AZ Monsoon Update: Creek Flooding, Up To 8 Inches Of Rain

TUCSON, AZ — A potentially historic rain event is expected to arrive in Tucson on Thursday, dropping multiple inches of rain on the region over the next 48-72 hours, the National Weather Service said.

The storms are capable of dropping anywhere from two-to-five inches of rain in the city of Tucson itself, with upwards of eight inches of rain in the Catalina and Rincon mountains around the city, the service said.

The storms have prompted the service to issue a flash flood watch for all of Southern Arizona, from 6 p.m. Thursday through 11 p.m. Saturday, as the surge in moisture will have the potential to cause creeks and rivers to swell over their banks.

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Meteorologist Rob Howlett told members of the media on Thursday that the storms would bring levels of rainfall unseen in the region in the past decade.

"We're still looking at heavy rainfall across the area, and some potential flooding," Howlett said. "... There's a broad line of showers and thunderstorms that'll be pushing through the area, before moving out to the west overnight."

An area of emphasis is the Bighorn Fire burn scar area, on the north side of Mount Lemmon, where close to 120,000 acres burned during the summer of 2020.

Howlett said that the mountain region around the burn scar could see close to two inches of rain on Thursday alone, which could cause flows of debris to cascade down toward lower elevation areas.

He said that mountain areas could see two rounds of heavy rain on Thursday, with the first batch hitting around noon and another coming through closer to the midnight hour.

From there, mountain areas could be inundated with heavy rain on Friday and Saturday through the day, forcing already swollen creeks and rivers to surge past their banks, Howlett added.

Three areas that National Oceanic and Atmospheric Administration official Erin Boyle highlighted for potential flooding were Sabino Creek, the Santa Cruz River near Marana and Pantano Wash, near Vail.

Those three bodies of water could see extreme flooding, with Sabino Creek expected to surge to nearly five feet in depth, which would be almost double the flood stage of 3.1 feet.

Pantano Wash is expected to hit close to 8.5 feet on Sunday, which would be more than half a foot higher than the flood stage for the water source (7.7 feet).

The Santa Cruz, meanwhile, is expected to virtually match its flood stage, which is around 14 feet, on Saturday and Sunday, Boyle said.