Flash Flood, San Mateo
- When
- January 1, 1:20 AM PST to 11:30 AM PST
- Where
- San Mateo County, Southwest Portion
- Coordinates
- 37.436, -122.356 (the zone’s center; the record gives no point)
Rain was falling at 1/2 inch per hour for two hours over the warning area. Rainfall rates were increasing and the rainy pattern was becoming more widespread as 88D radar was showing a band of heavy rain moving into central California.
Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MTR wrote it up.
Rain was falling at 1/2 inch per hour for two hours over the warning area. Rainfall rates were increasing and the rainy pattern was becoming more widespread as 88D radar was showing a band of heavy rain moving into central California. The ground was already saturated and many small streams were nearing bankfull. Mudslides were expected in steep terrain. Rainfall rates of 1/2 inch per hour continued for several hours over a wide part of the warned area.
The San Francisco radar (KMUX), 51 km away, was scanning. The volume nearest the first event began at 09:19 UTC.
6 flash flood. Local standard time, as filed.
Pescadero Creek reached flood stage by late morning. LaHonda Road closed due to mudslide at 1000 PST.
Spotter report of 1/2 inch rain in 20 minutes in Morgan Hill. City of Morgan Hill being evacuated at 1030 PST.
Spotter report of rain falling at 1 inch per hour rate and the small streams are full (1126 PST). San Lorenzo River at Felton rose above warning stage at 1100 PST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 1997Every state in 1997This day in weather historyWarnings in California, January 1997
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5623728, 5623729, 5623730, 5623731, 5623732, 5623733.