SEQUIM — The Dungeness Valley is famous for its many days in the sun.
But a weather observer’s yearlong sunshine study has concluded that Port Angeles is also “definitely” inside the famous Olympic rain shadow.
The Olympic rain shadow is a phenomenon caused by south-by-southwesterly wind blowing rain clouds up and around the Olympic Mountains, effectively blocking precipitation coming from Pacific storms.
The result: more sun, less rain than in the Seattle area.
It is a phenomenon often seen by airline pilots as a “blue hole” in the cloud cover over the Dungeness Valley.
The rain shadow runs from the Sequim-Dungeness Valley to Port Townsend, Coupeville and Whidbey Island, the San Juan Islands and Victoria.
Typical values are around 15 inches of rain a year for the Sequim-Dungeness area compared to 37 to 38 inches in Seattle.
Now — thanks to David Britton’s study — add Port Angeles to the rain shadow “banana belt.”
“It was really interesting to look at Port Angeles and see that in the darkest months, Sequim distances itself” with more sunshine, said Britton.
But, he adds, “in the summer, Port Angeles seems to do very well during that time.”
Britton lives on Seattle’s Capitol Hill district but also owns a home on Jamestown Beach Road near the Strait of Juan de Fuca.
The home is equipped with a calibrated rooftop weather station from which he spies remotely on local weather.
In addition to Jamestown Beach, he has a weather station at the historic Lincoln School site a few blocks south of the bluffs above Port Angeles Boat Haven marina.
Details of the yearlong study by Britton, a former Microsoft marketing director who now works for eLocal USA online directories, were amplified in a recent Internet posting by Cliff Mass, a University of Washington professor of meteorological sciences and author of The Weather of the Pacific Northwest.
In addition, he has a popular website, www.cliffmass.blogspot.com, and a radio show.
“Weather with Cliff Mass” airs on 89.3 FM via the Port Angeles-Victoria Striped Peak translator tower, and on KPLU 88.5 FM (89.3 FM in Port Angeles and Victoria) Friday mornings at 9 and twice during the “All Things Considered” broadcast segment between 3 p.m. and 6:30 p.m. Fridays.
Mass helped Britton set up his website and talked about the rain shadow and the “blue hole” during a recent radio show.
“We knew that it was drier,” Mass told the Peninsula Daily News, reacting to Britton’s findings about Port Angeles.
“Now we’re getting information that shows it’s sunnier.
“And it looks like Port Angeles is almost as sunny as Sequim.”
Highlights of study
Britton’s sunshine findings can be viewed on his website — click on www.olympicrainshadow.com.
Britton launched his study and his website about a year ago.
Highlights of his study also conclude:
■ The winter months of November-January saw five times as many mostly sunny days in the rain shadow areas versus Seattle.
■ Winter saw only a quarter as many dreary days in the rain shadow versus Seattle.
■ The spring months of February-May saw the highest number of rain shadow days per month — nearly eight.
Britton says a rain shadow day is when it is sunny in Sequim — but overcast or wet in Seattle.
■ The summer months of July-September saw rain shadow areas and Seattle with nearly an equal number of mostly sunny days.
Britton, who also a page on Facebook (Olympic Rain Shadow), said the month of March was the surprise month in his study, with 13 rain shadow days.
“Last March was a tremendously stormy period,” he said.
“March was the month when Hurricane Ridge’s snowpack was the highest.”
Sequim’s rainy July weather was “really freaky this year” during the Sequim Lavender Festival, he said, with a downpour that dampened the festival’s Friday opener during the late afternoon.
“I don’t think we’ll see a repeat of this,” Britton said.
A cool, wet spring and early summer set the valley’s lavender crops back about three weeks, growers said.
Lowest temperature
Another point of interest, Britton’s Jamestown Beach weather station on Sunday, Oct. 16, recorded the lowest overnight temperature — 28 degrees — on the entire Washington State University network of 135-plus weather stations statewide.
WSU’s agriculture weather stations site can be found at www.weather.wsu.edu/awn.php.
“I think this is a phenomena that will most frequently occur on clear nights in early fall, before the days are short enough to really allow the Eastern Washington temperatures to plummet, and also before the maritime influence starts to really buffer Sequim from frigid overnight temperatures,” he wrote in an email.
“That effect generally holds the low temperatures in Sequim above 20 degrees, though of course we have all seen Polar Express days in the teens or even single digits in the shadow.”
Britton can be reached at olympicrainshadow@gmail.com.
Mass said Californians call him between 10 and 15 times a month about Sequim’s weather.
“The Sequim rainfall is almost the same as Los Angeles,” Mass said.
“That’s a way of looking at it.”
________
Sequim-Dungeness Valley Editor Jeff Chew can be reached at 360-681-2391 or at jeff.chew@peninsuladailynews.com.
