As more households disconnect landline telephones and fewer families have access to broadcast television and radio, emergency managers have increasingly focused on wireless emergency notifications to instantly reach large numbers of people. But that modern system has its own limitations, relying on the resilience of cell networks and the proficiency of emergency crews across a patchwork of local agencies.

The patchwork nature of the system was made evident again last week, as Hurricane Idalia was barreling toward the Florida coast. As 30 counties announced various evacuation orders, some local agencies pushed them out via wireless alerts on the federal network, but many did not.

Unlike television, radio, road signs or social media, emergency managers can use wireless alerts to target specific neighborhoods with an alarm that can wake someone from sleep or jar them to attention.

Jeannette Sutton, a professor at the University of Albany who specializes in disaster warning alerts, said the system can be messy. There is little guidance for agencies on how to formulate the alerts, so they can sometimes go out with missing information or confusing instructions. They are often left to be sent by emergency personnel who are busy trying to fight fires or control floods.