CNN
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About 16 million people were under flood alerts in the Pacific Northwest on Tuesday night as a strong atmospheric river pelted the region, where at least one person was found dead this week after getting swept in floodwaters.
Emergency crews in Portland, Oregon, were unable to rescue a man swept away by a flooded creek on Monday. The man’s body was recovered from Johnson Creek later Monday afternoon, a Multnomah County sheriff’s deputy told CNN.
Investigators are still trying to determine how the man ended up in the fast-moving water.
The flood threat was mainly in western Washington state and Oregon, including Seattle and Portland. Most of the flood alerts in Washington were set to expire by 4 a.m. PT Wednesday, while many of Oregon’s alerts are expected to be active through Wednesday evening.
More than 8 inches of rain had fallen in parts of the Pacific Northwest from mid-morning Monday to early Tuesday evening, based on preliminary rainfall totals from the Weather Prediction Center.
And more is on the way: An additional 2 to 4 inches of rain are possible Wednesday. Rivers have been rising into flood stage, with some forecast to reach major flood levels Tuesday and Wednesday.
In Washington, the Skagit and Snoqualmie rivers are of particular concern. Portions of both rivers surged to major flood stage by late Tuesday morning and are forecast to flood roads, farms and even some residential areas.
Water levels on portions of the Skokomish River in western Washington climbed to moderate flood stage Tuesday morning and the Grays River in southern Washington skyrocketed to major flood stage.
The Stillaguamish River north of Seattle reached a record high Tuesday afternoon, according to preliminary data from the National Weather Service. The river reached 21.34 feet, topping the previous record of 21.16 feet, set in December 2010. Major flood stage is 19 feet.
Floodwater forced dozens of roadways to close in Washington on Tuesday. At least one driver was rescued after driving their car into floodwaters on a Snohomish County road.
A landslide amid heavy rainfall brought all Amtrak service between Seattle and Portland, Oregon, to an abrupt halt Tuesday. Service between the two hubs is suspended until Thursday morning, according to Amtrak.
Additional heavy rainfall through Wednesday will only make matters worse in parts of Oregon’s Cascade mountains, southern Washington and far northwest California. A slight risk, or Level 2 of 4, of excessive rainfall was in place Tuesday with a marginal risk, or Level 1 of 4, on Wednesday, according to the Weather Prediction Center.
In Washington, Granite Falls received 9.85 inches of rain from Monday morning through Tuesday evening, while Olympic National Park received 8.67 inches. In Oregon, Nehalem River near Foos saw 9.15 inches of rain during that time, and Lees Camp received 8.20 inches.
Flood watches stretched Tuesday from coastal Oregon and Washington into northeastern Washington and northern Idaho.
Washington’s Olympic mountains could receive over a foot of rain, and the Cascades could see between 5 to 9 inches, the weather service said. Along the coast, residents can expect 3 to 5 inches and 1 to 3 inches in the interior lowlands.
For residents caught in flood conditions, the weather service recommends staying indoors or seeking higher ground if shelter isn’t available.
By late Thursday and Friday, storm activity is forecast to ramp down across much of the Northwest, but showers and some high-elevation snow remain possible.
But the break from soggy weather may be short-lived. Confidence is growing in yet another atmospheric river that could hit the region by the early weekend.
The exact strength and overall impact of this potential event should become clearer once this week’s atmospheric river comes to an end on Wednesday.
The sequence of back-to-back atmospheric rivers, called an AR family, began Saturday and did not leave much of a break period before Monday night’s system began. This lack of recovery time is a major factor in the increased risk of flooding.
Parts of Utah and Colorado received snowfall on Monday, bringing total snowfall throughout the atmospheric river events to several feet in some places, including 50 inches in Collins, Utah, and 49 inches in Colorado’s Rabbit Ears Pass.
A Level 4 out of 5 atmospheric river event is forecast to hit roughly the entire coastline of Oregon this week. The severity of the atmospheric river reached a Level 5 out of 5 in the far northwestern part of the state Monday night into early Tuesday morning.
But this latest round of moisture also ushered in warmer temperatures, including a high temperature of 65 degrees in Portland, which ties with the city’s all-time high for the month of December last set in 1993.
These warm conditions have encouraged snowmelt across the Pacific Northwest and may lead to excessive runoff and rising creeks and streams.
Not all atmospheric river events are bad. In fact, AR event levels 1 and 2 are considered mostly beneficial rains and are much needed across the western US to build water supply levels. But AR event levels 4 and 5 are more hazardous than they are beneficial as the risk for flooding and travel dangers outweigh the benefits.
Correction: An earlier version of this article misstated when the Stillaguamish River reached a record high based on preliminary data. It was Tuesday.
CNN’s Andy Rose, Sara Smart, Allison Chinchar, Gene Norman and Sara Tonks contributed to this report.
