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Heavy rains in the Cascade Mountains into early Sunday carried the potential of triggering flooding around Western Washington along rivers already running high in an exceptionally soggy start to March.

Even if rains taper off Sunday as predicted, the chance of mudslides will likely continue for days as saturated slopes could give way, according to the National Weather Service.

As of 5 p.m. Saturday, Seattle-Tacoma International Airport had recorded 4.33 inches of rain in March.

Johnny Burg, weather-service meteorologist, said that surpasses a record for the airport’s rainiest first eight days in March, which had been 3.62 inches, set in 1950.

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It also swamps Sea-Tac’s normal total for all of March, 3.72 inches. Two to four inches of rain were expected in the Cascades overnight and into Sunday morning.

The Seattle area was expected to get about an inch, with some coastal areas getting up to three inches.

In King County, road crews Saturday were dealing with water or mud over the roadway in some often-flooded sites near Carnation, Fall City and Duvall.

Amtrak and Sounder rail passenger service between Everett and Seattle is halted until at least 4:30 p.m. Monday, because of mudslides across the tracks at Mukilteo. A slide about 5 feet deep covered the tracks Saturday afternoon. Though freight traffic has since resumed, passenger rail requires a 48-hour wait. Commuters are advised to check for updates.

The flood potential is compounded by the high freezing level in the mountains, 7,500 feet in the Central Cascades and 6,000 feet in the North Cascades.

“This is all coming down as rain, not snow, and flowing right into the rivers,” Burg said.

Sunday’s forecast in the Seattle area is for showers, mainly before 10 a.m., and a high near 56.

Showers are also likely for Monday, but then a drying trend kicks in: Tuesday and Wednesday are forecast to be mostly sunny, with highs in the upper 50s.

Jack Broom: or 206-464-2222

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