‘Extremely rare’ atmospheric river to drench Snohomish County

EVERETT — Don’t be fooled by the abundant sunshine and pleasant temperatures Friday.

Get ready for the June gloom to return Sunday in a big way.

An atmospheric river, considered “extremely rare” for this time of year, will move into Western Washington on Sunday, said Harrison Rademacher, a meteorologist with the National Weather Service. It will drench the Cascade Range and Olympic Mountains with up to 4 inches of rain, with possibly 1½ inches predicted for Everett late Sunday and into Monday.

“They call it June-uary for a reason,” Rademacher said.

Friday was the day to be outside, with highs around 70 degrees in Everett. On Saturday, temperatures will cool and rain showers return, but nothing like what is expected for Sunday. A series of moderate to heavy bands of rain will push through, thanks to remnants of moisture from a typhoon in the eastern Pacific. Atmospheric rivers — much like regular rivers, but in the sky — are long narrow regions in the atmosphere that carry water vapor from the tropics.

“This system does have potential to set daily rainfall records,” Rademacher said.

The unofficial daily record at Paine Field near Everett is 0.53 inches, set June 2, 2010.

Rain will continue through Tuesday, the meteorologist said. The series of storms, along with expected mountain runoff, could push rivers to minor flood stage. The Skykomish River is expected to reach the “action” flood stage between Gold Bar and Monroe.

Action flood stage means water may cause minor impacts. The water surface is generally near or slightly above the top of its banks, but no manmade structures are flooded. Rivers are expected to crest sometime between Sunday and Tuesday, the weather service said.

At North Bend, in the Snoqualmie River watershed, the forecast calls for perhaps 2 inches of rain in the 24 hours after sunrise Sunday. The Snoqualmie converges with the Skykomish to form the Snohomish River.

For those bummed out about the gloom, Rademacher has good news. A high pressure system should settle into Western Washington late next week, with daytime temperatures expected in the upper 70s to the low 80s. 

Michael Henneke: 425-339-3431; michael.henneke@heraldnet.com; Twitter: @ihenpecked.