About 7 million under flood watches from California to Colorado: up to 3 inches of rain, 5 in spots

About 7 million people across the Four Corners and California are under flood watches on Thursday, according to The Weather Channel, as a late-season surge of tropical moisture moves through seven states from California to Colorado. The National Weather Service (NWS) has active flood watches from Bakersfield to southwest Colorado, and Phoenix is under a watch through 5 PM Arizona time today. The population figure is The Weather Channel's; the watch areas below are from the NWS products themselves.

Where the watches are, and until when

• Arizona: the entire Phoenix metro, plus Tucson-area Pinal County and the Safford and Clifton area. The Phoenix and Pinal watches run through this afternoon or evening. Flagstaff's watch covers all of northern and central Arizona through Thursday evening.
• Utah: much of southern Utah, including Zion, Bryce Canyon, Capitol Reef and Lake Powell. NWS Salt Lake City says local totals above 3 inches are expected. Watches run into Thursday night.
• New Mexico: western and north-central parts, including Farmington and Gallup, through late tonight. NWS Albuquerque expects 0.25 to 1 inch, with locally up to 3 inches, and rates above 1 inch an hour in fast-moving storms. A watch for the Mimbres Valley and Gila foothills in the southwest runs until early Friday.
• Colorado: the San Juan Mountains and the Four Corners. NWS Grand Junction runs its watch through Friday around midday; NWS Pueblo's, covering the eastern San Juans and upper Rio Grande valley, runs to Friday afternoon.
• California: Bakersfield and the southern San Joaquin Valley, the Tehachapi area and Highway 58 near the Borel burn scar, through this evening. Los Angeles-area watches for the Malibu coast and Santa Monica Mountains, and Santa Barbara County, end Thursday afternoon or evening.
• Nevada and northwest Arizona: NWS Las Vegas has a watch for the Northwest Plateau through tonight.

How much rain

The Weather Channel puts the storm at up to 3 inches across parts of the Desert Southwest, with isolated spots up to 5 inches, and says forecast models show near-record October moisture, so totals could exceed forecasts. The NWS Phoenix and Tucson offices warn of rainfall rates of 1 to 2 inches an hour in stronger storms. Flash flood risk is highest in dry washes, slot canyons and recent burn scars.

The system has also produced severe weather. The Weather Channel reports 1.75-inch hail in downtown Flagstaff, a 72 mph gust at Flagstaff airport, and northern Arizona's first tornado watch in more than 16 years, issued Wednesday. At higher elevations the rain may change to snow; parts of the Sierra and Rockies could see their first significant snowfall of the season, with most totals under 6 inches.

Flights and driving

The FAA's airport status page showed a ground delay program at Phoenix Sky Harbor for thunderstorms at about 11 AM ET, averaging 40 minutes and peaking at 1 hour 24 minutes. We did not see storm-related closures at other Southwest hubs at that time. Conditions change by the hour, so check your airline's app before leaving for the airport, and expect knock-on delays for flights routed through Phoenix.

On the road, the NWS flags low-water crossings as a flood risk in several of the watch areas. Do not drive through flooded roads. In the mountains, expect closures or slick conditions where rain turns to snow, and note that backcountry roads in southern Utah may become impassable.

The money angle

• Insurance: FEMA's FloodSmart says most homeowners insurance does not cover flood damage; flood coverage is a separate policy. Check what you hold before the water arrives, not after.
• Documentation: photograph your property and inventory contents now if you are in a watch area, and move vehicles and equipment away from washes.
• Small businesses: contractors, landscapers and tour operators in the watch areas should expect lost days. National park trips to Zion and Bryce Canyon are the most exposed to cancellations, because slot canyons are off limits in flood conditions.

What a flood watch means

A watch means flooding is possible, not that it is happening. A warning means flooding is occurring or imminent. NWS asks people in watch areas to monitor later forecasts and be ready to act if warnings are issued. Current alerts are on weather.gov.

Sources: National Weather Service flood watch bulletins from the Phoenix, Tucson, Flagstaff, Las Vegas, Salt Lake City, Albuquerque, El Paso, Grand Junction, Pueblo, Hanford and Los Angeles offices; FAA National Airspace System status; The Weather Channel; FloodSmart.gov. Watch times were read the morning of October 22 and may have changed.