{
 "generated_utc": "2026-08-20T05:26:09Z",
 "gfs_cycle_utc": "2026-08-20T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 407.5,
  "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_20260820_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260820_00Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 81000
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 00:13:40",
   "seed_lat": -64.60417,
   "seed_lon": -143.74999,
   "seed_alt_m": 12240.0,
   "seed_age_h": 29.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": -70.30663,
    "lon": -125.75667,
    "alt_m": 12412.5
   },
   "member_spread_deg": {
    "lat": 32.35,
    "lon": 298.73
   },
   "member_spread_now_deg": {
    "lat": 1.36,
    "lon": 5.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 04:55:18",
   "seed_lat": 67.85417,
   "seed_lon": -173.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 05:00:00",
    "lat": 66.41001,
    "lon": -28.06954,
    "alt_m": 12481.4
   },
   "member_spread_deg": {
    "lat": 19.21,
    "lon": 61.57
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 19:59:18",
   "seed_lat": 51.08333,
   "seed_lon": -140.58333,
   "seed_alt_m": 14060.0,
   "seed_age_h": 9.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 23:30:00",
    "lat": 44.25919,
    "lon": 5.59632,
    "alt_m": 14287.0
   },
   "member_spread_deg": {
    "lat": 35.41,
    "lon": 92.41
   },
   "member_spread_now_deg": {
    "lat": 2.36,
    "lon": 4.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 04:39:00",
   "seed_lat": 53.60417,
   "seed_lon": 146.66667,
   "seed_alt_m": 12650.0,
   "seed_age_h": 0.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 04:15:00",
    "lat": 55.88225,
    "lon": -30.63203,
    "alt_m": 12533.3
   },
   "member_spread_deg": {
    "lat": 17.2,
    "lon": 64.08
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 245.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": -1.36127,
    "lon": -45.91971,
    "alt_m": 14036.0
   },
   "member_spread_deg": {
    "lat": 63.36,
    "lon": 173.34
   },
   "member_spread_now_deg": {
    "lat": 49.38,
    "lon": 111.12
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 17:16:00",
   "seed_lat": 51.75,
   "seed_lon": -17.25,
   "seed_alt_m": 12520.0,
   "seed_age_h": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 52.73864,
    "lon": -153.8775,
    "alt_m": 12815.0
   },
   "member_spread_deg": {
    "lat": 27.06,
    "lon": 337.18
   },
   "member_spread_now_deg": {
    "lat": 1.15,
    "lon": 8.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 03:57:00",
   "seed_lat": 47.0,
   "seed_lon": 127.375,
   "seed_alt_m": 13280.0,
   "seed_age_h": 1.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 03:30:00",
    "lat": 54.51068,
    "lon": -101.01102,
    "alt_m": 13119.8
   },
   "member_spread_deg": {
    "lat": 17.2,
    "lon": 53.43
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 1.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 04:43:00",
   "seed_lat": 80.97917,
   "seed_lon": 107.25,
   "seed_alt_m": 11880.0,
   "seed_age_h": 0.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 04:15:00",
    "lat": 71.87766,
    "lon": 9.09902,
    "alt_m": 11856.7
   },
   "member_spread_deg": {
    "lat": 13.77,
    "lon": 137.17
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 17:13:00",
   "seed_lat": 63.77083,
   "seed_lon": -25.29167,
   "seed_alt_m": 12700.0,
   "seed_age_h": 12.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 53.72311,
    "lon": 36.87695,
    "alt_m": 12638.2
   },
   "member_spread_deg": {
    "lat": 25.22,
    "lon": 86.76
   },
   "member_spread_now_deg": {
    "lat": 0.85,
    "lon": 1.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 104.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 28.35349,
    "lon": -108.74493,
    "alt_m": 13373.5
   },
   "member_spread_deg": {
    "lat": 25.55,
    "lon": 132.85
   },
   "member_spread_now_deg": {
    "lat": 27.04,
    "lon": 43.88
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 02:08:18",
   "seed_lat": 76.41667,
