Update, 4:05 p.m.: Social video footage of heavy rain and flooding in northern California.

Update, 3:45 p.m.: Some updated rainfall totals from northern California through noon local time…

Update, 2:45 p.m.: A wind gust to 147 mph was recorded at high altitude peak near Lake Tahoe. Wow.

Original post


Visualization of Pacific storm (earth.nullschool.net)

The most intense storm to affect the West Coast since 2009 is unleashing flooding rain, extremely powerful winds, and mountain snows in northern California. Impacts from the storm extend into the Pacific Northwest.

The powerhouse storm is funneling a raging river of moisture into the region, originating from Hawaii, along an atmospheric conveyor belt known as the Pineapple Express.

The rain, wind, and snow have all resulted in major impacts in northern California, including San Francisco, where schools closed due to the storm.

Related: California braces for heavy rain, damaging winds as monster storm bears down

The rain


Rainfall through 10 a.m. PT (NWS)

In the northern Bay area, widespread amounts of 3 inches or more, with isolated totals over 7 inches have already fallen.  Both the quantity and intensity (1 inch per hour rates) of the rain have led to flooding:

Flash flood warnings are in effect both in the northern Bay area (including Napa and Sonoma counties) and have been extended south into San Jose and Santa Cruz, where somewhat less rain has fallen (generally 1-2 inches):

An additional 2 to 6 inches of rain is possible in many areas of northern California, where the rain will continue into Friday before tapering off:


Rainfall forecast from National Weather Service through Friday morning (WeatherBell.com)

The wind

Strong wind gusts, exceeding 40-50 mph at low elevations have caused widespread power outages. More than 94,000 customers were without power in the San Francisco Bay area as of late this morning:

San Francisco has already logged wind gusts to 45 mph, and is under a high wind warning for gusts to 50-60 mph into this evening.

Winds rapidly increase with elevation, with gusts to 60 to 70 mph in some the hills adjacent to the Bay area.

At highest elevations and mountain peaks in the western part of the state, winds have exceeded hurricane force, with an incredible 135 mph gust recorded at Donner Pass not far from Lake Tahoe:

The winds at Lake Tahoe have whipped up huge waves:

High winds also extend into the Pacific Northwest, where Seattle is under a high wind warning:

The snow

The combination of the extremely powerful winds, exceeding hurricane force at high altitudes, and heavy snow has prompted blizzard warnings mostly for elevations above 6,500 feet.  Some areas could receive 2 to 3 feet of snow, and the National Weather Service cautions “extremely hazardous whiteout conditions” are expected.


High resolution NAM model snowfall simulation for northern California and the Pacific Northwest (WeatherBell.com)

Implications for the drought

Given how big the rainfall deficit is in California, no single storm can end the drought, but a super wet storm like this helps, even with the associated flooding and wind hazards.

Some more storm great visuals, via Twitter