National Weather Service United States Department of Commerce

Heavy Rainfall to Bring Flooding Threat to California; Heavy Snow in the Sierra

A strong atmospheric river will bring heavy rainfall to California through the holiday week. The heaviest rainfall is expected on Wednesday in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall is expected in the Sierra Nevada from the atmospheric river, raising concerns for major snow‐load impacts. Travel may be difficult to impossible over the passes. Read More >

Many different estimates of observed precipitation are used in the river forecast process. Sources include rain gauge networks (both official and volunteer) as well as radar estimates.

 

National Precipitation Totals

 

 

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Daily 24hr precipitation report (HYDORN)
Text only, forecaster QCed. Point observations from gauges. Updates daily.

Daily 24hr precipitation from CoCoRAHS volunteers
Static images, no QC. Point observations from gauges.

 

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Customizable gridded precipitation
Zoomable, panable map, forecaster QCed. Gridded estimates from a combination of rain gauges and radar. May be slow on mobile devices.