{
 "generated_utc": "2026-08-22T05:26:59Z",
 "gfs_cycle_utc": "2026-08-22T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 455.5,
  "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_20260822_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260822_00Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 86193
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 16:33:40",
   "seed_lat": -54.3125,
   "seed_lon": -4.04165,
   "seed_alt_m": 12300.0,
   "seed_age_h": 12.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 23:30:00",
    "lat": -70.16078,
    "lon": -42.13623,
    "alt_m": 12315.2
   },
   "member_spread_deg": {
    "lat": 34.47,
    "lon": 179.45
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 15.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 03:48:17",
   "seed_lat": 77.75,
   "seed_lon": -132.29167,
   "seed_alt_m": 12280.0,
   "seed_age_h": 1.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 03:15:00",
    "lat": 76.68381,
    "lon": 6.59239,
    "alt_m": 12255.7
   },
   "member_spread_deg": {
    "lat": 5.81,
    "lon": 79.28
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 1.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 00:33:18",
   "seed_lat": 54.8125,
   "seed_lon": -110.91667,
   "seed_alt_m": 14040.0,
   "seed_age_h": 4.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 00:00:00",
    "lat": 53.28548,
    "lon": 18.80514,
    "alt_m": 13931.2
   },
   "member_spread_deg": {
    "lat": 31.91,
    "lon": 134.61
   },
   "member_spread_now_deg": {
    "lat": 2.6,
    "lon": 4.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 02:46:30",
   "seed_lat": 40.16667,
   "seed_lon": -166.20833,
   "seed_alt_m": 12920.0,
   "seed_age_h": 2.56,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 02:15:00",
    "lat": 45.14474,
    "lon": 15.50978,
    "alt_m": 12737.1
   },
   "member_spread_deg": {
    "lat": 19.5,
    "lon": 79.62
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.73
   },
   "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": 293.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 6.56444,
    "lon": -42.52853,
    "alt_m": 14058.4
   },
   "member_spread_deg": {
    "lat": 50.04,
    "lon": 211.96
   },
   "member_spread_now_deg": {
    "lat": 49.59,
    "lon": 117.2
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 04:26:00",
   "seed_lat": 51.02083,
   "seed_lon": 64.29167,
   "seed_alt_m": 12530.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 04:30:00",
    "lat": 55.81613,
    "lon": -110.0654,
    "alt_m": 12688.0
   },
   "member_spread_deg": {
    "lat": 34.02,
    "lon": 50.1
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 02:17:00",
   "seed_lat": 52.58333,
   "seed_lon": 155.25,
   "seed_alt_m": 13100.0,
   "seed_age_h": 3.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 01:45:00",
    "lat": 47.37943,
    "lon": -47.77983,
    "alt_m": 13172.0
   },
   "member_spread_deg": {
    "lat": 12.8,
    "lon": 78.01
   },
   "member_spread_now_deg": {
    "lat": 0.77,
    "lon": 0.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 21:53:00",
   "seed_lat": 68.45833,
   "seed_lon": 144.08333,
   "seed_alt_m": 11860.0,
   "seed_age_h": 7.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 23:30:00",
    "lat": 75.07072,
    "lon": 150.76945,
    "alt_m": 11727.6
   },
   "member_spread_deg": {
    "lat": 28.2,
    "lon": 348.58
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 1.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 16:58:00",
   "seed_lat": 50.52083,
   "seed_lon": -6.45833,
   "seed_alt_m": 12630.0,
   "seed_age_h": 12.37,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:30:00",
    "lat": 75.72945,
    "lon": 97.20139,
    "alt_m": 12495.0
   },
   "member_spread_deg": {
    "lat": 13.37,
    "lon": 102.45
   },
   "member_spread_now_deg": {
    "lat": 0.85,
    "lon": 9.88
   },
   "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": 152.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 6.68459,
    "lon": -65.81312,
    "alt_m": 13378.6
   },
   "member_spread_deg": {
    "lat": 39.08,
    "lon": 239.96
   },
   "member_spread_now_deg": {
