Map Active NWS Warnings from GeoJSON

An active-warning map is more than a collection of colored polygons. Some NWS alerts include geometry, others identify zones or counties, and every feature has timing and message status that affects whether it belongs in the current view. The NWS Weather Alerts Scraper preserves geometry and geocodes alongside the human-readable alert.

Build a fallback hierarchy

First render valid GeoJSON geometry. When geometry is null, resolve official geocodes against a maintained zone or county boundary layer. Use affected-area text only as a final, visibly less precise fallback. Do not invent a point at a state's center, because that can imply false geographic accuracy.

{"areaCodes":["TX"],"maxResultsPerArea":100}

Use alert ID as the feature key. On each refresh, update headline, event, severity, urgency, onset, expiry, instruction, and geometry. Style primarily by event family and severity, but provide filters rather than hiding lower-severity messages. A legend should explain that warning, watch, advisory, and statement are different official products.

Time handling deserves explicit tests. Parse timestamps with their offsets, compare them in UTC, and display local time only at the interface layer. Keep expired records in an archive while removing them from the active layer. If a run fails or becomes stale, show the last successful update time and a warning instead of presenting an old map as current. Link every popup back to the official message and remind users that the map supports awareness; official NWS and local emergency instructions remain authoritative.