{
 "generated_utc": "2026-08-24T11:26:55Z",
 "gfs_cycle_utc": "2026-08-24T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 455.5,
  "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_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260824_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 86940
 },
 "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": 45.61,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": -69.38646,
    "lon": 80.1129,
    "alt_m": 12182.5
   },
   "member_spread_deg": {
    "lat": 20.42,
    "lon": 222.02
   },
   "member_spread_now_deg": {
    "lat": 10.2,
    "lon": 52.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 22:48:48",
   "seed_lat": 48.33333,
   "seed_lon": -72.91667,
   "seed_alt_m": 13800.0,
   "seed_age_h": 12.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 46.7404,
    "lon": 154.42031,
    "alt_m": 13846.9
   },
   "member_spread_deg": {
    "lat": 11.8,
    "lon": 139.47
   },
   "member_spread_now_deg": {
    "lat": 3.1,
    "lon": 20.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 00:34:00",
   "seed_lat": 32.5,
   "seed_lon": -121.04167,
   "seed_alt_m": 12920.0,
   "seed_age_h": 10.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 64.32832,
    "lon": 17.67025,
    "alt_m": 12072.2
   },
   "member_spread_deg": {
    "lat": 28.8,
    "lon": 94.62
   },
   "member_spread_now_deg": {
    "lat": 1.47,
    "lon": 1.8
   },
   "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": 3.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 07:30:00",
    "lat": 80.35011,
    "lon": 0.4748,
    "alt_m": 11972.2
   },
   "member_spread_deg": {
    "lat": 33.29,
    "lon": 107.27
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 1.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:47:00",
   "seed_lat": 40.66667,
   "seed_lon": -147.58333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 11.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 50.92319,
    "lon": 19.05276,
    "alt_m": 13051.8
   },
   "member_spread_deg": {
    "lat": 22.63,
    "lon": 80.13
   },
   "member_spread_now_deg": {
    "lat": 1.18,
    "lon": 3.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 02:23:00",
   "seed_lat": 72.83333,
   "seed_lon": -139.66667,
   "seed_alt_m": 11840.0,
   "seed_age_h": 8.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 65.34067,
    "lon": 64.51315,
    "alt_m": 11754.9
   },
   "member_spread_deg": {
    "lat": 28.83,
    "lon": 168.79
   },
   "member_spread_now_deg": {
    "lat": 5.07,
    "lon": 5.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 10:03:00",
   "seed_lat": 65.16667,
   "seed_lon": 36.70833,
   "seed_alt_m": 12470.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 09:30:00",
    "lat": 52.43013,
    "lon": 133.04105,
    "alt_m": 12893.5
   },
   "member_spread_deg": {
    "lat": 30.01,
    "lon": 327.0
   },
   "member_spread_now_deg": {
    "lat": 0.68,
    "lon": 1.47
   },
   "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": 206.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 28.89974,
    "lon": -44.00373,
    "alt_m": 13352.6
   },
   "member_spread_deg": {
    "lat": 41.92,
    "lon": 256.64
   },
   "member_spread_now_deg": {
    "lat": 26.14,
    "lon": 94.36
   },
   "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 04:33:49",
   "seed_lat": 54.95833,
   "seed_lon": 154.16667,
   "seed_alt_m": 13250.0,
   "seed_age_h": 6.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 62.25797,
    "lon": -77.5193,
    "alt_m": 13412.4
   },
   "member_spread_deg": {
    "lat": 30.46,
    "lon": 204.72
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 9.96
   },
   "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": 287.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 58.07002,
    "lon": 125.00505,
    "alt_m": 12701.5
   },
   "member_spread_deg": {
    "lat": 34.67,
    "lon": 307.07
   },
   "member_spread_now_deg": {
    "lat": 35.12,
    "lon": 302.86
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 16:54:00",
