{
 "generated_utc": "2026-09-06T05:26:36Z",
 "gfs_cycle_utc": "2026-09-06T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 465.5,
  "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_20260906_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260906_00Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 82638
 },
 "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": 205.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": -68.22281,
    "lon": -50.15982,
    "alt_m": 12362.2
   },
   "member_spread_deg": {
    "lat": 34.73,
    "lon": 251.23
   },
   "member_spread_now_deg": {
    "lat": 19.28,
    "lon": 57.31
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 22:12:18",
   "seed_lat": 37.70833,
   "seed_lon": -86.91667,
   "seed_alt_m": 14440.0,
   "seed_age_h": 7.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 44.16095,
    "lon": 9.90718,
    "alt_m": 14072.2
   },
   "member_spread_deg": {
    "lat": 30.22,
    "lon": 71.38
   },
   "member_spread_now_deg": {
    "lat": 0.9,
    "lon": 1.63
   },
   "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": 271.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 12.20046,
    "lon": -48.92758,
    "alt_m": 13178.6
   },
   "member_spread_deg": {
    "lat": 39.18,
    "lon": 115.13
   },
   "member_spread_now_deg": {
    "lat": 17.58,
    "lon": 54.47
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "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": 24.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 85.83194,
    "lon": 124.08533,
    "alt_m": 11711.4
   },
   "member_spread_deg": {
    "lat": 15.92,
    "lon": 310.19
   },
   "member_spread_now_deg": {
    "lat": 1.08,
    "lon": 43.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 02:37:00",
   "seed_lat": 50.3125,
   "seed_lon": -174.08333,
   "seed_alt_m": 13010.0,
   "seed_age_h": 2.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 02:00:00",
    "lat": 36.43545,
    "lon": -84.41754,
    "alt_m": 13674.6
   },
   "member_spread_deg": {
    "lat": 30.03,
    "lon": 140.94
   },
   "member_spread_now_deg": {
    "lat": 1.52,
    "lon": 5.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 09:41:00",
   "seed_lat": 46.375,
   "seed_lon": 57.29167,
   "seed_alt_m": 13450.0,
   "seed_age_h": 19.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 39.2314,
    "lon": -176.39031,
    "alt_m": 13833.7
   },
   "member_spread_deg": {
    "lat": 33.36,
    "lon": 348.83
   },
   "member_spread_now_deg": {
    "lat": 2.39,
    "lon": 7.18
   },
   "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": 139.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 67.21026,
    "lon": -132.40807,
    "alt_m": 11700.4
   },
   "member_spread_deg": {
    "lat": 34.25,
    "lon": 253.77
   },
   "member_spread_now_deg": {
    "lat": 20.71,
    "lon": 349.52
   },
   "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": 15.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 32.25207,
    "lon": -135.99556,
    "alt_m": 14249.9
   },
   "member_spread_deg": {
    "lat": 26.22,
    "lon": 333.44
   },
   "member_spread_now_deg": {
    "lat": 0.97,
    "lon": 4.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 303.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 35.89651,
    "lon": -140.17157,
    "alt_m": 13010.8
   },
   "member_spread_deg": {
    "lat": 17.6,
    "lon": 316.63
   },
   "member_spread_now_deg": {
    "lat": 22.81,
    "lon": 223.69
   },
   "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": 286.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 52.00382,
    "lon": -151.22904,
    "alt_m": 13697.4
   },
   "member_spread_deg": {
    "lat": 25.99,
    "lon": 317.55
   },
   "member_spread_now_deg": {
    "lat": 38.99,
    "lon": 210.58
   },
   "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 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 69.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 24.53792,
    "lon": 162.77761,
    "alt_m": 12881.5
   },
   "member_spread_deg": {
    "lat": 45.85,
    "lon": 321.16
   },
   "member_spread_now_deg": {
    "lat": 12.69,
    "lon": 355.61
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 17:50:00",
   "seed_lat": 30.08333,
   "seed_lon": -13.45833,
   "seed_alt_m": 12950.0,
   "seed_age_h": 11.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 42.19916,
    "lon": 76.75289,
    "alt_m": 12749.4
   },
   "member_spread_deg": {
    "lat": 5.06,
    "lon": 76.06
   },
   "member_spread_now_deg": {
    "lat": 2.82,
    "lon": 2.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 02:01:00",
   "seed_lat": 62.91667,
   "seed_lon": -150.16667,
   "seed_alt_m": 12300.0,
   "seed_age_h": 3.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 01:30:00",
    "lat": 41.75474,
    "lon": 26.21534,
    "alt_m": 12862.7
   },
   "member_spread_deg": {
    "lat": 40.45,
    "lon": 144.7
   },
   "member_spread_now_deg": {
    "lat": 0.73,
    "lon": 7.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 13.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 60.45574,
    "lon": -165.64021,
    "alt_m": 13181.6
   },
   "member_spread_deg": {
    "lat": 14.18,
    "lon": 344.23
   },
   "member_spread_now_deg": {
    "lat": 0.75,
    "lon": 1.67
   },
   "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": 253.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": 34.86519,
    "lon": 1.22071,
    "alt_m": 13415.1
   },
   "member_spread_deg": {
    "lat": 24.2,
    "lon": 188.29
   },
   "member_spread_now_deg": {
    "lat": 25.43,
    "lon": 85.28
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 03:03:00",
   "seed_lat": 28.04167,
   "seed_lon": -162.5,
   "seed_alt_m": 16300.0,
   "seed_age_h": 2.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 03:00:00",
    "lat": 27.18202,
    "lon": -173.35063,
    "alt_m": 16457.9
   },
   "member_spread_deg": {
    "lat": 32.48,
    "lon": 350.3
   },
   "member_spread_now_deg": {
    "lat": 1.05,
    "lon": 0.36
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 22:26:00",
   "seed_lat": 52.83333,
   "seed_lon": -93.54167,
   "seed_alt_m": 13200.0,
   "seed_age_h": 6.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:30:00",
    "lat": 52.2156,
    "lon": 89.05183,
    "alt_m": 13171.4
   },
   "member_spread_deg": {
    "lat": 32.61,
    "lon": 102.41
   },
   "member_spread_now_deg": {
    "lat": 1.93,
    "lon": 3.92
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:21:00",
   "seed_lat": -31.45833,
   "seed_lon": 12.45833,
   "seed_alt_m": 15480.0,
   "seed_age_h": 15.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 23:45:00",
    "lat": -27.16353,
    "lon": 96.28217,
    "alt_m": 15525.6
   },
   "member_spread_deg": {
    "lat": 16.23,
    "lon": 302.26
   },
   "member_spread_now_deg": {
    "lat": 2.61,
    "lon": 2.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}