The National Weather Service issued a dust storm alert on Saturday, July 11, for Maricopa, Pima and Pinal counties in Arizona. The warnings covered Interstate 10, Interstate 8, Route 85, Route 86 and Route 87, with visibility falling to less than a quarter mile in some areas.
By 8 p.m. MST, the weather service said a wall of dust stretched from 15 miles northwest of Santa Rosa to 10 miles southwest of Sells and was moving west at 25 mph. Its warning for northwestern Pima County ran until 10 p.m. MST, while the warning for southwestern Pinal County was set to expire at 9 p.m. MST and the Maricopa County and Pinal County warning at 8:30 p.m. MST.
Interstate 10 and Route 87
The National Weather Service in Tucson tied the Maricopa County and Pinal County warning to Interstate 10 between mile markers 186 and 204, Interstate 8 between mile markers 137 and 178, and Route 87 between mile markers 125 and 130. It also listed Casa Grande, Maricopa, Arizona City, La Palma, Toltec, Big Horn, Kaka, Freeman, Arizola, Randolph, Stanfield, Ak- Chin Village and East Chui-Chu in the affected area.
For southwestern Pinal County, the service said an area of blowing dust was near Eloy at 7:33 p.m. MST and extended west across the southwest portions of the county. That warning covered Route 87 between mile markers 116 and 124 and Interstate 10 between mile markers 205 and 218, along with the northern portions of the Tohono O'odham Nation and places including Eloy, Picacho, Chui-Chu, Picacho Peak State Park, Cockleburr, North Komelik, Kohatk, Jack Rabbit, Shopishk and East Chui-Chu.
Northwestern Pima County
At 8:09 p.m. MST, the weather service issued the northwestern Pima County warning until 10 p.m. MST. That area included Ajo, Pisinemo, GuVo, Hickiwan, Organ Pipe Cactus National Monument, Covered Wells, Gu Oidak, San Simon, Why, Cowlic, Gunsight, Charco 27, Ventana, Pia Oik, Vaya Chin, Santa Cruz, Mountain Village, San Simon West, KuKatch and Kupk, plus Route 85 between mile markers 34 and 76 and Route 86 between mile markers 53 and 101.
The service warned that dust storms lead to dangerous driving conditions with visibility reduced to near zero, and it told drivers to avoid them if possible. For anyone caught in one, the instruction was direct: pull off the road, turn off the lights and keep the foot off the brake.
The hardest part for drivers was the speed of the change. A wall of dust was moving west at 30 mph at 7:32 p.m. MST near Randolph, Arizola and Chui-Chu, then another dust area was already near Eloy a minute later. For anyone on those corridors, the useful window was short, and the route-specific warnings set the cutoff times for when conditions were expected to ease.
