Another heat wave is set to scorch the Southwest again this weekend, elevating wildfire concerns
By Hannah Gard and Monica Garrett, CNN
Stifling heat is searing the US West as the weekend approaches, with historic drought conditions worsening and fire danger escalating across much of the Northwest.
Daytime high temperatures across the West will threaten records once again, soaring into the 90s and triple digits through the end of the week. The brunt of the heat will hit Idaho, Utah and the desert Southwest before high pressure shifts back toward the West.
“Excessive heat warnings, watches, and heat advisories remain in effect across central California, the Southwest, and parts of the central/northern Great Basin,” said the Weather Prediction Center. The alerts cover nearly 25 million people.
Prolonged, unprecedented heat like the West is experiencing is made worse and more frequent by the climate crisis, experts have told CNN.
The interior Northwest has endured unrelenting heat since the end of June after a deadly heat wave in the Pacific Northwest stalled out over the region.
Boise, Idaho on Tuesday tied the record longest streak with nine over-100-degree days, matching streaks set in 2003, 2006 and 2015. Wednesday’s high in Boise only hit 99 degrees, ending the streak, but the forecast is expected to be over 100 again this weekend.
Wildfire weather worsens
Extreme heat and little rainfall are creating a recipe for wildfire disaster across the western US.
The drought in the West continues to worsen, the latest drought monitor released Thursday morning shows. Over 90% of the West is in drought, with several locations’ drought level worsening.
Across the US, the drought has nearly doubled in size from this time last year. Around 25% of the country was in drought conditions in July 2020; as of this week, nearly half is in drought.
Heat waves and their prolonged nature coupled with the historic drought are drying out the vegetation in the area, allowing for ripe fuel for fires.
Red flag warnings and fire weather watches Thursday span the Great Basin from California to the Rockies, where gusty winds and hot conditions could easily propel any ignited fires into dangerous size and strength.
“All the ingredients are there: dry conditions, dry lightning potential, and breezy winds, so new fire starts will be possible,” said the National Weather Service in Pendleton, Oregon.
Winds picking up through the day Thursday could exceed 25 mph, prompting critical fire weather conditions to extend from northern Nevada through southeastern Idaho.
Large fires have already ignited this week across the Pacific Northwest as hot and dry conditions persist. A wildfire prompted evacuations of around 200 homes Tuesday in Spokane, Washington.
In California, wildfires are an increasingly disruptive part of life, and 2021 is already proving to be an active fire season.
There have been more than 750 more fires and 42,000 more acres burned in 2021 than this time last year, with 4,599 fires ignited in California so far this year, according to CalFire.
Californians should prepare for wildfires as the danger is expected to grow this weekend with the next heat wave, authorities warned.
Critical fire conditions are expected to extend into the weekend.
Temperatures rise in the Southwest
Some records are in jeopardy over the next two days across California and Nevada before the heat will crescendo into the weekend, with additional records likely to fall.
“For the most part regional temperatures remain 5-10 degrees above average through the remainder of the week. This trend will continue into the weekend with some daytime and even higher overnight temps either touching or exceeding record territory,” said the weather service in Reno, Nevada.
By the weekend, the large ridge of high pressure over the region will expand, covering the southwestern US, leading to sweltering temperatures in central California, Nevada and Arizona.
“This will bring a trend up in temperatures into the weekend with atrocious afternoon temperatures topping out between 100 and 108 for valleys near and below 5000 feet for the weekend (versus mid 90’s to low 100’s prior to Saturday),” the weather service in Reno said.
In Las Vegas, the weather service forecasts a 43% chance of breaking the all-time high temperature record of 117 degrees on Saturday and a 61% chance of tying the record, which has only been done four times, most recently in 2005.
Death Valley could see temperatures climb to 130 degrees on Sunday, just 4 degrees shy of the official hottest temperature ever recorded on Earth, measured on July 10, 1913, at this same location.
“This next heat wave is looking pretty brutal and could bring with it record setting maximum temperatures and possible records for high minimum temperatures this weekend into early next week. Sadly, our next spell of triple digit heat looks like it could be our longest one yet this Summer,” said the National Weather Service in Hanford, California.
The extreme heat won’t be short-lived, as the high pressure is expected to park over California and Nevada throughout the beginning of next week.
“It’s best to think of this ridge as a very tall mountain of dry, stable air,” the weather service in Hanford said. “Tall mountains are difficult to move and the ensembles (weather models) suggest that no weather system will be strong enough to move this mountain of hot, dry air before the middle of next week.”
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