Flooding, feet of snow and high winds to threaten Northern California into Tuesday

By Renee Duff, AccuWeather meteorologist

February 20,2017, 12:44:29PM,EST

 

 Heavy rain, mountain snow and high winds will pound the northwestern United States early this week, with the most significant impacts targeting Northern California.

Storms have resumed their track across the region following a brief break from heavy precipitation to start the weekend.
A widespread 2 to 6 inches of rain can fall across the San Francisco Bay region and part of the Sacramento Valley through Tuesday. However, local amounts topping 8 inches are possible, including over the Santa Cruz Mountains and the Feather River Basin.
“While the storms will bring the risk of mudslides and avalanches, the greatest threat to lives and property will be from flooding,” AccuWeather Senior Meteorologist Alex Sosnowski said.

Significant rainfall so far this winter has left reservoirs full and many rivers near or above flood stage.
"There is not much room there for reservoirs to hold back water at this point, according to AccuWeather Meteorologist Jim Andrews. "A great deal of runoff from this rain will have to be released into already water levels on the rivers."
Additional rainfall will struggle to seep into the saturated ground causing excessive runoff.
Residents who live near streams and rivers as well as downstream of reservoirs should monitor the weather closely this week.
Evacuations may be ordered in some communities if the threat for flooding is imminent. This includes near Oroville Dam, where crews have been repairing a damaged emergency spillway that sparked fears of a major flooding disaster last weekend.
California Department of Water Resources officials are confident Lake Oroville will be able to withstand the rainfall early this week, according to The Sacramento Bee.
RELATED:
Aerial of the Oroville Dam and the state of the spillway
Photos show deadly flooding inundating Southern California
Northern California interactive radar
Motorists should be on alert for pooling of water on roadways and perhaps closed roads.
Significantly less rainfall will reach Portland, Oregon, to Seattle where the threat for flooding will be very isolated. Still, rain and a low cloud ceiling can make for disruptions to travel.
Unlike the deadly rainstorm that caused significant flooding to end the past week, this storm will stop short of spreading heavy rainfall into Southern California. At most, spotty rain and drizzle will affect the Los Angeles Basin early this week.
From 2 to 4 feet of snow will further bury the highest peaks of the Sierra Nevada.

"Snow levels are starting off near pass levels on Monday," according to AccuWeather Lead Storm Warning Meteorologist Eddie Walker. "Snow will pile up and travel conditions will deteriorate through Tuesday."
At least a couple of feet of snow will bury Donner Summit along Interstate 80 in California from through Tuesday. This stretch of I-80 may close for a time due to the amount of snow and whiteout conditions anticipated from strong winds.
While the snow will not be quite as heavy across the Cascades, slippery travel will still pose problems.
“Episodes of snow, an icy mix and strong winds will also lead to travel hazards over the interior Northwest, east of the Cascades and Sierra Nevada,” Sosnowski said.
Gusty winds will accompany the rain and snow and elevate the risk for fallen trees and sporadic power outages from the coast of Northern California and southern Oregon to southwestern Idaho.

While no major storms are expected to follow the early week deluge, several weaker storms will unload additional bouts of rain and snow across the West Coast into next week.
The wet weather from these storms will tend to be spottier and less intense.