Arizona monsoon storms expected into the weekend; flash flood watch in effect

Arizona’s monsoon storms will continue into the weekend according to the National Weather Service, with high chances of heavy rain for the Valley and many other parts of the state.

Most of Arizona, save for a small chunk in the southwest that includes Yuma, is still under a flash flood watch, which was extended until Friday at 5 a.m. Tom Frieders with NWS in Phoenix said the weather service is gauging daily how long the flash flood watch will last, and it's possible it could get another extension based on weather conditions.

“This pattern is kind of holding into early next week,” Frieders said. He also mentioned the storm patterns this weekend could produce extreme rainfall in the Valley.

From late morning to early afternoon Thursday, the weather service issued an increasing number of flash flood warnings for Central and Southern Arizona, a break from the standard earlier in the week of flash flood warnings primarily in Northern Arizona.

As of Thursday at 1:30 p.m., there are three different flash flood warnings southeast of Phoenix near Globe, which encompass Apache Junction and South Gila County, in effect until 4 p.m. There is also one including Rio Verde and Sunflower just north of Phoenix in effect until 5:30 p.m.

“Flash flooding is a significant risk with these storms as they are moving slowly; stay vigilant!” the weather service said in a tweet.

Flash flood warnings: Here's how to stay safe

The National Weather Service in Tucson also issued several flash flood warnings for areas in Southern Arizona, including northeastern Pima County and southeastern Pinal County until 3 p.m., West Central Graham County and East Central Pinal County until 2:30 p.m., and Southeastern Pima County until 2 p.m. and Central Pima County until 2:15 p.m.

Throughout the weekend, the weather service forecasts a 20-40% chance of rain for Phoenix daily, with the chances even higher for more elevated areas surrounding the city. And it won’t just be light showers.

Lightning strikes over the valley from a monsoon storm as seen from South Mountain Park and Preserve on July 16, 2022, in Phoenix.

“An abundance of moisture will allow any showers and storms that develop to produce heavy rainfall,” the weather service said in its forecast discussion.

According to the forecast, the chance of rain is fairly steady each day this weekend, although Frieders said Sunday has the potential for more widespread storm coverage. Frieders said spotty storms could still pose a significant risk for dangerous flooding, especially given how slowly they are moving.

“There’ll be that risk every day,” Frieders said.

Thunderstorms are predicted to continue through at least early next week.

The stormy weather is keeping the desert much cooler than it is on average, with high temperatures in the upper 90s and lows in the 100s in Phoenix over the weekend.

A tweet from the weather service in Phoenix said the city will usually see only about three days with highs under 100 degrees in July.

This July, temperatures are fairly consistent with that average, with Thursday being only the third day with a forecasted high of less than 100 degrees, according to Frieders.

Frieders said before this particular monsoon pattern, temperatures in Phoenix were above average.

I-10 road closure

With stormy weather carrying through the weekend, highway-goers should check for flash flood warnings before making the trip. This weekend, scheduled construction on the Interstate 10 Broadway Curve Improvement Project continues as it has for several weekends prior.

Crews will be working on the Broadway Road bridge, which will shut down westbound I-10 between U.S. 60 and State Route 143 from 10 p.m. Friday to 4 a.m. Monday, according to the Arizona Department of Transportation.

Ramps from westbound U.S. 60 and southbound S.R. 143 to westbound I-10 will also be closed during that period, along with westbound I-10 on-ramps from Elliot and Broadway roads.

Also in that same time frame, the westbound U.S. 60 on-ramps from McClintock Drive and Mill Avenue will be closed as well.

In Buckeye from 9 p.m. Friday to 5 a.m., westbound I-10 will also be narrowed to one lane between Verrado Way and Miller Road for a widening project.

Finally, State Route 24 between Loop 202 and Ellsworth Road will be closed in both directions from 5 a.m. Saturday to 6 p.m. Sunday.

Reach breaking news reporter Sam Burdette at or on Twitter @SuperSafetySam

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This article originally appeared on Arizona Republic: AZ monsoon storms expected this weekend; flash food watch in effect