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Northern California will get a break in the storm train on Wednesday, but it will be short. Another fairly weak storm arrives on Thursday, followed by what may be the strongest storm of the series, lasting from Friday through most of Saturday. This one storm alone has the potential to bring another 4 inches of rain to much of the North Bay.

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On Tuesday’s satellite view you can see our first storm moving south, bringing heavy rain to Central California and the Sierra. (Image 1) Notice the long fetch of moisture to the west across the Pacific. That moisture and storm energy will be coming our way from Thursday through Saturday.

You can also see the deep subtropical moisture in this image, being transported by a strong jet stream across the Pacific to California.
(Image 2)


The next storm will arrive early Thursday. It will be fairly weak. You can see its forecast arrival in this view. (Image 3) However, to the west lots of moisture and energy is being transported east…that will be the much larger storm expected on Friday and Saturday.


There may not be much lull between the Thursday storm and the Friday-Saturday storm complex. This one will most likely begin with an initial wave early Friday (Image 4), followed by reinforcing shots of storm energy late Friday through most of Saturday. (Image 5) This will feel like one long storm, with little break between pulses.

This storm will tap into deep moisture, with another atmospheric river plume pointed at Northern and Central California. (Image 6)

This time the hose of moisture may last much longer than our Monday-Tuesday storm, with even higher rain totals. The AR may arrive late Thursday, and continue almost non-stop through Friday, Friday night and early Saturday. (Image 7)

This is pretty good model agreement on this setup, which gives us increased confidence that it will happen.


Because of the extended duration of the atmospheric river plume, rainfall totals may be impressive. Here are estimates of additional rain by Sunday the 1st. This includes the Thursday storm, but most of this rain will come from early Friday through Saturday. Totals may reach an additional 3-6 inches, with more possible in the hills. (Image 8) Here is a closeup for the North Bay. (Image 9)

Because the soil is now saturated, this storm may bring increased runoff, which will help enhance local reservoir storage. However, this may also result in additional small stream and urban flooding on Friday and Saturday. The NWS may issue flood advisories and watches in the next two days as conditions evolve. More updates to come!

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