firestorm-potential-data

NWCG 7-Day Significant Fire Potential mirror for FIRESTORM.

Fetches every 3h from fsapps.nwcg.gov/psp/arcgis/rest/services/npsg/outlooks_forecast/MapServer, server-side geometry-simplified (maxAllowableOffset=0.05° ≈ 5 km, invisible loss at national scale), and publishes a slim data/potential.json for the FIRESTORM frontend to consume via raw.githubusercontent.com.

Why the bridge

The NWCG endpoint responds with ~30 MB of native GeoJSON per day and routinely returns HTTP 400 or times out beyond 25s. Under the old frontend-direct path (FIRESTORM fetchFirePotential at AbortSignal.timeout(30000)), timeouts caught silently and the map painted "NO OUTLOOK ISSUED · DAY 1" while the country actually had 18 CRITICAL zones + 1 IGNITION on Day 1 and 22 IGNITION zones on Day 5 (verified 2026-07-10).

Server-side decimation preserves 100% of the features (234 total / 213 valid / CRITICAL + IGNITION counts identical to native) and cuts payload to ~150 KB per day. Combined all-7-day file lands at ~1 MB, cold-start ~200 ms on any network path.

What's in data/potential.json

{
  "generated_at": "2026-07-10T17:36:32Z",
  "source": "fsapps.nwcg.gov/psp/arcgis/rest/services/npsg/outlooks_forecast/MapServer",
  "resolution_deg": 0.05,
  "counts": {
    "total_features": 1383,
    "valid_features": 1278,
    "critical": 28,
    "ignition": 36,
    "by_day": {
      "1": {"total":234,"valid":213,"critical":18,"ignition":1},
      // ...
      "7": {"total":213,"valid":213,"critical":0,"ignition":0}
    }
  },
  "day_source": { "1":"fresh", "2":"fresh", ..., "7":"fresh" },
  "days": {
    "1": [
      { "attrs":{"drynesscode":2,"type":null,"isvalid":1,
                 "gacc":"California North Ops","gacc_name":"California North Ops",
                 "nat_code":"NC03B","timestampdate":1783641600000},
        "rings":[[[lng,lat], ...], ...] },
      // ...
    ],
    "2": [...], ..., "7": [...]
  },
  "attribution": "NWCG Predictive Services · Significant Fire Potential Outlook · public domain"
}

day_source["N"] == "stale-carryover" means the fresh fetch for that day failed (NWCG intermittent 400) and the file is holding yesterday's outlook for that day. The overall file's generated_at still reflects the latest run; the frontend should badge stale-carryover days honestly.

Resilience

• Per-day retries with exponential backoff (4/8/16/32 s).
• Inter-day 3 s delay — NWCG returns 400 under back-to-back parallel geometry-simplified queries even at modest payload sizes.
• Per-day carryover — one day failing = keep yesterday's data for that day. All 7 days failing on a cold start = keep the whole prior file.

Field-name gotcha

The NWCG NPSG field for coordination center is gacc_name, NOT gacc. The pre-pipeline FIRESTORM code was passing outFields=gacc; NWCG accepts the invalid outField without error but omits it from features. fetch_potential.py uses gacc_name and emits BOTH gacc and gacc_name in the slim JSON so any frontend that read the old field continues to work.

No API key. Public domain.

NWCG NPSG is a .gov public service, no auth, no egress charge. Data is US Federal Government public domain (NIFC Predictive Services product).

Companion pipelines

Same architecture pattern as firestorm-lightning-data, firestorm-goes-fire-data, firestorm-ngfs-data, firestorm-cameras, firestorm-wind-data, firestorm-hrrr-data, firestorm-aircraft-data, firestorm-satellite-data, firestorm-aqi-data, firestorm-news-data, firestorm-imsr-data, firestorm-cams-aerosol-data.