{
 "generated_utc": "2026-08-23T23:27:27Z",
 "gfs_cycle_utc": "2026-08-23T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 497.5,
  "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_20260823_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260823_18Z.geojson.gz"
 },
 "counts": {
  "flights": 23,
  "members": 9,
  "rows": 97272
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 13:43:40",
   "seed_lat": -61.64583,
   "seed_lon": 25.04168,
   "seed_alt_m": 12480.0,
   "seed_age_h": 33.61,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": -58.24541,
    "lon": 96.37045,
    "alt_m": 12358.8
   },
   "member_spread_deg": {
    "lat": 16.22,
    "lon": 221.92
   },
   "member_spread_now_deg": {
    "lat": 12.49,
    "lon": 43.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:35:18",
   "seed_lat": 78.91667,
   "seed_lon": -71.08333,
   "seed_alt_m": 12340.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 22:00:00",
    "lat": 73.97688,
    "lon": 74.66109,
    "alt_m": 12097.9
   },
   "member_spread_deg": {
    "lat": 28.87,
    "lon": 86.18
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 21:40:18",
   "seed_lat": 47.70833,
   "seed_lon": -73.29167,
   "seed_alt_m": 13790.0,
   "seed_age_h": 1.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 21:15:00",
    "lat": 48.90657,
    "lon": 141.12221,
    "alt_m": 13733.4
   },
   "member_spread_deg": {
    "lat": 13.13,
    "lon": 135.54
   },
   "member_spread_now_deg": {
    "lat": 1.33,
    "lon": 0.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:29:00",
   "seed_lat": 31.5,
   "seed_lon": -122.41667,
   "seed_alt_m": 12940.0,
   "seed_age_h": 0.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 22:00:00",
    "lat": 42.77684,
    "lon": 46.81248,
    "alt_m": 12687.5
   },
   "member_spread_deg": {
    "lat": 21.5,
    "lon": 64.22
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.23
   },
   "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": 335.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": -0.68494,
    "lon": -13.43889,
    "alt_m": 13984.4
   },
   "member_spread_deg": {
    "lat": 70.28,
    "lon": 285.95
   },
   "member_spread_now_deg": {
    "lat": 56.63,
    "lon": 125.43
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 06:56:00",
   "seed_lat": 49.85417,
   "seed_lon": 87.375,
   "seed_alt_m": 12530.0,
   "seed_age_h": 16.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": 56.06445,
    "lon": -109.91188,
    "alt_m": 12549.9
   },
   "member_spread_deg": {
    "lat": 47.4,
    "lon": 239.79
   },
   "member_spread_now_deg": {
    "lat": 0.7,
    "lon": 8.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 21:57:00",
   "seed_lat": 41.91667,
   "seed_lon": -148.58333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 1.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 21:30:00",
    "lat": 50.68501,
    "lon": -21.33248,
    "alt_m": 12922.5
   },
   "member_spread_deg": {
    "lat": 19.62,
    "lon": 71.87
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:53:00",
   "seed_lat": 71.91667,
   "seed_lon": -144.66667,
   "seed_alt_m": 11890.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 23:00:00",
    "lat": 70.47597,
    "lon": 177.34841,
    "alt_m": 11781.7
   },
   "member_spread_deg": {
    "lat": 25.57,
    "lon": 265.65
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 0.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 15:53:00",
   "seed_lat": 53.35417,
   "seed_lon": 17.375,
   "seed_alt_m": 12510.0,
   "seed_age_h": 31.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": 50.74195,
    "lon": 133.3784,
    "alt_m": 12682.2
   },
   "member_spread_deg": {
    "lat": 31.58,
    "lon": 296.88
   },
   "member_spread_now_deg": {
    "lat": 7.41,
    "lon": 22.01
   },
   "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": 194.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": 3.89975,
    "lon": -69.73635,
    "alt_m": 13380.0
   },
   "member_spread_deg": {
    "lat": 44.22,
    "lon": 286.75
   },
   "member_spread_now_deg": {
    "lat": 21.72,
    "lon": 85.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:33:48",
   "seed_lat": 56.02083,
   "seed_lon": 145.41667,
   "seed_alt_m": 13240.0,
   "seed_age_h": 0.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 22:00:00",
    "lat": 61.99894,
    "lon": -72.41491,
    "alt_m": 13422.5
   },
   "member_spread_deg": {
    "lat": 32.89,
    "lon": 266.05
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.72
   },
