Rain, heavy rain, heavy rain, rain, rain, rain, rain and rain.
That’s the National Weather Service’s forecast for Monday to Thursday, day and night, out of the Chehalis-Centralia Airport.
According to a Flood Watch for Western Washington issued by the weather service, Monday and Tuesday will see “excessive rainfall,” due to an atmospheric river. An atmospheric river is a concentrated stream o rain moving through the atmosphere.
Sections of the Puget Lowland area, which includes most of Lewis County and the Interstate 5 corridor, are forecast to see 1.3 to 3 inches of rain on Monday and Tuesday, the Flood Watch states.
At Grand Mound, past where the Chehalis River joins with the Newaukum and Skookumchuck rivers, the Chehalis is forecasted to hit “minor” flooding around 10 a.m. on Wednesday morning. The Newaukum River near Chehalis is similarly set to enter the “minor” flood stage around midday Tuesday.
The Chehalis River, as of Monday morning, was not anticipated to hit flood stages at Centralia or Doty this week.
Midday on Tuesday, the Cowlitz River in Randle is expected to reach “moderate” flooding, which, according to the weather service, could “cause flooding from the vicinity of Randle downstream through Riffe Lake, inundating many roads including U.S. Highway 12 and much of the farm lands.”
The Flood Watch advises residents to “be prepared” as conditions are forecast to be “favorable for flooding.” Immediate action is not necessary until a “Flood Warning” is issued. As of Monday, the watch was set to end at 4 a.m. on Thursday, Dec. 7.
“That could all still change,” said Samantha Borth, a meteorologist with the National Weather Service office in Seattle, in a Friday interview with The Chronicle. “Right now, it looks like the rivers are likely to flood. But the timing and peak could be adjusted.”
The National Weather Service website shows forecasts for rivers and weather in general, and Borth said she recommends keeping an eye on the page.
The Chehalis River Basin Flood Authority has an email alert system that sends automatic email alerts about rising water at gauges of the receiver’s choice. To sign up or read about weather, inundation maps, river forecasts and more, visit https://chehalis.onerain.com.
To sign up for notifications from the county’s Division of Emergency Management, search online for Lewis County Alerts or visit https://lewiscountywa.gov/departments/emergency-management/lewis-county-alert.
Visitors to the NWS website can also customize and bookmark their own river gage observation page. It offers viewers a real-time view of river levels, such as the Cowlitz River at Packwood or the Chehalis River at Porter. Head to https://water.weather.gov/ahps2/index.php?wfo=SEW to find this tool for Washington.
