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Two neighbours on a quiet residential street comparing an emergency alert on their phones

Waypoint 2 of 4

Waypoint 2: How Alerts Reach You

You now know the language of warnings. At this stop we follow a single alert from the forecaster's desk to your pocket, your radio and your street — and learn why having more than one channel matters.

One message, many paths

When a warning is issued, the authority usually writes it once and sends it everywhere. The quiet hero here is the Common Alerting Protocol, or CAP — an open data format published by the standards body OASIS and also adopted by the International Telecommunication Union as Recommendation X.1303. CAP describes who issued an alert, the event, the area, the severity, urgency and certainty, and the instructions. Because it's a shared format, the same alert can feed phone networks, broadcasters, websites, apps and digital road signs without being retyped.

The World Meteorological Organization encourages national weather services to publish their warnings in CAP, which is one reason warnings now appear in so many places at once.

Cell broadcast: the loud buzz

Cell broadcast sends a message to every compatible phone connected to the mobile masts in an area. You don't need an app, a sign-up or even to share your number. That's why these alerts can arrive with a distinctive siren-like sound and vibration, sometimes even when your phone is on silent.

In the United States, Wireless Emergency Alerts have reached phones since 2012. The UK's Emergency Alerts service ran its first national test on 23 April 2023. In the European Union, the European Electronic Communications Code (Article 110) required member states to have a public warning system reaching mobile users by June 2022; many chose cell broadcast, often branded as EU-Alert.

A tip from the trail: check your phone's settings for an "emergency alerts" menu so you know which alerts you can and can't switch off. The most severe alerts are usually always on.

Radio and television

Broadcast is the old reliable. In the US, NOAA Weather Radio All Hazards transmits forecasts and warnings around the clock. Compatible receivers use Specific Area Message Encoding (SAME) codes, so a radio set to your county can stay silent until a warning for your area switches it on. Broadcasters also carry alerts through the Emergency Alert System.

Elsewhere, national broadcasters interrupt programmes or run on-screen tickers during severe weather. A battery or hand-crank radio keeps you connected when power and mobile networks fail — which is exactly when storms tend to test them.

Sirens, apps and neighbours

Outdoor sirens are designed to tell people outside to go in and find out more; they are not meant to be heard inside every building. Many towns test them on a set schedule, so learn your local test day and what a real activation sounds like.

Apps — official weather service apps and well-built third-party ones — offer detail and maps, but they depend on data, battery and your notification settings. Then there's the oldest channel of all: people. A neighbour knocking on the door still saves lives, particularly for older residents or anyone without a smartphone.

Build your layered set

No single channel is perfect, so experienced walkers carry a layered set:

  1. A phone with emergency alerts enabled.
  2. Your national weather service's official app or website bookmarked.
  3. A battery or hand-crank radio, with spare batteries.
  4. Knowledge of your local siren and its test schedule.
  5. A neighbour or friend you'll check on — and who'll check on you.

If one path goes quiet, another will still reach you. That redundancy is the whole lesson of this waypoint.