Fox News Weather Center

Late-week western US rain to bring needed dousing to drought zone but to cause travel delays

A storm will deliver several days of much-needed rain to the drought-stricken western United States late this week. However, rain could be heavy enough to cause flash flooding and travel delays.

Rain is desperately needed across most of the Southwest and parts of the Northwest. According to an April 26 report by the U.S. Drought Monitor, an estimated 45 million people are being affected by drought in the West.

Over 50 percent of California is in extreme or exceptional drought.

The first round of beneficial rain will arrive along coastal portions of Washington, Oregon and northern California late on Wednesday. A few thunderstorms could erupt east of the Cascades and across the Sierra Nevada.

As the storm dives farther south on Thursday into Friday, showers will expand across central and Southern California, Nevada, Utah and Arizona.

Clouds and showers could reach as far south as Phoenix on Friday, putting an end to the string of 90-degree Fahrenheit temperatures this week.

Thunderstorms will be embedded in some of the showers during the heating of the day, according to AccuWeather Meteorologist Brandon Zapolski.

"The pattern of pop-up showers and thunderstorms is more typical of summer in the West," he added.

Any thunderstorms that erupt could bring the hazards of damaging wind gusts, torrential downpours and small hail.

While each day should not be a washout, area residents will want to keep an umbrella handy in case of a sudden downpour.

The beneficial aspects of the rain will come with a few drawbacks.

Motorists should remain aware of rapidly deteriorating visibilities and road conditions. Roadways could be slick at the onset of rain due to a buildup of oil.

Airline passengers may face delays at local airports, including in San Francisco, Los Angeles and Las Vegas.

Locations that sit under the heaviest downpours will face an enhanced flash flooding threat.

"Flash flooding will mainly occur on a localized basis," Zapolski said, adding that pooling of water may take place in low-lying and poor-drainage areas.

An additional hazard to the area will be any dry thunderstorms that pop up across the Desert Southwest.

Dry thunderstorms are associated with dangerous lightning and sudden bursts of wind, but with little or no rainfall. These storms are just as dangerous as regular thunderstorms and can quickly kick up dust or spark wildfires.

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As rain moves away from coastal regions heading into the weekend, bouts of wet weather are expected to continue across the interior Southwest into Mother's Day.