Heat expected to swell over much of country this weekend
A sprawling dome of heat will park over the U.S. next week, bringing highs topping 90 degrees to 130 million Americans and triple-digit temperatures to some.
It will feel even hotter due to soaring humidity in the East, while the same dome of heat saps the West of moisture and bolsters late-season wildfire concerns. The core of the heat could eventually become centered over the Great Lakes as the massive ridge of high pressure spans coast to coast.
The first signs of the fledgling heat dome were already emerging in the West, where strong high pressure was bringing temperatures over 100 to the Central Valley of California and interior Washington State earlier in the week. Heat advisories blanketed the Columbia River Valley region, and the harshest temperatures have since expanded east.
National Weather Service data showed a record high of 106 in Bismarck, N.D., on Friday, with widespread hundred-degree readings across the Dakotas. The previous record in Bismarck, was 95 degrees in 1988. The city will probably nab a new record Saturday too, with a projected high of 97 degrees.
Salt Lake City was under an excessive heat warning for “dangerously hot conditions with temperatures around 100.” It hit 97 on Thursday, establishing a new record.
Phoenix and Las Vegas, Nev., also saw temperatures over 100 degrees, and Death Valley hit 120 degrees for the first time this year Thursday.
Accompanying the heat is a concern for wildfires. Red flag warnings for fire danger are up for central Washington, Oregon and northern California on Saturday, where lingering heat will combine with single digit relative humidity values and winds gusting up to 40 mph to bring an increased risk of wildfire ignition and growth.
Red flag warnings have also been issued in Montana, North Dakota and northern Minnesota, as well as in Utah. It marks the start of a long and likely significant wildfire season for the West, worsened by prolonged “extreme” to “exceptional” drought, a significant deficit in soil moisture resulting in dry vegetation, and the expectation that anomalously hot temperatures — due in part to human-induced climate change — will persist into the fall.
Over the weekend, the instigating ridge of high pressure and its associated warmth will flatten and expand eastward, draping a swath of heat, some significant, over most of the continental U.S. An exception may be areas around East Texas and the Gulf Coast, where temperatures will be closer to normal due to a weakening eddy of low pressure that could bring clouds and storms.
On Saturday, Chicago will climb into the 90s, as will Washington, D.C. Boston and New York will approach 90 too. In Minneapolis, Saturday’s high is forecast to reach 98, which would crush the existing record of 92 degrees from 1925 and 1911.
The nation’s capital could make it into the mid-90s on Sunday, when highs of at least 90 cover much the eastern half of the nation.
By Monday, much of the U.S. will see elevated temperatures, though a disturbance will also be working ashore in the Pacific Northwest, bringing unsettled conditions near the coast.