- TV, AM, FM and cable systems must take part in the Emergency Alert System.
- Phone alerts come in four classes, including Imminent Threat and AMBER alerts.
- NOAA Weather Radio carries warnings around the clock.
When a blizzard warning, a flood or a missing child alert goes out in Massachusetts, it can reach you on the TV, the car radio and your phone within minutes. Those are three separate systems that work together. Knowing how each one works helps you decide which to rely on.
System 1: The Emergency Alert System on TV and radio
The Emergency Alert System, or EAS, is defined in the FCC’s rules at 47 CFR Part 11. Those rules list who must take part: AM, FM and low-power FM radio stations, TV stations including Class A and low-power TV, cable systems, satellite TV and satellite radio, among others. The FCC calls them EAS Participants.
Under the rules at 47 CFR 11.31, an EAS activation is a four-part message, which is why alerts on TV and radio sound alike: a preamble and coded header, an audio attention signal made of two tones played together, the message itself, which may be audio, video or text, and an end-of-message code. The FCC’s equipment table requires TV stations to carry video messages as well as audio. You do not need to do anything to receive EAS alerts; they interrupt whatever station you are watching or hearing.
System 2: Wireless Emergency Alerts on your phone
Wireless Emergency Alerts, or WEA, are the messages that make phones sound a loud tone and vibrate. The National Weather Service describes them as emergency messages sent by authorized government alerting authorities through your mobile carrier, sent automatically to WEA-capable phones in the affected area. Partners include state and local public safety agencies, FEMA, the FCC and the Weather Service.
The FCC’s rules at 47 CFR 10.400 define the classes of alert carriers handle:
| Class | What it means |
|---|---|
| National Alert | Issued by the President, the President’s designee or the FEMA Administrator |
| Imminent Threat Alert | An urgent, severe and likely or observed threat to life or property |
| AMBER Alert | A child abduction meeting the Department of Justice’s criteria |
| Public Safety Message | An essential advisory that prescribes actions likely to save lives or safeguard property, issued alongside one of the other alerts |
Tip: Check your phone’s emergency alert settings once a year. Under 47 CFR 10.280, carriers may let you opt out of AMBER Alerts, Imminent Threat Alerts and Public Safety Messages, but the National Alert class is not on that list.
System 3: NOAA Weather Radio
NOAA Weather Radio broadcasts warnings, watches and forecasts 24 hours a day and, working with the EAS, carries non-weather emergencies too. Boston’s transmitter is KHB35 on 162.475 MHz. See Boston Weather and Storm Coverage: Where to Get Forecasts and Warnings for the nearby transmitters and how to set up a radio for your county.
Which one should you rely on?
| Situation | Most reliable |
|---|---|
| You are asleep at home | Weather radio with an alarm, or phone alerts |
| You are driving | Car radio (EAS) and phone alerts |
| Power and internet are out | Battery radio and NOAA Weather Radio |
| You want the full story after the alert | Local TV and radio newscasts |
The answer is usually more than one. An alert tells you something is happening; a local newscast tells you what to do about it. Boston’s news stations are listed in Boston TV Channels: Every Local Station You Can Get With an Antenna and Boston Radio Stations by Frequency: FM and AM Dial Guide.
What to do when an alert arrives
- Read or listen to the whole message; it says what is happening, where and what to do.
- Follow the instructions first and look for more information second.
- Check a trusted local source, such as a news station or the National Weather Service, for updates.
- Do not forward screenshots of alerts without checking that they are current.
Alerts are short by design. The fuller picture, which roads are closed, which towns are affected and when the danger ends, comes from local newscasts and the Weather Service. Keep one radio station and one TV or streaming source in mind so you know where to turn as soon as the alert ends.
Tests you will hear
Alert systems are tested from time to time. A test sounds like the real thing but says it is a test. If you hear an alert and are not sure whether it is real, tune to a local news station or check the National Weather Service before you act on rumors.
Children and older relatives may not know what the loud phone tone means. Take a minute to explain the sound, show them where alerts appear and agree on what the family will do, such as checking in by text and tuning to a local news station.
If you are deaf or hard of hearing
TV stations carry EAS alerts as video as well as audio, and the National Weather Service notes that phone alerts come with a unique sound and vibration. For watching TV news without cable, see How to Watch Boston Local News Without Cable.