By Ted Buehner, Northwest Region Meteorologist

Summer is just around the corner. The season offers warm, enjoyable sunshine and dry conditions across the Pacific Northwest. However, it can also bring hazardous weather. The following hazards can help you be better prepared when they occur.

Excessive Heat

In late June 2021, the Pacific Northwest experienced what is known as a “heat dome.” This phenomenon occurs when upper-air flow becomes cut off, leaving a large area of high pressure nearly stationary over a region.

In late June 2021, that region was the Pacific Northwest. During the three-day period from June 26 to June 28, temperatures soared to all-time record highs.

On Monday, June 28, Portland, Oregon, reached 116 degrees. Olympia recorded 110 degrees, exceeding its previous all-time high by 5 degrees. Seattle reached 106 degrees, surpassing its previous record of 103 degrees.

Eastern Washington also experienced extreme heat. Yakima reached 113 degrees, Pasco 115 degrees, and Spokane 109 degrees. Some locations southeast of the Tri-Cities exceeded 120 degrees.

A similar heat event could happen again. While rare, these conditions remain possible.

During extreme heat, take the following precautions:

• Spend time in an air-conditioned place such as a mall, theatre, or library for at least three hours per day.
• Drink plenty of water and avoid alcohol.
• Limit outdoor activity during the hottest part of the day.
• Wear lightweight, loose-fitting, light-colored clothing.

Thunderstorms

Thunderstorms can occur at any time of year, but in Western Washington they are most common in spring and fall. In Eastern Washington, summer is the peak season.

Thunderstorms can produce several hazards. Lightning is the most significant. If a thunderstorm approaches, go indoors or into a vehicle immediately. Avoid tall objects such as trees. Remember: when thunder roars, go indoors.

Washington State has not had a lightning-related fatality since 1996.

Additional thunderstorm hazards include bursts of heavy rainfall that can cause flash flooding, especially in Eastern Washington, as well as hail, strong winds, and tornadoes.

Washington averages two to three tornadoes each year. Some years have none, while others have more activity. In 1997, a record 14 tornadoes were reported. Most tornadoes in Washington are weak and last less than two minutes.

However, stronger tornadoes have occurred. Three F3 tornadoes, with winds exceeding 120 mph, have been recorded in the state. Two of these occurred on April 5, 1972. One struck Vancouver, destroying a bowling alley, a grocery store, and a school, killing six people and injuring several hundred. Later that day, another F3 tornado touched down near Davenport, west of Spokane. Washington State had the highest number of tornado-related fatalities in the nation that year.

Strong thunderstorm winds can also produce microbursts. During the dissipating stage of a storm, air rapidly descends to the ground and spreads outward, creating powerful winds. In Eastern Washington, microbursts can cause localized damage and reduce visibility by blowing dust into the air, creating hazardous driving conditions.

Wildfires

Wildfires are another significant summer hazard. In the past, they were primarily an issue in Eastern Washington. However, with warmer and drier summer conditions in recent years, wildfires are now occurring across the state, including west of the Cascades.

Wildfire smoke can also create poor air quality. In Western Washington, seven of the past nine summers have included periods of unhealthy air due to smoke. In many cases, the smoke originates outside the region, including British Columbia, Oregon, Eastern Washington, and California.

During periods of wildfire smoke:

• Stay indoors, especially if you have respiratory conditions.
• Keep windows and doors closed and turn off outside ventilation systems if possible.
• Wear a properly fitted N95 mask if you need to be outdoors.

Stay Informed

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