Bomb cyclone hits California with rain and snow

Satellite image of a colorful swirl of bomb cyclone off west coast of North America.
NOAA’s newest Geostationary Operational Environmental Satellite (now called GOES-West) helped to image the bomb cyclone that struck California this week. Image via University of Wisconsin-Madison.

A series of atmospheric rivers has been aimed at California this week, bringing torrents of rain and high winds since 2023 began. Atmospheric rivers are flowing columns of water vapor that can dump high amounts of precipitation in a relatively short time. Plus, the storm that’s striking California this week (January 4-6, 2023) underwent what meteorologists call bombogenesis. That’s when a mid-latitude storm’s low pressure falls by 24 millibars within 24 hours. When that happens, the storm rapidly intensifies.

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California experienced an earlier onslaught of precipitation on New Year’s Eve from an atmospheric river. And even when this current storm passes, the extended forecast for California still shows increased precipitation, as the atmospheric river will continue to aim for the West Coast. As a matter of fact, the National Weather Service’s outlook for January 10-14 still has California at 80-90% above normal for precipitation.

Bomb cyclone has impressive strength

Because the storm system is so strong, the Air Force sent five Hurricane Hunter planes to California to monitor and track it. Marin County, north of San Francisco, had one recorded wind gust of 101 miles per hour (about 160 kph)!

Impacts from the massive storm

As of Thursday morning, January 5, the storm had claimed two lives in California. A redwood tree falling onto a home killed a two-year-old, and a 19-year-old woman hydroplaned on a partly flooded road, striking a utility pole.

Also, there were many reports of flooding on roads on social media, and high winds closed some ski resorts in the Sierra Nevadas.

Alleviating drought?

So will all this rain and snow help alleviate the drought in California? On January 3, Scooty Nickerson of the Bay Area’s Mercury News said:

California’s Sierra is closing in on the 2nd-largest snowpack we’ve seen at this time of year in the last two decades.

But, he said, it’s too early to declare an end to the drought, because:

Last year, we started 2022 with a similar bounty – and then ended the snow season way, way, way below normal.

While some of the reservoirs are starting to feel the impact of the atmospheric river, it’s not affecting all of them. For example, Lake Mead gets its water from the Colorado River, which is to the east. By the way, you can track the water levels in California’s reservoirs at its Department of Water Resources website.

Bomb cyclone was not a surprise

At least, there was plenty of warning that the storm was coming. Weather forecasts showed satellite images of the giant swirl in the atmosphere days in advance as it approached the coast. And shoppers in California stocked up at the grocery stores in advance of the storm, emptying shelves.

Bottom line: A bomb cyclone hit California this week, bringing high winds plus heavy rains and snow. More rain is on the way.

January 5, 2023

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Kelly Kizer Whitt

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