{
 "generated_utc": "2026-08-19T23:26:07Z",
 "gfs_cycle_utc": "2026-08-19T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 401.5,
  "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_20260819_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260819_18Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 80487
 },
 "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": 23.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": -54.50882,
    "lon": 179.11911,
    "alt_m": 12450.0
   },
   "member_spread_deg": {
    "lat": 23.9,
    "lon": 330.79
   },
   "member_spread_now_deg": {
    "lat": 0.69,
    "lon": 2.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 05:41:19",
   "seed_lat": 67.33333,
   "seed_lon": 165.91667,
   "seed_alt_m": 12380.0,
   "seed_age_h": 17.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 73.50652,
    "lon": 9.84418,
    "alt_m": 12228.1
   },
   "member_spread_deg": {
    "lat": 37.18,
    "lon": 115.1
   },
   "member_spread_now_deg": {
    "lat": 6.27,
    "lon": 359.64
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 3.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 19:30:00",
    "lat": 39.9347,
    "lon": -2.2976,
    "alt_m": 14179.6
   },
   "member_spread_deg": {
    "lat": 30.14,
    "lon": 89.99
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 2.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 06:59:00",
   "seed_lat": 46.29167,
   "seed_lon": 130.91667,
   "seed_alt_m": 12620.0,
   "seed_age_h": 16.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:30:00",
    "lat": 39.55308,
    "lon": -64.71692,
    "alt_m": 12933.0
   },
   "member_spread_deg": {
    "lat": 44.06,
    "lon": 99.33
   },
   "member_spread_now_deg": {
    "lat": 4.16,
    "lon": 12.5
   },
   "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": 239.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": -2.8898,
    "lon": -50.31128,
    "alt_m": 13999.1
   },
   "member_spread_deg": {
    "lat": 61.62,
    "lon": 166.91
   },
   "member_spread_now_deg": {
    "lat": 49.84,
    "lon": 107.18
   },
   "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": 6.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 53.14285,
    "lon": -155.29181,
    "alt_m": 12910.3
   },
   "member_spread_deg": {
    "lat": 19.21,
    "lon": 344.53
   },
   "member_spread_now_deg": {
    "lat": 0.9,
    "lon": 3.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 07:32:00",
   "seed_lat": 45.77083,
   "seed_lon": 107.54167,
   "seed_alt_m": 13210.0,
   "seed_age_h": 15.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:30:00",
    "lat": 30.59333,
    "lon": -162.19185,
    "alt_m": 13254.1
   },
   "member_spread_deg": {
    "lat": 27.84,
    "lon": 78.96
   },
   "member_spread_now_deg": {
    "lat": 3.51,
    "lon": 7.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 14:13:00",
   "seed_lat": 83.8125,
   "seed_lon": 55.95833,
   "seed_alt_m": 11940.0,
   "seed_age_h": 9.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 76.21623,
    "lon": -16.55484,
    "alt_m": 11882.9
   },
   "member_spread_deg": {
    "lat": 13.24,
    "lon": 327.98
   },
   "member_spread_now_deg": {
    "lat": 0.61,
    "lon": 14.03
   },
   "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": 6.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 57.82441,
    "lon": 52.49051,
    "alt_m": 12419.8
   },
   "member_spread_deg": {
    "lat": 8.79,
    "lon": 132.22
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 0.68
   },
   "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": 98.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 21.02504,
    "lon": -95.20682,
    "alt_m": 13377.7
   },
   "member_spread_deg": {
    "lat": 22.77,
    "lon": 106.99
   },
   "member_spread_now_deg": {
    "lat": 24.72,
    "lon": 42.95
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 22:09:03",
   "seed_lat": 76.60417,
   "seed_lon": 77.16667,
   "seed_alt_m": 13220.0,
   "seed_age_h": 1.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 21:45:00",
    "lat": 58.36329,
    "lon": -168.32358,
    "alt_m": 13383.4
   },
   "member_spread_deg": {
    "lat": 11.31,
    "lon": 316.22
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.52
   },
   "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": 179.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 54.8312,
    "lon": 98.1494,
    "alt_m": 12579.5
   },
   "member_spread_deg": {
    "lat": 48.42,
    "lon": 300.35
   },
   "member_spread_now_deg": {
    "lat": 23.02,
    "lon": 282.79
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 22:25:00",
   "seed_lat": 46.5,
   "seed_lon": 167.375,
   "seed_alt_m": 13130.0,
   "seed_age_h": 0.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 22:30:00",
    "lat": 46.30186,
    "lon": -111.31946,
    "alt_m": 12992.5
   },
   "member_spread_deg": {
    "lat": 23.06,
    "lon": 72.65
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.58
   },
   "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": 5.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:30:00",
    "lat": 72.98902,
    "lon": 159.33369,
    "alt_m": 11913.3
   },
   "member_spread_deg": {
    "lat": 33.53,
    "lon": 310.82
   },
   "member_spread_now_deg": {
    "lat": 1.44,
    "lon": 3.44
   },
   "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": 146.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 46.56673,
    "lon": 76.82317,
    "alt_m": 11106.4
   },
   "member_spread_deg": {
    "lat": 24.12,
    "lon": 208.45
   },
   "member_spread_now_deg": {
    "lat": 17.39,
    "lon": 95.78
   },
   "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": 14.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:30:00",
    "lat": 73.48161,
    "lon": 146.09863,
    "alt_m": 12950.8
   },
   "member_spread_deg": {
    "lat": 20.68,
    "lon": 343.65
   },
   "member_spread_now_deg": {
    "lat": 0.98,
    "lon": 4.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:38:00",
   "seed_lat": 10.89583,
   "seed_lon": 88.58333,
   "seed_alt_m": 16500.0,
   "seed_age_h": 12.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": 25.23899,
    "lon": -15.0506,
    "alt_m": 16536.3
   },
   "member_spread_deg": {
    "lat": 18.47,
    "lon": 17.85
   },
   "member_spread_now_deg": {
    "lat": 2.49,
    "lon": 4.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 21:56:00",
   "seed_lat": 39.04167,
   "seed_lon": -144.79167,
   "seed_alt_m": 13460.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 21:30:00",
    "lat": 35.96224,
    "lon": 18.62501,
    "alt_m": 13605.8
   },
   "member_spread_deg": {
    "lat": 37.29,
    "lon": 135.46
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 0.07
   },
   "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": 3.04,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 19:45:00",
    "lat": 55.5386,
    "lon": -1.55916,
    "alt_m": 13264.8
   },
   "member_spread_deg": {
    "lat": 22.41,
    "lon": 18.9
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.66
   },
   "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": 50.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 17:30:00",
    "lat": -23.22745,
    "lon": 59.02234,
    "alt_m": 12395.6
   },
   "member_spread_deg": {
    "lat": 24.51,
    "lon": 292.75
   },
   "member_spread_now_deg": {
    "lat": 31.46,
    "lon": 74.24
   },
   "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": 184.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 17:45:00",
    "lat": -34.40864,
    "lon": 27.27239,
    "alt_m": 15639.4
   },
   "member_spread_deg": {
    "lat": 33.39,
    "lon": 280.95
   },
   "member_spread_now_deg": {
    "lat": 26.15,
    "lon": 151.85
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}