Flood Watches are in effect across Arizona, Utah, New Mexico and Colorado from late tonight through Friday, as a surge of tropical moisture brings repeated rounds of heavy rain.
A strong Pacific storm system is driving the moisture north.
Flash flooding is possible in creeks, dry washes and recently burned areas.
Several NWS offices also warn of severe thunderstorms.
Northern and Central Arizona
NWS Flagstaff has a Flood Watch for all of northern and central Arizona.
It runs late tonight through Thursday evening.
Showers and thunderstorms develop early Wednesday morning and continue through Thursday evening.
Flash flooding is possible in creeks, normally dry washes, swimming holes and recently burned areas.
Low-water crossings may be flooded.
Cities include Flagstaff, Prescott, Sedona, Cottonwood, Camp Verde, Payson, Show Low, Winslow, Holbrook, Page, Tuba City, Kayenta, Chinle and Window Rock.
It also covers the Grand Canyon, Williams, Fredonia, Springerville and Pinetop-Lakeside.
NWS Las Vegas has a Flood Watch for the Northwest Plateau in Mohave County, from late tonight through Thursday afternoon.
Phoenix Area and South Central Arizona
NWS Phoenix has two Flood Watches.
Phoenix metro: Wednesday evening through Thursday afternoon.
The watch covers Phoenix, Scottsdale, Tempe, Chandler, Mesa, Gilbert, Glendale, Peoria, Surprise, Goodyear, Avondale, Queen Creek and Apache Junction.
Mountains and Gila County: Wednesday morning through Thursday evening.
The watch covers Globe, Miami, Superior, San Carlos, Hayden, Tonto Basin and the Superstition Mountains.
Rainfall rates could reach 1 to 2 inches per hour at times.
NWS Phoenix also warns of isolated strong to severe storms, with damaging winds and large hail.
The chance of an isolated tornado is below 5 percent.
Southeast Arizona
NWS Tucson has three Flood Watches for southeast Arizona.
Southeast Pinal County (Mammoth and Oracle) and the Upper Gila River Valley (Safford, Clifton and Mount Graham) run from late Wednesday morning through Thursday evening.
South Central Pinal County runs from Wednesday evening through Thursday afternoon.
Thursday has the higher chance of rainfall rates of 1 to 2 inches per hour.
Southern Utah
NWS Salt Lake City has a Flood Watch from Wednesday morning through Thursday evening.
A late-season surge of tropical moisture brings moderate to heavy rain.
Local totals above 3 inches are expected through Thursday evening.
The watch covers Zion National Park, Bryce Canyon Country, Capitol Reef, Lake Powell, St. George, Kanab, Hurricane, Ivins, Panguitch and Springdale.
Dry washes, slot canyons and burn scars are at risk.
Backcountry roads may become impassable, so carry an alternate route.
Southwest Colorado and Southeast Utah
NWS Grand Junction has a Flood Watch from Wednesday afternoon through Friday morning.
Strong thunderstorms could develop Wednesday afternoon.
Widespread moderate to heavy rain follows from Wednesday night through Friday morning.
The watch covers Durango, Cortez, Pagosa Springs, Silverton, Mancos, Bayfield and Ignacio in Colorado.
In Utah it covers Moab, Monticello, Blanding, Bluff, Mexican Hat and Monument Valley.
Storm drains and ditches may become clogged with debris.
New Mexico
NWS Albuquerque has a Flood Watch from Wednesday afternoon through late Thursday night.
It covers western, central and north-central New Mexico, mainly along and west of the Continental Divide.
Fast-moving thunderstorms can pass over the same areas repeatedly.
Recent burn scars may see flash flooding, and minor river flooding is possible.
Areas include the Chuska Mountains, the Tusas Mountains including Chama, and the San Francisco River Valley.
How to Stay Safe
A Flood Watch means flooding is possible.
Have a way to receive Flash Flood Warnings and be ready to act.
Avoid washes, slot canyons and low-water crossings.
Never drive through flooded roads.
Hikers and backcountry travelers should check the forecast and plan a second route.
Local forecasts and alerts: NWS Flagstaff and NWS Phoenix.
For more, see the NWS Flood Safety guide.
