CW3E AR Update: 3 January 2023 Outlook

January 3, 2023

Click here for a pdf of this information.

Atmospheric River to Bring Significant Rainfall to Northern and Central California

  • An atmospheric river in association with a strong low-pressure system over the North Pacific will bring significant precipitation to Northern California between Wednesday morning and Thursday afternoon
  • IVT associated with this AR will exceed 750 kg m-1 s-1 along the coast of Northern California, making this an AR 3 based on the Ralph et al. 2019 AR Scale
  • This AR will be the first of three landfalling ARs over the next 7 days, with the following two ARs also forecast to impact Northern and Central California with additional precipitation over the weekend and into early next week
  • The NWS Weather Prediction Center (WPC) has forecast 7-day precipitation totals to exceed 15 inches along the coast of Central California and the Northern Sierra Nevada
  • NWS WPC has issued a moderate risk for excessive rainfall with the potential for flash flooding along much of coastal California over the coming days, highlighting the enhanced risk due to saturated antecedent soil conditions
  • Precipitation forecasts over the next 7 days for watersheds in northern California and the Northern Sierra are between 6–8 inches, with the ECMWF forecasting higher precipitation totals along the coast and less in the Sierra Nevada compared to the GFS
  • NWS Weather Forecast Offices have begun issuing watches and warnings for flood, high wind, and winter weather hazards in association with this AR
  • The NWS California Nevada River Forecast Center (CNRFC) has forecast multiple rivers to exceed flood stage in association with the precipitation from this AR
  • Stay alert to official NWS forecasts, watches, and warnings at and follow guidance from local emergency management officials

Click images to see loops of GFS IVT and IWV forecasts

Valid 1200 UTC 3 January – 1200 UTC 10 January 2023














Summary provided by S. Bartlett, S. Roj, C. Castellano, J. Kalansky, and F. M. Ralph; 03 January 2023

To sign up for email alerts when CW3E post new AR updates click here.

*Outlook products are considered experimental