A widespread Flood Watch covers much of Arizona and Utah as tropical moisture from the eastern Pacific combines with an approaching storm system, raising the risk of flash flooding through Tuesday night.
National Weather Service offices in Flagstaff, Phoenix, Tucson, Las Vegas, Salt Lake City and Grand Junction have all issued watches tied to the same moisture surge, which forecasters say could bring rainfall rates of 1 to 2 inches per hour in the heaviest storms.
Northern and Central Arizona
NWS Flagstaff has a Flood Watch in effect from Sunday evening through Tuesday evening for all of northern and central Arizona.
The watch covers the Grand Canyon Country, the Kaibab Plateau, Marble and Glen Canyons, the Coconino Plateau, the Mogollon Rim, the White Mountains and the Little Colorado River Valley.
Cities in the watch include Flagstaff, Page, Window Rock, Tuba City, Winslow, Sedona, Payson, Williams, Prescott, Show Low, Pinetop-Lakeside, Springerville, St. Johns, Chinle, Kayenta and Grand Canyon Village.
Forecasters say low pressure interacting with tropical moisture could produce numerous showers and embedded thunderstorms, with heavy rain falling on already saturated soils and burn scars.
That combination raises the risk of localized flash flooding and rises on rivers such as the Little Colorado.
Northwest Arizona
NWS Las Vegas has issued two separate watches for northwest Arizona. The first covers Lake Havasu, Fort Mohave and the Arizona sides of Lake Mead and Lake Mohave from early Monday through early Tuesday morning, including Lake Havasu City and Bullhead City.
A second watch covers the Hualapai Mountains and the Northwest Plateau and Deserts from late tonight through Tuesday evening, including Kingman, Colorado City, Valentine, Dolan Springs and Wikieup. Showers and thunderstorms capable of producing flash flooding are expected in both areas.
South Central and Southeast Arizona
Farther south, NWS Phoenix has a watch in effect from late Monday night through Tuesday evening for south central Arizona, including Apache Junction, Fountain Hills, Cave Creek, Superior, Globe and Tonto Basin. Rainfall rates of 1 to 2 inches per hour are possible, with some areas seeing repeated rounds of storms.
NWS Tucson has a matching watch for southeast Arizona from Monday morning through Tuesday evening, covering the Tucson metro area, Sierra Vista, Nogales, Bisbee, Douglas, Willcox and the Chiricahua, Santa Rita and Huachuca mountains. Rainfall totals of 1 to 2 inches are expected, with locally heavier amounts under the strongest storms.
Southern and Central Utah
In Utah, NWS Salt Lake City has issued a Flood Watch from Monday morning through early Tuesday morning covering much of central and southern Utah. The watch includes the Central Mountains, Castle Country, the San Rafael Swell, Bryce Canyon Country, Capitol Reef National Park, Zion National Park and the Glen Canyon Recreation Area around Lake Powell.
Cities in the watch include St. George, Kanab, Springdale, Hurricane, Bryce Canyon City, Panguitch, Escalante and Green River. Forecasters warn that slot canyons, dry washes and recent burn scars, including Cottonwood, Monroe Canyon and Silver King, face the highest flooding risk.
Southeast Utah
NWS Grand Junction has extended its own Flood Watch into southeast Utah from Monday morning through late Tuesday night, covering the La Sal and Abajo Mountains and the Canyonlands/Natural Bridges area. Blanding, Monticello, Bluff and Mexican Hat, along with Canyonlands National Park, are all included.
Remnant moisture from Hurricane Polo is expected to fuel numerous showers and embedded thunderstorms, with heavy rain on saturated soils and burn scars raising the risk of flash flooding and rises on local rivers.
Safety Reminders
Residents in both states should avoid low-water crossings, slot canyons and dry washes during and after heavy rain, since flash floods can arrive with little warning.
Those living near burn scars or in flood-prone areas are urged to monitor later forecasts and be ready to act quickly if a Flood Warning is issued.
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