{
 "generated_utc": "2026-08-24T23:27:11Z",
 "gfs_cycle_utc": "2026-08-24T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 467.5,
  "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_20260824_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260824_18Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 88110
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 13:43:40",
   "seed_lat": -61.64583,
   "seed_lon": 25.04168,
   "seed_alt_m": 12480.0,
   "seed_age_h": 57.61,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": -66.49795,
    "lon": 112.39187,
    "alt_m": 11988.1
   },
   "member_spread_deg": {
    "lat": 28.79,
    "lon": 255.73
   },
   "member_spread_now_deg": {
    "lat": 9.02,
    "lon": 64.84
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:47:17",
   "seed_lat": 57.39583,
   "seed_lon": -60.0,
   "seed_alt_m": 13900.0,
   "seed_age_h": 6.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 49.67546,
    "lon": 167.6028,
    "alt_m": 13958.4
   },
   "member_spread_deg": {
    "lat": 14.28,
    "lon": 351.14
   },
   "member_spread_now_deg": {
    "lat": 4.33,
    "lon": 13.57
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 22:09:00",
   "seed_lat": 46.33333,
   "seed_lon": -102.45833,
   "seed_alt_m": 12920.0,
   "seed_age_h": 1.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 21:45:00",
    "lat": 49.22349,
    "lon": 53.32108,
    "alt_m": 12848.0
   },
   "member_spread_deg": {
    "lat": 45.06,
    "lon": 52.23
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 08:01:00",
   "seed_lat": 51.77083,
   "seed_lon": 124.25,
   "seed_alt_m": 12400.0,
   "seed_age_h": 15.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:30:00",
    "lat": 48.56166,
    "lon": -105.11086,
    "alt_m": 12709.6
   },
   "member_spread_deg": {
    "lat": 18.47,
    "lon": 107.29
   },
   "member_spread_now_deg": {
    "lat": 0.67,
    "lon": 6.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 21:07:00",
   "seed_lat": 34.77083,
   "seed_lon": -134.08333,
   "seed_alt_m": 13320.0,
   "seed_age_h": 2.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 20:30:00",
    "lat": 54.30187,
    "lon": 41.91569,
    "alt_m": 13069.2
   },
   "member_spread_deg": {
    "lat": 20.6,
    "lon": 86.31
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 21:03:00",
   "seed_lat": 78.79167,
   "seed_lon": -110.04167,
   "seed_alt_m": 11860.0,
   "seed_age_h": 2.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 20:30:00",
    "lat": 67.44995,
    "lon": -151.79136,
    "alt_m": 11871.5
   },
   "member_spread_deg": {
    "lat": 37.18,
    "lon": 278.52
   },
   "member_spread_now_deg": {
    "lat": 1.17,
    "lon": 1.58
   },
   "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": 9.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 49.31862,
    "lon": 124.29618,
    "alt_m": 12655.0
   },
   "member_spread_deg": {
    "lat": 26.3,
    "lon": 326.97
   },
   "member_spread_now_deg": {
    "lat": 4.51,
    "lon": 8.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 218.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 24.50018,
    "lon": -62.31246,
    "alt_m": 13350.9
   },
   "member_spread_deg": {
    "lat": 43.58,
    "lon": 292.96
   },
   "member_spread_now_deg": {
    "lat": 35.03,
    "lon": 107.57
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 22:57:03",
   "seed_lat": 57.95833,
   "seed_lon": -177.5,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 23:00:00",
    "lat": 56.01774,
    "lon": -58.4308,
    "alt_m": 13481.5
   },
   "member_spread_deg": {
    "lat": 33.77,
    "lon": 263.69
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.72
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 299.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 53.20489,
    "lon": 130.43584,
    "alt_m": 12607.3
   },
   "member_spread_deg": {
    "lat": 29.17,
    "lon": 310.37
   },
   "member_spread_now_deg": {
    "lat": 37.19,
    "lon": 298.71
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:19:00",
   "seed_lat": 25.33333,
