Highs to plummet 20-30 degrees following record-breaking heat across the western US

By Brett Rathbun, AccuWeather.com Meteorologist

June 9,2016; 7:00PM,EDT

 

 

May-like weather is set to return to the Western states after record-breaking heat gripped the area during the first several days of June.
"After several days of record-breaking heat, a cooler and wetter pattern is in store for the Pacific Northwest" AccuWeather Meteorologist Ryan Adamson said.
The jet stream will dip southward and usher in cooler air for the next several days.
The jet stream is a narrow zone of strong winds in the upper levels of the atmosphere that separate the warm air to the south and cooler air to the north.
Highs through Saturday will be in the 60s and 70s F across much of the Northwest including Seattle and Portland, Oregon. This will be a 20- to 30-degree temperature drop from highs during the first week of June.

This dip in the jet stream will also open the door for a storm to bring wet weather to the Northwest.
"While showers will begin on Thursday, the cool and wet weather will be in full force Friday and Saturday," Adamson said.
Spotty showers will dampen any outdoor activities, such as golfing, hiking or any sporting event across much of Washington and Oregon. Thunderstorms will occur across portions of Idaho and Montana.
The heavier showers could also produce small hail.
There will be enough cold air for snow showers to return to the higher elevations of the Washington and Oregon cascades, but no accumulation is expected.
"Any snow should be confined only to elevations above 6,000 feet, well above pass level," Adamson said.
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While wet weather will not be a threat to the Southwest, highs in this region will trend downward, especially in the interior locations.
Highs will be as much as 20 degrees Fahrenheit lower than during the peak of the heat in early June from the California Central Valley to Nevada and the Desert Southwest.
Highs across the Central Valley will drop into the 80s in most locations by the start of the weekend, including in Sacramento and Fresno, California.

An onshore flow will keep the California coast cool from San Francisco to Los Angeles and San Diego.
The cooler air will not reach the Intermountain West until later this weekend and into early next week. This cooler air could cause highs to fail to reach 100 F in Phoenix, Arizona, for the first time this month.
As a slight warmup may be in store early next week across portions of the West Coast, cooler air will return for the remainder of next week. The next major warmup may not reach the Western states until Father's Day weekend.