Southwestern States Face Multi-Day Flood Threat From Pacific Moisture
Pacific moisture streaming from the remnants of a tropical system off the Mexican coast will trigger a multi-day flash flood threat across seven U.S. states from California to Colorado, weather.com reported. A dip in the jet stream is combining with a strong low-pressure system to funnel moisture into the region, creating conditions capable of producing heavy rainfall rates up to two inches per hour.
Rainfall Timing Across Arizona, New Mexico, and California
The highest risk of flooding on Wednesday covers much of Arizona and New Mexico, along with portions of Colorado, Utah, and Southern California. Weather.com noted that an abundance of moisture will support heavy downpours and training storms, which are storms that produce heavy rain over the same areas for extended periods. Forecasters warn of potential mudslides over recent burn scar areas, as well as rising water in slow canyons and arroyos. Alongside the heavy rain, a severe weather threat on Wednesday brings isolated strong winds, hail, and a brief tornado possibility to parts of Arizona, southern Utah, and western New Mexico.
Moisture Pumping Into Saturated Soils on Thursday
On Thursday, moisture will continue to pump into the Southwest, increasing the flood threat over already saturated ground. Forecast models suggest near-record levels of moisture for October in the region, raising concerns that final rainfall totals could exceed current projections. While the greatest flood risk moves out of California by Thursday, it remains active across Arizona, Nevada, New Mexico, Colorado, and Utah, threatening metropolitan areas including Las Vegas, Phoenix, Tucson, and Albuquerque. A slight threat of severe weather will also persist across the Great Basin and the Desert Southwest.
Desert Southwest Rain Risks Flash Flooding
The region expects between 3 and 5 inches of rain across parts of the Desert Southwest, which is enough to trigger flash flooding. Higher elevations in the Sierra and the Rockies could also see the first significant snow of the season. While widespread snowfall totals will stay under 6 inches, isolated peaks could accumulate up to a foot of snow, potentially providing a base for ski resorts affected by low snow totals last winter.
Frequently Asked Questions About the Southwestern Storm System
Which areas face the highest risk of severe weather and flooding?
Wednesday’s highest flood risk covers much of Arizona and New Mexico, portions of Colorado and Utah, and Southern California, while severe weather threats including isolated strong winds, hail, and a brief tornado are possible in parts of Arizona, southern Utah, and western New Mexico.
How much rainfall is expected in the Desert Southwest?
Forecasters expect widespread rainfall totals of up to 3 inches across portions of the Desert Southwest, with isolated locations potentially seeing up to 5 inches.
What are the primary hazards in high-elevation areas?
Higher elevations in the Sierra and the Rockies could receive up to a foot of snow on isolated peaks, creating potential travel hazards as rain quickly changes to snow.
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