West Coast Stays Cool in a Blistering Summer

August 3, 2011; 12:12 PM ET
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As the central and eastern parts of the nation have sweltered with record heat this summer, the West Coast has been cool, and at times wet, since June 1.

Temperatures have been on the cool side up and down the Pacific coast due to two main factors: cool air aloft and an eastward shift of the typical summertime high pressure system.

According to Expert Senior Meteorologist Ken Clark, "In a typical year, surface high pressure is centered over the Four Corners by the beginning of August, instead of over Texas and Great Plains as it is currently."

"The current high placement has kept coastal and inland locations in the West cooler than normal throughout the summer," Clark added.

This large area of high pressure that has received much media attention over the past month has acted as a giant roadblock, keeping the weather pattern locked in its current state.

According to Long Range Expert Paul Pastelok, "Looking ahead into August, a similar pattern will continue at least until the middle of the month."

After that, some of our forecast tools suggest the West, especially Southern California, will see a warming trend as the central U.S. heat dome slides westward. The Pacific Northwest will continue to remain cooler than normal as a train of disturbances slides just north of the area.

Weather observing stations along the West Coast have reported below-average temperatures since June 1.

The map shows temperature departures from normal across the West in July. Courtesy of the National Weather Service's High Plains Regional Climate Center

Seattle, Wash., has experienced temperatures averaging 1.2 degrees below normal.

In Portland, Ore., it has been 1.2 degrees cooler than average.

In Los Angeles, temperatures have dipped to 1.8 degrees below normal for the summer months.

Even inland areas such as Sacramento, Riverside and Palm Springs, Calif., as well as Pendleton, Ore., and Spokane Wash., have been given a little cold shoulder from Mother Nature with temperatures ranging from 1 to 5 degrees below normal so far this summer.

Meanwhile, in San Francisco, record rainfall was received in the first week of June. The city ended the month with 1.49 inches of rain, which is 1.38 inches above normal.

By AccuWeather.com Meteorologist Dan DePodwin


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