{
 "generated_utc": "2026-09-08T17:27:16Z",
 "gfs_cycle_utc": "2026-09-08T12:00:00Z",
 "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_20260908_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260908_12Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 79254
 },
 "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": 265.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": -62.9487,
    "lon": 4.84564,
    "alt_m": 12020.7
   },
   "member_spread_deg": {
    "lat": 37.41,
    "lon": 181.2
   },
   "member_spread_now_deg": {
    "lat": 19.58,
    "lon": 176.66
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 19:10:19",
   "seed_lat": 33.60417,
   "seed_lon": -62.70833,
   "seed_alt_m": 14540.0,
   "seed_age_h": 22.16,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 39.07007,
    "lon": -22.83288,
    "alt_m": 14298.8
   },
   "member_spread_deg": {
    "lat": 31.57,
    "lon": 57.89
   },
   "member_spread_now_deg": {
    "lat": 7.9,
    "lon": 15.23
   },
   "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": 331.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 1.33619,
    "lon": -19.60446,
    "alt_m": 13210.1
   },
   "member_spread_deg": {
    "lat": 54.3,
    "lon": 115.59
   },
   "member_spread_now_deg": {
    "lat": 15.09,
    "lon": 74.77
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 84.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 78.86069,
    "lon": -141.71964,
    "alt_m": 11679.3
   },
   "member_spread_deg": {
    "lat": 23.33,
    "lon": 270.58
   },
   "member_spread_now_deg": {
    "lat": 17.22,
    "lon": 128.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:37:00",
   "seed_lat": 38.625,
   "seed_lon": -125.5,
   "seed_alt_m": 13290.0,
   "seed_age_h": 17.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 23.49113,
    "lon": -62.33415,
    "alt_m": 13582.1
   },
   "member_spread_deg": {
    "lat": 30.54,
    "lon": 174.56
   },
   "member_spread_now_deg": {
    "lat": 2.55,
    "lon": 7.66
   },
   "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": 17.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 24.03027,
    "lon": 147.13616,
    "alt_m": 14019.5
   },
   "member_spread_deg": {
    "lat": 46.49,
    "lon": 137.91
   },
   "member_spread_now_deg": {
    "lat": 6.98,
    "lon": 4.28
   },
   "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": 199.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 54.28145,
    "lon": -123.84465,
    "alt_m": 12052.2
   },
   "member_spread_deg": {
    "lat": 44.75,
    "lon": 283.67
   },
   "member_spread_now_deg": {
    "lat": 30.8,
    "lon": 299.08
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 06:11:23",
   "seed_lat": 45.72917,
   "seed_lon": 115.79167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 35.14,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 59.56061,
    "lon": -2.24159,
    "alt_m": 13906.6
   },
   "member_spread_deg": {
    "lat": 35.32,
    "lon": 303.34
   },
   "member_spread_now_deg": {
    "lat": 5.07,
    "lon": 354.81
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 08:15:00",
   "seed_lat": 40.16667,
   "seed_lon": 61.0,
   "seed_alt_m": 12620.0,
   "seed_age_h": 9.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 50.26707,
    "lon": -65.62351,
    "alt_m": 12256.7
   },
   "member_spread_deg": {
    "lat": 26.26,
    "lon": 128.86
   },
   "member_spread_now_deg": {
    "lat": 2.14,
    "lon": 3.83
   },
   "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": 129.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 19.38692,
    "lon": 174.49644,
    "alt_m": 12875.4
   },
   "member_spread_deg": {
    "lat": 23.8,
    "lon": 314.71
   },
   "member_spread_now_deg": {
    "lat": 26.66,
    "lon": 305.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 16:10:00",
   "seed_lat": 33.625,
   "seed_lon": 12.33333,
   "seed_alt_m": 12860.0,
   "seed_age_h": 1.17,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 15:45:00",
    "lat": 54.43714,
    "lon": -152.58268,
    "alt_m": 12936.6
   },
   "member_spread_deg": {
    "lat": 30.96,
    "lon": 293.0
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 16:21:00",
   "seed_lat": 53.39583,
   "seed_lon": -70.08333,
   "seed_alt_m": 12340.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 15:45:00",
    "lat": 51.68488,
    "lon": 45.62191,
    "alt_m": 12548.8
   },
   "member_spread_deg": {
    "lat": 14.47,
    "lon": 351.29
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 0.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 12:05:45",
   "seed_lat": 65.33328,
   "seed_lon": 66.70835,
   "seed_alt_m": 13300.0,
   "seed_age_h": 5.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:30:00",
    "lat": 65.00871,
    "lon": -60.19208,
    "alt_m": 12775.9
   },
   "member_spread_deg": {
    "lat": 16.39,
    "lon": 128.63
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 9.92
   },
   "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": 313.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 31.35671,
    "lon": -2.53128,
    "alt_m": 13425.6
   },
   "member_spread_deg": {
    "lat": 45.96,
    "lon": 190.29
   },
   "member_spread_now_deg": {
    "lat": 34.34,
    "lon": 96.77
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 02:11:00",
   "seed_lat": 33.04167,
   "seed_lon": -157.83333,
   "seed_alt_m": 16240.0,
   "seed_age_h": 15.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 11:45:00",
    "lat": 45.96024,
    "lon": -91.10164,
    "alt_m": 15932.6
   },
   "member_spread_deg": {
    "lat": 30.95,
    "lon": 96.07
   },
   "member_spread_now_deg": {
    "lat": 2.49,
    "lon": 7.9
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 16:46:00",
   "seed_lat": 37.72917,
   "seed_lon": -12.5,
   "seed_alt_m": 13550.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 16:45:00",
    "lat": 28.88286,
    "lon": 4.05263,
    "alt_m": 13566.2
   },
   "member_spread_deg": {
    "lat": 15.0,
    "lon": 115.1
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 15:55:23",
   "seed_lat": 51.14578,
   "seed_lon": -100.20831,
   "seed_alt_m": 13240.0,
   "seed_age_h": 1.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 15:30:00",
    "lat": 52.5553,
    "lon": 72.39121,
    "alt_m": 13328.7
   },
   "member_spread_deg": {
    "lat": 32.73,
    "lon": 86.79
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 13:06:00",
   "seed_lat": -17.85417,
   "seed_lon": 31.875,
   "seed_alt_m": 15640.0,
   "seed_age_h": 4.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 12:30:00",
    "lat": -13.52173,
    "lon": 123.14992,
    "alt_m": 15693.0
   },
   "member_spread_deg": {
    "lat": 18.3,
    "lon": 339.6
   },
   "member_spread_now_deg": {
    "lat": 0.73,
    "lon": 2.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}