The rain shadow may have protected most of the Puget Sound lowlands from the heaviest precipitation of an atmospheric river that swept through the region Monday, but it still will be plenty wet this week.

The National Weather Service (NWS) said the river was making its way south Monday evening, but it still could lead to heavy snow in the Cascades and avalanche danger.

Seattle’s rain shadow — which the NWS describes as “an area of reduced precipitation on the lee side of a mountain barrier caused by warming of air and dissipation of cloudiness as air descends the barrier” — limited the precipitation early Monday.

Rain and gusty winds out of the southwest continued through most of the day, with some warmer temperatures, meteorologist Justin Pullin said early Monday.

“Our heavier rain was last night,” Pullin said.

Heavier rain in the mountain passes led to closures Sunday of the three main routes across the Cascades — Snoqualmie Pass, Stevens Pass and White Pass — because of increased avalanche danger.

Tracking Washington state’s snowpack through maps and charts

On Monday, the Washington State Department of Transportation (WSDOT) reopened White Pass around 10 a.m., Snoqualmie Pass around noon, and Stevens Pass around 2 p.m., although it said chains are required on Stevens Pass. With snow in the forecast, Stevens Pass was shut down overnight, but WSDOT said it reopened around 7:45 a.m. Tuesday.

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Temperatures climbed a bit Monday, but don’t start thinking it’s spring.

A cold front is expected to move in, bringing the possibility of isolated thunderstorms and lowering temperatures by Tuesday night back into the low-to-mid-30s, he said.

After a brief, dry respite Wednesday, in which peeks of the sun are possible, “we’re going back to wet and active to close out the week,” Pullin said.

It’s possible, too, that the weekend could be on the dry side, although Pullin said he didn’t know if he would go so far as to predict nice weather.

“I’m not too sure about that,” he said.


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