Severe Alerts

What it shows

Every active alert issued by the US National Weather Service — warnings, watches AND advisories — painted over the map as shaded areas. A warning means the hazard is happening or imminent (take action); a watch means conditions are favourable (be prepared); an advisory means the event is expected to be a hazard-with-caution rather than a threat to life. Short-fuse warnings arrive with their own storm-drawn polygon; the majority of alerts are issued for predefined forecast zones, counties and marine areas, and the layer resolves those zone codes to their real official boundaries so the whole national alert set paints — not just the storm polygons. Coverage is the United States and its territories (the NWS feed); more regions are planned, and the scope is stated on the map.

How to read it

The shading is the NWS’s own severity field, in the map’s semantic alert colours: Extreme paints red, Severe paints amber, Moderate paints blue, Minor paints grey — red on this layer only ever means danger. Tap any shaded area for the full alert: the event name, the exact area, the official instructions and when it expires. Stack it with the rain radar to watch warnings track with the storms that triggered them, or with Storm Energy (CAPE) to see the fuel behind a watch. Alerts refresh on a minutes cadence; when an alert cannot yet be resolved to a shape, the readout counts it honestly ("mapped N of M") rather than inventing a boundary.

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