Powerful storms to deluge northwestern US into next week may be a sign of winter conditions to come

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

October 12,2016; 11:31PM,EDT

 

 

At least three potent storms will blast the northwestern United States from the latter part of this week to the early part of next week.
The storms could be an early sign of a La Niña-like pattern for the winter ahead. La Niña is a pattern noted by a zone of cooler-than-average water temperatures in the tropical Pacific Ocean. Depending on the strength and extent of this cool puddle, weather patterns across much of the globe can be affected.
"The series of storms will bring heavy rain, high country snow and high winds to portions of Washington, Oregon, Idaho, northern California and western Montana, as well as neighboring British Columbia into next week," according to AccuWeather Senior Meteorologist Brett Anderson.

The storms will bring winds strong enough to down trees, trigger power outages and perhaps cause minor property damage.
The first storm on Thursday into Friday will bring gusts between 40 and 80 mph on the coasts from northernmost California to Oregon and Washington on Thursday.

Stronger storms with the potential for more powerful winds will follow into next week.
From Saturday to Sunday, the second storm may contain moisture and some of the remnant circulation from Typhoon Songda, currently in the western Pacific.
While the system this weekend may be non-tropical in nature by the time it reaches the Northwest, it could hit with the force and some impact of a hurricane. Gusts in some coastal areas of Oregon and Washington could range between 75 and 100 mph.

Seas will quickly build to dangerous heights ahead of the second storm. Serious beach erosion and coastal flooding will be possible along the Washington, Oregon and northern California coastlines.
A third storm will follow from Monday night into Tuesday.
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Through next Tuesday, many locations along the coast, including the Olympic range as well as the west-facing slopes of the Cascades and northern Sierra Nevada, will receive 12 inches of rain with locally higher amounts.
The Portland Bureau of Transportation urged residents on Tuesday night to begin clearing debris out of storm drains to prevent urban flooding.
Travel along the Interstate 5 corridor could be difficult due to the rounds of heavy rain and strong winds. Airline delays and flight cancellations are possible at Seattle-Tacoma International Airport.
Some rain and wind from the storms will reach as far south as San Francisco and the Bay Region.
A general 1-2 inches of rain is likely in the agricultural regions of central Washington and Oregon with a few inches of rain possible farther to the east in Washington, Oregon, central and northern Idaho and western Montana.
While the rainfall will ease the abnormally dry and drought conditions in the region, too much rain may fall too fast in coastal areas and along the mountainsides. People should be prepared for flooding, mudslides and road washouts as the series of storms continues in these areas.
Heavy snow will fall over the high country of the Northwest. Hikers should avoid the ridges and peaks in the region as weather conditions can rapidly become dangerous and life-threatening from episodes of heavy snow, high winds and plunging temperatures from Thursday through at least Tuesday.
Actual snow levels will vary during each storm. However, several feet of snow will have fallen above 7,000 feet in the northern Cascades by the middle of next week.
Wet snow can mix at times close to pass levels in the Cascades and northern Sierra Nevada.
Little to no rain and snow will reach the drought-ravaged areas of Southern California during the stormy onslaught into next week.
Will the short-term stormy pattern foretell a stormy winter for the Northwest?
The weather pattern setting up starting late this week could be a harbinger of things to come for the northwestern U.S. and British Columbia this winter, or at least into the start of the winter.
"A strong northern jet stream is expected to be directed into the northwestern U.S. and southern British Columbia during December," Anderson said.

This pattern will lead to a stormy start to the winter and a favorable start to the ski season in the region, Anderson stated.
The jet stream is a fast river of air high in the atmosphere that separates cold conditions to its north from warm conditions to its south. The jet stream is often a major highway for weather systems to move along.
A strong northern branch of the jet stream is indicative of a La Niña pattern, whether exact criteria is set for La Niña or not.
"As the winter progresses, the pattern may evolve enough to turn off the powerful storm track in the northwestern U.S. during mid- to late-winter," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
The demise of the storm track would be brought about by anticipated warmer-than-average waters near the coast of British Columbia.
If these waters end up being cooler than anticipated, the northwestern U.S. and southern British Columbia could remain stormy for much of the winter.