{
 "generated_utc": "2026-09-11T05:27:12Z",
 "gfs_cycle_utc": "2026-09-11T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 487.5,
  "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_20260911_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260911_00Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 68976
 },
 "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": 325.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 23:45:00",
    "lat": -69.12899,
    "lon": 101.79346,
    "alt_m": 12174.7
   },
   "member_spread_deg": {
    "lat": 33.53,
    "lon": 305.69
   },
   "member_spread_now_deg": {
    "lat": 15.64,
    "lon": 305.82
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 17:05:17",
   "seed_lat": 35.33333,
   "seed_lon": -19.45833,
   "seed_alt_m": 14660.0,
   "seed_age_h": 12.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 35.60847,
    "lon": 4.6193,
    "alt_m": 14171.1
   },
   "member_spread_deg": {
    "lat": 22.21,
    "lon": 62.86
   },
   "member_spread_now_deg": {
    "lat": 3.55,
    "lon": 2.83
   },
   "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": 144.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 23:45:00",
    "lat": 76.44407,
    "lon": -69.13738,
    "alt_m": 11604.7
   },
   "member_spread_deg": {
    "lat": 22.44,
    "lon": 344.65
   },
   "member_spread_now_deg": {
    "lat": 21.84,
    "lon": 111.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 18:42:00",
   "seed_lat": 31.89583,
   "seed_lon": -51.625,
   "seed_alt_m": 13630.0,
   "seed_age_h": 10.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:45:00",
    "lat": 33.71793,
    "lon": 8.41446,
    "alt_m": 13445.6
   },
   "member_spread_deg": {
    "lat": 28.1,
    "lon": 110.63
   },
   "member_spread_now_deg": {
    "lat": 2.87,
    "lon": 6.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 21:01:00",
   "seed_lat": 45.875,
   "seed_lon": -130.79167,
   "seed_alt_m": 13480.0,
   "seed_age_h": 8.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 44.67533,
    "lon": 48.73465,
    "alt_m": 13423.3
   },
   "member_spread_deg": {
    "lat": 27.13,
    "lon": 57.17
   },
   "member_spread_now_deg": {
    "lat": 4.27,
    "lon": 8.89
   },
   "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": 259.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 62.01998,
    "lon": -97.0549,
    "alt_m": 11839.3
   },
   "member_spread_deg": {
    "lat": 41.95,
    "lon": 343.27
   },
   "member_spread_now_deg": {
    "lat": 43.41,
    "lon": 309.37
   },
   "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": 135.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": -2.48092,
    "lon": 156.12224,
    "alt_m": 14636.5
   },
   "member_spread_deg": {
    "lat": 52.9,
    "lon": 327.27
   },
   "member_spread_now_deg": {
    "lat": 32.33,
    "lon": 265.41
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 05:25:00",
   "seed_lat": 48.52083,
   "seed_lon": 159.54167,
   "seed_alt_m": 12130.0,
   "seed_age_h": 23.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 28.8261,
    "lon": -55.93092,
    "alt_m": 12756.0
   },
   "member_spread_deg": {
    "lat": 21.75,
    "lon": 237.2
   },
   "member_spread_now_deg": {
    "lat": 13.92,
    "lon": 7.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 189.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 40.50232,
    "lon": 167.77929,
    "alt_m": 12837.1
   },
   "member_spread_deg": {
    "lat": 20.06,
    "lon": 345.71
   },
   "member_spread_now_deg": {
    "lat": 13.13,
    "lon": 326.95
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 01:15:00",
   "seed_lat": 41.3125,
   "seed_lon": 93.625,
   "seed_alt_m": 12640.0,
   "seed_age_h": 4.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 00:45:00",
    "lat": 46.18862,
    "lon": -135.40136,
    "alt_m": 12831.8
   },
   "member_spread_deg": {
    "lat": 15.79,
    "lon": 115.14
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 1.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 17:16:00",
   "seed_lat": 51.1875,
   "seed_lon": -40.375,
   "seed_alt_m": 12600.0,
   "seed_age_h": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:45:00",
    "lat": 50.37126,
    "lon": 148.57577,
    "alt_m": 12882.4
   },
   "member_spread_deg": {
    "lat": 20.7,
    "lon": 343.5
   },
   "member_spread_now_deg": {
    "lat": 1.76,
    "lon": 2.94
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 07:35:45",
   "seed_lat": 48.41661,
   "seed_lon": 121.04169,
   "seed_alt_m": 13390.0,
   "seed_age_h": 21.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 64.04241,
    "lon": 0.71704,
    "alt_m": 12830.8
   },
   "member_spread_deg": {
    "lat": 44.67,
    "lon": 100.17
   },
   "member_spread_now_deg": {
    "lat": 2.61,
    "lon": 10.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 02:18:00",
   "seed_lat": 22.95833,
   "seed_lon": -151.54167,
   "seed_alt_m": 16440.0,
   "seed_age_h": 3.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 01:45:00",
    "lat": 64.05229,
    "lon": -12.78578,
    "alt_m": 15306.4
   },
   "member_spread_deg": {
    "lat": 39.75,
    "lon": 344.29
   },
   "member_spread_now_deg": {
    "lat": 0.47,
    "lon": 2.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 16:31:00",
   "seed_lat": 31.3125,
   "seed_lon": 1.20833,
   "seed_alt_m": 13350.0,
   "seed_age_h": 12.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 45.8062,
    "lon": 158.32423,
    "alt_m": 13338.5
   },
   "member_spread_deg": {
    "lat": 12.39,
    "lon": 342.17
   },
   "member_spread_now_deg": {
    "lat": 1.69,
    "lon": 2.05
   },
   "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": 55.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 23:30:00",
    "lat": 48.43758,
    "lon": 123.15689,
    "alt_m": 13195.3
   },
   "member_spread_deg": {
    "lat": 26.7,
    "lon": 331.32
   },
   "member_spread_now_deg": {
    "lat": 6.89,
    "lon": 69.26
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 04:06:00",
   "seed_lat": -19.66667,
   "seed_lon": 62.66667,
   "seed_alt_m": 15590.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 04:00:00",
    "lat": -17.15805,
    "lon": 121.3569,
    "alt_m": 15641.8
   },
   "member_spread_deg": {
    "lat": 23.7,
    "lon": 302.58
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}