It is the first test of the national wireless emergency system by FEMA. The message will be broadcast by cell towers for 30 minutes, so it’s possible some people may get it at a different time. The alerts will sound as long as the device is turned on — even if it’s on mute or do not disturb, and it may also appear on smart watches, officials said.

Tyler Esh with Eau Claire County Emergency Management told News 18 this alert is only used if the American people are in danger – like a nuclear threat or an act of terrorism. The alert will not be used for severe weather.

News 18 Chief Meteorologist Nick Grunseth said severe weather is a possibility Wednesday afternoon, so it is important to keep your eyes open for other alerts that may come out – like thunderstorm or tornado information if it is needed.

Esh added the timing for this test is not ideal with the possibility of severe weather at the same time. He said the test was supposed to be a couple of weeks ago, but it was delayed because of Hurricane Florence.

A second alert on television broadcast and radio will go off at 1:20 p.m. CDT. The TV and radio alert has been tested for several years.

The system test is for a high-level “presidential” alert that would be used only in a nationwide emergency. It is being completed in coordination with the Federal Communications Commission. FEMA officials said Tuesday they would share test result data on how the testing went with mobile carriers to help ensure the system works well in a true emergency.

Phones with mobile carriers that participate in the wireless emergency alert system, which sends out information on hazardous weather, or missing children, will get the alert. FEMA officials estimate it will reach about 75 percent of all mobile phones in the country, including phones on all of the major carriers.

The wireless alert system launched in 2012. While users can opt out of messages on missing children and natural disasters, they can’t opt out of the presidential alerts, which are issued at the direction of the White House and activated by FEMA.

FEMA officials said the administration can only send such an alert for national emergencies or if the public were in peril, rules outlined in a 2006 law, and they say it can’t be used for any sort of personal message from the president.

A group of New Yorkers filed a lawsuit in federal court in New York arguing they should not be compelled to receive the alerts under their right to free speech.