Severe thunderstorm watch in effect
July 20, 2012
Areas shaded light mauve indicate the scope of the severe thunderstorm watch issued this morning be the National Weather Service.
At 11:34 a.m. today, the National Weather Service, Norman, Oklahoma, issued a severe thunderstorm watch for a large portion of the Pacific Northwest, including Boundary County, Idaho, through 8 p.m. this evening.

The watch area is defined as being along a 130-mile line running east and west from approximately 90 miles east northeast of Omak, Washington to 50 miles south of Lewiston, Idaho.

According to the National Weather Service, conditions in this area are favorable for wind gusts up to 70 miles per hour, hail as much as two inches in diameter nand dangerous lightning. While rare in this region, they advise that this system could spawn tornadic activity.

As of noon, scattered thunderstorms were intensifying across parts of northern Oregon and central Washington ahead of an approaching mid-level shortwave trough. Strong heating into the afternoon will result in steepening low-level lapse rates and a moderately unstable air mass.

Aviators are advised that these storms will carry extreme turbulence and vertical shear, wind gusts of up to 60 miles per hour and damaging hail aloft. A few cumulonimbi with maximum tops to 450 and a mean storm motion vector of 22030.