(SOURCE) A brutal heat wave kicking in later this week may shatter June or even a few all-time records in parts of the Great Basin and Northwest. Furthermore, it may last into the first days of July.
June has already been a hot month in parts of the West.
Earlier in the month, Yakima, Washington, tied its all-time June high of 105 degrees. This occurred 15 days earlier on the calendar than the previous June 105-degree high. Medford, Oregon, is pacing for their hottest June on record, dating to 1911. Portland, Oregon, has already tallied 4 days of 90-degree-plus heat this month through Monday, just 2 days shy of the June record set in 2003.
The culprit in this hot setup is part of an overall pattern shift taking place this week across the United States.
A dome of high pressure aloft that has been searing the Desert Southwest over the past week will surge northwestward, becoming established over the Great Basin by late this week.
In addition to suppressing thunderstorm development over much of the Great Basin, this will allow the sizzling late-June sun to send temperatures soaring not simply in the typically hot Desert Southwest, but also locations well to the north including the Pacific Northwest, interior Northwest and northern Rockies.
By late this week into the weekend, highs in the triple digits are possible in many lower-elevation locations west of the Continental Divide and inland from the Pacific Coast.
This includes parts of Nevada, California’s Sacramento Valley, the Salt Lake Valley, Idaho’s Snake River Plain, much of Oregon’s lower elevations east of the immediate coast, and areas to the east of the Cascades in Washington State. Valley locations in western Montana such as Kalispell and Missoula will also top the century mark by this weekend into early next week.
In particular, parts of the Columbia Basin and lower Snake River Valley may surge above 110 degrees. This includes cities such as Yakima, Kennewick and Walla Walla in Washington as well as Lewiston, Idaho.
Compared to what the more arid Great Basin is used to, evening and overnight temperatures will be slow to drop, possibly only bottoming out in the 70s in the hottest locations.
This heat appears to be locked in place well into next week, as the upper-level dome of high pressure remains camped out. There may be some relief in sight in the Northwest as we get closer to the Independence Day holiday.
The hot, dry weather will also produce high fire danger, as drought conditions have worsened over the Northwest and northern Rockies in the spring.
In mid-May, Washington Gov. Jay Inslee issued a statewide drought emergency, and spring runoff from winter’s paltry snowpack was expected to be the least in 64 years.
Seattle has seen only 7 days with measurable rain since May 1, one-third the average number of such days, according to NWS-Seattle. Portland, Oregon, has set a new record June dry streak of 19 straight days through Monday, according to NWS-Portland.