    "lat": 26.64,
    "lon": 56.38
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 03:57:04",
   "seed_lat": 63.9375,
   "seed_lon": 111.08333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 1.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 03:30:00",
    "lat": 75.77095,
    "lon": -46.54135,
    "alt_m": 13127.5
   },
   "member_spread_deg": {
    "lat": 24.85,
    "lon": 104.15
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.36
   },
   "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": 233.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 58.54959,
    "lon": 115.38198,
    "alt_m": 12544.3
   },
   "member_spread_deg": {
    "lat": 37.94,
    "lon": 337.42
   },
   "member_spread_now_deg": {
    "lat": 26.89,
    "lon": 290.92
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 04:00:00",
   "seed_lat": 41.64583,
   "seed_lon": -175.66667,
   "seed_alt_m": 13050.0,
   "seed_age_h": 1.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 03:30:00",
    "lat": 33.34173,
    "lon": -176.89303,
    "alt_m": 12996.1
   },
   "member_spread_deg": {
    "lat": 13.73,
    "lon": 353.66
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:01:00",
   "seed_lat": 85.25,
   "seed_lon": 45.875,
   "seed_alt_m": 11960.0,
   "seed_age_h": 43.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 23:30:00",
    "lat": 82.26475,
    "lon": 126.61443,
    "alt_m": 11581.9
   },
   "member_spread_deg": {
    "lat": 39.23,
    "lon": 293.57
   },
   "member_spread_now_deg": {
    "lat": 6.94,
    "lon": 36.98
   },
   "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": 200.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 12.49061,
    "lon": -69.44553,
    "alt_m": 11187.2
   },
   "member_spread_deg": {
    "lat": 42.59,
    "lon": 326.89
   },
   "member_spread_now_deg": {
    "lat": 15.3,
    "lon": 102.23
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 23:15:45",
   "seed_lat": 72.08328,
   "seed_lon": -162.83331,
   "seed_alt_m": 12780.0,
   "seed_age_h": 6.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 74.48521,
    "lon": -170.36203,
    "alt_m": 12765.0
   },
   "member_spread_deg": {
    "lat": 22.61,
    "lon": 307.99
   },
   "member_spread_now_deg": {
    "lat": 1.81,
    "lon": 1.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 12:21:00",
   "seed_lat": 12.97917,
   "seed_lon": 50.95833,
   "seed_alt_m": 16600.0,
   "seed_age_h": 16.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 19.41832,
    "lon": -27.50826,
    "alt_m": 16408.6
   },
   "member_spread_deg": {
    "lat": 19.04,
    "lon": 63.72
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 2.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 23:46:00",
   "seed_lat": 53.77083,
   "seed_lon": -119.08333,
   "seed_alt_m": 13370.0,
   "seed_age_h": 5.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": 48.90595,
    "lon": 92.89841,
    "alt_m": 13146.9
   },
   "member_spread_deg": {
    "lat": 26.68,
    "lon": 230.78
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 4.92
   },
   "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": 104.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 23:30:00",
    "lat": -27.89958,
    "lon": -48.39044,
    "alt_m": 12504.6
   },
   "member_spread_deg": {
    "lat": 25.06,
    "lon": 118.27
   },
   "member_spread_now_deg": {
    "lat": 27.23,
    "lon": 135.56
   },
   "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": 238.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 23:45:00",
    "lat": -25.88226,
    "lon": 117.12809,
    "alt_m": 15713.8
   },
   "member_spread_deg": {
    "lat": 37.45,
    "lon": 245.71
   },
   "member_spread_now_deg": {
    "lat": 20.1,
    "lon": 183.28
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 04:06:00",
   "seed_lat": -26.54167,
   "seed_lon": 87.20833,
   "seed_alt_m": 15520.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 03:30:00",
    "lat": -33.32186,
    "lon": -49.16503,
    "alt_m": 14934.7
   },
   "member_spread_deg": {
    "lat": 21.81,
    "lon": 70.06
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.93
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}