{
 "generated_utc": "2026-09-02T05:25:24Z",
 "gfs_cycle_utc": "2026-09-02T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 369.5,
  "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_20260902_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260902_00Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 64602
 },
 "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": 109.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": -64.24564,
    "lon": 128.11686,
    "alt_m": 12529.0
   },
   "member_spread_deg": {
    "lat": 19.45,
    "lon": 87.95
   },
   "member_spread_now_deg": {
    "lat": 14.93,
    "lon": 295.64
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 23:04:18",
   "seed_lat": 53.97917,
   "seed_lon": 172.375,
   "seed_alt_m": 13860.0,
   "seed_age_h": 30.26,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": 26.64688,
    "lon": -79.93136,
    "alt_m": 14586.3
   },
   "member_spread_deg": {
    "lat": 25.61,
    "lon": 48.65
   },
   "member_spread_now_deg": {
    "lat": 16.89,
    "lon": 14.77
   },
   "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": 175.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": 31.89067,
    "lon": -95.86495,
    "alt_m": 13167.1
   },
   "member_spread_deg": {
    "lat": 46.28,
    "lon": 92.87
   },
   "member_spread_now_deg": {
    "lat": 16.86,
    "lon": 24.67
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 15:06:00",
   "seed_lat": 68.20833,
   "seed_lon": 3.5,
   "seed_alt_m": 12060.0,
   "seed_age_h": 14.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": 72.21539,
    "lon": 59.03253,
    "alt_m": 12068.3
   },
   "member_spread_deg": {
    "lat": 13.2,
    "lon": 238.22
   },
   "member_spread_now_deg": {
    "lat": 5.11,
    "lon": 7.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 04:42:00",
   "seed_lat": 46.5625,
   "seed_lon": 62.875,
   "seed_alt_m": 13040.0,
   "seed_age_h": 0.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 04:45:00",
    "lat": 64.64142,
    "lon": -116.33331,
    "alt_m": 12848.9
   },
   "member_spread_deg": {
    "lat": 34.56,
    "lon": 60.11
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.16
   },
   "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": 43.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": 59.63792,
    "lon": 148.03607,
    "alt_m": 11713.7
   },
   "member_spread_deg": {
    "lat": 20.56,
    "lon": 215.93
   },
   "member_spread_now_deg": {
    "lat": 14.18,
    "lon": 88.52
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 207.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": 61.73371,
    "lon": -116.59618,
    "alt_m": 12930.1
   },
   "member_spread_deg": {
    "lat": 31.31,
    "lon": 289.27
   },
   "member_spread_now_deg": {
    "lat": 22.3,
    "lon": 285.01
   },
   "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": 190.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": 31.75402,
    "lon": 169.24631,
    "alt_m": 13913.5
   },
   "member_spread_deg": {
    "lat": 50.67,
    "lon": 344.61
   },
   "member_spread_now_deg": {
    "lat": 26.1,
    "lon": 226.46
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 03:46:30",
   "seed_lat": 31.875,
   "seed_lon": 112.08333,
   "seed_alt_m": 12660.0,
   "seed_age_h": 1.56,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 03:15:00",
    "lat": 25.69618,
    "lon": 146.31169,
    "alt_m": 12871.9
   },
   "member_spread_deg": {
    "lat": 49.77,
    "lon": 303.8
   },
   "member_spread_now_deg": {
    "lat": 0.65,
    "lon": 0.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 21:10:00",
   "seed_lat": 31.29167,
   "seed_lon": -62.75,
   "seed_alt_m": 13100.0,
   "seed_age_h": 8.17,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": 32.73323,
    "lon": 10.80309,
    "alt_m": 12948.3
   },
   "member_spread_deg": {
    "lat": 12.05,
    "lon": 65.72
   },
   "member_spread_now_deg": {
    "lat": 0.78,
    "lon": 0.56
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 04:26:00",
   "seed_lat": 66.25,
   "seed_lon": 146.66667,
   "seed_alt_m": 12460.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 04:00:00",
    "lat": 54.1896,
    "lon": -62.55638,
    "alt_m": 12053.2
   },
   "member_spread_deg": {
    "lat": 34.71,
    "lon": 179.14
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 0.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 19:45:45",
   "seed_lat": 66.64578,
   "seed_lon": -43.24998,
   "seed_alt_m": 12960.0,
   "seed_age_h": 9.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": 60.69929,
    "lon": 48.40354,
    "alt_m": 13271.1
   },
   "member_spread_deg": {
    "lat": 24.47,
    "lon": 43.5
   },
   "member_spread_now_deg": {
    "lat": 2.96,
    "lon": 3.39
   },
   "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": 157.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": 48.86809,
    "lon": 23.09423,
    "alt_m": 13240.6
   },
   "member_spread_deg": {
    "lat": 18.75,
    "lon": 73.84
   },
   "member_spread_now_deg": {
    "lat": 27.43,
    "lon": 40.73
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 23:21:00",
   "seed_lat": 40.39583,
   "seed_lon": 126.58333,
   "seed_alt_m": 16040.0,
   "seed_age_h": 5.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 23:45:00",
    "lat": 24.40431,
    "lon": -166.01194,
    "alt_m": 16425.7
   },
   "member_spread_deg": {
    "lat": 43.86,
    "lon": 145.7
   },
   "member_spread_now_deg": {
    "lat": 2.45,
    "lon": 6.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-02 02:36:00",
   "seed_lat": 39.8125,
   "seed_lon": -156.66667,
   "seed_alt_m": 13650.0,
   "seed_age_h": 2.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-09 02:00:00",
    "lat": 52.13485,
    "lon": 20.03878,
    "alt_m": 13186.9
   },
   "member_spread_deg": {
    "lat": 16.79,
    "lon": 129.18
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 0.93
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 18:26:00",
   "seed_lat": -21.41667,
   "seed_lon": -36.70833,
   "seed_alt_m": 15750.0,
   "seed_age_h": 10.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 23:30:00",
    "lat": -31.68937,
    "lon": 32.24106,
    "alt_m": 15465.2
   },
   "member_spread_deg": {
    "lat": 36.16,
    "lon": 55.17
   },
   "member_spread_now_deg": {
    "lat": 4.35,
    "lon": 3.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}