EVERETT, MARCH 25: A rare and significant weather pattern is expected to develop Wednesday, bringing a good risk of thunderstorms late in the day and into the evening. These thunderstorms will produce a lot of lightning, heavy rainfall, and strong winds. The threat of large hail and even tornadoes or waterspouts cannot be ruled out.
This kind of weather is unusual for Western Washington and the North Sound, and is reminiscent of a Midwest or Plains state weather pattern that can produce severe weather. An upper level low is forecast to set up camp off the Pacific Northwest coast. The southerly flow aloft along its east flank will send warm moist unstable air into the region, setting up the environment for these active thunderstorms.
Thunderstorm Recipe
As taught in Skywarn Weather Spotter and other weather courses, thunderstorms need three primary ingredients – moisture, an unstable air mass, and lift.
Given all the recent rain and how muggy it feels outside, moisture is certainly in place. The combination of well above average late March temperatures cracking the 70 degree mark and much cooler air aloft involved with the offshore upper level low, the air mass will become unstable meaning easy for the warm moist surface air to rise, create clouds and storms.
The upper level low itself will provide the lift given the southerly flow aloft on its eastern perimeter. So, all three thunderstorms ingredients will be in place for an active thunderstorm episode late Wednesday.
As noted, the thunderstorms will involve plenty of lightning and heavy rainfall or downpours. The National Weather Service’s Storm Prediction Center has indicated a risk of severe weather for the region as well. The greatest risk is severe thunderstorms with wind gusts in excess of 58 mph. These kinds of thunderstorms can also produce large hail of one inch diameter or greater, as well as a tornado or waterspout.
Safety Actions
Late Wednesday afternoon and evening will be a period of time to keep an eye on the sky, and monitor weather conditions such as the Doppler weather radar on websites such as the weather page on everettpost.com and weather apps. If threatening weather approaches, move indoors. The phrase – When Thunder Roars, Go Indoors – applies here. There has not been a lightning fatality in the state since 1996 – let’s keep it that way.
Heavy downpours can result in ponding of water on roadways and even the possibility of local flash flooding. Any strong damaging winds can blow down trees and create local power outages.
Tornadoes Cannot Be Ruled Out
Nearly all tornadoes are borne from thunderstorms. Washington State averages about two to three tornadoes per year. This weather pattern has the environment and potential to produce tornadoes – quite rare in this region. The chances of a tornado are quite low, yet the threat cannot be ruled out.
Here are some helpful tornado preparedness videos on how to remain safe in case of a tornadic event.
Before a Tornado During a Tornado After a Tornado
Happened Before Recently
The last time this region had a weather pattern similar to this one that had the potential to produce severe weather was back on May 4th, 2017. A severe thunderstorm struck the area in and around Lacey, Washington, with strong winds blowing down trees, knocking out power, heavy rainfall resulting in flooded streets, and hundreds of lightning strikes.
Many parts of Western Washington and the North Sound experienced frequent lightning, downpours of rain, and strong gusty winds during this thunderstorm outbreak.
The Rest of the Week
The severe weather threat will be over. The upper level low is expected to remain off the coast and send cooler conditions onshore with frequent showers Thursday and Friday before tapering off this weekend. High temperatures will cool back down into the 50s.
Be Prepared
The kind of weather pattern Wednesday is one to pay a great deal of attention to, given how rare it occurs in Western Washington and the North Sound. Keep an eye to the sky, and be prepared to take action in case threatening weather approaches.
