Weather Deck

Sunday, July 5, 2015

Fires in the Pac.NW

From the desk of Wildfire Season Returns With a Vengeance to Pacific Northwest By Becky Elliott June 30, 2015; 10:05 AM ET We are well into the driest time of year for the Pacific Northwest and the vicious threat of wildfire has already reared its head. When thinking about the Pacific Northwest, cities like Seattle and Portland probably come to mind. There is also the thought that those cities are usually pretty rainy and wet. Sometimes the association is then made that the entire region has a wet climate, but that is not at all the case. West of the Washington and Oregon Cascades, the climate is considered to be temperate maritime. The region experiences mild temperatures year round and receives an average of 30 inches of rain annually. Some locations can pick up as much as 200 inches, the majority of which falls in the winter. On the east side of the Cascades lies the Yakima Valley, the Columbia River Basin and the Harney Basin. These regions are considered continental and semi-arid. They can be compared to the deserts in California and Nevada. These desert regions usually only receive between 5-10 inches of rainfall each year. The reason for this drastic difference in rainfall amounts is the terrain. The Cascade mountains reach a peak elevation of 14,411 feet at the summit of Mount Rainier. This creates what is called the "rain-shadow effect." When storm systems move onshore in the Pacific Northwest, the air is forced to lift up and over the mountains. This is called orographic lifting. All of the moisture gathered from the Pacific Ocean is forced to rise and as it rises, the parcel of air cools and creates clouds and precipitation. Once the air mass has made it over the 10-14 thousand foot peaks and begins to descend into the valleys, most of the moisture has already fallen. This is why regions east of the Cascade Mountains are so arid and rarely receive wet weather. This year is no exception. Wenatchee, Washington is located right in the center of Washington state, on the confluence of the Columbia and Washington Rivers. Wenatchee's rainfall total for the year is 3.73 inches. June has been a particularly dry month, with only 0.04 inch of rain, all of which fell on Tuesday. This is only 6 percent of normal precipitation. While the exact cause is still unknown, the dry weather has helped the Sleepy Hollow Fire near Wenatchee burn out of control since it started on Sunday. Fire burning in Wenatchee. Black smoke is from a tire store on fire, and the hills behind are still burning, flamed by winds. (Photo taken by Chad Dahmen) The Incident Information states that nearly 30 residents have been burned and the fire is estimated to be 4,000 acres. The other major contributing factor to the wildfire is the extremely hot temperatures across the region. The normal high temperature this time of year in Wenatchee is 83 degrees. The temperature has been 95 or higher since June 25 and above 100 for three of those days. The high temperature reached a blistering 109 F on Monday, which is 23 degrees above normal. Unfortunately, the end to the scorching weather is nowhere in sight for central Washington. Temperatures are forecast to be in the upper 90s or above well into next week, with several of those days approaching or breaking high temperature records.

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