Imagine a dust storm, driven by monsoon downbursts, building near the Maricopa-Pinal county line. There are thousands of Interstate 10 motorists and hundreds of thousands of Phoenix exurb residents who would probably want to know about such a storm before the stinging, blinding wall of sand arrives. But does all of metro Phoenix need to get the alert? Likely not, but the National Weather Service’s Ken Waters told the dozens of attendees at the annual dust-storm workshop in Coolidge last week that that’s exactly what would happen with the existing cellphone warning system in place for dust events. “If I’m...