PROJECT ALERT NOTICE (CA) Runoff in San Diego and Riverside Counties

Date: Thu, 01 Jan 2026 13:24:26 EST

Summary: Overnight precip requiring some follow up measurements.

A small upper level low pressure system spinning off the Central Ca Coast is entraining some tropical moisture and funneling it into Southern California for the past 6-8 hours. Rainfall amounts in the San Diego Foothills are currently averaging about 2 inches over that time while rainfall tapers off farther north into Riverside county. We have one gage at Minor Flood stage, (11023000, an FPS site) which is currently peaking at a tad less than 3K CFS. There is enough runoff to justify mobilizing staff out of our PWY FO to make some mid level measurements for Rating development at newer sites. Currently there are three staff in process to various gages for that purpose. Rainfall is tapering off and most gages are in recession. After this event the NWS is forecasting a couple days break before the next round begins to impact the state. We'll see how that develops. Stay tuned.