{
 "generated_utc": "2026-09-11T11:27:08Z",
 "gfs_cycle_utc": "2026-09-11T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 493.5,
  "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_20260911_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260911_06Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 69336
 },
 "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": 331.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 05:45:00",
    "lat": -71.87094,
    "lon": 98.61658,
    "alt_m": 12039.8
   },
   "member_spread_deg": {
    "lat": 16.09,
    "lon": 293.21
   },
   "member_spread_now_deg": {
    "lat": 15.43,
    "lon": 357.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 10:58:49",
   "seed_lat": 40.27083,
   "seed_lon": -18.83333,
   "seed_alt_m": 14590.0,
   "seed_age_h": 0.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 11:00:00",
    "lat": 31.09187,
    "lon": -8.69574,
    "alt_m": 14045.8
   },
   "member_spread_deg": {
    "lat": 11.77,
    "lon": 69.93
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.11
   },
   "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": 150.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 05:45:00",
    "lat": 56.91298,
    "lon": -55.45966,
    "alt_m": 11906.8
   },
   "member_spread_deg": {
    "lat": 30.49,
    "lon": 339.1
   },
   "member_spread_now_deg": {
    "lat": 18.55,
    "lon": 114.71
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 18:42:00",
   "seed_lat": 31.89583,
   "seed_lon": -51.625,
   "seed_alt_m": 13630.0,
   "seed_age_h": 16.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 05:45:00",
    "lat": 19.45468,
    "lon": -50.77617,
    "alt_m": 13771.5
   },
   "member_spread_deg": {
    "lat": 22.5,
    "lon": 65.87
   },
   "member_spread_now_deg": {
    "lat": 4.7,
    "lon": 10.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 21:01:00",
   "seed_lat": 45.875,
   "seed_lon": -130.79167,
   "seed_alt_m": 13480.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": 38.59186,
    "lon": 79.09078,
    "alt_m": 13457.0
   },
   "member_spread_deg": {
    "lat": 26.5,
    "lon": 114.03
   },
   "member_spread_now_deg": {
    "lat": 5.68,
    "lon": 17.53
   },
   "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": 265.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": 67.29259,
    "lon": -166.80838,
    "alt_m": 12021.6
   },
   "member_spread_deg": {
    "lat": 40.26,
    "lon": 338.92
   },
   "member_spread_now_deg": {
    "lat": 50.02,
    "lon": 315.26
   },
   "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": 141.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": -11.73671,
    "lon": 165.38905,
    "alt_m": 14537.8
   },
   "member_spread_deg": {
    "lat": 64.8,
    "lon": 137.72
   },
   "member_spread_now_deg": {
    "lat": 30.39,
    "lon": 252.59
   },
   "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": 29.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": 30.23657,
    "lon": -57.27281,
    "alt_m": 12777.4
   },
   "member_spread_deg": {
    "lat": 24.56,
    "lon": 183.74
   },
   "member_spread_now_deg": {
    "lat": 12.51,
    "lon": 12.74
   },
   "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": 195.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": 38.70497,
    "lon": 175.09867,
    "alt_m": 12885.5
   },
   "member_spread_deg": {
    "lat": 30.28,
    "lon": 308.46
   },
   "member_spread_now_deg": {
    "lat": 17.46,
    "lon": 325.16
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 09:35:00",
   "seed_lat": 40.4375,
   "seed_lon": 108.79167,
   "seed_alt_m": 12700.0,
   "seed_age_h": 1.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 09:00:00",
    "lat": 54.35356,
    "lon": -18.39136,
    "alt_m": 12554.3
   },
   "member_spread_deg": {
    "lat": 15.2,
    "lon": 127.91
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.75
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 10:16:00",
   "seed_lat": 56.64583,
   "seed_lon": -10.75,
   "seed_alt_m": 12700.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 09:45:00",
    "lat": 44.90587,
    "lon": 150.91114,
    "alt_m": 12939.5
   },
   "member_spread_deg": {
    "lat": 14.47,
    "lon": 303.14
   },
   "member_spread_now_deg": {
    "lat": 0.54,
    "lon": 0.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 06:50:45",
   "seed_lat": 52.43745,
   "seed_lon": 153.50002,
   "seed_alt_m": 13180.0,
   "seed_age_h": 4.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 06:15:00",
    "lat": 62.30548,
    "lon": 7.34304,
    "alt_m": 12914.0
   },
   "member_spread_deg": {
    "lat": 20.46,
    "lon": 298.16
   },
   "member_spread_now_deg": {
    "lat": 0.36,
    "lon": 3.71
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 02:18:00",
   "seed_lat": 22.95833,
   "seed_lon": -151.54167,
   "seed_alt_m": 16440.0,
   "seed_age_h": 9.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 05:45:00",
    "lat": 62.60315,
    "lon": -9.90338,
    "alt_m": 15369.8
   },
   "member_spread_deg": {
    "lat": 39.84,
    "lon": 344.86
   },
   "member_spread_now_deg": {
    "lat": 2.29,
    "lon": 8.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 10:11:00",
   "seed_lat": 37.89583,
   "seed_lon": 7.04167,
   "seed_alt_m": 13380.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 09:45:00",
    "lat": 41.94031,
    "lon": -157.32983,
    "alt_m": 13102.3
   },
   "member_spread_deg": {
    "lat": 9.64,
    "lon": 339.12
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.23
   },
   "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": 61.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 05:30:00",
    "lat": 47.03544,
    "lon": 140.51897,
    "alt_m": 13304.4
   },
   "member_spread_deg": {
    "lat": 29.31,
    "lon": 326.76
   },
   "member_spread_now_deg": {
    "lat": 7.89,
    "lon": 76.85
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 10:51:00",
   "seed_lat": -21.66667,
   "seed_lon": 67.0,
   "seed_alt_m": 15600.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 10:15:00",
    "lat": -21.99776,
    "lon": 178.04314,
    "alt_m": 15574.5
   },
   "member_spread_deg": {
    "lat": 20.16,
    "lon": 328.59
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}