Weather

Here’s what to expect this week as latest storm takes aim at state

What is an atmospheric river?

Atmospheric rivers have a significant impact the U.S. west coast. Snow, rain and flooding due to the weather phenomenon can cause major damage to property.
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Atmospheric rivers have a significant impact the U.S. west coast. Snow, rain and flooding due to the weather phenomenon can cause major damage to property.

An atmospheric river is expected to glance Sacramento starting Tuesday afternoon on its path toward Southern California and the Central Coast, leaving one to three inches of rain behind in the valley and up to five feet of snow in the Sierra Nevada by the time it finishes Saturday morning.

Here’s what you need to know about the storm:

  • Rain should come rolling into Sacramento on Tuesday afternoon and stay drizzling through Wednesday evening. A half-inch is expected Thursday morning before skies turn dry in the afternoon, and only minimal showers are predicted Friday through Saturday morning.
  • Thursday will be the worst day for mountain travel. A winter storm watch is in effect the whole day across the Sierra Nevada’s western slope, and downed trees and power lines could scatter across rural roads. Visibility is also expected to be severely impaired at higher elevations, and snow levels could drop from 7,000 feet to below 3,000 throughout the day.
  • The storm could be the final blessing in a much-needed, unusually wet month. The Sierra Nevada snowpack now sits at 48 percent of its year-to-date average, double what it was on March 1. Sacramento saw no rain in February until two days before the month’s end.
  • Santa Barbara and Ventura counties faces serious flooding and mudslide risks tied to wildfires last December. So serious, in fact, that some regions in both counties have mandatory evacuation orders ahead of five to 10 inches of rainfall over the next four days.
  • Flights to the East Coast may be delayed or canceled due to Winter Storm Toby, the fourth nor'easter this month. A massive amount of snow is expected from Massachusetts down to the Great Smoky Mountains in North Carolina.
  • Winds should be pretty mild in inland Northern California. They aren’t expected to top 20 MPH the entire week in Sacramento, Truckee or Stockton, though the Bay Area could see 35 MPH gusts Wednesday night and Thursday.

As a reminder, here are what a few commonly used weather terms really mean:

  • Atmospheric river: Sometimes called “horizontal hurricanes,” they occur when winds drag a stream of moisture from the tropics to northern land masses such as the West Coast. For further explanation, check out this video.
  • Pineapple express: No, not that kind of pineapple express. An atmospheric river which originates around Hawaii and spreads east to the California and its neighboring states.
  • Winter storm watch: Snow may build up to the point where roads close or chains are required. Not as serious as a winter storm warning, but travelers are advised to monitor the latest forecasts.
  • Snowpack: The layer of snow built up on a mountaintop. In California, this often refers to the average water content of 100 stations in the Sierra Nevada.

  • Nor'easter: A widespread cyclone on the East Coast usually accompanied by intense snow and wind. Most common from October to March.

Benjy Egel: (916) 321-1052, begel@sacbee.com

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