Alert archive / California / Alameda County
Weather alerts in Alameda County, California, 2019
57 weather alerts in 2019, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Alameda County and its neighbors
Each county as a circle sized by its count in 2019. Tap one for its archive.
- Alerts
- 57
- Warnings
- 8
- Watches
- 12
- Advisories
- 37
- Busiest month
- January13 alerts
- Busiest day
- October 25, 20194 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
Alameda County, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 0 | 0 | ||||
| Flash flood warnings | 0 | 1 | 0% |
Each office's whole area, 2019
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Sacramento, CA: tornado warnings | 9 | 1 | 89% | 3 | 33% | 5 min |
| NWS Sacramento, CA: severe thunderstorm warnings | 17 | 6 | 65% | 24 | 54% | 16 min |
| NWS Sacramento, CA: flash flood warnings | 11 | 4 | 64% | 21 | 43% | 52 min |
| NWS Hanford, CA: tornado warnings | 9 | 2 | 78% | 12 | 8% | 25 min |
| NWS Hanford, CA: severe thunderstorm warnings | 33 | 1 | 97% | 7 | 14% | 42 min |
| NWS Hanford, CA: flash flood warnings | 34 | 6 | 82% | 50 | 14% | 51 min |
| NWS Phoenix, AZ: tornado warnings | 3 | 1 | 67% | 7 | 14% | 0 min |
| NWS Phoenix, AZ: severe thunderstorm warnings | 80 | 24 | 70% | 73 | 68% | 16 min |
| NWS Phoenix, AZ: flash flood warnings | 123 | 61 | 50% | 115 | 83% | 86 min |
| NWS San Francisco Bay Area, CA: tornado warnings | 0 | 2 | 0% | |||
| NWS San Francisco Bay Area, CA: severe thunderstorm warnings | 1 | 0 | 100% | 1 | 0% | |
| NWS San Francisco Bay Area, CA: flash flood warnings | 4 | 1 | 75% | 102 | 1% | 62 min |
| NWS Los Angeles, CA: tornado warnings | 3 | 0 | 100% | 1 | 0% | |
| NWS Los Angeles, CA: severe thunderstorm warnings | 5 | 0 | 100% | 0 | ||
| NWS Los Angeles, CA: flash flood warnings | 23 | 3 | 87% | 52 | 4% | 38 min |
| NWS Eureka, CA: severe thunderstorm warnings | 0 | 4 | 0% | |||
| NWS Eureka, CA: flash flood warnings | 0 | 6 | 0% | |||
| NWS Medford, OR: tornado warnings | 0 | 1 | 0% | |||
| NWS Medford, OR: severe thunderstorm warnings | 17 | 1 | 94% | 2 | 50% | 27 min |
| NWS Medford, OR: flash flood warnings | 1 | 1 | 0% | 1 | 100% | 140 min |
| NWS Las Vegas, NV: tornado warnings | 0 | 1 | 0% | |||
| NWS Las Vegas, NV: severe thunderstorm warnings | 22 | 5 | 77% | 34 | 32% | 20 min |
| NWS Las Vegas, NV: flash flood warnings | 60 | 23 | 62% | 102 | 55% | 105 min |
| NWS San Diego, CA: tornado warnings | 1 | 0 | 100% | 0 | ||
| NWS San Diego, CA: severe thunderstorm warnings | 16 | 5 | 69% | 18 | 67% | 16 min |
| NWS San Diego, CA: flash flood warnings | 36 | 16 | 56% | 84 | 48% | 97 min |
| NWS Reno, NV: severe thunderstorm warnings | 7 | 0 | 100% | 3 | 0% | |
| NWS Reno, NV: flash flood warnings | 6 | 0 | 100% | 1 | 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 | Lasted |
|---|---|---|---|
| Jan 4, 7:04 AM PST | Wind Advisory | MTR | 33 hr |
| Jan 6, 2:30 AM PST | Wind Advisory | MTR | 22 hr |
| Jan 10, 8:50 PM PST | Dense Fog Advisory | MTR | 6 hr |
| Jan 14, 12:57 PM PST | High Wind Watch | MTR | 24 hr |
| Jan 15, 11:18 AM PST | Flash Flood Watch | MTR | 37 hr |
| Jan 15, 1:23 PM PST | Wind Advisory | MTR | 35 hr |
| Jan 16, 10:53 AM PST | Coastal Flood Advisory | MTR | 22 hr |
| Jan 16, 2:44 PM PST | Areal Flood Advisory | MTR | 8 hr |
| Jan 19, 12:15 PM PST | Coastal Flood Advisory | MTR | 24 hr |
