Weekend weather was wet, wasn’t worrisome

Photo By Tom Conning | Kasi Underhill, Northwestern Division Hydrologic Engineering Group team lead, monitors weather systems like the one that hit the Pacific Northwest February 22nd through 23rd. The atmospheric river had potential to unleash a good amount of precipitation; however, The storm didn’t impact how USACE managed inflows to its projects, as Underhill and her team checked in with the region beforehand and during the event. (Photo by Tom Conning, U.S. Army Corps of Engineers)  

PORTLAND, OREGON, UNITED STATES

03.04.2025

Story by Tom Conning 

U.S. Army Corps of Engineers, Northwestern Division

Dry January
Dry January is typically associated with people making New Years resolutions to stop drinking alcohol for the month, but the U.S. Army Corps of Engineers (USACE) is the original instigator of this fad. Many USACE dams have flood risk management as an authorized purpose, which means the agency uses them to help reduce flooding to downstream communities.

So far this winter it has been a Dry January and February in the Columbia River Basin. Water managers have been concerned about the lack of precipitation and predict that the region could again see its communities struggle to keep enough water in local reservoirs for the rest of the year, unless conditions improve. The National Weather Service predicted that the February 22nd through 23rd weekend weather could help reduce long-term concerns about water supply. In the short term, it produced some localized flooding

“We definitely got some rain in different spots throughout the basin,” said Kasi Underhill, Northwestern Division Hydrologic Engineering Group team lead. “This rain melted off a lot of low-level snow,” she said. “We saw the Snake [River] levels increase – we saw the Columbia [River] increase, too, but it wasn’t anything concerning.”

Weekend forecast
The National Weather Service predicted that an atmospheric river would bring three to five inches of rainfall to the Pacific Northwest. The observed rainfall varied throughout the region and measured over three inches in the downtown Portland area.

The National Oceanic and Atmospheric Administration (NOAA) describes atmospheric rivers as, “relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. While atmospheric rivers can vary greatly in size and strength, the average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.”

The storm didn’t impact how USACE managed inflows to its projects, as Underhill and her team checked in with the region beforehand and during the event.

“In the Willamette Basin, they were definitely looking forward to getting some decent inflows,” she said. “They were below rule curve at quite a few reservoirs, which meant they had additional space. In the Seattle District area, they were not seeing any major concerns but saw some localized small stream flooding.” Underhill added that there is always uncertainty with weather events and their impacts, but the National Weather Service does a good job tracking and announcing potential issues.

The National Weather Service forecasted the Columbia River at Vancouver to remain below nine feet (flood stage is 16 feet), so water regulators didn’t anticipate needing to implement flood risk management actions.
“Long story, short: we were in a good position with our reservoirs to handle this event, but there are still a lot of question marks as to how beneficial it was to the future water outlook,” said Underhill.

Local flood concerns
Atmospheric rivers aren’t new for the region or water and emergency management offices at USACE. Northwestern Division holds flood risk management reviews with other readiness, levee and dam safety offices and NOAA on an annual basis before flood season. These collaborative reviews focus on basin conditions, authorities and flood fight preparations like team training, levee rehabs, dam operations and communicating with state and local officials. States and counties have the primary responsibility to respond to local flooding. Residents should call their local emergency management offices if there are needs or concerns. Also, no one action or agency can eliminate flood risks; however, USACE:

• Improves public understanding of federal, state and local agencies’ roles.
• Assists communities in developing responses to flood risks and hazards.
• Encourages better decision-making by governments, individuals, the private sector NGOs.
• Counters or corrects rumors to improve public understanding of risks from flooding.

• Date Taken: 03.04.2025
• Date Posted: 03.04.2025 14:03
• Story ID: 492002
• Location: PORTLAND, OREGON, US