{
 "generated_utc": "2026-08-22T11:27:04Z",
 "gfs_cycle_utc": "2026-08-22T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 461.5,
  "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_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260822_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 87237
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 10:53:40",
   "seed_lat": -60.91667,
   "seed_lon": 21.87501,
   "seed_alt_m": 12480.0,
   "seed_age_h": 0.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 11:00:00",
    "lat": -67.49697,
    "lon": 2.19633,
    "alt_m": 12181.3
   },
   "member_spread_deg": {
    "lat": 30.91,
    "lon": 205.35
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 10:03:17",
   "seed_lat": 79.1875,
   "seed_lon": -124.0,
   "seed_alt_m": 12260.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 09:30:00",
    "lat": 55.04819,
    "lon": 48.71007,
    "alt_m": 12535.7
   },
   "member_spread_deg": {
    "lat": 22.18,
    "lon": 80.15
   },
   "member_spread_now_deg": {
    "lat": 0.23,
    "lon": 1.02
   },
   "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": 10.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 05:30:00",
    "lat": 46.68065,
    "lon": 68.29443,
    "alt_m": 13902.2
   },
   "member_spread_deg": {
    "lat": 34.07,
    "lon": 153.16
   },
   "member_spread_now_deg": {
    "lat": 6.9,
    "lon": 8.37
   },
   "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": 8.56,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 46.74041,
    "lon": 9.19982,
    "alt_m": 12559.8
   },
   "member_spread_deg": {
    "lat": 20.86,
    "lon": 96.96
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 3.02
   },
   "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": 299.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": -4.83386,
    "lon": -20.81198,
    "alt_m": 13988.2
   },
   "member_spread_deg": {
    "lat": 47.98,
    "lon": 203.01
   },
   "member_spread_now_deg": {
    "lat": 50.69,
    "lon": 119.01
   },
   "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 10:36:00",
   "seed_lat": 49.3125,
   "seed_lon": 68.58333,
   "seed_alt_m": 12580.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 10:00:00",
    "lat": 70.36101,
    "lon": -88.31668,
    "alt_m": 12259.8
   },
   "member_spread_deg": {
    "lat": 20.47,
    "lon": 299.97
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.09
   },
   "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": 9.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 40.84505,
    "lon": -34.19059,
    "alt_m": 13275.6
   },
   "member_spread_deg": {
    "lat": 13.41,
    "lon": 73.96
   },
   "member_spread_now_deg": {
    "lat": 2.21,
    "lon": 3.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 06:13:00",
   "seed_lat": 68.125,
   "seed_lon": 149.83333,
   "seed_alt_m": 11900.0,
   "seed_age_h": 5.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 58.34542,
    "lon": 73.43365,
    "alt_m": 11709.8
   },
   "member_spread_deg": {
    "lat": 39.5,
    "lon": 274.66
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 10:33:00",
   "seed_lat": 51.52083,
   "seed_lon": 12.625,
   "seed_alt_m": 12520.0,
   "seed_age_h": 0.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 10:00:00",
    "lat": 71.82737,
    "lon": 151.12193,
    "alt_m": 12645.1
   },
   "member_spread_deg": {
    "lat": 15.68,
    "lon": 81.81
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.28
   },
   "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": 158.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 6.67855,
    "lon": -62.39022,
    "alt_m": 13356.6
   },
   "member_spread_deg": {
    "lat": 53.56,
    "lon": 262.33
   },
   "member_spread_now_deg": {
    "lat": 21.61,
    "lon": 59.83
   },
   "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 10:57:04",
   "seed_lat": 62.95833,
   "seed_lon": 113.625,
   "seed_alt_m": 13270.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 11:00:00",
    "lat": 77.43642,
    "lon": 24.65626,
    "alt_m": 13047.6
   },
   "member_spread_deg": {
    "lat": 34.59,
    "lon": 151.88
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.06
   },
   "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": 239.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 59.80612,
    "lon": 120.51265,
    "alt_m": 12735.4
   },
   "member_spread_deg": {
    "lat": 21.57,
    "lon": 318.14
   },
   "member_spread_now_deg": {
    "lat": 26.08,
    "lon": 293.17
   },
   "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 05:00:00",
   "seed_lat": 41.27083,
   "seed_lon": -175.58333,
   "seed_alt_m": 13040.0,
   "seed_age_h": 6.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:30:00",
    "lat": 31.96351,
    "lon": -166.18903,
    "alt_m": 13021.2
   },
   "member_spread_deg": {
    "lat": 26.61,
    "lon": 37.47
   },
   "member_spread_now_deg": {
    "lat": 1.17,
    "lon": 0.57
   },
   "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": 49.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 05:30:00",
    "lat": 85.01385,
    "lon": 111.92916,
    "alt_m": 11632.2
   },
   "member_spread_deg": {
    "lat": 21.04,
    "lon": 273.84
   },
   "member_spread_now_deg": {
    "lat": 5.54,
    "lon": 352.13
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 206.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 0.79097,
    "lon": -68.11392,
    "alt_m": 11108.9
   },
   "member_spread_deg": {
    "lat": 64.05,
    "lon": 301.83
   },
   "member_spread_now_deg": {
    "lat": 11.92,
    "lon": 102.59
   },
   "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": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 76.85042,
    "lon": -175.94657,
    "alt_m": 12725.9
   },
   "member_spread_deg": {
    "lat": 12.32,
    "lon": 339.05
   },
   "member_spread_now_deg": {
    "lat": 4.04,
    "lon": 2.67
   },
   "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": 22.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 32.64877,
    "lon": 24.7006,
    "alt_m": 16311.6
   },
   "member_spread_deg": {
    "lat": 16.64,
    "lon": 64.47
   },
   "member_spread_now_deg": {
    "lat": 1.77,
    "lon": 4.51
   },
   "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": 11.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": 44.78358,
    "lon": 118.10166,
    "alt_m": 12941.3
   },
   "member_spread_deg": {
    "lat": 29.35,
    "lon": 227.95
   },
   "member_spread_now_deg": {
    "lat": 5.33,
    "lon": 9.22
   },
   "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": 110.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 05:30:00",
    "lat": -27.16505,
    "lon": -43.69719,
    "alt_m": 12520.4
   },
   "member_spread_deg": {
    "lat": 26.38,
    "lon": 135.52
   },
   "member_spread_now_deg": {
    "lat": 20.11,
    "lon": 139.84
   },
   "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": 244.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 05:45:00",
    "lat": -26.13619,
    "lon": 116.94692,
    "alt_m": 15729.6
   },
   "member_spread_deg": {
    "lat": 28.25,
    "lon": 238.87
   },
   "member_spread_now_deg": {
    "lat": 20.47,
    "lon": 186.28
   },
   "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 09:41:00",
   "seed_lat": -27.0625,
   "seed_lon": 95.04167,
   "seed_alt_m": 15530.0,
   "seed_age_h": 1.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 09:15:00",
    "lat": -28.23609,
    "lon": -55.92053,
    "alt_m": 15194.1
   },
   "member_spread_deg": {
    "lat": 22.87,
    "lon": 61.39
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 1.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}