{
 "generated_utc": "2026-09-10T11:26:50Z",
 "gfs_cycle_utc": "2026-09-10T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 469.5,
  "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_20260910_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260910_06Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 66411
 },
 "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": 307.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 05:45:00",
    "lat": -64.55038,
    "lon": 66.50616,
    "alt_m": 12078.5
   },
   "member_spread_deg": {
    "lat": 19.23,
    "lon": 223.38
   },
   "member_spread_now_deg": {
    "lat": 17.08,
    "lon": 335.28
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 10:14:48",
   "seed_lat": 34.1875,
   "seed_lon": -18.83333,
   "seed_alt_m": 14660.0,
   "seed_age_h": 1.09,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 09:45:00",
    "lat": 42.89488,
    "lon": 13.7858,
    "alt_m": 13970.9
   },
   "member_spread_deg": {
    "lat": 37.13,
    "lon": 66.76
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.43
   },
   "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": 126.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 05:45:00",
    "lat": 82.64811,
    "lon": -91.95629,
    "alt_m": 11585.7
   },
   "member_spread_deg": {
    "lat": 30.29,
    "lon": 315.97
   },
   "member_spread_now_deg": {
    "lat": 19.53,
    "lon": 357.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 19:57:00",
   "seed_lat": 44.4375,
   "seed_lon": -63.625,
   "seed_alt_m": 13290.0,
   "seed_age_h": 15.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 25.32366,
    "lon": -72.15096,
    "alt_m": 13735.0
   },
   "member_spread_deg": {
    "lat": 24.93,
    "lon": 210.71
   },
   "member_spread_now_deg": {
    "lat": 3.87,
    "lon": 8.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 03:16:00",
   "seed_lat": 52.33333,
   "seed_lon": -154.54167,
   "seed_alt_m": 13720.0,
   "seed_age_h": 8.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:45:00",
    "lat": 42.63861,
    "lon": 25.88855,
    "alt_m": 13338.2
   },
   "member_spread_deg": {
    "lat": 33.8,
    "lon": 94.22
   },
   "member_spread_now_deg": {
    "lat": 1.16,
    "lon": 7.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 241.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 64.99797,
    "lon": -167.95555,
    "alt_m": 11852.0
   },
   "member_spread_deg": {
    "lat": 29.85,
    "lon": 326.77
   },
   "member_spread_now_deg": {
    "lat": 42.78,
    "lon": 314.22
   },
   "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": 117.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 36.03317,
    "lon": 147.71246,
    "alt_m": 14587.6
   },
   "member_spread_deg": {
    "lat": 37.52,
    "lon": 137.65
   },
   "member_spread_now_deg": {
    "lat": 31.21,
    "lon": 306.35
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 05:25:00",
   "seed_lat": 48.52083,
   "seed_lon": 159.54167,
   "seed_alt_m": 12130.0,
   "seed_age_h": 5.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 40.85087,
    "lon": -48.0188,
    "alt_m": 12786.8
   },
   "member_spread_deg": {
    "lat": 33.34,
    "lon": 176.26
   },
   "member_spread_now_deg": {
    "lat": 3.5,
    "lon": 1.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 171.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 12.46655,
    "lon": 171.94571,
    "alt_m": 12841.5
   },
   "member_spread_deg": {
    "lat": 25.6,
    "lon": 275.71
   },
   "member_spread_now_deg": {
    "lat": 8.55,
    "lon": 330.06
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 10:50:00",
   "seed_lat": 42.02083,
   "seed_lon": 71.58333,
   "seed_alt_m": 12780.0,
   "seed_age_h": 0.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 10:45:00",
    "lat": 58.36103,
    "lon": -139.87171,
    "alt_m": 12673.0
   },
   "member_spread_deg": {
    "lat": 24.28,
    "lon": 134.12
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.39
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 18:21:00",
   "seed_lat": 42.75,
   "seed_lon": -52.91667,
   "seed_alt_m": 12370.0,
   "seed_age_h": 16.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:45:00",
    "lat": 49.13193,
    "lon": 91.22606,
    "alt_m": 12654.0
   },
   "member_spread_deg": {
    "lat": 9.57,
    "lon": 84.19
   },
   "member_spread_now_deg": {
    "lat": 5.82,
    "lon": 6.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 07:35:45",
   "seed_lat": 48.41661,
   "seed_lon": 121.04169,
   "seed_alt_m": 13390.0,
   "seed_age_h": 3.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 07:00:00",
    "lat": 76.09417,
    "lon": 9.14206,
    "alt_m": 13077.5
   },
   "member_spread_deg": {
    "lat": 39.27,
    "lon": 83.8
   },
   "member_spread_now_deg": {
    "lat": 1.31,
    "lon": 1.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 02:08:00",
   "seed_lat": 35.14583,
   "seed_lon": -153.95833,
   "seed_alt_m": 16500.0,
   "seed_age_h": 9.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:45:00",
    "lat": 29.1617,
    "lon": -145.57982,
    "alt_m": 16374.2
   },
   "member_spread_deg": {
    "lat": 32.55,
    "lon": 339.05
   },
   "member_spread_now_deg": {
    "lat": 5.1,
    "lon": 2.91
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 10:46:00",
   "seed_lat": 29.35417,
   "seed_lon": -0.75,
   "seed_alt_m": 13390.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 10:45:00",
    "lat": 46.08739,
    "lon": 170.76566,
    "alt_m": 13252.2
   },
   "member_spread_deg": {
    "lat": 10.97,
    "lon": 334.38
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.09
   },
   "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": 37.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:30:00",
    "lat": 45.63273,
    "lon": 95.0862,
    "alt_m": 13098.2
   },
   "member_spread_deg": {
    "lat": 20.58,
    "lon": 44.98
   },
   "member_spread_now_deg": {
    "lat": 7.9,
    "lon": 27.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 10:41:00",
   "seed_lat": -18.72917,
   "seed_lon": 52.79167,
   "seed_alt_m": 15610.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-17 10:45:00",
    "lat": -19.60553,
    "lon": 161.59724,
    "alt_m": 15627.2
   },
   "member_spread_deg": {
    "lat": 32.53,
    "lon": 317.91
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}