Alert archive / California / San Mateo County
Weather alerts in San Mateo County, California, 2017
111 weather alerts in 2017, 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 2017. Tap one for its archive.
- Alerts
- 111
- Warnings
- 24
- Watches
- 14
- Advisories
- 53
- Busiest month
- January39 alerts
- Busiest day
- February 20, 20177 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, 2017
| 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 | 4 | 0 | 100% | 16 | 0% |
Each office's whole area, 2017
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS San Francisco Bay Area, CA: severe thunderstorm warnings | 0 | 2 | 0% | |||
| NWS San Francisco Bay Area, CA: flash flood warnings | 71 | 5 | 93% | 177 | 4% | 160 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, 11:59 AM PST | Flash Flood Watch | MTR | 25 hr |
| Jan 3, 12:17 PM PST | Wind Advisory | MTR | 13 hr |
| Jan 3, 5:31 PM PST | Areal Flood Warning | MTR | 6 hr |
| Jan 3, 5:43 PM PST | Areal Flood Advisory | MTR | 12 hr |
| Jan 6, 3:26 AM PST | Flash Flood Watch | MTR | 3 days |
| Jan 6, 3:38 AM PST | High Wind Watch | MTR | 8 hr |
| Jan 6, 11:26 AM PST | High Wind Warning | MTR | 55 hr |
| Jan 6, 11:26 AM PST | Wind Advisory | MTR | 55 hr |
| Jan 8, 1:49 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Jan 9, 2:55 AM PST | Coastal Flood Advisory | MTR | 3 days |
| Jan 9, 3:02 AM PST | High Wind Watch | MTR | 11 hr |
| Jan 9, 2:17 PM PST | High Wind Warning | MTR | 34 hr |
| Jan 9, 2:17 PM PST | Wind Advisory | MTR | 34 hr |
| Jan 9, 2:39 PM PST | Flash Flood Watch | MTR | 37 hr |
| Jan 10, 2:55 PM PST | Areal Flood Advisory | MTR | 2 hr |
| Jan 10, 5:46 PM PST | Areal Flood Advisory | MTR | 4 hr |
| Jan 10, 11:07 PM PST | Areal Flood Advisory | MTR | 113 min |
| Jan 11, 12:27 AM PST | Areal Flood Advisory | MTR | 4 hr |
| Jan 12, 1:02 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Jan 14, 2:21 PM PST | Beach Hazards Statement | MTR | 31 hr |
| Jan 17, 3:36 AM PST | Wind Advisory | MTR | 45 hr |
| Jan 18, 3:55 PM PST | Areal Flood Advisory | MTR | 4 hr |
| Jan 19, 4:28 AM PST | High Surf Warning | MTR | 71 hr |
| Jan 19, 12:51 PM PST | Wind Advisory | MTR | 21 hr |
| Jan 20, 3:39 AM PST | Special Weather Statement | MTR | 36 min |
| Jan 20, 4:14 AM PST | Special Weather Statement | MTR | 31 min |
| Jan 20, 5:27 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Jan 20, 12:51 PM PST | High Wind Watch | MTR | 15 hr |
| Jan 20, 1:27 PM PST | Flash Flood Watch | MTR | 3 days |
| Jan 21, 4:12 AM PST | High Wind Warning | MTR | 29 hr |
| Jan 21, 4:12 AM PST | Wind Advisory | MTR | 29 hr |
| Jan 22, 2:47 AM PST | High Surf Advisory | MTR | 48 hr |
| Jan 22, 4:30 AM PST | Areal Flood Advisory | MTR | 60 min |
| Jan 22, 12:27 PM PST | Areal Flood Advisory | MTR | 6 hr |
| Jan 22, 1:43 PM PST | Mesoscale Discussion | SPC | 2 hr |
| Jan 22, 2:29 PM PST | Special Weather Statement | MTR | 16 min |
| Jan 24, 4:25 AM PST | High Surf Advisory | MTR | 12 hr |
| Jan 25, 8:13 AM PST | High Surf Advisory | MTR | 43 hr |
| Jan 31, 2:08 AM PST | Wind Advisory | MTR | 55 hr |
| Feb 6, 2:25 AM PST | Wind Advisory | MTR | 35 hr |
| Feb 6, 9:17 AM PST | Flash Flood Watch | MTR | 31 hr |
| Feb 7, 10:26 AM PST | Areal Flood Warning | MTR | 11 hr |
| Feb 7, 10:47 AM PST | Flash Flood Warning | MTR | 3 hr |
| Feb 8, 1:57 AM PST | Wind Advisory | MTR | 38 hr |
| Feb 8, 9:18 AM PST | Flash Flood Watch | MTR | 41 hr |
| Feb 8, 2:43 PM PST | Coastal Flood Warning | MTR | 21 hr |
| Feb 15, 1:15 PM PST | High Surf Advisory | MTR | 27 hr |
| Feb 16, 1:27 PM PST | Wind Advisory | MTR | 28 hr |
| Feb 18, 4:33 AM PST | High Surf Advisory | MTR | 13 hr |
| Feb 18, 10:06 AM PST | Flood Watch | MTR | 64 hr |
| Feb 18, 2:23 PM PST | Wind Advisory | MTR | 60 hr |
| Feb 19, 1:33 PM PST | High Wind Warning | MTR | 37 hr |
| Feb 20, 7:35 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 7:44 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 10:34 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 10:48 AM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 1:32 PM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 1:48 PM PST | Areal Flood Advisory | MTR | 3 hr |
