 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 35 min |
| Jul 24, 3:12 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 63 min |
| Jul 24, 3:50 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 41 min |
| Aug 4, 6:28 PM PDT | Severe Thunderstorm Warning | MFR | Siskiyou | 21 min |
| Aug 9, 11:56 PM PDT | Severe Thunderstorm Warning | STO | Shasta, Tehama | 49 min |
| Aug 10, 12:48 PM PDT | Severe Thunderstorm Warning | STO | Butte, Glenn, Tehama | 44 min |
| Aug 28, 3:39 PM PDT | Severe Thunderstorm Warning | REV | Lassen | 22 min |
| Sep 1, 9:34 PM PDT | Severe Thunderstorm Warning | PSR | Riverside | 41 min |
| Sep 1, 10:12 PM PDT | Severe Thunderstorm Warning | PSR | Riverside | 48 min |
| Sep 2, 2:25 PM PDT | Severe Thunderstorm Warning | SGX | Riverside | 65 min |
| Sep 3, 3:11 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 49 min |
| Sep 4, 1:31 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 59 min |
| Sep 4, 3:10 PM PDT | Severe Thunderstorm Warning | REV | Lassen, Plumas | 35 min |
| Sep 4, 3:19 PM PDT | Severe Thunderstorm Warning | SGX | Riverside, San Diego | 56 min |
| Sep 4, 4:15 PM PDT | Severe Thunderstorm Warning | REV | Plumas, Sierra | 30 min |
| Sep 4, 6:16 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 44 min |
| Sep 4, 8:01 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 44 min |
| Sep 5, 1:45 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 60 min |
| Sep 5, 2:04 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 56 min |
| Sep 23, 12:13 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 47 min |
| Sep 23, 5:18 PM PDT | Severe Thunderstorm Warning | VEF | San Bernardino | 42 min |
| Sep 25, 2:13 PM PDT | Severe Thunderstorm Warning | PSR | Imperial | 62 min |
| Sep 26, 2:23 PM PDT | Severe Thunderstorm Warning | PSR | Riverside | 37 min |
| Sep 26, 3:58 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 62 min |
| Sep 28, 6:08 PM PDT | Severe Thunderstorm Warning | STO | Sacramento, Solano, Sutter, Yolo | 52 min |
| Nov 28, 4:45 PM PST | Severe Thunderstorm Warning | PSR | Riverside | 30 min |
| Nov 28, 4:51 PM PST | Severe Thunderstorm Warning | PSR | Imperial, Riverside | 24 min |
| Nov 28, 5:15 PM PST | Severe Thunderstorm Warning | PSR | Imperial, Riverside | 45 min |
| Nov 28, 5:16 PM PST | Severe Thunderstorm Warning | PSR | Riverside | 44 min |
| Nov 28, 7:35 PM PST | Severe Thunderstorm Warning | SGX | San Diego | 32 min |
| Dec 8, 1:45 PM PST | Severe Thunderstorm Warning | HNX | Kern | 30 min |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- San Diego County13
- Kern County12
- Tulare County11
- Riverside County11
- Mariposa County9
- Madera County8
- Fresno County8
- Merced County7
- Plumas County6
- Imperial County6
- Tuolumne County5
- San Bernardino County5
- Santa Barbara County5
- Shasta County4
- Kings County4
- Butte County4
- Sierra County3
- Tehama County3
- San Luis Obispo County3
- Sutter County2
- Nevada County2
- Placer County2
- Lassen County2
- Colusa County1
- Yuba County1
- Santa Clara County1
- Siskiyou County1
- Glenn County1
- Sacramento County1
- Solano County1
- Yolo County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20182020
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.