Hail Tile (GeoJSON) for Map Rendering
Return all hail grid cells within a Web Mercator tile that recorded hail in the requested time window.
Return all hail grid cells within a Web Mercator tile that recorded hail in the requested time window.
Optimized for live map rendering, returns results in milliseconds per tile.
Tile Coordinates
Standard Web Mercator (XYZ) tile scheme, same as MapLibre, Mapbox, and Leaflet. Request tiles at the zoom level appropriate for your viewport.
Response
GeoJSON FeatureCollection of Point features, one per grid cell (~1 km² at z≥10).
Returns empty features: [] for tiles with no hail, never a 404.
Properties per cell
| Field | Description | Use for |
|---|---|---|
max_hail_size_in | FLASH AI hail size estimate, inches | Tooltip label, "1.75 inch hail" |
raw_mrms_size_in | Radar-derived size before FLASH AI calibration | Debug / transparency |
coverage | Spatial coverage fraction 0–1 | Optional dot size / opacity |
duration_min | Peak event duration in minutes | Tooltip detail |
hail_index | 0.0–5.0 impact score | Map color ramp |
event_count | # events in window | Badge / timeline |
peak_start_time | Timestamp of peak event | Timeline scrubbing |
Recommended color mapping for hail_index
< 1.5→ transparent / gray (skip, sub-damage signal)1.5–2.9→ yellow (monitor)3.0–3.9→ orange (evaluate)≥ 4.0→ red (dispatch, confirmed damaging hail)
Archive Coverage
2021-05-01 to present (5-year rolling window).
Token-based authentication with required prefix "Token"
In: header
Query Parameters
Query window end, ISO-8601
Query window start, ISO-8601 (earliest: 2021-05-01T00:00:00)
Web Mercator tile column
Web Mercator tile row
Web Mercator zoom level (0–18)
Response Body
application/json
application/json
application/json
application/json
curl -X GET "https://example.com/lookback/hail/tile/?end=2023-05-31T23%3A59%3A59&start=2023-05-01T00%3A00%3A00&x=959&y=393&z=7"{ "type": "FeatureCollection", "features": [ { "type": "Feature", "geometry": { "type": "Point", "coordinates": [ -97.5164, 35.4676 ] }, "properties": { "max_hail_size_in": 1.75, "raw_mrms_size_in": 1.65, "coverage": 0.22, "duration_min": 48, "hail_index": 4.1, "event_count": 1, "peak_start_time": "2023-05-15T18:00:00+00:00" } }, { "type": "Feature", "geometry": { "type": "Point", "coordinates": [ -97.5056, 35.4586 ] }, "properties": { "max_hail_size_in": 1.25, "raw_mrms_size_in": 1.2, "coverage": 0.15, "duration_min": 30, "hail_index": 3.2, "event_count": 1, "peak_start_time": "2023-05-15T18:02:00+00:00" } }, { "type": "Feature", "geometry": { "type": "Point", "coordinates": [ -97.4948, 35.4496 ] }, "properties": { "max_hail_size_in": 0.75, "raw_mrms_size_in": 0.78, "coverage": 0.08, "duration_min": 18, "hail_index": 1.4, "event_count": 2, "peak_start_time": "2023-05-15T17:58:00+00:00" } } ]}