   "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": 275.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": 58.33398,
    "lon": 125.61785,
    "alt_m": 12540.8
   },
   "member_spread_deg": {
    "lat": 37.25,
    "lon": 297.92
   },
   "member_spread_now_deg": {
    "lat": 22.55,
    "lon": 311.04
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 16:54:00",
   "seed_lat": 33.3125,
   "seed_lon": -26.5,
   "seed_alt_m": 12770.0,
   "seed_age_h": 6.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": 39.66918,
    "lon": 97.67224,
    "alt_m": 12572.6
   },
   "member_spread_deg": {
    "lat": 14.55,
    "lon": 176.04
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 1.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:40:00",
   "seed_lat": 23.14583,
   "seed_lon": -178.70833,
   "seed_alt_m": 13110.0,
   "seed_age_h": 0.67,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 22:15:00",
    "lat": 43.36772,
    "lon": -119.03868,
    "alt_m": 12719.3
   },
   "member_spread_deg": {
    "lat": 13.98,
    "lon": 145.85
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:36:00",
   "seed_lat": 73.20833,
   "seed_lon": -150.91667,
   "seed_alt_m": 11870.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 22:00:00",
    "lat": 67.02063,
    "lon": 99.40795,
    "alt_m": 12125.3
   },
   "member_spread_deg": {
    "lat": 23.51,
    "lon": 193.66
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.26
   },
   "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": 242.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": 19.32752,
    "lon": -48.57589,
    "alt_m": 11098.6
   },
   "member_spread_deg": {
    "lat": 40.87,
    "lon": 296.6
   },
   "member_spread_now_deg": {
    "lat": 28.88,
    "lon": 119.62
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 01:45:45",
   "seed_lat": 81.20828,
   "seed_lon": -145.74998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 21.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": 80.42265,
    "lon": -132.5654,
    "alt_m": 12688.4
   },
   "member_spread_deg": {
    "lat": 21.63,
    "lon": 159.51
   },
   "member_spread_now_deg": {
    "lat": 3.71,
    "lon": 96.31
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-23 18:00:24",
   "seed_lat": 51.81083,
   "seed_lon": -61.64733,
   "seed_alt_m": 12996.0,
   "seed_age_h": 5.33,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": 37.93034,
    "lon": 167.00139,
    "alt_m": 12979.4
   },
   "member_spread_deg": {
    "lat": 17.67,
    "lon": 60.69
   },
   "member_spread_now_deg": {
    "lat": 2.17,
    "lon": 9.77
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 15:23:00",
   "seed_lat": 17.52083,
   "seed_lon": 13.625,
   "seed_alt_m": 16640.0,
   "seed_age_h": 7.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": 46.52658,
    "lon": 76.98535,
    "alt_m": 15905.6
   },
   "member_spread_deg": {
    "lat": 36.08,
    "lon": 167.88
   },
   "member_spread_now_deg": {
    "lat": 0.75,
    "lon": 1.57
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 21:21:00",
   "seed_lat": 51.9375,
   "seed_lon": -68.66667,
   "seed_alt_m": 13160.0,
   "seed_age_h": 1.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 20:45:00",
    "lat": 44.78274,
    "lon": 162.89127,
    "alt_m": 13124.8
   },
   "member_spread_deg": {
    "lat": 19.24,
    "lon": 337.28
   },
   "member_spread_now_deg": {
    "lat": 1.05,
    "lon": 1.82
   },
   "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": 146.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": -18.86691,
    "lon": -23.40755,
    "alt_m": 12474.5
   },
   "member_spread_deg": {
    "lat": 24.52,
    "lon": 139.25
   },
   "member_spread_now_deg": {
    "lat": 9.77,
    "lon": 335.0
   },
   "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": 280.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 17:45:00",
    "lat": -17.65,
    "lon": 109.42884,
    "alt_m": 16053.1
   },
   "member_spread_deg": {
    "lat": 35.35,
    "lon": 218.23
   },
   "member_spread_now_deg": {
    "lat": 31.95,
    "lon": 213.78
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 08:01:00",
   "seed_lat": -21.5,
   "seed_lon": 112.91667,
   "seed_alt_m": 15710.0,
   "seed_age_h": 15.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 17:30:00",
    "lat": -31.32644,
    "lon": -33.75299,
    "alt_m": 15236.0
   },
   "member_spread_deg": {
    "lat": 34.19,
    "lon": 55.79
   },
   "member_spread_now_deg": {
    "lat": 5.0,
    "lon": 8.14
   },
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   "display_reason": "fresh"
  }
 ]
}