Surge of moisture into northwestern US to bring rain, snow

A renewed round of stormy weather is taking aim at the Northwest through Tuesday. As March concluded with below-normal precipitation for cities such as Seattle, Portland, Oregon, Spokane, Washington, and Boise, Idaho, this next push of moisture will be a dramatic change for area residents.

A storm pushing into British Columbia, Canada, is expected to dive southeastward across southern Alberta and spread an expansive swath of rain, snow and gusty winds to Washington, Oregon, Idaho, Montana, and even portions of Northern California.

"This abundant availability of moisture will allow heavy rain to fall at lower elevations, while heavy snow targets the higher elevations of the Cascades," explained AccuWeather Meteorologist Mary Gilbert.

AccuWeather meteorologists say that this feature will likely arrive across the Midwest and Great Lakes by mid- to late week as it continues to barrel eastward.

Into Tuesday night, general rainfall amounts of 1 to 2 inches are expected along inland regions of southern British Columbia, Washington, Oregon, and far northwestern California.


"As drenching rain falls across portions of the region, concerns for both river and urban flooding will increase. Motorists should never attempt to forge floodwaters as a seemingly shallow pool of water can turn dangerous rapidly," stated Gilbert.

Locations along the coastlines of British Columbia, Washington, northwestern Oregon and the west-facing slopes of the Northern Cascades will likely face an increased flood threat with possible rainfall totals of 2 to 4 inches from into Tuesday night.

Cities such as Seattle and Portland, Oregon, can experience outbreaks of rain and showers early next week, with general rainfall amounts of 1 to 2 inches possible.

"From Jan. 1 to March 31, Seattle recorded 114% of its average rainfall for the time period. Any additional rain will help bulk up the wetter-than-average year in the Emerald City," noted Gilbert.

For April, the city of Seattle typically observes 3.18 inches of rain, while Portland generally falls a bit lower at 2.89 inches of rain. Forecasters say it is not out of the question for the two cities to record roughly one-third of their regular monthly rainfall by Tuesday.

In addition to steady rainfall anticipated across lowland areas of the Northwest, heavy snowfall accompanied by blustery winds is also expected across the Cascade Range through Tuesday night.

Heavy snowfall accumulations are likely into early Tuesday morning, when snow levels across the region can fall to roughly 2,000-2,500 feet. During this time frame, the higher levels of the Cascades can pick up an additional 1 to 2 feet of snow.

Motorists traveling Interstate 90, Routes 2 and 12 are cautioned to check the roadway conditions before embarking on any trip, with challenging travel increasingly likely through the Cascade passes as heavy snow spreads across the region.

On Monday morning, a semi-truck blocked all westbound travel of Interstate 90 when it became stranded in heavy snow near the summit of Snoqualmie Pass. Washington DOT advised traction tires and after additional crashes were reported across I-90 Monday.

Gusty winds will also be a concern across the Northwest as this storm sweeps through. Wind gusts of 40-60 mph will be possible across Washington and Oregon into Tuesday morning. By Monday evening, winds can become more widespread and shift across the northern Rockies.

Impacts such as strong crosswinds and blowing dust will become a concern for high-profile vehicles and travelers utilizing portions of Interstate 90 and Routes 2, 26, 195 and 395 throughout the daytime and overnight period on Monday.

By Wednesday, the stormy period will begin to wrap up across the Northwest as the energy pushes east of the northern Rocky Mountains and northern Plains. A period of dry weather is expected to briefly return to Washington and Oregon before another chance for rain arrives by late next week.

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