West’s ‘heat dome’ could last all week
The record-breaking heat across much of the West was easing somewhat Monday, but a “heat dome” means temperatures could remain well above average highs all week, forecasters say.
The weather setup is similar to what the region saw two weeks ago, when extreme heat sweeping across the Pacific Northwest and western Canada broke records and fueled devastating wildfires.
“This time, the core of the high pressure and heat has been anchored farther to the south and has allowed excessive heat to build up across the region,” Accuweather Senior Meteorologist Adam Douty said.
The National Weather Service warned Americans facing the oppressive heat to stay hydrated, seek shade and not leave children or pets alone in vehicles.
“Another day of potentially recordbreaking heat is in store for portions of the western US today,” the National Weather Service tweeted. “Heat-related illness can sneak up on you. Know the signs.”
The heat is straining power grids and fueling wildfires across almost 500 square miles in six Western states.
In Oregon, the Bootleg Fire was the biggest, burning across more than 220 square miles and 0% contained. In California, the Beckwourth Complex Fire had burned more than 140 square miles, making it the state’s largest fire this year. It was 20% contained early Monday. State residents were asked to limit power consumption after fire knocked out interstate power lines, jeopardizing up to 5,500 megawatts of electricity.
Heat warnings have been in effect for almost a week across much of the Southwest. Douty said that, while the peak of the heat has passed for places such as Death Valley and Las Vegas, temperatures will remain 5 to 15 degrees above normal for much of the week.
Daily records were tied or broken over the weekend across California, Nevada and Arizona, and extreme heat extended into Idaho and interior parts of the Pacific Northwest. Accuweather expected the temperature in Death Valley to reach 127 degrees Monday, just shy of the area’s record high of 129. The world record high is 134 degrees.
St. George, Utah, reportedly reached 117 degrees Friday. If confirmed, that would tie for the hottest day on record for the state. Las Vegas also set a new daily record-high temperature on Friday of 116.
“Lasvegas went from record-breaking heat yesterday, to record-breaking rainfall today,” the National Weather Service in Las Vegas tweeted late Saturday, saying the 0.1 inches of rain measured at Mccarran International Airport is the most rain on any July 11 since records began in 1937.
Blame the heat dome. A heat dome is the result of a strong change in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter, according to the National Ocean Service. The warm air coming from the west part of the Pacific Ocean then gets trapped in the jet stream as it approaches land.
When that hot air arrives over land, the atmosphere traps the hot air as if a lid were put on it. Winds can move the heat dome around; hence it is also referred to as a heat wave.