(Nov. 11) Major flooding expected on some rivers Friday, Saturday

The rain is very heavy and will continue to be so tonight through Friday morning before tapering from north to south early Friday afternoon. Rainfall totals will vary quite a bit in the lowlands because of the rain shadowing effect of the Olympic Mountains, but this is a rough estimate of how much rain will fall in lowland locations

Coast: 3-4 inches

San Juans and Whatcom County: 2-3 inches

Everett area and Whidbey Island: 0.75-1.5 inches

Port Townsend, Sequim areas: 0.5 inches due to rain shadowing

Seattle area: from 1.5 inches north of downtown to 2.5 inches south of Sea-Tac Airport

South Sound and south through southern Washington: 2.5-3.5 inches

In the mountains, the snow level has popped up above Paradise and will be above 8,000 feet through Friday, meaning almost no snow falls except on the highest peaks and volcanoes. Rainfall amounts from 5-9 inches will occur over the next 24 hours in the mountains and thus river levels will rise dramatically through Friday. Unlike many of our previous flood events, this one will be sharp and fast with an almost equally-dramatic decline in river levels after crest. But on a few rivers, waters will reach a level not seen in several years, if briefly.

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Fortunately, we get a mainly dry day Saturday before another atmospheric river hits the area Sunday and Monday. However, that second system should be so brief as to not spike rivers back up to their Friday/early Saturday crests. We’ll go back to mainly standard Northwest rain on late Monday and Tuesday and snow will return at times to the Cascade passes. It looks to turn drier and colder for a time later next week.

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