It's just a test, but officials worry it won't seem that way.
If all goes according to plan, at 2:00 p.m. viewers will see and hear a 45 second test alert.
The problem is, no one knows if it will go according to plan, because it's never been done quite like this.
For almost 15 years, the federal government has maintained a nationwide alert system. However in all that time, the system was never tested.
The alerts most people are used to seeing are local ones
"What happen was in June, at a regular meeting they do at the FCC, FEMA and Homeland Security thought it was time to find out if it actually works," said Hank Volpe, Chief Engineer with Action News.
Tomorrow afternoon, the White House will initiate a nationwide test.
Originally, it was to be 3 minutes long with President Obama himself making an appearance.
Now bowing to concerns it may cause undue panic, the message will be shorter, and be read by someone else.
For days, the government has kept people informed through Public Service Announcements.
The reason for the concern is the uncertainty of what viewers will actually see if it doesn't work the way it should.
Here at Action News we'll broadcast the alert, but cable customers will see something else, covering our message with theirs.
Anticipating some concern, police in Boston have added staff to field additional 911 calls however Philadelphia Police say they have no such plans.
The bottom line is what you see at 2:00 p.m. tomorrow is no cause for panic. It is just a test, and there is no need to worry.