Weather enthusiast studies rain shadow, shares findings
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Weather enthusiast David Britton uses equipment atop his Jamestown Beach Road home to gather data that he puts on his website,

By Jeff Chew
Peninsula Daily News

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DUNGENESS -- David Britton is fascinated with the Sequim-Dungeness Valley's weather and how the famous Olympic rain shadow affects it.

His interest has led him to place a weather station atop his Jamestown Beach Road home and build a website,, to share his findings and network with others who have weather stations on the North Olympic Peninsula.

He is setting up a blog on his site to do just that and collaborated with University of Washington weather expert Cliff Mass, who blogs at and is the author of the book The Weather of Pacific Northwest.

Britton's weather station and website allow the part-time Dungeness resident and full-time Seattle software marketer to collect weather data to better understand the sunny side of Sequim and help others do so.

Olympic rain shadow

"For a lot of people, the rainfall is interesting, but no one knows a lot about the sunshine," said Britton, a former Microsoft marketing director who now works for eLocal USA online directories.

The Olympic rain shadow weather phenomenon is the result of storms and prevailing winds typically coming from the south and west.

They hit the Olympic Mountains, dropping up to 200 inches of precipitation over the range, and then tend to part, leaving the leeward side of the mountains drier and much sunnier.

Topographical changes

The rain shadow is considered to stretch from Port Angeles to Sequim, but Britton said he notices changes in weather primarily from Morse Creek eastward to Hood Canal.

It extends from the eastern Peninsula lowlands north through Whidbey and the San Juan Islands, and the result is similar land and plant features associated with drier, cooler climates, he said.

Sunshine analysis

Britton's website includes information on the location, climate, meteorology and a live weather station with a "Sunshine Analysis" report from October.

"The report compares the amount of sun at a location within the rain shadow with two locations in the greater Seattle area," he said. "The findings are striking."

For example, the October analysis showed:

• Sequim averaged 2.34 hours of bright sunshine per day and had only one "dreary" day.

• Sequim recorded 17 mostly sunny days, compared with Seattle's 12 and only three in Redmond/West Lake Sammamish

• During a five-day stormy period, Sequim recorded more than five times the solar radiation of the Redmond/West Lake Sammamish area.

• Even in a relatively sunny fall month, Sequim was dramatically brighter and sunnier than the eastern Puget Sound location and measurably sunnier than even the sunniest locations in downtown Seattle.

• Autumn stormy periods with fast-moving storms may very well be dry and with quite a bit of sun in the Olympic rain shadow towns.

Those feeling they live in dreary neighborhoods in the eastern Puget Sound or Cascade foothills could take a road trip to the Olympic rain shadow and likely see a lot more light during the darker months and stormy periods, Britton said.

Britton said that, over time, he hopes to debunk a number of myths about the rain shadow and verify a number of informal observations.

For example, when it comes to the notion that Sequim sees more than 300 sunny days a year, he said, "We feel that is a bit optimistic, but still, rain shadow areas see substantially more sun than surrounding areas."

Center of rain shadow

The center of the rain shadow in terms of maximum sunshine and minimum precipitation is near the tip of Dungeness Spit in Sequim, he said.

To say that the rain shadow is a tropical banana belt is a misnomer, he said.

It is actually a "quite cool but clear, sunny and windy climate overall."

Heavy snowfall, such as the Nov. 22-23 storm that dumped more than a foot of snow on the Sequim-Dungeness Valley, is what Britton called a "reverse rain shadow," in which the storm moves in from the north, in this case from the Fraser River Valley in British Columbia.

Britton said he hopes to network with others on the Peninsula with weather stations.

"It would be nice to connect with others who have weather stations to share information and network about it," said Britton, an outdoorsman who loves to cross-country ski on Hurricane Ridge.

There is interest in the valley's weather from Seattle-area residents who experience wetter climate longer in the spring while the Dungeness Valley is dry and sunny by comparison.

"There's some interest in the bicycling community because in the spring, it's so wet over here," he said of Seattle.

Britton can be reached at


Sequim-Dungeness Valley Editor Jeff Chew can be reached at 360-681-2391 or at

Last modified: December 06. 2010 12:13PM
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