The system began operation in April, and it has had its hiccups. One problem is that the area warned has tended to exceed the area endangered, said NOAA's John Ferree, a warning specialist in Norman, Okla.
He said that's a function of the location of cell towers. The warning signals are being beeped out a bit too expansively.
"The problem is known, and the problem is being worked on," he said tonight.
Ideally, the CMAS system should target the endangered. However, today's alert swamped cellphones across the region.
Fans of the phillyinquirer Facebook page reported that they had received the alert even in areas where the sun was still shining and there hadn't been a drop of rain.
"What's this all about?" said one fan adding she "didn't sign up for any service."
On Twitter, a follower of the @phillyinquirer account said she had received the alert via AT&T.
"I'm more freaked out about the fact that my phone knows where I am enough to warn me," she tweeted.
Flash flood warnings were issued at 5 p.m. for much of Philadelphia and southeastern Montgomery County noting that the scattered storms - which have already drenched some areas with up to two inches of rain - could drop an addition 1 to 2 inches before 9:15 p.m.
Among the towns and muncipalities under the flash flood warning include:
Conshohocken, Jenkintown, Narberth, Philadelphia, Rockledge, Germantown, Center City, Chestnut Hill, Holmesberg, Kensington, Morris Park, Northeast Philadelphia, Roxborough, Tacony and Wissinoming.
In a March presentation, Ferree predicted that with the new system, "There will be growing pains."
Today, he said, provided verification of that prediction.
Contact the Online News Desk at 215-854-2443 or email@example.com
Follow the Inquirer at www.Twitter.com/PhillyInquirer and www.Facebook.com/PhillyInquirer