Check out this ‘amazing’ rainshadow over Puget Sound
Dec 30, 2016, 7:57 AM
The North Puget Sound region got to experience a rainshadow on Thursday that is more often seen north of the Olympic Mountains.
The National Weather Service says the rainshadow was caught on radar around mid-day.
Imagery shows a cloudless “hole” over portions of Kitsap, King, and Snohomish counties, as well as over Whidbey Island.
Olympic rain shadow over N Puget Sound 1245pm. #wawx pic.twitter.com/Ctq0CLseeQ
— NWS Seattle (@NWSSeattle) December 29, 2016
Here’s another graphic created by the Weather Service, detailing areas with lower relative humidity:
Olympic rainshadow forecast graphic. WSW winds 5K-10kft over Olympics. Colors show lower RH about where the rainshadow is. #wawx pic.twitter.com/FYO6VfPQnD
— NWS Seattle (@NWSSeattle) December 29, 2016
University of Washington Climatologist Cliff Mass says moisture from the west rose on the western side of the Olympics and sank on the eastern side.
“The result is a distinct hole in precipitation to the [east] of the Olympic barrier … a rainshadow,” Mass wrote in his blog. “As the air rises again on the Cascades, precipitation reforms.”
A rainshadow typically forms over Sequim and surrounding areas. The result is “drier and brighter weather.” The rainshadow formed over North Puget Sound because of westerly wind, rather than the “typical south-southwesterly flow of winter,” according to Mass.
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