{
 "generated_utc": "2026-09-03T05:25:39Z",
 "gfs_cycle_utc": "2026-09-03T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 393.5,
  "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_20260903_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260903_00Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 66744
 },
 "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": 133.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": -62.3289,
    "lon": 1.58983,
    "alt_m": 11948.9
   },
   "member_spread_deg": {
    "lat": 33.79,
    "lon": 343.92
   },
   "member_spread_now_deg": {
    "lat": 13.66,
    "lon": 267.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 00:05:48",
   "seed_lat": 32.64583,
   "seed_lon": -134.625,
   "seed_alt_m": 14550.0,
   "seed_age_h": 5.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:30:00",
    "lat": 39.23912,
    "lon": -14.07533,
    "alt_m": 14670.0
   },
   "member_spread_deg": {
    "lat": 22.91,
    "lon": 104.7
   },
   "member_spread_now_deg": {
    "lat": 0.88,
    "lon": 0.91
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:29:00",
   "seed_lat": 33.10417,
   "seed_lon": -84.75,
   "seed_alt_m": 13050.0,
   "seed_age_h": 199.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:30:00",
    "lat": 22.45036,
    "lon": -99.88026,
    "alt_m": 13242.1
   },
   "member_spread_deg": {
    "lat": 25.84,
    "lon": 77.13
   },
   "member_spread_now_deg": {
    "lat": 16.2,
    "lon": 39.37
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 15:26:00",
   "seed_lat": 77.3125,
   "seed_lon": 23.41667,
   "seed_alt_m": 11990.0,
   "seed_age_h": 13.9,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-09 23:30:00",
    "lat": 66.67569,
    "lon": -59.25793,
    "alt_m": 11684.9
   },
   "member_spread_deg": {
    "lat": 14.53,
    "lon": 204.99
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 22.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 03:57:00",
   "seed_lat": 48.14583,
   "seed_lon": 97.75,
   "seed_alt_m": 13020.0,
   "seed_age_h": 1.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-10 03:30:00",
    "lat": 47.37753,
    "lon": -66.19237,
    "alt_m": 13145.6
   },
   "member_spread_deg": {
    "lat": 19.04,
    "lon": 43.5
   },
   "member_spread_now_deg": {
    "lat": 0.58,
    "lon": 0.51
   },
   "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": 67.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-09 23:30:00",
    "lat": 60.61396,
    "lon": 131.61136,
    "alt_m": 11834.1
   },
   "member_spread_deg": {
    "lat": 26.81,
    "lon": 293.07
   },
   "member_spread_now_deg": {
    "lat": 26.65,
    "lon": 92.56
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 231.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": 59.02971,
    "lon": -103.8314,
    "alt_m": 12912.4
   },
   "member_spread_deg": {
    "lat": 32.32,
    "lon": 233.51
   },
   "member_spread_now_deg": {
    "lat": 32.79,
    "lon": 286.36
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 06:33:48",
   "seed_lat": 61.6875,
   "seed_lon": -165.70833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 214.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:30:00",
    "lat": 27.05215,
    "lon": 168.26695,
    "alt_m": 14089.3
   },
   "member_spread_deg": {
    "lat": 54.99,
    "lon": 338.39
   },
   "member_spread_now_deg": {
    "lat": 18.87,
    "lon": 184.98
   },
   "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 04:39:00",
   "seed_lat": 35.5625,
   "seed_lon": 128.83333,
   "seed_alt_m": 12780.0,
   "seed_age_h": 0.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-10 04:45:00",
    "lat": 4.95619,
    "lon": 138.95933,
    "alt_m": 12826.3
   },
   "member_spread_deg": {
    "lat": 50.75,
    "lon": 300.11
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 21:50:00",
   "seed_lat": 26.54167,
   "seed_lon": -59.625,
   "seed_alt_m": 13060.0,
   "seed_age_h": 7.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": 23.51536,
    "lon": -52.15103,
    "alt_m": 12970.3
   },
   "member_spread_deg": {
    "lat": 16.96,
    "lon": 92.77
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 0.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 04:51:00",
   "seed_lat": 56.97917,
   "seed_lon": 150.70833,
   "seed_alt_m": 12260.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-10 04:45:00",
    "lat": 79.76601,
    "lon": -54.7687,
    "alt_m": 11837.0
   },
   "member_spread_deg": {
    "lat": 27.21,
    "lon": 131.1
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 19:20:45",
   "seed_lat": 61.74995,
   "seed_lon": -37.41665,
   "seed_alt_m": 13030.0,
   "seed_age_h": 9.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": 48.22391,
    "lon": 58.54172,
    "alt_m": 13285.8
   },
   "member_spread_deg": {
    "lat": 22.38,
    "lon": 80.32
   },
   "member_spread_now_deg": {
    "lat": 1.35,
    "lon": 0.56
   },
   "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": 181.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": 41.72837,
    "lon": 20.96768,
    "alt_m": 13169.8
   },
   "member_spread_deg": {
    "lat": 35.11,
    "lon": 79.51
   },
   "member_spread_now_deg": {
    "lat": 10.67,
    "lon": 55.76
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 04:23:00",
   "seed_lat": 40.66667,
   "seed_lon": 158.58333,
   "seed_alt_m": 16100.0,
   "seed_age_h": 0.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-10 04:00:00",
    "lat": 37.74142,
    "lon": -168.53472,
    "alt_m": 16201.9
   },
   "member_spread_deg": {
    "lat": 11.87,
    "lon": 106.52
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.86
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 02:51:00",
   "seed_lat": 51.125,
   "seed_lon": -157.875,
   "seed_alt_m": 13550.0,
   "seed_age_h": 2.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-10 02:15:00",
    "lat": 61.40201,
    "lon": 40.45599,
    "alt_m": 13023.4
   },
   "member_spread_deg": {
    "lat": 35.51,
    "lon": 140.29
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 1.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 17:41:00",
   "seed_lat": -22.60417,
   "seed_lon": -26.08333,
   "seed_alt_m": 15680.0,
   "seed_age_h": 11.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-09 23:45:00",
    "lat": -21.91164,
    "lon": 27.9587,
    "alt_m": 15697.5
   },
   "member_spread_deg": {
    "lat": 21.97,
    "lon": 20.97
   },
   "member_spread_now_deg": {
    "lat": 1.8,
    "lon": 1.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}