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Showing posts from December, 2019

Will it Happen Again? When the Mother of All Gap Windstorms Hit the Cascade Foothills

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The year was 1983.  Michael Jackon's “Billie Jean” hit #1 on the Billboard 100 while movie hits like “Scarface” and “Return of the Jedi” were rolling out of the box office.   And on Christmas Eve of that year, “A Christmas Story” was not yet in marathon-mode on TBS, but actually in theatres near you!   However, for people living in the Cascade foothill communities that day the atmosphere was not so jolly. The mother of all gap windstorms was striking with hurricane-like force!   Renowned meteorologist and University of Washington Atmospheric Sciences professor  Cliff Mass has called it, “probably the greatest downslope windstorm of the past century in the Pacific Northwest”. In the city of Enumclaw, which by the way is a name derived from a Salish term that translates as "place of evil spirits", several spotters reported peak wind gusts exceeding 120 mph with sustained winds of 75 mph for over 18 hours. Yikes! Enumclaw’s location is considered by several meteoro

December storm to soak Snoqualmie Valley, bring heavy snow to mountain passes through the weekend

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Update (Sat 12/21/2019):  Snoqualmie River near the Falls crested about 8 pm last night (Friday) @ 22,830 cfs.  It was evident  by Thursday night the  atmospheric river of moisture with this potent December storm had shifted further north than initially expected, aiming the fire hose directly at the Puget Sound region, pulling in warmer air with it, and increasing snow levels to around 4,000ft, compounding the river flow problem given heavy rainfall even at higher elevations.   Originally published 12/19/2019 12:55 PM Here come's the highly anticipated atmospheric river! Note the yellow circular graphic behind current location (below) isn't showing intense showers, but the small earthquake recorded this morning, a 3.4 magnitude near Fall City and one of three small quakes in the area over the last 24-hours. Those traveling across the passes should be prepared for periods of heavy snow and possibly even temporary closures for  avalanche control  Thursday afternoon i

Fog to blow out of Snoqualmie Valley soon; little rain, but relatively quiet weather until mid-December

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Visibility really dropped on Wednesday, December 4th, as the fog rolled in.  You can see why this happened (from the chart below) – as the day rolled on temperature and dew point nearly converged. Wunderground weather station (KWASNOQU33) from Snoqualmie Ridge  Fog can begin to form when the difference between air temperature and dew point is less than ~4° F.  Water vapor condenses into tiny liquid water droplets that are suspended in the air. I was driving through downtwon Snoqualmie last night and the sky looked eerily red and gray, like something out of Stranger Things. I gathered it was due to reflection off water vapor from the mix of Christmas lights in the surrounding area, as well as the field lights that were on at Mount Si High School.   The fog also made for some really cool Christmas light reflections in my neck of the woods. As for the rest of the week, another pressure gradient should form over the Cascades bringing back our beloved Snoqualmie Valley gap win