{
 "generated_utc": "2026-09-05T11:26:30Z",
 "gfs_cycle_utc": "2026-09-05T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 447.5,
  "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_20260905_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260905_06Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 82539
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 187.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": -55.3276,
    "lon": -115.64998,
    "alt_m": 12337.3
   },
   "member_spread_deg": {
    "lat": 33.48,
    "lon": 310.57
   },
   "member_spread_now_deg": {
    "lat": 24.83,
    "lon": 67.71
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 00:17:49",
   "seed_lat": 40.33333,
   "seed_lon": -102.5,
   "seed_alt_m": 14550.0,
   "seed_age_h": 11.04,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": 32.74502,
    "lon": 14.18387,
    "alt_m": 14175.3
   },
   "member_spread_deg": {
    "lat": 17.22,
    "lon": 113.74
   },
   "member_spread_now_deg": {
    "lat": 0.55,
    "lon": 6.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:29:00",
   "seed_lat": 33.10417,
   "seed_lon": -84.75,
   "seed_alt_m": 13050.0,
   "seed_age_h": 253.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 4.0941,
    "lon": -53.43391,
    "alt_m": 13167.4
   },
   "member_spread_deg": {
    "lat": 32.19,
    "lon": 90.04
   },
   "member_spread_now_deg": {
    "lat": 19.93,
    "lon": 51.18
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 04:41:00",
   "seed_lat": 86.0,
   "seed_lon": 110.20833,
   "seed_alt_m": 11660.0,
   "seed_age_h": 6.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": 83.67917,
    "lon": -70.81423,
    "alt_m": 11650.2
   },
   "member_spread_deg": {
    "lat": 9.18,
    "lon": 209.24
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 1.53
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 06:27:00",
   "seed_lat": 41.83333,
   "seed_lon": 143.0,
   "seed_alt_m": 13010.0,
   "seed_age_h": 4.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 06:00:00",
    "lat": 58.59708,
    "lon": -33.10922,
    "alt_m": 12954.7
   },
   "member_spread_deg": {
    "lat": 37.03,
    "lon": 90.02
   },
   "member_spread_now_deg": {
    "lat": 1.19,
    "lon": 2.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 09:41:00",
   "seed_lat": 46.375,
   "seed_lon": 57.29167,
   "seed_alt_m": 13450.0,
   "seed_age_h": 1.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 09:15:00",
    "lat": 43.39525,
    "lon": -162.9858,
    "alt_m": 13854.0
   },
   "member_spread_deg": {
    "lat": 36.31,
    "lon": 299.62
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 121.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 60.53158,
    "lon": -169.82556,
    "alt_m": 11664.8
   },
   "member_spread_deg": {
    "lat": 29.77,
    "lon": 326.14
   },
   "member_spread_now_deg": {
    "lat": 35.04,
    "lon": 338.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 10:01:15",
   "seed_lat": 46.375,
   "seed_lon": 57.04167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 1.31,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-12 09:30:00",
    "lat": 42.54829,
    "lon": -160.23894,
    "alt_m": 14434.5
   },
   "member_spread_deg": {
    "lat": 32.77,
    "lon": 328.43
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 285.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": 23.27515,
    "lon": -72.09986,
    "alt_m": 13520.6
   },
   "member_spread_deg": {
    "lat": 43.21,
    "lon": 262.95
   },
   "member_spread_now_deg": {
    "lat": 19.83,
    "lon": 265.33
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 06:33:48",
   "seed_lat": 61.6875,
   "seed_lon": -165.70833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 268.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 34.93023,
    "lon": -152.01718,
    "alt_m": 13964.4
   },
   "member_spread_deg": {
    "lat": 45.63,
    "lon": 324.71
   },
   "member_spread_now_deg": {
    "lat": 38.06,
    "lon": 173.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 51.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 28.84932,
    "lon": 117.02526,
    "alt_m": 12872.7
   },
   "member_spread_deg": {
    "lat": 27.76,
    "lon": 337.46
   },
   "member_spread_now_deg": {
    "lat": 3.82,
    "lon": 357.51
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 10:40:00",
   "seed_lat": 28.27083,
   "seed_lon": -18.54167,
   "seed_alt_m": 12980.0,
   "seed_age_h": 0.67,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 10:15:00",
    "lat": 45.46296,
    "lon": 83.0344,
    "alt_m": 12860.7
   },
   "member_spread_deg": {
    "lat": 7.96,
    "lon": 37.22
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 02:36:00",
   "seed_lat": 55.70833,
   "seed_lon": -173.95833,
   "seed_alt_m": 12060.0,
   "seed_age_h": 8.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 41.58031,
    "lon": 8.5067,
    "alt_m": 12702.6
   },
   "member_spread_deg": {
    "lat": 31.33,
    "lon": 77.79
   },
   "member_spread_now_deg": {
    "lat": 0.23,
    "lon": 4.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 10:55:45",
   "seed_lat": 58.89578,
   "seed_lon": 12.20835,
   "seed_alt_m": 13000.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:00:00",
    "lat": 58.66472,
    "lon": -165.79242,
    "alt_m": 13003.6
   },
   "member_spread_deg": {
    "lat": 12.16,
    "lon": 355.96
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 235.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": 41.52121,
    "lon": 1.62373,
    "alt_m": 13285.7
   },
   "member_spread_deg": {
    "lat": 24.38,
    "lon": 157.63
   },
   "member_spread_now_deg": {
    "lat": 14.65,
    "lon": 76.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 03:01:00",
   "seed_lat": 35.79167,
   "seed_lon": -162.375,
   "seed_alt_m": 16200.0,
   "seed_age_h": 8.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 27.65167,
    "lon": -161.92952,
    "alt_m": 16519.9
   },
   "member_spread_deg": {
    "lat": 25.97,
    "lon": 348.58
   },
   "member_spread_now_deg": {
    "lat": 3.79,
    "lon": 1.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 00:41:00",
   "seed_lat": 40.0,
   "seed_lon": -118.95833,
   "seed_alt_m": 13080.0,
   "seed_age_h": 10.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:45:00",
    "lat": 53.02744,
    "lon": 67.25556,
    "alt_m": 13047.2
   },
   "member_spread_deg": {
    "lat": 31.62,
    "lon": 83.81
   },
   "member_spread_now_deg": {
    "lat": 4.91,
    "lon": 5.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-04 23:05:23",
   "seed_lat": 65.56245,
   "seed_lon": -134.08331,
   "seed_alt_m": 13180.0,
   "seed_age_h": 12.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 05:30:00",
    "lat": 23.91986,
    "lon": -55.01243,
    "alt_m": 13868.3
   },
   "member_spread_deg": {
    "lat": 42.25,
    "lon": 122.22
   },
   "member_spread_now_deg": {
    "lat": 6.83,
    "lon": 4.92
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 10:51:00",
   "seed_lat": -31.91667,
   "seed_lon": 11.79167,
   "seed_alt_m": 15480.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 10:15:00",
    "lat": -25.0284,
    "lon": 77.76833,
    "alt_m": 15499.3
   },
   "member_spread_deg": {
    "lat": 18.01,
    "lon": 290.02
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}