Wet, wintry weather to chill northwestern US this week

A stretch of unsettled weather across the Northwestern states will keep residents reaching for jackets and umbrellas as temperatures rival levels more typical of the middle of winter this week, AccuWeather forecasters say.

The first half of April has been both wetter and cooler than the historical averages along the Interstate 5 corridor from Seattle to Portland and Eugene, Oregon. As of April 18, Seattle has received 140% of its month-to-date historical average rainfall of 2.07 inches. The surplus in precipitation has come with more clouds and subsequently lower temperatures than what the Emerald City is accustomed to at this point in the year.

AccuWeather meteorologists say the damp, cool weather pattern will continue during the first half of this week, resulting in persistent showery weather and an even chillier burst of air that may rival record-low temperatures.

AccuWeather's Enhanced RealVue™ Satellite showed a swirl of clouds off the Pacific Northwest coast on Monday morning, April 17, 2023. This swirl of clouds is indicative of a storm that will move into the region with showers and a burst of cold air. (AccuWeather)

"A multiday stretch of wet and chilly conditions is in store for places like Seattle and Portland through the first half of this week," AccuWeather Meteorologist Brandon Buckingham said.

High temperatures will may be no better than the low 50s F in Seattle and Portland through Wednesday, approximately 10 degrees below the historical averages for each city. Tuesday's high in Seattle was 47 F, while the high reached 52 in Portland.

A handful of locations closer to the coast in Washington, Oregon and northwestern California could even rival record-low daytime temperatures. These locations include Olympia, Washington; Astoria, Oregon; and Crescent City, California.

Waves of moisture will accompany the cold air, resulting in snow for the mountains.

"Snow levels will dip below pass level, impacting travel along I-90's Snoqualmie Pass through Wednesday night. Other major passes such as Stevens Pass and Stampede Pass can also face tricky travel conditions through midweek as rounds of snow pass through the mountains," Buckingham said.

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Rounds of moisture will move east of the Cascades and bring accumulating snow to the Blue Mountains in northeastern Oregon and the northern Rockies through Wednesday. Snow will has begun to clip northern portions of the Sierras, a trend that continued through the day Tuesday. Soda Springs, California picked up 8.3 inches of snow on Tuesday, while Palisades Tahoe, California accumulated 6 inches.

Across the lower elevations, umbrellas will be needed on occasion as on-and-off rain showers dampen the region amid the cool, unsettled pattern. A few rumbles of thunder can even occur.

"Moisture will struggle to extend into Central and Southern California, the Great Basin and the Southwest this week. The main highlight from the train of storms off to the north will be rounds of strong, gusty winds through Wednesday," Buckingham said.

Buckingham noted that temperatures will begin to moderate toward the end of the week and the upcoming weekend as an area of high pressure builds along the West Coast.

While this high-pressure system may help to limit the coverage of precipitation for a time in the Northwest, AccuWeather meteorologists say rounds of unsettled conditions could persist right into the last week of April across the region.

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