{
 "generated_utc": "2026-09-09T17:26:40Z",
 "gfs_cycle_utc": "2026-09-09T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 451.5,
  "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_20260909_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260909_12Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 61776
 },
 "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": 289.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 11:45:00",
    "lat": -67.59171,
    "lon": 57.86255,
    "alt_m": 12009.0
   },
   "member_spread_deg": {
    "lat": 15.78,
    "lon": 196.11
   },
   "member_spread_now_deg": {
    "lat": 22.56,
    "lon": 303.17
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 15:55:48",
   "seed_lat": 39.875,
   "seed_lon": -15.58333,
   "seed_alt_m": 14620.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 15:30:00",
    "lat": 38.39936,
    "lon": -3.25961,
    "alt_m": 14352.8
   },
   "member_spread_deg": {
    "lat": 21.84,
    "lon": 67.23
   },
   "member_spread_now_deg": {
    "lat": 0.59,
    "lon": 0.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 108.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 11:45:00",
    "lat": 78.60749,
    "lon": -106.76655,
    "alt_m": 11779.0
   },
   "member_spread_deg": {
    "lat": 24.77,
    "lon": 316.52
   },
   "member_spread_now_deg": {
    "lat": 25.68,
    "lon": 216.87
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 15:57:00",
   "seed_lat": 47.58333,
   "seed_lon": -68.625,
   "seed_alt_m": 13270.0,
   "seed_age_h": 1.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 15:30:00",
    "lat": 21.33047,
    "lon": -58.30562,
    "alt_m": 13645.1
   },
   "member_spread_deg": {
    "lat": 8.61,
    "lon": 84.08
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:36:00",
   "seed_lat": 50.91667,
   "seed_lon": 151.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 41.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 13.97937,
    "lon": 119.14842,
    "alt_m": 14040.0
   },
   "member_spread_deg": {
    "lat": 36.75,
    "lon": 246.71
   },
   "member_spread_now_deg": {
    "lat": 17.4,
    "lon": 355.03
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 223.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 72.03071,
    "lon": -158.16876,
    "alt_m": 11744.6
   },
   "member_spread_deg": {
    "lat": 48.82,
    "lon": 309.49
   },
   "member_spread_now_deg": {
    "lat": 38.22,
    "lon": 322.22
   },
   "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 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 99.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 29.77934,
    "lon": 145.76112,
    "alt_m": 14543.0
   },
   "member_spread_deg": {
    "lat": 35.29,
    "lon": 147.42
   },
   "member_spread_now_deg": {
    "lat": 22.49,
    "lon": 337.96
   },
   "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": 153.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 7.67129,
    "lon": 175.94711,
    "alt_m": 12859.7
   },
   "member_spread_deg": {
    "lat": 47.85,
    "lon": 249.0
   },
   "member_spread_now_deg": {
    "lat": 20.51,
    "lon": 305.14
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 14:15:00",
   "seed_lat": 37.16667,
   "seed_lon": 42.29167,
   "seed_alt_m": 12780.0,
   "seed_age_h": 3.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 13:45:00",
    "lat": 38.73634,
    "lon": -129.32174,
    "alt_m": 12816.7
   },
   "member_spread_deg": {
    "lat": 43.85,
    "lon": 238.56
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 1.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 16:51:00",
   "seed_lat": 42.33333,
   "seed_lon": -53.75,
   "seed_alt_m": 12370.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 16:45:00",
    "lat": 41.91911,
    "lon": 126.23959,
    "alt_m": 12789.8
   },
   "member_spread_deg": {
    "lat": 49.16,
    "lon": 139.09
   },
   "member_spread_now_deg": {
    "lat": 0.23,
    "lon": 0.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 09:35:45",
   "seed_lat": 59.81245,
   "seed_lon": 102.54169,
   "seed_alt_m": 13330.0,
   "seed_age_h": 7.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 77.71236,
    "lon": -58.83757,
    "alt_m": 12599.3
   },
   "member_spread_deg": {
    "lat": 29.56,
    "lon": 67.04
   },
   "member_spread_now_deg": {
    "lat": 3.33,
    "lon": 3.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 02:18:00",
   "seed_lat": 40.89583,
   "seed_lon": -153.54167,
   "seed_alt_m": 16360.0,
   "seed_age_h": 15.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 11:45:00",
    "lat": 52.96442,
    "lon": -58.92634,
    "alt_m": 15594.8
   },
   "member_spread_deg": {
    "lat": 40.62,
    "lon": 343.0
   },
   "member_spread_now_deg": {
    "lat": 8.39,
    "lon": 3.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 16:11:00",
   "seed_lat": 30.16667,
   "seed_lon": -7.83333,
   "seed_alt_m": 13400.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 15:45:00",
    "lat": 34.9414,
    "lon": 123.99236,
    "alt_m": 13382.0
   },
   "member_spread_deg": {
    "lat": 15.45,
    "lon": 136.21
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 21:35:23",
   "seed_lat": 52.33328,
   "seed_lon": -95.95831,
   "seed_alt_m": 12860.0,
   "seed_age_h": 19.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 11:30:00",
    "lat": 42.52941,
    "lon": 71.4523,
    "alt_m": 13179.6
   },
   "member_spread_deg": {
    "lat": 35.32,
    "lon": 79.83
   },
   "member_spread_now_deg": {
    "lat": 4.3,
    "lon": 8.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 13:36:00",
   "seed_lat": -15.125,
   "seed_lon": 40.41667,
   "seed_alt_m": 15630.0,
   "seed_age_h": 3.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-16 13:00:00",
    "lat": -17.89197,
    "lon": 135.90573,
    "alt_m": 15676.8
   },
   "member_spread_deg": {
    "lat": 30.04,
    "lon": 306.57
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 2.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}