Northern California to be lashed with heavy rains, wind

Doyle Rice, USA TODAY | USATODAY

Show Caption Hide Caption National weather forecast for Wednesday Nov. 28 Another storm in the West: Afternoon rain from Los Angeles to Seattle; Snow in the Sierra; Snow showers in the Great Lakes; Drying out in the East and chilly

Some spots could receive up to 20 inches of rain

Flooding, mudslides, debris flows all possible

Wind, snow for the mountains

An intense storm will slam into Northern California on Wednesday with strong winds and heavy rain, the first in a series of powerful storms forecast to hit the state over the next several days. Wednesday's storm should roar into the San Francisco area with lightning and wind in the morning before moving inland.

Rain totals should top a foot in some spots by the time the storms end Sunday, and wind gusts are expected to howl up to 95 mph in the mountains.

The rain will likely lead to flash and river floods, along with mudslides and debris flows, says George Cline, a meteorologist with the National Weather Service in Sacramento.

Debris flows are when water, rocks, trees, clay, mud and dirt careen down mountainsides scorched bare by earlier wildfires.

The weather service is warning that power outages should be expected in Northern California because of downed trees and limbs. Cline says this will be the most rain California has seen since last year.

The storms, which are rotating around a large area of low pressure in the Gulf of Alaska, will be fueled in part by the so-called "pineapple express," an atmospheric river of tropical moisture that moves from the Hawaiian Islands to the West Coast.

Meteorologists use the term "atmospheric river" to describe a long, narrow plume that pipes moisture from the tropics into the USA, according to Weather Channel meteorologist Jonathan Erdman. The pineapple express typically runs a few times each winter.

Separate storms will move along this "river" every day through Sunday, according to AccuWeather meteorologist Ken Clark. Although each individual storm wouldn't be enough to cause major problems, Clark says it's the cumulative effect of the storms that could cause the flooding problems.

The heaviest rain is likely for higher elevations northeast of Sacramento, Clark reports. In general, by Sunday, rain amounts of 3-7 inches are forecast in the valleys, 6-12 in the foothills and 10 to 20 in the mountains, the weather service forecasts.

Southern Oregon will also see heavy rain and strong winds from the storms. However, Southern California will not see the level of rain that Northern California is expected to get.

The storms will produce up to at least a foot of snow over the highest elevations of the Sierra, the Bitterroots, Tetons and the Washington Cascades, Erdman says.

The news isn't all bad, as rain events such as this bring the needed water that California depends on for agriculture and for its reservoirs. However, this could be "too much in too short of a time," Clark says.