{
 "generated_utc": "2026-09-12T11:26:29Z",
 "gfs_cycle_utc": "2026-09-12T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 451.5,
  "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_20260912_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260912_06Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 62856
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 10:56:49",
   "seed_lat": 41.6875,
   "seed_lon": -8.83333,
   "seed_alt_m": 14580.0,
   "seed_age_h": 0.39,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 11:00:00",
    "lat": 50.52479,
    "lon": 32.54712,
    "alt_m": 13999.6
   },
   "member_spread_deg": {
    "lat": 19.53,
    "lon": 48.1
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.15
   },
   "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": 174.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 05:45:00",
    "lat": 55.6445,
    "lon": -17.62481,
    "alt_m": 11776.5
   },
   "member_spread_deg": {
    "lat": 25.65,
    "lon": 241.9
   },
   "member_spread_now_deg": {
    "lat": 12.06,
    "lon": 205.44
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 10:42:00",
   "seed_lat": 30.5,
   "seed_lon": -39.125,
   "seed_alt_m": 13760.0,
   "seed_age_h": 0.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 10:15:00",
    "lat": 46.9733,
    "lon": 30.26027,
    "alt_m": 13386.8
   },
   "member_spread_deg": {
    "lat": 22.11,
    "lon": 74.18
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 22:36:00",
   "seed_lat": 51.33333,
   "seed_lon": -81.83333,
   "seed_alt_m": 13260.0,
   "seed_age_h": 12.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 45.32123,
    "lon": 59.91016,
    "alt_m": 13234.4
   },
   "member_spread_deg": {
    "lat": 24.2,
    "lon": 172.31
   },
   "member_spread_now_deg": {
    "lat": 5.52,
    "lon": 6.78
   },
   "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": 289.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 64.10437,
    "lon": -94.68324,
    "alt_m": 11705.8
   },
   "member_spread_deg": {
    "lat": 36.65,
    "lon": 254.05
   },
   "member_spread_now_deg": {
    "lat": 44.59,
    "lon": 320.82
   },
   "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": 165.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 22.21647,
    "lon": 155.04219,
    "alt_m": 14556.9
   },
   "member_spread_deg": {
    "lat": 35.3,
    "lon": 312.65
   },
   "member_spread_now_deg": {
    "lat": 33.6,
    "lon": 213.91
   },
   "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": 53.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 26.58217,
    "lon": -84.82376,
    "alt_m": 12761.3
   },
   "member_spread_deg": {
    "lat": 42.09,
    "lon": 229.06
   },
   "member_spread_now_deg": {
    "lat": 10.92,
    "lon": 59.75
   },
   "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": 219.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 18.58224,
    "lon": 169.21773,
    "alt_m": 12885.8
   },
   "member_spread_deg": {
    "lat": 30.26,
    "lon": 342.98
   },
   "member_spread_now_deg": {
    "lat": 25.21,
    "lon": 306.86
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 06:05:00",
   "seed_lat": 45.47917,
   "seed_lon": 159.375,
   "seed_alt_m": 12660.0,
   "seed_age_h": 5.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 52.46826,
    "lon": -51.30459,
    "alt_m": 12579.8
   },
   "member_spread_deg": {
    "lat": 17.43,
    "lon": 86.64
   },
   "member_spread_now_deg": {
    "lat": 0.38,
    "lon": 3.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 10:46:00",
   "seed_lat": 39.72917,
   "seed_lon": 6.375,
   "seed_alt_m": 12880.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 10:15:00",
    "lat": 44.59093,
    "lon": 178.77773,
    "alt_m": 12966.3
   },
   "member_spread_deg": {
    "lat": 10.62,
    "lon": 44.82
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 03:55:45",
   "seed_lat": 60.18745,
   "seed_lon": -174.66665,
   "seed_alt_m": 13120.0,
   "seed_age_h": 7.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 69.23763,
    "lon": 106.74713,
    "alt_m": 13171.1
   },
   "member_spread_deg": {
    "lat": 12.38,
    "lon": 71.51
   },
   "member_spread_now_deg": {
    "lat": 1.61,
    "lon": 5.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 01:21:00",
   "seed_lat": 23.89583,
   "seed_lon": -142.91667,
   "seed_alt_m": 16440.0,
   "seed_age_h": 9.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:45:00",
    "lat": 51.38235,
    "lon": 9.87407,
    "alt_m": 15732.4
   },
   "member_spread_deg": {
    "lat": 42.86,
    "lon": 151.54
   },
   "member_spread_now_deg": {
    "lat": 6.7,
    "lon": 7.72
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 10:41:00",
   "seed_lat": 43.83333,
   "seed_lon": 24.875,
   "seed_alt_m": 13260.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 10:15:00",
    "lat": 54.68395,
    "lon": -141.85112,
    "alt_m": 12900.2
   },
   "member_spread_deg": {
    "lat": 27.58,
    "lon": 296.59
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.22
   },
   "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": 85.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 05:30:00",
    "lat": 42.39908,
    "lon": 167.58011,
    "alt_m": 13363.0
   },
   "member_spread_deg": {
    "lat": 39.35,
    "lon": 335.61
   },
   "member_spread_now_deg": {
    "lat": 18.06,
    "lon": 77.56
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 09:06:00",
   "seed_lat": -19.02083,
   "seed_lon": 87.91667,
   "seed_alt_m": 15680.0,
   "seed_age_h": 2.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-19 08:30:00",
    "lat": -26.6639,
    "lon": -166.3107,
    "alt_m": 15486.5
   },
   "member_spread_deg": {
    "lat": 35.13,
    "lon": 316.41
   },
   "member_spread_now_deg": {
    "lat": 0.36,
    "lon": 1.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}