Pattern change to return rain to Pacific Northwest and California by the weekend

·3 min read

Following a quiet first few days of March, a slow-moving storm is expected to douse the Pacific Northwest coast later this week, eventually reaching portions of California by the weekend.

Residents and visitors will have a great opportunity to get outside and enjoy the first days of meteorological spring through the middle of the week as dry weather and near- to slightly above-average temperatures will dominate, thanks to a broad area of high pressure overhead.

This image, captured on Tuesday, March 2, 2021, shows a break from storms over the western United States. However, a storm spinning off the coast has eyes for Southern California starting on Wednesday. (CIRA at Colorado State/GOES-West)

A Pacific storm, is forecast to push through Southern California and the Desert Southwest and spare the Northwest region of any wet weather into Wednesday night.

As the high pressure system slowly shifts eastward over the interior West later in the week, however, this will open up the gates for stormier weather to return to coastal areas farther north.

"A storm will arrive late this week and bring rain and mountain snow to the Pacific Northwest and Northern California," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said.

Rain is expected to reach the immediate coasts of Washington and Oregon late Thursday, and rounds of rain, some of which can be heavy, are likely to persist in these same areas through Friday night and perhaps early Saturday.

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For at least a day or two, the broad area of high pressure to the east will essentially act like a road block for the storm and its associated rainfall from making much progress inland. This will prolong the soaking rainfall and could lead to rainfall amounts of 1-3 inches from the far northwest corner of California to coastal Washington.

These persistent downpours will act to not only slow travel, but also raise the risk of localized flooding.

The heaviest rain may set up just west of Seattle and Portland, Oregon, but people in these areas will still need to break out the rain gear once again toward the end of the week with periods of wet weather expected.

It may take until the weekend for moisture to reach farther south in California into places such as San Francisco and perhaps even Fresno and Los Angeles. This far out, there remains question as to how much rain and mountain snow will fall across the state, which will depend on the exact track and intensity of the storm system by that point.

AccuWeather meteorologists will continue to monitor the storm throughout the week and fine-tune the details of the forecast in the coming days.

"We're monitoring yet another storm that will track into the West Coast on Monday, which may have a better chance of spreading precipitation into central and Southern California, as well as the Great Basin and Southwest later next week," Pastelok said.

Indications are the storm that is forecast to move in early next week has the potential to unload heavy snow on the Sierra Nevada, which could be a big shot in the arm in terms of moisture to be released into streams and reservoirs moving forward this spring and summer.

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