Submitted by Grays Harbor County Emergency Management
The National Weather Service in Seattle held a webinar this afternoon, discussing the approach of an Atmospheric River Weather Pattern this weekend. 1 – ½ inches of rain are expected throughout the County with the Olympic & Cascade Mountains receiving much more.
The Atmospheric River Weather Pattern will begin to affect the area starting Saturday night into Sunday. The plume of heavier rainfall is expected to shift north into British Columbia Sunday, then sag back to the south Monday morning. If the weather pattern carries to the south earlier than forecast, significant more rain will fall in the mountains affecting all area rivers.
Expect rises on all area rivers with the potential for flooding. There could be urban and small stream flooding and ponding of water on all area roadways.
At this time, The Satsop River and the Chehalis Rivers are forecast to reach flood Stage. The forecasted flooding is expected to be minor on both rivers.
CHEHALIS RIVER – forecast to reach flood stage (21 feet at Porter), at 10:00 p.m. Monday evening, crest mid-day Tuesday at 21.49 feet, then recede.
SATSOP RIVER – forecast to reach flood stage (34 feet at Satsop) at 4:00 p.m. Monday afternoon, crest at 34.16 feet at 10:00 p.m. Monday evening, then recede.
There is an increased landslide risk due to heavily saturated ground and more rain expected.
*At this time there is a fair amount of uncertainty in terms of the timing and evolution of the heavy precipitation associated with the Atmospheric River pattern. Grays Harbor Emergency Management will continue to monitor the developments and update as necessary.