{
 "generated_utc": "2026-09-09T05:27:03Z",
 "gfs_cycle_utc": "2026-09-09T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 488.0,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260909_00Z.geojson.gz"
 },
 "counts": {
  "flights": 17,
  "members": 9,
  "rows": 73269
 },
 "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": 277.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": -71.49521,
    "lon": 4.04572,
    "alt_m": 12069.6
   },
   "member_spread_deg": {
    "lat": 31.76,
    "lon": 269.62
   },
   "member_spread_now_deg": {
    "lat": 16.05,
    "lon": 183.88
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 19:10:19",
   "seed_lat": 33.60417,
   "seed_lon": -62.70833,
   "seed_alt_m": 14540.0,
   "seed_age_h": 34.16,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 33.71395,
    "lon": -14.01348,
    "alt_m": 14447.5
   },
   "member_spread_deg": {
    "lat": 21.42,
    "lon": 56.63
   },
   "member_spread_now_deg": {
    "lat": 5.25,
    "lon": 26.18
   },
   "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": 96.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 78.62003,
    "lon": -137.90209,
    "alt_m": 11621.7
   },
   "member_spread_deg": {
    "lat": 16.37,
    "lon": 318.11
   },
   "member_spread_now_deg": {
    "lat": 21.24,
    "lon": 180.46
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 22:07:00",
   "seed_lat": 48.27083,
   "seed_lon": -99.75,
   "seed_alt_m": 13110.0,
   "seed_age_h": 7.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 23.63115,
    "lon": -62.03935,
    "alt_m": 13672.3
   },
   "member_spread_deg": {
    "lat": 22.0,
    "lon": 145.6
   },
   "member_spread_now_deg": {
    "lat": 0.97,
    "lon": 7.44
   },
   "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": 29.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 38.40637,
    "lon": 174.29212,
    "alt_m": 13972.5
   },
   "member_spread_deg": {
    "lat": 42.84,
    "lon": 269.34
   },
   "member_spread_now_deg": {
    "lat": 11.74,
    "lon": 359.88
   },
   "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": 211.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 53.64086,
    "lon": -119.18249,
    "alt_m": 12222.1
   },
   "member_spread_deg": {
    "lat": 35.29,
    "lon": 298.21
   },
   "member_spread_now_deg": {
    "lat": 34.16,
    "lon": 310.29
   },
   "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": 87.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 24.77457,
    "lon": 159.8866,
    "alt_m": 14515.1
   },
   "member_spread_deg": {
    "lat": 40.61,
    "lon": 179.99
   },
   "member_spread_now_deg": {
    "lat": 16.81,
    "lon": 356.76
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 08:15:00",
   "seed_lat": 40.16667,
   "seed_lon": 61.0,
   "seed_alt_m": 12620.0,
   "seed_age_h": 21.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 43.81412,
    "lon": -98.7824,
    "alt_m": 12519.1
   },
   "member_spread_deg": {
    "lat": 13.21,
    "lon": 148.04
   },
   "member_spread_now_deg": {
    "lat": 5.99,
    "lon": 13.14
   },
   "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": 141.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 19.20494,
    "lon": 169.78089,
    "alt_m": 12886.2
   },
   "member_spread_deg": {
    "lat": 26.3,
    "lon": 263.37
   },
   "member_spread_now_deg": {
    "lat": 31.58,
    "lon": 297.12
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 16:10:00",
   "seed_lat": 33.625,
   "seed_lon": 12.33333,
   "seed_alt_m": 12860.0,
   "seed_age_h": 13.17,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 35.24378,
    "lon": -141.57572,
    "alt_m": 12837.4
   },
   "member_spread_deg": {
    "lat": 22.84,
    "lon": 301.75
   },
   "member_spread_now_deg": {
    "lat": 1.39,
    "lon": 5.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 18:51:00",
   "seed_lat": 51.25,
   "seed_lon": -68.91667,
   "seed_alt_m": 12340.0,
   "seed_age_h": 10.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 52.21459,
    "lon": 92.6867,
    "alt_m": 12610.5
   },
   "member_spread_deg": {
    "lat": 43.9,
    "lon": 298.09
   },
   "member_spread_now_deg": {
    "lat": 5.05,
    "lon": 1.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 04:55:45",
   "seed_lat": 62.22911,
   "seed_lon": 96.25002,
   "seed_alt_m": 13420.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 05:00:00",
    "lat": 67.6057,
    "lon": -20.45771,
    "alt_m": 12930.8
   },
   "member_spread_deg": {
    "lat": 24.22,
    "lon": 131.84
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.71
   },
   "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": 325.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 40.70106,
    "lon": -8.92598,
    "alt_m": 13412.5
   },
   "member_spread_deg": {
    "lat": 35.65,
    "lon": 299.29
   },
   "member_spread_now_deg": {
    "lat": 38.88,
    "lon": 123.9
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 3.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 01:45:00",
    "lat": 47.02697,
    "lon": -73.48965,
    "alt_m": 15939.8
   },
   "member_spread_deg": {
    "lat": 38.08,
    "lon": 353.75
   },
   "member_spread_now_deg": {
    "lat": 0.96,
    "lon": 2.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 17:16:00",
   "seed_lat": 37.5,
   "seed_lon": -12.41667,
   "seed_alt_m": 13540.0,
   "seed_age_h": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:45:00",
    "lat": 46.9989,
    "lon": 92.71754,
    "alt_m": 13194.4
   },
   "member_spread_deg": {
    "lat": 19.27,
    "lon": 126.74
   },
   "member_spread_now_deg": {
    "lat": 4.34,
    "lon": 3.85
   },
   "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": 7.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": 46.95148,
    "lon": 77.55785,
    "alt_m": 13128.1
   },
   "member_spread_deg": {
    "lat": 33.41,
    "lon": 61.82
   },
   "member_spread_now_deg": {
    "lat": 2.03,
    "lon": 0.77
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 13:06:00",
   "seed_lat": -17.85417,
   "seed_lon": 31.875,
   "seed_alt_m": 15640.0,
   "seed_age_h": 16.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 23:30:00",
    "lat": -17.47093,
    "lon": 130.18525,
    "alt_m": 15600.4
   },
   "member_spread_deg": {
    "lat": 24.16,
    "lon": 312.31
   },
   "member_spread_now_deg": {
    "lat": 1.5,
    "lon": 9.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}