Monsoonal moisture sweeping across the Southwest triggered a series of severe-thunderstorm and flash-flood warnings in Arizona on 15 July. The U.S. National Weather Service placed Coconino and Navajo counties under successive warnings from 3:00 p.m. to 4:15 p.m. MST, citing wind gusts of up to 60 mph and hail roughly the size of half dollars. Advisories later expanded to Pima, Pinal, Cochise, Gila and Santa Cruz counties, covering the Tucson metropolitan area and outlying communities such as Jakes Corner and Chevelon Canyon Lake. Repeated cloudbursts quickly saturated normally dry washes. Flash-flood warnings were issued for Wildcat Canyon, Chevelon Canyon and urban areas around Oro Valley, Vail and Nogales, where forecasters urged residents to move to higher ground and avoid low-water crossings. Local stream gauges indicated water rising well above bankfull in parts of southern Navajo County, and social-media images from Nogales, Sonora showed vehicles partially submerged on city streets. The same storm system pushed deep into central Mexico. In Mexico City, late-afternoon downpours flooded stretches of Calzada Ignacio Zaragoza, Eje 6 Sur and adjoining avenues, snarling traffic in the Iztapalapa borough. The city’s Civil Protection agency raised an Orange Alert for eight boroughs, warning of additional flash floods and possible hail. Saturated soil toppled a 15-metre tree in the Benito Juárez district, damaging two parked vehicles; no injuries were reported. The mid-July outbreak follows an earlier round of monsoon storms on 3 July that prompted similar warnings in southern Arizona. Forecasters expect the seasonal pattern to persist through the week and advise motorists to check road conditions, replace worn windshield wipers and never drive through standing water.