CW3E AR Update: 10 February 2025 Outlook

February 10, 2025

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Atmospheric River Forecast to Impact California This Week

A weak pulse of moisture transport is forecast to move onshore late Tue 11 Feb and bring light precipitation to coastal Central and Southern California.
A stronger atmospheric river (AR) associated with a low-pressure system is forecast to bring heavy rain and mountain snow to much of California late Wed 12 Feb through Fri 14 Feb.
Ensemble and deterministic models are still showing some subtle differences in both the initial moisture pulse and the subsequent AR.
The GEFS control member is forecasting an AR 2 (based on the Ralph et al. 2019 AR Scale) over coastal Central California and an AR 1 over coastal Southern California, whereas the EPS control member is forecasting an AR 3 over San Diego County.
Storm-total precipitation amounts of 5–10 inches are possible in the Sierra Nevada, Central California Coast Ranges, and Southern California Transverse Ranges.
The heaviest precipitation and greatest impacts from this AR are expected Thu 13 Feb into Fri 14 Feb. The NWS Weather Prediction Center (WPC) has issued a slight risk excessive rainfall outlook (ERO) for much of coastal California, the Central/Southern Sierra Nevada, and portions of the Central Valley.
Compared to the deterministic GFS, the deterministic ECMWF is forecasting lower precipitation amounts over the Sierra Nevada and higher precipitation amounts over the Central California Coast Ranges and Southern California.
Heavy snowfall is also likely in the higher terrain of the Sierra Nevada, with >4 feet possible in the Central and Southern Sierra Nevada. Major-to-extreme winter storm impacts are likely in these areas.