Update: The Atmospheric River. Where Will It Stall?

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With rain spreading across the North Bay…the big question among forecasters is…where will the Atmospheric River of heaviest rain stall over the next 24-36 hours?

High resolution models show the fire hose of moisture trained on Sonoma and Marin Counties over the next 24 hours at least, extending down to the central Bay Area.

The AR is narrow…usually less than 100 miles wide.  So where it comes ashore will determine how much rain falls over the North Bay Area in the next 2 days….and how extreme river and small stream flooding will be across Sonoma County and rest of the North Bay.

A small movement north or south can dramatically change rainfall totals.

Here is the high resolution NAM model, which also shows the AR stalling over the North Bay over the next 24 hours, then shifting south.

Other models have slightly different solutions…and forecasters are generally going with an average right now.  That means we’re still on track for 6-12 inches of rain across Sonoma, Marin, Lake and Napa Counties between Monday and late Wednesday.

Here’s the latest North Bay forecast for rain by Thursday.


The Russian and Napa rivers are currently forecast to reach flood stage late Tuesday or early Wednesday, with a crest on the Russian, 6 feet over flood stage, expected late Wednesday night.

A flood watch is in effect for Marin and Sonoma Counties through Wednesday night.




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