| Feb 20, 2:40 PM PST | Areal Flood Advisory | MTR | 65 min |
| Feb 20, 5:29 PM PST | Flash Flood Warning | MTR | 2 hr |
| Feb 20, 6:03 PM PST | Areal Flood Advisory | MTR | 4 hr |
| Feb 20, 7:17 PM PST | Flash Flood Warning | MTR | 3 hr |
| Feb 20, 10:15 PM PST | Flash Flood Warning | MTR | 3 hr |
| Feb 21, 1:09 AM PST | Areal Flood Warning | MTR | 6 hr |
| Feb 21, 4:01 PM PST | Special Weather Statement | MTR | 14 min |
| Feb 25, 2:21 PM PST | Beach Hazards Statement | MTR | 21 hr |
| Mar 4, 8:45 PM PST | Areal Flood Advisory | MTR | 2 hr |
| Mar 24, 2:51 AM PDT | Wind Advisory | MTR | 10 hr |
| Mar 28, 2:31 AM PDT | Beach Hazards Statement | MTR | 41 hr |
| Mar 29, 6:21 PM PDT | Wind Advisory | MTR | 26 hr |
| Apr 1, 1:42 PM PDT | Beach Hazards Statement | MTR | 45 hr |
| Apr 5, 4:40 AM PDT | High Wind Watch | MTR | 23 hr |
| Apr 6, 3:17 AM PDT | High Wind Warning | MTR | 25 hr |
| Apr 6, 3:17 AM PDT | Wind Advisory | MTR | 25 hr |
| Apr 6, 2:20 PM PDT | Beach Hazards Statement | MTR | 49 hr |
| May 5, 12:14 PM PDT | Wind Advisory | MTR | 22 hr |
| May 6, 8:49 PM PDT | High Surf Advisory | MTR | 17 hr |
| Jun 13, 12:56 PM PDT | Excessive Heat Watch | MTR | 48 hr |
| Jun 15, 12:51 PM PDT | Heat Advisory | MTR | 8 days |
| Jun 20, 1:11 PM PDT | Excessive Heat Warning | MTR | 56 hr |
| Jul 7, 5:52 PM PDT | Heat Advisory | MTR | 27 hr |
| Jul 10, 7:38 PM PDT | Beach Hazards Statement | MTR | 60 hr |
| Jul 13, 12:58 PM PDT | Heat Advisory | MTR | 3 days |
| Jul 15, 2:00 PM PDT | Red Flag Warning | MTR | 31 hr |
| Jul 29, 1:19 AM PDT | Beach Hazards Statement | MTR | 67 hr |
| Jul 31, 1:54 AM PDT | Heat Advisory | MTR | 4 days |
| Aug 25, 8:03 AM PDT | Excessive Heat Warning | MTR | 4 days |
| Aug 25, 8:03 AM PDT | Heat Advisory | MTR | 4 days |
| Aug 29, 7:47 AM PDT | Excessive Heat Watch | MTR | 30 hr |
| Aug 30, 12:00 PM PDT | Red Flag Warning | MTR | 3 days |
| Aug 30, 1:27 PM PDT | Excessive Heat Warning | MTR | 4 days |
| Aug 30, 1:27 PM PDT | Heat Advisory | MTR | 47 hr |
| Sep 2, 9:16 PM PDT | Heat Advisory | MTR | 24 hr |
| Sep 11, 6:24 PM PDT | Special Weather Statement | MTR | 51 min |
| Sep 11, 9:25 PM PDT | Special Weather Statement | MTR | 65 min |
| Sep 18, 2:06 PM PDT | Beach Hazards Statement | MTR | 55 hr |
| Oct 5, 12:36 PM PDT | Beach Hazards Statement | MTR | 4 days |
| Oct 6, 9:49 AM PDT | Red Flag Warning | MTR | 4 days |
| Oct 10, 11:14 AM PDT | Red Flag Warning | MTR | 54 hr |
| Oct 18, 8:36 AM PDT | High Surf Advisory | MTR | 57 hr |
| Oct 20, 1:01 PM PDT | Beach Hazards Statement | MTR | 32 hr |
| Oct 26, 11:48 AM PDT | Beach Hazards Statement | MTR | 3 days |
| Nov 14, 2:12 AM PST | Wind Advisory | MTR | 49 hr |
| Nov 27, 8:55 PM PST | Beach Hazards Statement | MTR | 48 hr |
| Nov 29, 9:24 PM PST | Beach Hazards Statement | MTR | 6 hr |
| Dec 2, 7:01 PM PST | Coastal Flood Warning | MTR | 40 hr |
| Dec 14, 9:21 AM PST | Fire Weather Watch | MTR | 17 hr |
| Dec 14, 9:25 AM PST | Wind Advisory | MTR | 3 days |
| Dec 15, 2:00 AM PST | Red Flag Warning | MTR | 56 hr |
| Dec 21, 2:09 AM PST | Frost Advisory | MTR | 31 hr |
| Dec 21, 2:09 AM PST | Freeze Warning | MTR | 31 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 | |
| Mesoscale Discussion | 1 |
| Special Weather Statement | 6 |
| Flooding | |
| Areal Flood Warning | 3 |
| Flash Flood Warning | 4 |
| Flash Flood Watch | 6 |
| Flood Watch | 1 |
| Areal Flood Advisory | 20 |
| Heat | |
| Excessive Heat Warning | 3 |
| Excessive Heat Watch | 2 |
| Heat Advisory | 7 |
| Cold | |
| Freeze Warning | 1 |
| Frost Advisory | 1 |
| Wind and dust | |
| High Wind Warning | 5 |
| High Wind Watch | 4 |
| Wind Advisory | 17 |
| Fire | |
| Red Flag Warning | 5 |
| Fire Weather Watch | 1 |
| Coast and beach | |
| Coastal Flood Warning | 2 |
| High Surf Warning | 1 |
| Coastal Flood Advisory | 1 |
| High Surf Advisory | 7 |
| Beach Hazards Statement | 13 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20162018
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.