{
 "generated_utc": "2026-08-20T11:26:24Z",
 "gfs_cycle_utc": "2026-08-20T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 413.5,
  "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_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260820_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 81405
 },
 "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": 35.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": -70.68359,
    "lon": -119.95695,
    "alt_m": 12469.1
   },
   "member_spread_deg": {
    "lat": 17.76,
    "lon": 266.4
   },
   "member_spread_now_deg": {
    "lat": 2.85,
    "lon": 8.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 06:13:49",
   "seed_lat": 67.79167,
   "seed_lon": -172.20833,
   "seed_alt_m": 12390.0,
   "seed_age_h": 5.1,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 66.80373,
    "lon": -25.5437,
    "alt_m": 12562.3
   },
   "member_spread_deg": {
    "lat": 25.26,
    "lon": 155.92
   },
   "member_spread_now_deg": {
    "lat": 0.87,
    "lon": 1.95
   },
   "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": 15.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 05:30:00",
    "lat": 41.03974,
    "lon": 12.61708,
    "alt_m": 14401.4
   },
   "member_spread_deg": {
    "lat": 30.77,
    "lon": 103.59
   },
   "member_spread_now_deg": {
    "lat": 4.49,
    "lon": 3.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 05:49:00",
   "seed_lat": 54.375,
   "seed_lon": 147.75,
   "seed_alt_m": 12620.0,
   "seed_age_h": 5.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 47.66064,
    "lon": -22.067,
    "alt_m": 12491.2
   },
   "member_spread_deg": {
    "lat": 16.77,
    "lon": 70.73
   },
   "member_spread_now_deg": {
    "lat": 1.59,
    "lon": 2.79
   },
   "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": 251.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 3.15772,
    "lon": -44.10846,
    "alt_m": 14031.5
   },
   "member_spread_deg": {
    "lat": 40.52,
    "lon": 141.46
   },
   "member_spread_now_deg": {
    "lat": 49.19,
    "lon": 114.74
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:16:00",
   "seed_lat": 52.08333,
   "seed_lon": 6.16667,
   "seed_alt_m": 12390.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 09:45:00",
    "lat": 51.07185,
    "lon": -133.9234,
    "alt_m": 12798.4
   },
   "member_spread_deg": {
    "lat": 30.11,
    "lon": 271.62
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 0.92
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 07:22:00",
   "seed_lat": 46.85417,
   "seed_lon": 130.41667,
   "seed_alt_m": 13220.0,
   "seed_age_h": 3.97,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 06:45:00",
    "lat": 49.21576,
    "lon": -94.16286,
    "alt_m": 13177.6
   },
   "member_spread_deg": {
    "lat": 23.75,
    "lon": 51.08
   },
   "member_spread_now_deg": {
    "lat": 0.5,
    "lon": 4.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:08:00",
   "seed_lat": 78.95833,
   "seed_lon": 117.79167,
   "seed_alt_m": 11880.0,
   "seed_age_h": 1.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 09:45:00",
    "lat": 71.05866,
    "lon": 12.85498,
    "alt_m": 11944.4
   },
   "member_spread_deg": {
    "lat": 10.86,
    "lon": 115.78
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:13:00",
   "seed_lat": 60.20833,
   "seed_lon": -19.79167,
   "seed_alt_m": 12650.0,
   "seed_age_h": 1.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 09:45:00",
    "lat": 61.50995,
    "lon": 58.56871,
    "alt_m": 12373.4
   },
   "member_spread_deg": {
    "lat": 26.69,
    "lon": 310.41
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.3
   },
   "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": 110.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 21.48408,
    "lon": -95.08462,
    "alt_m": 13377.3
   },
   "member_spread_deg": {
    "lat": 42.14,
    "lon": 179.54
   },
   "member_spread_now_deg": {
    "lat": 27.39,
    "lon": 43.57
   },
   "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 10:57:03",
   "seed_lat": 74.85417,
   "seed_lon": 93.875,
   "seed_alt_m": 13270.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:00:00",
    "lat": 80.5494,
    "lon": -104.38597,
    "alt_m": 13003.4
   },
   "member_spread_deg": {
    "lat": 23.3,
    "lon": 269.9
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.09
   },
   "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": 191.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 52.9886,
    "lon": 112.51905,
    "alt_m": 12769.7
   },
   "member_spread_deg": {
    "lat": 23.31,
    "lon": 324.23
   },
   "member_spread_now_deg": {
    "lat": 26.58,
    "lon": 293.93
   },
   "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 05:57:30",
   "seed_lat": 47.08333,
   "seed_lon": 167.5,
   "seed_alt_m": 13130.0,
   "seed_age_h": 5.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:30:00",
    "lat": 37.85885,
    "lon": -95.94766,
    "alt_m": 13093.1
   },
   "member_spread_deg": {
    "lat": 9.81,
    "lon": 66.55
   },
   "member_spread_now_deg": {
    "lat": 2.51,
    "lon": 1.62
   },
   "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": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 09:30:00",
    "lat": 69.42617,
    "lon": 156.2165,
    "alt_m": 11889.2
   },
   "member_spread_deg": {
    "lat": 18.03,
    "lon": 344.05
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 7.62
   },
   "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": 158.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 45.02412,
    "lon": 44.48482,
    "alt_m": 10972.5
   },
   "member_spread_deg": {
    "lat": 18.74,
    "lon": 207.88
   },
   "member_spread_now_deg": {
    "lat": 14.9,
    "lon": 94.77
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 07:15:45",
   "seed_lat": 67.12495,
   "seed_lon": 152.95835,
   "seed_alt_m": 12930.0,
   "seed_age_h": 4.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 06:45:00",
    "lat": 79.62819,
    "lon": 94.22566,
    "alt_m": 12704.6
   },
   "member_spread_deg": {
    "lat": 13.76,
    "lon": 151.76
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:21:00",
   "seed_lat": 8.5625,
   "seed_lon": 71.58333,
   "seed_alt_m": 16300.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 09:45:00",
    "lat": -1.40891,
    "lon": -0.67689,
    "alt_m": 16413.7
   },
   "member_spread_deg": {
    "lat": 18.4,
    "lon": 51.88
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.63
   },
   "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": 8.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:30:00",
    "lat": 39.75124,
    "lon": 20.13821,
    "alt_m": 13499.0
   },
   "member_spread_deg": {
    "lat": 30.71,
    "lon": 109.39
   },
   "member_spread_now_deg": {
    "lat": 2.59,
    "lon": 2.57
   },
   "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": 15.04,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": 55.59031,
    "lon": 9.43521,
    "alt_m": 13406.6
   },
   "member_spread_deg": {
    "lat": 38.85,
    "lon": 90.76
   },
   "member_spread_now_deg": {
    "lat": 0.63,
    "lon": 2.35
   },
   "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": 62.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 05:30:00",
    "lat": -30.19867,
    "lon": 77.24029,
    "alt_m": 12272.5
   },
   "member_spread_deg": {
    "lat": 17.02,
    "lon": 287.07
   },
   "member_spread_now_deg": {
    "lat": 22.98,
    "lon": 98.94
   },
   "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": 196.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 05:45:00",
    "lat": -37.98065,
    "lon": 107.42548,
    "alt_m": 15272.5
   },
   "member_spread_deg": {
    "lat": 34.74,
    "lon": 284.66
   },
   "member_spread_now_deg": {
    "lat": 24.82,
    "lon": 160.82
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}