   "seed_lon": -28.04167,
   "seed_alt_m": 12830.0,
   "seed_age_h": 7.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 36.18346,
    "lon": 120.7142,
    "alt_m": 12587.1
   },
   "member_spread_deg": {
    "lat": 22.58,
    "lon": 155.48
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 2.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 21:15:00",
   "seed_lat": 27.47917,
   "seed_lon": -169.66667,
   "seed_alt_m": 7840.0,
   "seed_age_h": 2.08,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 4,
   "nominal_end": {
    "valid_time": "2026-08-31 20:45:00",
    "lat": 33.5801,
    "lon": -157.44599,
    "alt_m": 7886.8
   },
   "member_spread_deg": {
    "lat": 20.31,
    "lon": 98.81
   },
   "member_spread_now_deg": {
    "lat": 0.65,
    "lon": 0.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 24.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 17:30:00",
    "lat": 60.37002,
    "lon": 96.8248,
    "alt_m": 12155.3
   },
   "member_spread_deg": {
    "lat": 31.79,
    "lon": 257.99
   },
   "member_spread_now_deg": {
    "lat": 10.81,
    "lon": 85.16
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 266.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 27.27473,
    "lon": -41.15501,
    "alt_m": 11159.3
   },
   "member_spread_deg": {
    "lat": 47.54,
    "lon": 326.02
   },
   "member_spread_now_deg": {
    "lat": 41.56,
    "lon": 135.73
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 01:45:45",
   "seed_lat": 81.20828,
   "seed_lon": -145.74998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 45.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": 76.21923,
    "lon": -36.11648,
    "alt_m": 12730.1
   },
   "member_spread_deg": {
    "lat": 35.53,
    "lon": 328.54
   },
   "member_spread_now_deg": {
    "lat": 5.98,
    "lon": 85.51
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-24 16:57:38",
   "seed_lat": 35.22266,
   "seed_lon": -24.3055,
   "seed_alt_m": 13436.0,
   "seed_age_h": 6.37,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:30:00",
    "lat": 42.56773,
    "lon": -137.12545,
    "alt_m": 13224.4
   },
   "member_spread_deg": {
    "lat": 16.7,
    "lon": 319.7
   },
   "member_spread_now_deg": {
    "lat": 0.94,
    "lon": 1.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:03:30",
   "seed_lat": 18.77083,
   "seed_lon": 0.75,
   "seed_alt_m": 16715.0,
   "seed_age_h": 7.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:30:00",
    "lat": 34.55458,
    "lon": 40.65783,
    "alt_m": 16412.2
   },
   "member_spread_deg": {
    "lat": 25.11,
    "lon": 107.55
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 18:41:00",
   "seed_lat": 38.54167,
   "seed_lon": -28.04167,
   "seed_alt_m": 13530.0,
   "seed_age_h": 4.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 18:15:00",
    "lat": 53.74543,
    "lon": 171.71833,
    "alt_m": 13173.8
   },
   "member_spread_deg": {
    "lat": 18.56,
    "lon": 314.42
   },
   "member_spread_now_deg": {
    "lat": 1.61,
    "lon": 2.76
   },
   "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": 170.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 17:30:00",
    "lat": -20.7514,
    "lon": 6.32917,
    "alt_m": 12634.0
   },
   "member_spread_deg": {
    "lat": 27.11,
    "lon": 145.57
   },
   "member_spread_now_deg": {
    "lat": 9.53,
    "lon": 309.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 304.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-31 17:45:00",
    "lat": -30.7176,
    "lon": 123.55826,
    "alt_m": 15913.9
   },
   "member_spread_deg": {
    "lat": 36.1,
    "lon": 232.41
   },
   "member_spread_now_deg": {
    "lat": 34.64,
    "lon": 244.76
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 22:41:00",
   "seed_lat": -24.35417,
   "seed_lon": 146.33333,
   "seed_alt_m": 15600.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 22:15:00",
    "lat": -29.95522,
    "lon": -13.69355,
    "alt_m": 15423.9
   },
   "member_spread_deg": {
    "lat": 48.75,
    "lon": 51.15
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}