   "seed_lat": 33.3125,
   "seed_lon": -26.5,
   "seed_alt_m": 12770.0,
   "seed_age_h": 18.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 36.2552,
    "lon": 108.53668,
    "alt_m": 12511.6
   },
   "member_spread_deg": {
    "lat": 17.84,
    "lon": 187.43
   },
   "member_spread_now_deg": {
    "lat": 2.33,
    "lon": 2.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 04:20:00",
   "seed_lat": 22.60417,
   "seed_lon": -175.375,
   "seed_alt_m": 13080.0,
   "seed_age_h": 7.0,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 45.56827,
    "lon": -85.65851,
    "alt_m": 12986.6
   },
   "member_spread_deg": {
    "lat": 15.92,
    "lon": 92.35
   },
   "member_spread_now_deg": {
    "lat": 1.43,
    "lon": 1.47
   },
   "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": 12.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 52.41975,
    "lon": 68.74446,
    "alt_m": 12129.2
   },
   "member_spread_deg": {
    "lat": 25.51,
    "lon": 206.55
   },
   "member_spread_now_deg": {
    "lat": 3.98,
    "lon": 5.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 254.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 11.51057,
    "lon": -31.63167,
    "alt_m": 11166.1
   },
   "member_spread_deg": {
    "lat": 49.6,
    "lon": 303.87
   },
   "member_spread_now_deg": {
    "lat": 39.71,
    "lon": 131.78
   },
   "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": 33.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": 69.69268,
    "lon": -49.8551,
    "alt_m": 12926.5
   },
   "member_spread_deg": {
    "lat": 27.69,
    "lon": 341.0
   },
   "member_spread_now_deg": {
    "lat": 2.82,
    "lon": 157.18
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-23 18:00:24",
   "seed_lat": 51.81083,
   "seed_lon": -61.64733,
   "seed_alt_m": 12996.0,
   "seed_age_h": 17.33,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": 42.85395,
    "lon": 179.54737,
    "alt_m": 13225.8
   },
   "member_spread_deg": {
    "lat": 29.61,
    "lon": 352.93
   },
   "member_spread_now_deg": {
    "lat": 8.33,
    "lon": 13.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 09:51:00",
   "seed_lat": 18.5,
   "seed_lon": 4.0,
   "seed_alt_m": 16600.0,
   "seed_age_h": 1.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 09:15:00",
    "lat": 44.68183,
    "lon": 46.47965,
    "alt_m": 15750.2
   },
   "member_spread_deg": {
    "lat": 26.02,
    "lon": 116.47
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 10:41:00",
   "seed_lat": 47.27083,
   "seed_lon": -40.66667,
   "seed_alt_m": 13420.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 10:45:00",
    "lat": 47.83646,
    "lon": 177.70148,
    "alt_m": 13437.5
   },
   "member_spread_deg": {
    "lat": 19.74,
    "lon": 192.14
   },
   "member_spread_now_deg": {
    "lat": 0.38,
    "lon": 0.26
   },
   "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": 158.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 05:30:00",
    "lat": -21.38904,
    "lon": -6.12504,
    "alt_m": 12535.7
   },
   "member_spread_deg": {
    "lat": 26.26,
    "lon": 156.35
   },
   "member_spread_now_deg": {
    "lat": 8.89,
    "lon": 310.56
   },
   "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": 292.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-31 05:45:00",
    "lat": -16.45521,
    "lon": 127.13442,
    "alt_m": 16065.3
   },
   "member_spread_deg": {
    "lat": 33.62,
    "lon": 226.93
   },
   "member_spread_now_deg": {
    "lat": 34.93,
    "lon": 229.77
   },
   "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 08:06:00",
   "seed_lat": -23.4375,
   "seed_lon": 133.08333,
   "seed_alt_m": 15530.0,
   "seed_age_h": 3.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 07:30:00",
    "lat": -28.81624,
    "lon": -18.89011,
    "alt_m": 15387.8
   },
   "member_spread_deg": {
    "lat": 42.51,
    "lon": 44.85
   },
   "member_spread_now_deg": {
    "lat": 0.52,
    "lon": 2.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}