Arizona Desert Floods Unleash Killer Currents

A flash flood warning was issued by the National Weather Service in Tucson at 4:53 p.m. MST on Monday, August 17. The warning specifically targeted northeastern Pima County in southeastern Arizona and was set to remain in effect until 8 p.m. MST. Meteorologists indicated that Doppler radar detected thunderstorms generating significant rainfall across the warned region, with accumulations between 0.8 and 1.3 inches reported.

This heavy rainfall led to ongoing flash flooding or the imminent threat of it. The impacts included flooding of small creeks and streams, urban areas, highways, streets, and underpasses, as well as other poorly drained and low-lying locations. Redington Road north of Redington was identified as one specific area that would experience flash flooding.

Arizona's desert terrain is inherently prone to flash floods, which are defined by the weather service as floods caused by excessive rainfall over a short period, typically under six hours. These events can develop rapidly and violently. The article emphasizes that even distant rainfall can cause dangerous flows in dry riverbeds miles away, and that desert soils have a limited capacity to absorb water, especially after dry spells, leading to increased runoff. Topography, such as canyons and dry washes, along with areas impacted by wildfires, further exacerbates the risk.

The National Weather Service distinguishes between a flash flood watch, which signals favorable conditions for flooding, and a flash flood warning, indicating that flooding is already occurring or is about to happen. During a flood watch, residents are advised to monitor forecasts, plan evacuation routes, and move vehicles from low-lying areas. A warning signifies a more urgent threat.