SEATTLE NEWS ARCHIVES & FEATURES
Raise the curtain on Western Washington’s thunderstorm season
Mar 14, 2016, 10:15 AM | Updated: 10:55 am
Thunderstorms aren't uncommon in Washington, but the peak season is spring. (AP file photo)
(AP file photo)
The forecast has a threat of thunderstorms for much of Western Washington on Monday.
Thunderstorms can occur year-round, yet spring is the peak of our thunderstorm season. The combination of longer and warmer days with cooler air aloft still flowing onshore aloft from the northeast Pacific Ocean means a more frequent unstable air mass resulting in thunderstorms.
Our active convective season usually occurs during our transition seasons into and out of winter – both spring and fall. April is usually the peak month for convection.
Compared with areas east of the Rockies, Western Washington does not get many thunderstorms. For instance, some parts of Florida get more than 100 thunderstorms per year while this region averages close to 10.
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Thunderstorms can produce strong damaging winds, urban or flash flooding from heavy rainfall, large hail, lightning and even tornadoes.
Washington averages between one and two tornadoes per year. In our history, the bulk of our tornadoes have occurred in April and May, including two of the three F3 tornadoes ever reported in the state. Recently, F0 tornados touched down in Eatonville in April 2014, Napavine in May 2011, Tenino in May 2004, and Sumas in April 2004.
Lightning is dangerous and is the second major cause of thunderstorm-related fatalities and injuries. The last Washington lightning-related fatality was in 1996.