The most dangerous conditions are expected from approximately 3 p.m. through 10 p.m. local time. Forecasters warned that visibility could suddenly collapse to as little as one-quarter of a mile, creating especially dangerous conditions for motorists.
Dust storms can transform a clear roadway into a near-zero visibility environment within seconds. Drivers who see blowing dust approaching are being urged not to attempt to race through it.
“If you encounter blowing dust or blowing sand on the roadway or see it approaching, pull off the road as far as possible and put your vehicle in park. Turn the lights all the way off and keep [your] foot off the brake pedal. Remember, ‘Pull Aside, Stay Alive,’” the NWS advised in their alert.
But the approaching dust may pose concerns beyond dangerous driving conditions.
Arizona’s soil is known to contain Coccidioides, a microscopic fungus that can become airborne when strong winds disturb dry ground. People who breathe in the spores can develop Valley fever, an illness that primarily affects the lungs and can become severe in some cases.
Officials have not confirmed that the incoming dust storm will contain the fungus. However, the Centers for Disease Control and Prevention has identified Coccidioides as occurring throughout Arizona and other parts of the Southwest.
The National Weather Service also urged residents with respiratory concerns to take extra precautions.
“Persons with respiratory problems should make preparations to stay indoors until the storm passes. Be ready for a sudden drop in visibility to near zero,” the NWS warned in a statement.
Those with asthma, heart problems, and chronic respiratory conditions could face greater difficulties if heavy dust fills the air. Forecasters suggested avoiding unnecessary outdoor activity and keeping windows and doors shut while the storm moves through.
“Those most at risk may feel better if they avoid outside exercise today, keeping windows and doors closed to help reduce exposure,” the weather agency added.
For many people exposed to Coccidioides, the body’s immune system can prevent serious illness. Others may experience symptoms resembling the flu, including fever, coughing, and headaches.
In more serious cases, however, the infection can spread beyond the lungs and affect other parts of the body. Severe complications can involve the bones and organs and may become life-threatening.
The CDC has estimated that Coccidioides exposure is responsible for between 15% and 30% of pneumonia cases in the Phoenix and Tucson areas, underscoring the significance of the fungus in Arizona’s desert environment.
The powerful winds could also generate haboobs — massive walls of dust that can sweep across the landscape with little warning. These storms are particularly common when strong thunderstorm winds collide with extremely dry ground.
Arizona’s combination of prolonged drought, intense heat, and monsoon weather can create ideal conditions for powerful dust storms. When those winds disturb contaminated soil, fungal spores may also be carried through the air.
As if the dust threat were not enough, much of the same region remains under an extreme heat warning through Friday.
Temperatures and humidity could combine to push the heat index — commonly described as the “feels like” temperature — toward 110 degrees. High humidity can make conditions feel significantly hotter than the actual air temperature and place additional stress on the body.
“Overexposure can cause heat cramps and heat exhaustion to develop and, without intervention, can lead to heat stroke,” NWS said.
The brutal forecast is being driven by a massive heat dome stretching across much of the western United States. The powerful area of high pressure acts like a lid, trapping heat near the surface and preventing hotter air from escaping.
For Arizona residents, the result could be a punishing stretch of dangerous heat, violent winds, and potentially blinding walls of dust.
Residents in affected areas are being urged to monitor local weather alerts, avoid unnecessary travel when dust storms develop, and take additional precautions if they suffer from respiratory problems.
With extreme heat already gripping the region and powerful winds capable of turning Arizona’s dry landscape into a massive cloud of dust, conditions could deteriorate rapidly — leaving millions of residents facing a dangerous and unpredictable night.
