Flooding rain, wintry hazards to plunge southward across US West Coast this week


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Flooding rain, wintry hazards to plunge southward across US West Coast this week

By Kristina Pydynowski, AccuWeather senior meteorologist
January 15, 2017, 3:02:18 PM EST

The river of moisture will once again target the West Coast starting this week, first hitting the northwestern United States before heavy rain and mountain snow plunges back into California late in the week.

“After several dry days in the West, a pattern change will occur this week as a series of storms slam into the region,” AccuWeather Meteorologist Jordan Root said.

Storms will roar back into the Northwest early this week with flooding rain, strong winds and interior snow and ice. More storms will follow at midweek and beyond with impacts also spreading into California and the Rockies.

Millions of residents all along the West Coast can anticipate a renewed threat of flooding, travel disruptions, mudslides and erosion.

Storm train to first slam Northwest with heavy rain, snow and ice

“An atmospheric river of moisture originating near the tropics in the West Pacific Ocean will stretch across the Pacific and help fuel heavy rain across the Northwest Monday night through Wednesday,” Root said.

“This will likely result in some dangerous flooding and mudslides, especially near the coast.”

Unlike last week when Portland, Oregon, endured ice and then one of its snowiest 24-hour periods on record, the track of the storms will bring milder conditions and mostly rain to the I-5 corridor of the Northwest.

Lingering cold should cause the rain to briefly begin as a period of ice and slick travel in Portland on Monday evening.

Rainfall generally totaling 2 to 4 inches will otherwise soak Portland and the other I-5 cities of Seattle and Olympia, Washington, and Salem and Eugene, Oregon.

Travel delays to both motorists and airline passengers can be anticipated. Flash flooding can also result, especially in urban and low-lying areas. The combination of the rain, melting snow and clogged storm drains will further heighten the risk of flooding in Portland.

More widespread flash flooding will threaten places along the coast and the western slopes of the northern Cascade Mountains, where rainfall should total 4-8 inches.

Rivers and streams may overflow their banks and flood neighboring communities and streams.

The one good news for western Washington is that many of the rivers are running at their lowest levels since the end of the summer, according to the National Weather Service in Seattle.

The rain will be windswept at times. The strength of the winds toward midweek could lead to sporadic tree damage and power outages along the coast. Seas will build as the winds howl, threatening to cause beach erosion.