“River in the Sky” Brings Rain, Wind, and Flooding to Pacific Northwest

Posted: January 13, 2021 8:16 pm

Hurricane Hunters Summoned to Learn More About Weather Phenomenon

To say that it has been a wet and windy week in the Pacific Northwest would be a severe understatement. A rare category 5 atmospheric river event is drenching the region, leading to record rainfall amounts, widespread flooding, and dangerous wind conditions.

What Has Happened So Far: Less than two weeks into the new year and the city of Seattle has already received almost seven inches of rain. An additional two to four inches are expected in the coming days. If this happens as predicted, the city will hit 25% of its annual rainfall amount by January 15. All of this rain could mean that Seattle breaks a record for its wettest start to the year. The standing record occurred in 1956 when Seattle saw seven inches of rain during the first 15 days of January.

Defining an Atmospheric River: An atmospheric river is defined as a long and narrow area that acts as a river in the sky. As it hovers in the atmosphere, it transports water vapor throughout the region. The weather phenomenon carries large amounts of moisture from tropical regions and then releases this moisture in the form of rain or snow into other areas. As this river in the sky set up over the Pacific Northwest, the area became socked in with unrelenting moisture.

One of the most well-known regularly occurring atmospheric rivers is the Pineapple Express. This river is situated between Hawaii and the West Coast, regularly bringing heavy rains to the Pacific Northwest and down into parts of California.

Current Atmospheric River: This current atmospheric river stretches for over 2,700 miles with the heaviest rain falling in the Pacific Northwest. According to the Center for Western Weather and Water Extremes, the category 5 designation is the highest that it offers, signaling the potential of severe weather with this event.

Approximately 15 million people in the region are now under a flood watch or advisory. Some areas of western Washington may see up to 300% of their usual rainfall as the atmospheric event continues its wrath. What is most concerning is that the soil saturation levels are already high.

Because there are warmer than average temperatures associated with this weather event, the snow levels will rise to over 6,000 feet. Anything located below this elevation will likely just see rain. However, elevations of the Cascades above 6,000 feet should be prepared for heavy snow as a result of the conditions. As the snow continues to fall, there is also an elevated risk of avalanches.

In addition to the flooding risk, there is also the chance that the heavy rain will trigger landslides.

Brace for Windy Conditions: The wind picked up substantially overnight Tuesday and into Wednesday with more gusty conditions on the horizon. The entirety of the Oregon coastline has been under some type of wind watch or warning over the last 24 hours. The highest gusts could reach up to 75 mph. As of Wednesday morning, nearly 400,000 people in the Puget Sound region of Seattle are without power. One woman is dead in Spokane, Washington, after a tree fell on her car.

Travel has continued to be impacted because of the wind and rain. One stretch of Interstate 5 was closed in Washington state overnight Tuesday because of downed power lines.

Hurricane Hunters Arrive: This weather event has activated the arrival of hurricane hunters. The pilots will fly into the atmospheric river in an effort to collect data and learn more about this phenomenon. This is the second time this winter season that the hurricane hunters have traveled into the bullseye of the river in the sky.