The multistate storm's combination of heavy snow, treacherous ice and subzero temperatures shows why it's best to seek out forecasters who can explain its nuances via local TV or radio newscasts, online livestreams or detailed websites, said meteorologists interviewed by The Associated Press. The data is changing rapidly before and during the storm, and the distance of a few miles can mean the difference between snow, sleet or dangerous freezing rain.

"Weather apps are really bad at storms that have multiple types of precipitation and it really makes messaging hard," said University of Georgia meteorology professor Marshall Shepherd, a past president of the American Meteorological Society. "Apps don't understand the details of why snow, sleet or freezing rain happens."

University of Oklahoma meteorology professor Jason Furtado and other experts said humans are important in these cases, especially those with local expertise.

"For extreme weather events, it is especially important to know there are human forecasters interpreting the data and making the best localized forecasts for your area," Furtado said. "Unfortunately, many of the weather forecast apps use AI methods to either make the forecast or 'interpolate' from larger grids to your hometown, introducing the potential for significant errors."