Round Two’ Strikes the Pacific Northwest: Landslide and Flood Risks Spike as Atmospheric River Stalls

SEATTLE, Wash. — Just as residents began to assess the damp aftermath of early week storms, the Pacific Northwest is bracing for a “second surge.”

A relentless atmospheric river, which briefly dipped south into Oregon, has shifted its trajectory back north overnight. As of Wednesday morning, Western Washington is absorbing a renewed deluge that the National Weather Service (NWS) warns will trigger a dangerous combination of river flooding and geological instability through Thursday.

Here is the status report on the system currently battering the region and the long-range forecast that suggests this is only the beginning.

The Mechanics: A “Second Crest”

The primary concern for meteorologists is not just the rain, but the timing. The ground in the Puget Sound region is already saturated.

According to NWS data, this second wave of moisture is causing area rivers to rise for a “second crest” starting Tuesday night and continuing through Wednesday.

• The Shift: The system had temporarily moved toward Oregon but has “boomeranged” back, effectively parking a firehose of moisture over the Seattle metro area and the Cascade foothills.

• The Watch: The entire western half of the state remains under a Flood Watch through Friday.

The Threat Zones: Landslides and Valleys

While urban flooding is a nuisance, the deeper danger lies in the geology.

Landslide Risk: With the soil capacity reached, the NWS has issued heightened warnings for the Cascade foothills and valleys. The risk of landslides—mud, rocks, and debris giving way—is significantly elevated for Wednesday.

Specific Impact Areas:

• Seattle Metro & South Puget Sound: High volume rainfall leading to urban ponding and potential basement flooding.

• Skagit County & Chehalis Valley: These river basins are particular hotspots for flooding through Thursday as runoff from the mountains meets the lowland rain.

• Coastal Regions: Minor coastal flooding is expected in Friday Harbor, Cherry Point, and the Hood Canal due to the combination of high tides and storm surge.

The Numbers: Inches vs. Feet

This system is characterized by a sharp divide between the lowlands and the peaks.

• Lowlands: Rainfall totals are projected to range between 1 to 6 inches, a massive variance depending on local topography and “rain shadow” effects.

• Mountains: Above the freezing line, the precipitation is falling as snow, with up to 15 inches expected. While this builds the snowpack, it also complicates travel through the passes.

Travel Warning: Officials urge extreme caution. “Turn Around, Don’t Drown” remains the standing order, as ponding on roadways like I-5 and coastal highways can conceal deep washouts.

The Outlook: A Brief Pause, Then Snow?

The immediate intensity will begin to taper off between Thursday and Friday. By the weekend (Saturday and Sunday), the region will see a drier, weaker system moving to the north, though major rivers may remain swollen due to lag time in runoff.

However, long-range models are already flagging the next potential event.

• The Dates: December 17-20.

• The Threat: Early forecasts suggest a colder system that could bring heavy snow and high winds to Western Washington, potentially disrupting holiday travel logistics.

KING 5 Weather has activated “First Alert” status, signaling that this weather event poses a direct threat to life and property.