# Rules and channels

> What an alert rule can match on, how a place and a channel combine their rules, and the channels an alert can reach you on.

Alerts and places · Reference · https://wxalerts.org/docs/alerts/rules-and-channels/

To set a rule up, see
[Add a saved place and reach more than one person](/docs/alerts/saved-places/).

## What a rule can watch

Rules match on the alert, not on the weather. Two axes:

- **Significance**, the VTEC letter: warnings, watches, advisories,
  statements. This is the axis the NWS asks people to read, and the one the
  map colours by.
- **Hazard**: tornado, severe thunderstorm, flash flood, hurricane, storm
  surge, blizzard, ice storm, high wind, excessive heat, fire weather and the
  rest of the VTEC phenomenon codes.

Both are needed because significance alone cannot separate a tornado warning
from a severe thunderstorm warning: both are significance W and differ only by
hazard code.

## How rules combine

A place carries one list of significances, which every channel on it inherits.
Any channel can then override it with a rule of its own. That is what lets a
single place call your phone for a tornado warning, text you for a
thunderstorm, and do nothing louder than a push notification for an advisory.

Leaving the hazard list empty means every hazard. An allow-list only ever
exists because somebody typed one, so a hazard nobody thought to list still
arrives rather than going quietly undelivered.

## Channels

| Channel | Available on | Notes |
| --- | --- | --- |
| Push | Every plan | The mobile apps, on the devices signed in to your account, or an iPhone's Home Screen ([without the app](/docs/alerts/iphone-without-the-app/)) |
| Email | Every plan | Any address you add and confirm |
| Webhook | Every plan | A signed POST to a public HTTPS address you control |
| Text message | Supporter: 100 a month, plus 50 per Top-up | Carrier messages cost real money per message, hence the plan |
| Phone call | Supporter: 20 a month, plus 5 per Top-up | Tornado Warnings never count against calls or texts |

Running out of a text allowance does not stop the alert. Push, email, webhooks
and calls carry on, free.

## Plan limits

How many places you can save, and how many people each one can notify, is what
a plan buys. See [pricing](/pricing/).