Pacific Northwest in Line for Flooding Rain Through Wednesday

Posted: January 11, 2022 1:06 pm

Moisture to Stay to the Northwest, Sparing Areas East and South

While it will not be the record rainfall that befell parts of the Pacific Northwest last week, another major rainmaker is heading into this corner of the country over the next few days. This drenching rainfall will raise the risk of flash flooding once again.

Different Week, Same Story for the Pacific Northwest

Loads of moisture is about to unleash once again on the Pacific Northwest, bringing rain to the coastal areas and mountain snow to the higher elevations. The area is still recovering from last week’s record rainfall that triggered deadly flooding. In addition to the rain, the warmer conditions accelerated the melting of the snow from the previous days. This rapid snowmelt was responsible for rising river levels. At least one death was reported after a vehicle was washed away by floodwaters near Cosmopolis in southwest Washington.

The flooding also forced numerous evacuations and road closures, including a portion of Interstate 5 near Chehalis, Washington. The heavy snow closed the majority of Washington’s mountain passes over the week, keeping residents from being able to reach the other side of the state.

Week Ahead for the Region

After a brief reprieve over the weekend, the rain returned again on Monday. Heavy rain began falling along the Olympic Peninsula in Washington late Monday. This rain is forecast to move inland on Tuesday and into Wednesday.

Unlike last week’s system, this new round of rain is expected to stay positioned over the Pacific Northwest rather than gradually expanding to the east. The bulk of the moisture along the West Coast will be confined to Washington and western Oregon this week. The highest threat of flooding will be in the coastal areas and toward the mountains in western Washington, putting the Seattle area once again at risk.

A little farther to the north, Vancouver, British Columbia will also be in the path of the heavy rain and potential flooding problems by the middle of the week. It will be heavy snow that is the story in the higher terrains of southwestern British Columbia. This could complicate travel in the coming days.

Because temperatures are predicted to be moderate this week, snow levels will rise to about 5,000 to 7,000 feet. This is in contrast to the last few weeks when bitterly cold temperatures brought unusual amounts of heavy snow to Portland and Seattle.

The warmer temperatures in the mountains will increase the risk of avalanches in the backcountry as the heavy snowpack from the last week starts to melt.

Temperatures will peak around Wednesday for the Interstate 5 corridor, including Vancouver, Seattle, and Portland. Portland is forecast to climb into the middle 50s by the middle of the week, well above average for this time of the year.

Moving to the South

The storm track is expected to stay positioned in the northwestern tier of this region. Areas to the south and east will likely be spared the heavy moisture. This means drier conditions for cities such as Eugene and Medford, Oregon. Farther to the east, cities such as Boise, Idaho will enjoy a break from the winter precipitation.

The active weather will move farther north over the weekend, giving Washington a break from the rain and snow. High pressure will also begin to build farther south by the end of the week, helping to alleviate some of the constant moisture.

However, meteorologists caution that the stagnant air in the interior valley of California may trigger heavy fog and hazy conditions. This could reduce visibility and disrupt air quality levels.