| Jan 20, 3:38 AM PST | Wind Advisory | MTR | 23 hr |
| Jan 20, 2:05 PM PST | Coastal Flood Advisory | MTR | 23 hr |
| Jan 31, 10:06 AM PST | High Wind Watch | MTR | 22 hr |
| Jan 31, 10:57 AM PST | Flash Flood Watch | MTR | 45 hr |
| Feb 1, 8:34 AM PST | High Wind Warning | MTR | 23 hr |
| Feb 1, 12:49 PM PST | Coastal Flood Advisory | MTR | 23 hr |
| Feb 2, 12:28 PM PST | Wind Advisory | MTR | 10 hr |
| Feb 11, 1:09 PM PST | Flash Flood Watch | MTR | 69 hr |
| Feb 11, 1:19 PM PST | High Wind Watch | MTR | 13 hr |
| Feb 12, 2:38 AM PST | High Wind Warning | MTR | 55 hr |
| Feb 12, 2:38 AM PST | Wind Advisory | MTR | 55 hr |
| Feb 13, 10:49 AM PST | Areal Flood Advisory | MTR | 116 min |
| Feb 13, 12:40 PM PST | Coastal Flood Advisory | MTR | 19 hr |
| Feb 14, 10:37 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 14, 2:39 PM PST | Coastal Flood Advisory | MTR | 19 hr |
| Feb 24, 1:38 PM PST | Flash Flood Watch | MTR | 61 hr |
| Jun 7, 10:10 AM PDT | Heat Advisory | MTR | 59 hr |
| Jun 9, 1:43 PM PDT | Heat Advisory | MTR | 31 hr |
| Jun 10, 11:44 AM PDT | Excessive Heat Warning | MTR | 9 hr |
| Jun 10, 5:03 PM PDT | Excessive Heat Warning | MTR | 28 hr |
| Jun 10, 5:03 PM PDT | Heat Advisory | MTR | 28 hr |
| Jul 25, 1:39 PM PDT | Excessive Heat Watch | MTR | 23 hr |
| Jul 26, 12:36 PM PDT | Heat Advisory | MTR | 55 hr |
| Aug 13, 9:24 AM PDT | Heat Advisory | MTR | 59 hr |
| Aug 16, 7:27 AM PDT | Heat Advisory | MTR | 13 hr |
| Sep 12, 8:47 AM PDT | Heat Advisory | MTR | 10 hr |
| Sep 12, 8:47 AM PDT | Heat Advisory | MTR | 34 hr |
| Sep 23, 1:32 PM PDT | Heat Advisory | MTR | 53 hr |
| Sep 23, 1:32 PM PDT | Heat Advisory | MTR | 29 hr |
| Oct 6, 3:00 PM PDT | Fire Weather Watch | MTR | 37 hr |
| Oct 8, 3:32 AM PDT | Red Flag Warning | MTR | 61 hr |
| Oct 22, 9:27 AM PDT | Red Flag Warning | MTR | 55 hr |
| Oct 24, 9:21 AM PDT | Heat Advisory | MTR | 10 hr |
| Oct 24, 4:03 PM PDT | Fire Weather Watch | MTR | 19 hr |
| Oct 24, 7:19 PM PDT | High Wind Watch | MTR | 16 hr |
| Oct 25, 7:21 AM PDT | Heat Advisory | MTR | 12 hr |
| Oct 25, 10:35 AM PDT | Red Flag Warning | MTR | 3 days |
| Oct 25, 11:12 AM PDT | Wind Advisory | MTR | 66 hr |
| Oct 28, 1:04 PM PDT | Red Flag Warning | MTR | 51 hr |
| Nov 16, 5:21 AM PST | Dense Fog Advisory | MTR | 4 hr |
| Nov 26, 6:43 PM PST | Areal Flood Advisory | MTR | 62 min |
| Nov 26, 7:35 PM PST | Areal Flood Advisory | MTR | 55 min |
| Nov 28, 2:51 AM PST | Frost Advisory | MTR | 30 hr |
| Nov 29, 3:33 AM PST | High Wind Watch | MTR | 10 hr |
| Nov 29, 1:42 PM PST | Wind Advisory | MTR | 61 hr |
| Dec 5, 1:38 PM PST | Wind Advisory | MTR | 38 hr |
| Dec 7, 2:59 PM PST | Areal Flood Advisory | MTR | 61 min |
| Dec 9, 4:47 AM PST | Dense Fog Advisory | MTR | 5 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Flooding | |
| Flash Flood Watch | 4 |
| Areal Flood Advisory | 6 |
| Heat | |
| Excessive Heat Warning | 2 |
| Excessive Heat Watch | 1 |
| Heat Advisory | 12 |
| Cold | |
| Frost Advisory | 1 |
| Wind and dust | |
| High Wind Warning | 2 |
| High Wind Watch | 5 |
| Wind Advisory | 9 |
| Fire | |
| Red Flag Warning | 4 |
| Fire Weather Watch | 2 |
| Fog and smoke | |
| Dense Fog Advisory | 3 |
| Coast and beach | |
| Coastal Flood Advisory | 6 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe 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.