Fox News Weather Center

Increased thunderstorms to be double-edged sword for western US next week

An increase in soaking thunderstorms across the western United States next week will be beneficial for firefighters, but could lead to other hazards.

During the first and middle part of next week, the door will open for monsoon moisture to surge northward out of the Southwest and across the Great Basin and the northern Rockies.

An increase in thunderstorms will follow suit from Palm Springs, California, to Las Vegas and Flagstaff, Arizona, to Salt Lake City, Pocatello, Idaho, and Yellowstone National Park.

Recently, most of the thunderstorms that sparked over the northern Rockies have produced more lightning strikes than rainfall--a recipe for high fire danger. The upcoming surge of moisture will be great enough to allow for more soaking thunderstorms to erupt.

West July 22

Increased rainfall will definitely benefit some of the fire crews battling the dozens of blazes burning across the West.

The middle of July brought downpours to the Desert Southwest, dousing the raging wildfires across the region. Firefighters farther north are likely hoping for similar help from Mother Nature next week.

The Four Season Complex Fire has already charred nearly 160,000 acres in northern Nevada, while the Cedar Mountain Fire has burned more than 17,000 acres in northern Utah, according to InciWeb.

However, the downpours are likely to steer away from the massive Detwiler Fire burning near Mariposa, California, and the other large blazes burning in Washington.

As was evident by the deadly flash flooding in Arizona last weekend, the increased thunderstorm activity brings other hazards to fire crews and residents.

Lightning can strike parched vegetation away from the thunderstorm’s rain, sparking new wildfires.

Some of the thunderstorms can also produce strong, gusty winds. In addition to sporadic damage, ongoing blazes can be fanned and break fire containment lines. The erratic nature of these winds could put firefighters and other structures in danger.

Haboobs could get kicked up in the deserts ahead of any soaking rain from this weekend to early next week. Motorists planning to travel on stretches of Interstates 8, 10 and 15 should stay alert for a sudden and dramatic reduction in visibility.

SW weekend July 22

Flash flooding and localized mudslides may unfold where too much rain pours down in a short amount of time. Desert locations and recently-burned areas are especially susceptible to flooding.

Anyone living, camping or enjoying other recreational activities near streams or arroyos should remain vigilant and be ready to move to higher ground when a thunderstorm threatens or passes close by.

"Arroyos can suddenly fill up even from a thunderstorm miles away as runoff from the rain rushes downstream," AccuWeather Meteorologist Jim Andrews said.

As is typical, the thunderstorms across the Intermountain West will be most numerous during the afternoon and evening hours. However, pockets of flooding downpours may linger into the morning.

"Thunderstorms in this type of pattern tend to blossom over the mountainous areas during the afternoon hours before drifting over valley locations toward the evening," AccuWeather Meteorologist Renee Duff said.

Later this week, a push of drier air is expected to suppress the drenching thunderstorms back to the south.