Wet and wild: More severe weather expected in Arizona this week

Storm clouds approach downtown Phoenix from the southwest on Monday evening. (Photo by Jordan Evans/Cronkite News)

Story updated Tuesday at 3:20 p.m.

PHOENIX — A powerful storm system brought flooding and power outages to parts of metro Phoenix on Monday evening, and more severe weather could be on the way this week.

Flash flooding remains a concern; the National Weather Service has issued a flash flood watch for much of Arizona, including Maricopa County, starting Wednesday morning.

Coming on the heels of early morning storms that pounded the East Valley, severe thunderstorms moved over Phoenix during the evening rush hour Monday. The National Weather Service reported penny- to nickel-size hail north of downtown Phoenix and in Paradise Valley.

A severe thunderstorm over Cave Creek on Monday afternoon prompted the weather service to issue a tornado warning for the area. It was the Phoenix office’s first tornado warning in five years.

The intersection of Crismon and Baseline roads in Mesa was one of many roadways that flooded Monday morning in the East Valley. (Photo by Cassidy McCauley/Cronkite News)

High winds damaged this gas station canopy at Signal Butte Road and Apache Trail. The storm rolled through the East Valley overnight and into Monday. (Photo by Sarah Farrell/Cronkite News)

Water flows over the streets near Crismon and Baseline roads in east Mesa late Monday morning. Almost 2.5 inches of rain fell in the area. (Photo by Sarah Farrell/Cronkite News)

Vehicles splash through runoff at the intersection of Crismon and Baseline roads in Mesa, which was closed late Monday morning. (Photo by Cassidy McCauley/Cronkite News)

The City of Mesa Basin, which doubles as a recreation area, was severely flooded Monday. (Photo by Cassidy McCauley/Cronkite News)

Crews remove landscaping debris on East Southern Avenue in Mesa. It was a common scene Monday morning all around the East Valley. (Photo by Sarah Farrell/Cronkite News)

The City of Mesa Basin has some weather damage due to the storm early Monday. The baseball and soccer fields are completely flooded. (Photo by Cassidy McCauley/Cronkite News)

Water at Crismon and Baseline road in east Mesa stood more than 6 inches deep in some places. (Photo by Sarah Farrell/Cronkite News)

Heavy rains overnight and Monday in the East Valley caused severe flooding and prompted several rescue calls. (Photo by Cassidy McCauley/Cronkite News)

Mesa authorities closed the intersection of Crismon and Baseline roads about 11 a.m. – one of many road closures around the East Valley due to heavy rains early Monday. (Photo by Sarah Farrell/Cronkite News)

No games today. Soccer and baseball fields under water in the City of Mesa Basin. (Photo by Sarah Farrell/Cronkite News)

Crews push mud off Southern Avenue, which flooded from overflow at the City of Mesa Basin, which is a recreation area and floodwater retention basin. (Photo by Sarah Farrell/Cronkite News)

Erosion from flooding is evident at City of Mesa Basin. (Photo by Cassidy McCauley/Cronkite News)

Areas of east Mesa and Apache Junction received more than 2 inches of rain in just a few hours early Monday. Crews worked throughout the morning to close roads and clean up debris carried by the floodwaters. (Photo by Sarah Farrell/Cronkite News)

Videos of the possible twister surfaced on social media, and the National Weather Service confirmed Tuesday that a tornado did touch down in New River.

People posted photos showing walls of dust south of Phoenix. Visibility was reduced to less than a quarter of a mile along Interstate 10 from Casa Grande to Tucson.

Storms dropped more than 2 inches of rain in parts of Mesa and 3 inches in Apache Junction. Record amounts of rain fell in Scottsdale, north Phoenix and Surprise.

Mesa Fire & Medical rescued several stranded drivers in their vehicles, and the National Weather Service reported street flooding in parts of Mesa, Apache Junction and Fountain Hills.

The atmospheric setup

Ahead of Monday’s storm system, ample moisture from the remnants of tropical storms Lorena and Mario, which dissipated last weekend, fueled the atmosphere.

The atmospheric setup Monday was similar to two previous severe weather events over Arizona. In late September 2014, an intense line of thunderstorms moved through the Valley and central Arizona bringing high wind gusts near 70 mph that damaged some of the terminals at Phoenix Sky Harbor International Airport.

In early October 2010, Phoenix saw its largest hailstone ever, at 3 inches in diameter – nearly the size of a baseball. This was a rare event for Phoenix, as hail this big primarily occurs over the Great Plains. This was also the same storm system where multiple tornadoes touched down in the high country, including one that damaged homes in Bellemont.

What you need to know

Big hail and tornadoes are extremely rare in Arizona, but they aren’t out of the question for today. Have an action plan in case severe weather strikes.

If a thunderstorm is approaching, make sure you have a safe and sturdy structure to shelter in. The National Weather Service also recommends staying away from windows and avoiding corded electrical equipment. If you’re in a vehicle, safely drive to a sturdy structure for shelter.

Keep in contact with loved ones by creating a communication plan. Prepare your home by securing loose objects outside and closing doors and windows.

Have extra batteries and chargers for your cellphone ready, in case the power goes out. More safety tips about how to prepare for severe weather can be found here.

Most importantly, do not drive into flooded roadways. It only takes 12 inches of water to float compact vehicles.

Sustainability Reporter, Phoenix
Sports Photographer, Phoenix
Sports Reporter, Phoenix