{
 "generated_utc": "2026-08-31T05:26:53Z",
 "gfs_cycle_utc": "2026-08-31T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 482.5,
  "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_20260831_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260831_00Z.geojson.gz"
 },
 "counts": {
  "flights": 17,
  "members": 9,
  "rows": 68067
 },
 "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": 61.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": -45.99878,
    "lon": 64.48427,
    "alt_m": 12242.2
   },
   "member_spread_deg": {
    "lat": 23.14,
    "lon": 124.33
   },
   "member_spread_now_deg": {
    "lat": 14.94,
    "lon": 63.13
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 04:48:48",
   "seed_lat": 43.64583,
   "seed_lon": 151.83333,
   "seed_alt_m": 13970.0,
   "seed_age_h": 0.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-07 04:45:00",
    "lat": 34.6185,
    "lon": -76.01287,
    "alt_m": 14311.8
   },
   "member_spread_deg": {
    "lat": 12.55,
    "lon": 45.77
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.54
   },
   "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": 127.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:30:00",
    "lat": 19.47495,
    "lon": -104.67532,
    "alt_m": 13166.1
   },
   "member_spread_deg": {
    "lat": 15.44,
    "lon": 62.79
   },
   "member_spread_now_deg": {
    "lat": 12.82,
    "lon": 24.92
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 17:11:00",
   "seed_lat": 62.79167,
   "seed_lon": -38.45833,
   "seed_alt_m": 12130.0,
   "seed_age_h": 12.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 71.31272,
    "lon": -172.94255,
    "alt_m": 11922.9
   },
   "member_spread_deg": {
    "lat": 23.25,
    "lon": 194.48
   },
   "member_spread_now_deg": {
    "lat": 0.88,
    "lon": 6.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 15:47:00",
   "seed_lat": 50.16667,
   "seed_lon": 16.875,
   "seed_alt_m": 13220.0,
   "seed_age_h": 13.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 52.76436,
    "lon": -139.34978,
    "alt_m": 12931.4
   },
   "member_spread_deg": {
    "lat": 26.05,
    "lon": 326.44
   },
   "member_spread_now_deg": {
    "lat": 5.58,
    "lon": 3.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 04:23:00",
   "seed_lat": 59.04167,
   "seed_lon": 88.75,
   "seed_alt_m": 11880.0,
   "seed_age_h": 0.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-07 04:00:00",
    "lat": 72.21521,
    "lon": -4.56778,
    "alt_m": 12106.7
   },
   "member_spread_deg": {
    "lat": 27.81,
    "lon": 328.25
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.07
   },
   "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": 159.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 64.58749,
    "lon": -114.71052,
    "alt_m": 12771.1
   },
   "member_spread_deg": {
    "lat": 20.72,
    "lon": 286.56
   },
   "member_spread_now_deg": {
    "lat": 20.34,
    "lon": 302.85
   },
   "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": 142.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:30:00",
    "lat": 58.34988,
    "lon": 84.42092,
    "alt_m": 13265.6
   },
   "member_spread_deg": {
    "lat": 44.35,
    "lon": 225.5
   },
   "member_spread_now_deg": {
    "lat": 32.46,
    "lon": 210.92
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 00:39:00",
   "seed_lat": 37.72917,
   "seed_lon": 102.75,
   "seed_alt_m": 12510.0,
   "seed_age_h": 4.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-07 00:15:00",
    "lat": 27.15979,
    "lon": 155.89116,
    "alt_m": 12701.2
   },
   "member_spread_deg": {
    "lat": 45.01,
    "lon": 277.92
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 23:25:00",
   "seed_lat": 45.10417,
   "seed_lon": -99.54167,
   "seed_alt_m": 12890.0,
   "seed_age_h": 5.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:30:00",
    "lat": 24.95488,
    "lon": -34.26344,
    "alt_m": 13079.8
   },
   "member_spread_deg": {
    "lat": 17.64,
    "lon": 49.64
   },
   "member_spread_now_deg": {
    "lat": 1.21,
    "lon": 4.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 11:11:00",
   "seed_lat": 53.6875,
   "seed_lon": 74.70833,
   "seed_alt_m": 12000.0,
   "seed_age_h": 18.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 66.42762,
    "lon": -111.88369,
    "alt_m": 12209.7
   },
   "member_spread_deg": {
    "lat": 19.77,
    "lon": 321.49
   },
   "member_spread_now_deg": {
    "lat": 5.46,
    "lon": 1.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 21:45:45",
   "seed_lat": 81.47911,
   "seed_lon": -97.12498,
   "seed_alt_m": 12900.0,
   "seed_age_h": 7.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 51.52842,
    "lon": 29.65404,
    "alt_m": 13077.5
   },
   "member_spread_deg": {
    "lat": 27.77,
    "lon": 63.79
   },
   "member_spread_now_deg": {
    "lat": 2.27,
    "lon": 16.89
   },
   "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": 109.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 23:45:00",
    "lat": 46.14582,
    "lon": -47.07653,
    "alt_m": 12971.4
   },
   "member_spread_deg": {
    "lat": 21.31,
    "lon": 50.06
   },
   "member_spread_now_deg": {
    "lat": 12.64,
    "lon": 26.32
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 04:41:00",
   "seed_lat": 44.89583,
   "seed_lon": 84.875,
   "seed_alt_m": 16070.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-07 04:45:00",
    "lat": 25.55054,
    "lon": 179.10012,
    "alt_m": 16341.7
   },
   "member_spread_deg": {
    "lat": 40.87,
    "lon": 353.44
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 04:16:00",
   "seed_lat": 57.25,
   "seed_lon": -179.33333,
   "seed_alt_m": 13330.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-07 03:45:00",
    "lat": 40.6802,
    "lon": -124.47275,
    "alt_m": 13380.2
   },
   "member_spread_deg": {
    "lat": 32.12,
    "lon": 147.63
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 1.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 20:59:00",
   "seed_lat": -20.58333,
   "seed_lon": -72.33333,
   "seed_alt_m": 12210.0,
   "seed_age_h": 320.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 23:30:00",
    "lat": -29.34231,
    "lon": -74.67527,
    "alt_m": 12151.4
   },
   "member_spread_deg": {
    "lat": 20.46,
    "lon": 237.75
   },
   "member_spread_now_deg": {
    "lat": 27.09,
    "lon": 108.24
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 20:26:00",
   "seed_lat": -18.0,
   "seed_lon": -59.16667,
   "seed_alt_m": 15810.0,
   "seed_age_h": 8.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 23:30:00",
    "lat": -10.91771,
    "lon": -61.46282,
    "alt_m": 15724.1
   },
   "member_spread_deg": {
    "lat": 6.82,
    "lon": 42.95
   },
   "member_spread_now_deg": {
    "lat": 3.16,
    "lon": 0.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}