Get nearest RAOB radiosonde soundings.

Returns the N nearest RAOB (radiosonde) vertical soundings to a point, deduplicated to the latest sounding per station, sorted by distance. Soundings are launched at 00Z/12Z, so data can be several hours old.

Each feature carries:

• profile — the pressure-indexed thermodynamic sounding (mandatory
  • significant-temperature levels merged, sorted surface-first) with aligned arrays pressure_hpa, height_m (null at significant-temperature-only levels), temperature_c, dewpoint_c, wind_dir, wind_speed_kt, plus level_count.
• wind_profile — a height-indexed wind sounding (mandatory + significant-wind levels, sorted ascending by height MSL) with aligned arrays height_m, wind_dir, wind_speed_kt, plus wind_level_count. Use this for hodographs and shear.
• derived — server-computed thermodynamic/kinematic indices (metric-raw, every field nullable): sbcape/sbcin, mucape/mucin, mlcape/mlcin (J/kg); lifted_index, k_index, total_totals (°C); pwat_mm; freezing_level_m; lcl_*/lfc_*/el_* pressure and height; bulk_shear_0_6km_kt.
• station metadata: station_id, observed_at, elevation_m.

The full properties bag is forward-compatible: the data pipeline may add keys without a sw-api release, so treat unknown keys as opaque.

Pass one location: lat and lon, zip, or location. A request without one returns 400; a ZIP or name that does not resolve returns 404; while location lookup is unavailable, a zip or location request returns 503 with Retry-After.

A point outside the 50 US states and DC returns 404 outside-coverage with next_steps.