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Regional Forecasts

Record river flooding is ongoing in parts of Washington State, but following a drier weekend, a new worry for wetter weather will arise early this week.

Jonathan Belles
ByJonathan Belles14 hours ago

Rescue Crews Brave Floodwaters In Washington

The Pacific Northwest has had a couple of days to dry out after days of flooding rainfall, but there is another atmospheric river washing ashore early this week.

Flooding will continue as runoff from previous events continues to move through the Cascades and down toward Puget Sound.

(MORE: Latest News From Washington State)

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Here's a current look at the atmospheric river off the Pacific Coast:

Warmer colors indicate deeper moisture content in the atmosphere.

Precipitable Water And Infrared Satellite

Timing Through Early Week

Peak Flood Potential: Through Monday in Washington, Oregon; Tuesday in Northern California

Departure: Early Tuesday in Washington, but with potential for a reinforcing shot late in the day

1214_flood_forecast.png

Flood Outlook For Early Week

(Data: Weather Prediction Center)

How This Event Compares

  • This singular event will have a shorter duration compared to the back-to-back events that occurred on Monday and Wednesday of this past week
  • Rainfall totals appear to be lighter than the event that occurred Wednesday.
  • Rainfall rates may be slightly lower due to the change in orientation of this upcoming atmospheric river, which will come in less perpendicular to the mountain ranges.
  • The upcoming event is likely to be classified as a Category 4 event, which is the same rating given to the previous atmospheric river that came ashore Wednesday.
  • Snow levels appear to be similarly high compared to previous events, although they could come down quicker on the backside of this event.

(MORE: Where It Isn't Raining, It Is Record Warmth Forecast In The West)

Rainfall Totals

Rainfall will generally be lighter than what was seen in the Pacific Northwest over the last week, but it also won’t take as much rainfall to create significant issues, especially in Washington.

Parts of the Cascades and Olympics will see 3-6 inches of rainfall while the Interstate-5 corridor should see 1-2 inches of rain as far south as central Oregon.

This atmospheric river will drop further south into Northern California than those of the previous week, so some new areas will pick up rainfall there, but totals will be light.

Snowfall will be confined to the highest elevations of the Cascades and Northern Rockies, but over a foot is possible, especially in the Washington Cascades.

Areas receiving snow are depicted in white.

Rainfall Totals Through Tuesday

More Atmospheric Rivers Later This Month?

Most people in the Pacific Northwest, and probably people around the country who know people who live in the Pacific Northwest, are likely wondering if a more long-term dryness is in the forecast.

I hate to be the bearer of bad news, but we may have more atmospheric rivers later in December.

The atmospheric conditions, including a mid-level ridge over the Bering Sea and a downstream trough in the northeastern Pacific, will serve as a a sort of an atmospheric nozzle that will likely steer additional moisture to the already waterlogged Northwest.

I guess a slight silver lining here is that most models are suggesting that the heaviest rain is expected across southwestern Oregon and northwestern California, however, should any new rainfall hit Washington, it could easily cause flooding due to saturated soils.

Another slight sign of good news is that temperatures may not be as warm in the coming weeks across the West as they are currently, which means snowfall is more likely across the Cascades and Sierra Nevada.

Note that snowmelt across the Cascades exacerbated the flooding from the heavy rainfall across the Pacific Northwest, so more of the precipitation across the mountains falling as snow will help to reduce some river flooding and can also help rebuild snow for skiiers and snowboarders planning to hit the slopes to end 2025.

Jonathan Belles has been a digital meteorologist for weather.com for 9 years. His favorite weather is tropical weather, but also enjoys covering high-impact weather and news stories and winter storms. He's a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.

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