Alert archive / California / San Mateo County
Weather alerts in San Mateo County, California, 2012
49 weather alerts in 2012, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
San Mateo County and its neighbors
Each county as a circle sized by its count in 2012. Tap one for its archive.
- Alerts
- 49
- Warnings
- 7
- Watches
- 4
- Advisories
- 34
- Busiest month
- December12 alerts
- Busiest day
- December 24, 20124 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
San Mateo County, 2012
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 0 | 0 | ||||
| Severe thunderstorm warnings | 1 | 0 | 100% | 0 | ||
| Flash flood warnings | 2 | 0 | 100% | 1 | 0% |
Each office's whole area, 2012
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS San Francisco Bay Area, CA: severe thunderstorm warnings | 3 | 0 | 100% | 1 | 0% | |
| NWS San Francisco Bay Area, CA: flash flood warnings | 17 | 3 | 82% | 10 | 20% | 69 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 | Lasted |
|---|---|---|---|
| Jan 3, 6:03 AM PST | Dense Fog Advisory | MTR | 4 hr |
| Jan 5, 2:40 AM PST | High Surf Advisory | MTR | 39 hr |
| Jan 15, 8:08 PM PST | Freeze Watch | MTR | 7 hr |
| Jan 16, 3:19 AM PST | Freeze Warning | MTR | 29 hr |
| Jan 20, 10:14 AM PST | High Surf Advisory | MTR | 48 hr |
| Jan 22, 2:33 AM PST | Wind Advisory | MTR | 27 hr |
| Jan 26, 5:04 AM PST | High Surf Advisory | MTR | 10 hr |
| Jan 26, 3:16 PM PST | High Surf Advisory | MTR | 3 hr |
| Feb 5, 1:55 PM PST | High Wind Watch | MTR | 13 hr |
| Feb 6, 2:53 AM PST | Wind Advisory | MTR | 31 hr |
| Feb 7, 1:52 PM PST | High Surf Advisory | MTR | 25 hr |
| Feb 13, 9:13 AM PST | High Surf Advisory | MTR | 30 hr |
| Feb 29, 4:54 AM PST | High Surf Advisory | MTR | 28 hr |
| Mar 5, 2:35 AM PST | Wind Advisory | MTR | 44 hr |
| Mar 16, 8:50 PM PDT | Areal Flood Advisory | MTR | 115 min |
| Mar 17, 2:58 AM PDT | High Surf Advisory | MTR | 41 hr |
| Mar 30, 3:01 AM PDT | High Surf Advisory | MTR | 35 hr |
| Mar 31, 2:30 PM PDT | High Surf Warning | MTR | 25 hr |
| Apr 1, 3:06 PM PDT | High Surf Advisory | MTR | 17 hr |
| Apr 12, 4:16 AM PDT | Areal Flood Advisory | MTR | 89 min |
| Apr 12, 8:14 PM PDT | Severe Thunderstorm Warning | MTR | 31 min |
| May 16, 11:20 AM PDT | Beach Hazards Statement | MTR | 5 days |
| May 21, 11:27 AM PDT | Beach Hazards Statement | MTR | 48 hr |
| May 29, 11:31 AM PDT | Beach Hazards Statement | MTR | 17 days |
| Jun 19, 11:09 AM PDT | Beach Hazards Statement | MTR | 14 days |
| Sep 3, 3:02 AM PDT | Dense Fog Advisory | MTR | 6 hr |
| Sep 28, 10:57 AM PDT | Excessive Heat Watch | MTR | 40 hr |
| Oct 29, 3:16 AM PDT | Dense Fog Advisory | MTR | 5 hr |
| Oct 29, 1:20 PM PDT | Dense Fog Advisory | MTR | 20 hr |
| Nov 26, 3:52 AM PST | Dense Fog Advisory | MTR | 5 hr |
| Nov 27, 3:39 AM PST | Wind Advisory | MTR | 34 hr |
| Nov 27, 1:53 PM PST | High Wind Warning | MTR | 21 hr |
| Nov 29, 3:14 AM PST | High Surf Advisory | MTR | 54 hr |
| Nov 29, 11:22 AM PST | Flash Flood Watch | MTR | 3 days |
| Nov 29, 11:23 AM PST | Wind Advisory | MTR | 27 hr |
| Nov 30, 8:27 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Nov 30, 11:25 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Dec 1, 10:23 AM PST | Wind Advisory | MTR | 26 hr |
| Dec 2, 7:19 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Dec 2, 9:20 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Dec 18, 3:04 AM PST | Frost Advisory | MTR | 29 hr |
| Dec 19, 6:09 PM PST | Wind Advisory | MTR | 40 hr |
| Dec 21, 2:51 AM PST | High Surf Advisory | MTR | 35 hr |
| Dec 22, 1:41 PM PST | Wind Advisory | MTR | 24 hr |
| Dec 23, 4:04 PM PST | Areal Flood Advisory | MTR | 3 hr |
| Dec 23, 5:05 PM PST | Flash Flood Warning | MTR | 115 min |
| Dec 23, 7:04 PM PST | Flash Flood Warning | MTR | 86 min |
| Dec 23, 7:30 PM PST | Areal Flood Warning | MTR | 105 min |
| Dec 27, 12:39 PM PST | High Surf Advisory | MTR | 57 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 | 1 |
| Flooding | |
| Areal Flood Warning | 1 |
| Flash Flood Warning | 2 |
| Flash Flood Watch | 1 |
| Areal Flood Advisory | 7 |
| Heat | |
| Excessive Heat Watch | 1 |
| Cold | |
| Freeze Warning | 1 |
| Freeze Watch | 1 |
| Frost Advisory | 1 |
| Wind and dust | |
| High Wind Warning | 1 |
| High Wind Watch | 1 |
| Wind Advisory | 8 |
| Fog and smoke | |
| Dense Fog Advisory | 5 |
| Coast and beach | |
| High Surf Warning | 1 |
| High Surf Advisory | 13 |
| Beach Hazards Statement | 4 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20112013
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.