Thunderstorm Outbreak Possible In Puget Sound — Here's Why

SEATTLE, WA — Thunderstorms are rare in the Pacific Northwest, but we might see a few Friday night and into Saturday morning thanks to a shift in weather patterns.

According to the Seattle Weather Blog, there's a low pressure system hanging off the Pacific Coast near Eureka, Calif., that will make conditions just right.

"[The low pressure system] allows storms over the Cascades to be steered from SE to NW — smack dab into Seattle. This looks to be the case later today,"forecaster Justin Shaw wrote on Twitter Friday.

Thunderstorms could develop late in the afternoon Friday, according to the National Weather Service. Heavy rains and gusty winds will likely accompany the storms. The lowlands and the Cascades will be in the crosshairs.

"An unstable atmosphere will lead to the development of thunderstorms across the Cascades later today, a few of which could drift into the lowlands, mainly east of the I-5 corridor. The chance for severe storms will remain to our south across Oregon," the NWS wrote on Twitter.

A thunderstorm outbreak two weeks ago caused a rash of small wildfires on the east side of the Cascades, but Puget Sound has only seen one serious storm this summer. Why don't we get more thunder and lightning? Washington — on both sides of the mountains — lacks one thunderstorm ingredient that other coastal cities have plenty of.

"A key ingredient missing here is humidity, or plenty of water vapor in the low levels of the atmosphere. Unlike breezes from the warm Gulf of Mexico, air blowing off the chilly Pacific waters is cool. Because cooler air near the ground provides a relatively small amount of vertical temperature difference, the air is less likely to rush upward and produce thunderclouds," Washington State University meteorologist Nic Loyd explains.