SAN FRANCISCO (KRON) – The first significant rainstorm of the season is hitting the Bay Area Tuesday thanks to a bomb cyclone.

The rain arrived mid-day. The heaviest of rain is expected to fall late this afternoon and early evening, making for a wet commute home.

Showers will continue on and off through the evening and into tomorrow, making for a very busy travel day.

The weather phenomenon “bomb cyclone” will hit Northern California and Oregon at one of the busiest travel times of the year.

A bomb cyclone forms when air pressure drops by 24 millibars in a 24-hour period.

The National Weather Service says the storm expected Tuesday into Wednesday could be like nothing experienced in the area for 20 years.

Mountain passes in northern California and southern Oregon could get up to two feet of snow.

Thanksgiving Day is looking to be dryer overall, with a few spotted showers.

Sunshine and dry conditions return for Black Friday but it will be cool – so bundle up if you’re planning on shopping.

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