All of Arizona under a Flood Watch Wednesday

For Tucson residents, Wednesday’s statewide flood watch brought an unusual mix of conditions: the city was expected to stay mostly sunny and relatively dry, while the Tucson area remained within a broader zone where rainfall could still contribute to flash flooding. The National Weather Service placed the Tucson area in a 40 percent category for rain capable of producing flash flooding, alongside the Phoenix Valley and much of Gila County. That elevated concern came as storms were causing flooding, road closures and water rescues elsewhere in Arizona.

The greatest impacts Wednesday were reported in the Phoenix area, where showers and thunderstorms developed from late morning into the afternoon. A flash flood warning covered Maricopa County until 5 p.m., and a flood watch continued through 11 p.m. Forecasters said isolated locations in higher terrain could receive 1 to 2 inches of rain, while rainfall totals in the Valley could reach roughly one half-inch to one inch. The watch also extended into portions of La Paz and Yuma counties because storms could repeatedly form over the same locations.

That repeated storm pattern, known as training, was one of the main flooding concerns. In that setup, one shower or thunderstorm develops behind another over nearly the same area, allowing rainfall to accumulate quickly. The concern was particularly significant around Phoenix, where storms were expected to continue through the evening and potentially persist in parts of the Valley until about 2 a.m. Thursday. A storm system south of Phoenix was moving north through Casa Grande, adding to the potential for additional rain across central Arizona.

Tucson’s immediate forecast was considerably quieter. A few showers could linger before dawn, followed by mostly sunny conditions for much of the day. Daytime heating could produce a few very widely scattered thunderstorms in eastern Arizona near the New Mexico border, but the forecast called for only a limited chance of storms in the Tucson area. The expected high was near 91 degrees, with an east southeast wind around 6 mph becoming calm during the morning. Overnight skies were expected to remain mostly clear, with a low near 71 and light, variable winds.

Even with that relatively calm city forecast, the broader flood outlook matters for people traveling between Tucson and other parts of the state, especially toward central and southern Arizona. The storm activity around Casa Grande and Phoenix demonstrated how quickly conditions could change across short distances. The National Weather Service’s rainfall outlook placed Tucson in the same 40 percent flash flood potential category as the Phoenix Valley and much of Gila County. Forecasters also noted that the last time a moderate flood risk covered this general area was in 2022.

Rain cooled Phoenix temperatures after highs reached the mid-90s Wednesday afternoon. Conditions there were expected to become quieter overnight as drier air moved in Thursday, with temperatures again reaching the mid-90s. Overnight lows across the region were forecast to drop into the 70s over the next several days. In Tucson, the outlook similarly pointed toward improving nighttime comfort, with lows near 70 rather than the warmer, stickier conditions that had recently persisted.

For Tucson, the forecast then shifts toward a hotter and mostly dry stretch. Friday was expected to be sunny with a high near 96, followed by another sunny day Saturday with a similar high. Saturday night could fall to about 70, while Sunday night was expected to remain mostly clear with a low near 72. Monday was forecast to be mostly sunny and near 97 degrees. Only a 10 percent chance of showers and thunderstorms was listed for Tuesday and Wednesday, with both days otherwise expected to be sunny and reach about 97 degrees.

The immediate flood threat was therefore concentrated in storm-affected portions of central and western Arizona, but the statewide watch and the elevated outlook for Tucson underscored the need for residents to pay attention to changing conditions Wednesday. Flooding did occur around Phoenix, including road closures and water rescues, while Tucson was largely expected to avoid the day’s most active storms. By Thursday, the overall pattern was expected to dry out, although hotter temperatures were forecast to return, with Phoenix reaching triple digits from Friday through the weekend and into next week.