{
 "generated_utc": "2026-09-09T11:27:10Z",
 "gfs_cycle_utc": "2026-09-09T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 494.0,
  "output_interval_min": 30,
  "integration_step_s": 900,
  "wind_field_interval_h": 3
 },
 "staleness": {
  "fresh_seed_max_h": 24.0,
  "served_until_h": 336.0,
  "track_max_age_h": 72.0,
  "region_spread_deg": 60.0,
  "note": "A trajectory is served for 336 h after the last real fix and then the flight disappears. That matches the archive's own bridging limit: 23% of flights go quiet for over a week and are then heard again, so a shorter window drops balloons that are still flying. Past dead_reckoned flights the balloon has not been heard from since seed_time, so its present position is a prediction too -- the silent period is reconstructed from GFS analyses of weather that has already happened, which is why wind_source distinguishes analysis from forecast. Use display_as, not seed_age_h, to decide how to draw a flight: 'track' means the members still agree and a line is meaningful, 'region' means draw the member envelope instead because the nominal member is no better than any other."
 },
 "members": {
  "offsets_m": [
   -2000,
   -1500,
   -1000,
   -500,
   0,
   500,
   1000,
   1500,
   2000
  ],
  "nominal_offset_m": 0,
  "note": "Each member is seeded at the last observed altitude plus its offset and then conserves the density it started with. The ladder is a sensitivity fan, not a probability distribution: adjacent members diverge by roughly 1,200 km over seven days. levels_spanned reports how many GFS levels the fan actually straddles, usually 2 or 3."
 },
 "files": {
  "trajectories_csv_gz": "PBA_forecast_20260909_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260909_06Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 70128
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 283.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 05:45:00",
    "lat": -66.89047,
    "lon": 57.73593,
    "alt_m": 11971.1
   },
   "member_spread_deg": {
    "lat": 33.93,
    "lon": 271.73
   },
   "member_spread_now_deg": {
    "lat": 19.15,
    "lon": 191.16
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 10:10:49",
   "seed_lat": 42.77083,
   "seed_lon": -17.58333,
   "seed_alt_m": 14520.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 09:45:00",
    "lat": 36.53955,
    "lon": -9.05808,
    "alt_m": 14364.7
   },
   "member_spread_deg": {
    "lat": 20.18,
    "lon": 56.84
   },
   "member_spread_now_deg": {
    "lat": 0.46,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 04:41:00",
   "seed_lat": 86.0,
   "seed_lon": 110.20833,
   "seed_alt_m": 11660.0,
   "seed_age_h": 102.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 05:45:00",
    "lat": 76.69052,
    "lon": -107.39529,
    "alt_m": 11609.5
   },
   "member_spread_deg": {
    "lat": 29.72,
    "lon": 314.81
   },
   "member_spread_now_deg": {
    "lat": 23.67,
    "lon": 197.31
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 22:07:00",
   "seed_lat": 48.27083,
   "seed_lon": -99.75,
   "seed_alt_m": 13110.0,
   "seed_age_h": 13.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 34.52971,
    "lon": -33.83258,
    "alt_m": 13378.7
   },
   "member_spread_deg": {
    "lat": 29.57,
    "lon": 142.52
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 9.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:36:00",
   "seed_lat": 50.91667,
   "seed_lon": 151.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 35.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 34.17129,
    "lon": 178.76815,
    "alt_m": 13901.3
   },
   "member_spread_deg": {
    "lat": 43.12,
    "lon": 289.79
   },
   "member_spread_now_deg": {
    "lat": 14.75,
    "lon": 359.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 217.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 52.59924,
    "lon": -107.79146,
    "alt_m": 12229.5
   },
   "member_spread_deg": {
    "lat": 44.19,
    "lon": 292.23
   },
   "member_spread_now_deg": {
    "lat": 34.07,
    "lon": 315.48
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 93.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 32.98149,
    "lon": 146.4025,
    "alt_m": 14582.2
   },
   "member_spread_deg": {
    "lat": 44.02,
    "lon": 146.15
   },
   "member_spread_now_deg": {
    "lat": 19.79,
    "lon": 356.02
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 147.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 26.11106,
    "lon": 144.38632,
    "alt_m": 12894.2
   },
   "member_spread_deg": {
    "lat": 37.79,
    "lon": 249.6
   },
   "member_spread_now_deg": {
    "lat": 24.78,
    "lon": 297.99
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 10:35:00",
   "seed_lat": 37.75,
   "seed_lon": 36.16667,
   "seed_alt_m": 12820.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 10:00:00",
    "lat": 36.90914,
    "lon": -142.36577,
    "alt_m": 12776.4
   },
   "member_spread_deg": {
    "lat": 39.37,
    "lon": 252.25
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 18:51:00",
   "seed_lat": 51.25,
   "seed_lon": -68.91667,
   "seed_alt_m": 12340.0,
   "seed_age_h": 16.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 05:45:00",
    "lat": 44.26839,
    "lon": 74.28119,
    "alt_m": 12738.7
   },
   "member_spread_deg": {
    "lat": 37.66,
    "lon": 315.15
   },
   "member_spread_now_deg": {
    "lat": 1.97,
    "lon": 3.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 09:35:45",
   "seed_lat": 59.81245,
   "seed_lon": 102.54169,
   "seed_alt_m": 13330.0,
   "seed_age_h": 1.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 09:00:00",
    "lat": 75.89033,
    "lon": -43.88653,
    "alt_m": 12722.8
   },
   "member_spread_deg": {
    "lat": 29.56,
    "lon": 75.74
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 1.18
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 331.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:45:00",
    "lat": 49.98462,
    "lon": 5.18019,
    "alt_m": 13088.0
   },
   "member_spread_deg": {
    "lat": 46.23,
    "lon": 310.02
   },
   "member_spread_now_deg": {
    "lat": 35.27,
    "lon": 140.0
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 02:18:00",
   "seed_lat": 40.89583,
   "seed_lon": -153.54167,
   "seed_alt_m": 16360.0,
   "seed_age_h": 9.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:45:00",
    "lat": 47.96888,
    "lon": -77.20145,
    "alt_m": 15787.2
   },
   "member_spread_deg": {
    "lat": 31.59,
    "lon": 352.24
   },
   "member_spread_now_deg": {
    "lat": 4.59,
    "lon": 2.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 10:51:00",
   "seed_lat": 31.45833,
   "seed_lon": -9.66667,
   "seed_alt_m": 13520.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 10:45:00",
    "lat": 44.90521,
    "lon": 106.61807,
    "alt_m": 13319.2
   },
   "member_spread_deg": {
    "lat": 20.85,
    "lon": 160.61
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 21:35:23",
   "seed_lat": 52.33328,
   "seed_lon": -95.95831,
   "seed_alt_m": 12860.0,
   "seed_age_h": 13.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:30:00",
    "lat": 48.25515,
    "lon": 71.9538,
    "alt_m": 13054.6
   },
   "member_spread_deg": {
    "lat": 39.24,
    "lon": 79.13
   },
   "member_spread_now_deg": {
    "lat": 3.52,
    "lon": 3.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 10:51:00",
   "seed_lat": -15.14583,
   "seed_lon": 38.91667,
   "seed_alt_m": 15620.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-16 10:45:00",
    "lat": -17.60096,
    "lon": 132.02819,
    "alt_m": 15708.7
   },
   "member_spread_deg": {
    "lat": 31.26,
    "lon": 299.16
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}