   "seed_lon": 82.875,
   "seed_alt_m": 13280.0,
   "seed_age_h": 3.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 01:45:00",
    "lat": 70.20782,
    "lon": -119.01227,
    "alt_m": 13382.0
   },
   "member_spread_deg": {
    "lat": 20.51,
    "lon": 270.61
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 185.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 54.66486,
    "lon": 94.30163,
    "alt_m": 12472.1
   },
   "member_spread_deg": {
    "lat": 24.14,
    "lon": 286.62
   },
   "member_spread_now_deg": {
    "lat": 23.31,
    "lon": 287.01
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 04:35:00",
   "seed_lat": 46.95833,
   "seed_lon": 167.33333,
   "seed_alt_m": 13165.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 04:00:00",
    "lat": 44.85426,
    "lon": -98.28469,
    "alt_m": 13086.5
   },
   "member_spread_deg": {
    "lat": 10.47,
    "lon": 72.38
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 17:56:00",
   "seed_lat": 82.1875,
   "seed_lon": 1.45833,
   "seed_alt_m": 12060.0,
   "seed_age_h": 11.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 23:30:00",
    "lat": 85.95253,
    "lon": 69.33808,
    "alt_m": 12122.5
   },
   "member_spread_deg": {
    "lat": 27.43,
    "lon": 289.65
   },
   "member_spread_now_deg": {
    "lat": 1.79,
    "lon": 30.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 152.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 29.59807,
    "lon": -43.41245,
    "alt_m": 11272.4
   },
   "member_spread_deg": {
    "lat": 47.96,
    "lon": 183.59
   },
   "member_spread_now_deg": {
    "lat": 13.76,
    "lon": 94.79
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 08:25:45",
   "seed_lat": 62.85411,
   "seed_lon": 132.87502,
   "seed_alt_m": 13000.0,
   "seed_age_h": 20.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:30:00",
    "lat": 75.26613,
    "lon": 120.53066,
    "alt_m": 12934.8
   },
   "member_spread_deg": {
    "lat": 16.21,
    "lon": 293.56
   },
   "member_spread_now_deg": {
    "lat": 0.83,
    "lon": 5.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 04:01:00",
   "seed_lat": 7.4375,
   "seed_lon": 75.08333,
   "seed_alt_m": 16330.0,
   "seed_age_h": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 03:30:00",
    "lat": -1.11575,
    "lon": 1.24898,
    "alt_m": 16485.4
   },
   "member_spread_deg": {
    "lat": 12.92,
    "lon": 58.94
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 0.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 02:31:00",
   "seed_lat": 35.79167,
   "seed_lon": -143.83333,
   "seed_alt_m": 13400.0,
   "seed_age_h": 2.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 02:00:00",
    "lat": 39.57333,
    "lon": 7.21796,
    "alt_m": 13614.1
   },
   "member_spread_deg": {
    "lat": 37.25,
    "lon": 104.05
   },
   "member_spread_now_deg": {
    "lat": 1.44,
    "lon": 0.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 20:17:53",
   "seed_lat": 64.74995,
   "seed_lon": -118.70831,
   "seed_alt_m": 12900.0,
   "seed_age_h": 9.04,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": 55.76516,
    "lon": 8.58202,
    "alt_m": 13480.2
   },
   "member_spread_deg": {
    "lat": 20.76,
    "lon": 86.34
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 1.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 20:59:00",
   "seed_lat": -20.58333,
   "seed_lon": -72.33333,
   "seed_alt_m": 12210.0,
   "seed_age_h": 56.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 23:30:00",
    "lat": -21.07239,
    "lon": 52.99727,
    "alt_m": 12467.7
   },
   "member_spread_deg": {
    "lat": 13.11,
    "lon": 306.76
   },
   "member_spread_now_deg": {
    "lat": 28.0,
    "lon": 89.09
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 190.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 23:45:00",
    "lat": -39.92199,
    "lon": 97.36051,
    "alt_m": 15342.5
   },
   "member_spread_deg": {
    "lat": 49.47,
    "lon": 347.62
   },
   "member_spread_now_deg": {
    "lat": 25.14,
    "lon": 156.01
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}