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Northwestern US heat wave to jeopardize all-time record highs

By Kristina Pydynowski, AccuWeather senior meteorologist
August 03, 2017, 2:19:43 PM EDT

Dangerous heat will build across the western United States, putting all-time record highs in jeopardy across the I-5 corridor of the Northwest this week.

"The current heat wave in the Northwest may end up being the most notable event of the entire summer for the U.S.," according to AccuWeather Chief Meteorologist Elliot Abrams.

Records have been maintained as far back as the late 1800s in the northwestern U.S.

An all-time high occurs when a temperature equals or tops the highest temperature for any calendar day in any year since records have been kept.

“An abnormally strong ridge of high pressure will bring record-shattering heat to the Pacific Northwest,” AccuWeather Senior Meteorologist Dan Pydynowski said.

Static Northwest Heat Wave Through Friday

The heat dome produced by the weather pattern will expand to include areas from California to Washington, Idaho and British Columbia during much of this week.

Temperatures will climb 5 to 15 degrees Fahrenheit above average with multiple days in the 100s from Fresno and Redding, California, to Reno, Nevada; Boise, Idaho; and Pendleton, Oregon.

However, communities west of the Cascade Mountains will endure the greatest departures from normal.

“The heat will peak through Thursday,” Pydynowski said.

Daily record highs will be shattered these days as triple digit-heat is expected to engulf most of the I-5 corridor in Washington and Oregon.

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More typical highs as July transitions to August range from the upper 70s in Seattle to the lower 80s in Portland, Oregon, to the lower 90s in Medford, Oregon.

Medford will join Portland and Eugene, Oregon, and other communities in flirting with all-time record highs through Thursday. This corridor should also turn hotter than Phoenix these days. Monsoonal thunderstorms and clouds will keep temperatures in check across the Desert Southwest.

All-time records July 30

“During the extreme heat wave, people should wear light-colored clothing, stay well-hydrated with water and try to limit time outdoors to the mornings and evenings,” Pydynowski said.

“If you have to be outside during the day, take as many breaks as possible in the shade or indoors in air conditioning.”

Residents without air conditioning will want to crank up fans or seek cool air in a basement or local shopping center. Be sure to check in on the elderly without air conditioning to make sure they are following these precautions.

The increased energy usage could lead to power blackouts.

As sizzling sunshine sends temperatures soaring, remember to never leave children or pets locked in a car even for a short amount of time.

Residents should also use care with cigarette butts or campfires as an elevated fire danger will accompany the extreme heat.

Those looking to beat the heat can head to the cooler mountains or the immediate coast.

Static Thursday NW

However, an offshore flow may be enough to minimize the cooling effect from the ocean and cause temperatures to still soar along the Washington coast on Thursday.

It will take until the weekend for the heat to finally release its grip on the Northwest.

“The ridge should begin to weaken heading into Friday and Saturday,” Pydynowski said. “So while it will still be very warm with above-normal temperatures, the record-breaking heat should come to an end.”

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