{
 "generated_utc": "2026-09-07T11:27:11Z",
 "gfs_cycle_utc": "2026-09-07T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 495.5,
  "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_20260907_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260907_06Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 90306
 },
 "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": 235.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": -67.97452,
    "lon": -2.69797,
    "alt_m": 12143.1
   },
   "member_spread_deg": {
    "lat": 45.59,
    "lon": 257.25
   },
   "member_spread_now_deg": {
    "lat": 37.24,
    "lon": 130.5
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 19:02:18",
   "seed_lat": 32.0,
   "seed_lon": -77.625,
   "seed_alt_m": 14580.0,
   "seed_age_h": 16.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 29.66,
    "lon": -6.43895,
    "alt_m": 14562.0
   },
   "member_spread_deg": {
    "lat": 23.57,
    "lon": 33.34
   },
   "member_spread_now_deg": {
    "lat": 2.2,
    "lon": 7.73
   },
   "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": 301.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 8.45726,
    "lon": -50.27423,
    "alt_m": 13160.7
   },
   "member_spread_deg": {
    "lat": 31.83,
    "lon": 99.79
   },
   "member_spread_now_deg": {
    "lat": 13.33,
    "lon": 61.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 54.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 79.32274,
    "lon": 132.47268,
    "alt_m": 11707.4
   },
   "member_spread_deg": {
    "lat": 19.04,
    "lon": 263.36
   },
   "member_spread_now_deg": {
    "lat": 5.92,
    "lon": 34.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 01:52:00",
   "seed_lat": 41.85417,
   "seed_lon": -141.29167,
   "seed_alt_m": 13380.0,
   "seed_age_h": 9.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 24.23436,
    "lon": -48.46603,
    "alt_m": 13592.7
   },
   "member_spread_deg": {
    "lat": 39.81,
    "lon": 116.17
   },
   "member_spread_now_deg": {
    "lat": 0.75,
    "lon": 2.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 04:56:00",
   "seed_lat": 45.0,
   "seed_lon": 119.0,
   "seed_alt_m": 13370.0,
   "seed_age_h": 6.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 39.02333,
    "lon": -123.48306,
    "alt_m": 13635.0
   },
   "member_spread_deg": {
    "lat": 41.68,
    "lon": 296.49
   },
   "member_spread_now_deg": {
    "lat": 0.52,
    "lon": 3.35
   },
   "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": 169.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 55.56442,
    "lon": 130.75018,
    "alt_m": 11954.2
   },
   "member_spread_deg": {
    "lat": 39.37,
    "lon": 303.52
   },
   "member_spread_now_deg": {
    "lat": 22.62,
    "lon": 314.46
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 06:11:23",
   "seed_lat": 45.72917,
   "seed_lon": 115.79167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 5.14,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 57.8285,
    "lon": -13.42803,
    "alt_m": 13717.6
   },
   "member_spread_deg": {
    "lat": 35.69,
    "lon": 194.28
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 4.55
   },
   "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": 333.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 33.60235,
    "lon": -146.35138,
    "alt_m": 13141.3
   },
   "member_spread_deg": {
    "lat": 38.76,
    "lon": 325.95
   },
   "member_spread_now_deg": {
    "lat": 32.02,
    "lon": 240.05
   },
   "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": 316.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 25.04675,
    "lon": 151.71907,
    "alt_m": 14161.2
   },
   "member_spread_deg": {
    "lat": 57.93,
    "lon": 340.23
   },
   "member_spread_now_deg": {
    "lat": 33.6,
    "lon": 221.2
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 99.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 20.0592,
    "lon": 124.09483,
    "alt_m": 12843.5
   },
   "member_spread_deg": {
    "lat": 25.12,
    "lon": 289.68
   },
   "member_spread_now_deg": {
    "lat": 27.91,
    "lon": 322.57
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 10:40:00",
   "seed_lat": 25.91667,
   "seed_lon": -2.33333,
   "seed_alt_m": 12980.0,
   "seed_age_h": 0.67,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 10:45:00",
    "lat": 57.99355,
    "lon": -137.6063,
    "alt_m": 12824.6
   },
   "member_spread_deg": {
    "lat": 24.98,
    "lon": 320.55
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 22:56:00",
   "seed_lat": 62.79167,
   "seed_lon": -124.54167,
   "seed_alt_m": 12340.0,
   "seed_age_h": 12.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 39.6292,
    "lon": 19.1281,
    "alt_m": 12623.2
   },
   "member_spread_deg": {
    "lat": 22.69,
    "lon": 103.55
   },
   "member_spread_now_deg": {
    "lat": 2.37,
    "lon": 16.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 43.9,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:30:00",
    "lat": 70.22643,
    "lon": -77.55481,
    "alt_m": 12935.6
   },
   "member_spread_deg": {
    "lat": 20.71,
    "lon": 190.46
   },
   "member_spread_now_deg": {
    "lat": 5.36,
    "lon": 4.45
   },
   "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": 283.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 28.8004,
    "lon": -7.84939,
    "alt_m": 13463.9
   },
   "member_spread_deg": {
    "lat": 50.35,
    "lon": 215.81
   },
   "member_spread_now_deg": {
    "lat": 16.17,
    "lon": 117.76
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 02:41:00",
   "seed_lat": 24.25,
   "seed_lon": -159.45833,
   "seed_alt_m": 16160.0,
   "seed_age_h": 8.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 21.68922,
    "lon": -168.80769,
    "alt_m": 16459.7
   },
   "member_spread_deg": {
    "lat": 46.79,
    "lon": 119.55
   },
   "member_spread_now_deg": {
    "lat": 5.0,
    "lon": 6.71
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 10:51:00",
   "seed_lat": 45.27083,
   "seed_lon": -49.83333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 10:45:00",
    "lat": 38.11418,
    "lon": 114.32969,
    "alt_m": 13359.1
   },
   "member_spread_deg": {
    "lat": 23.31,
    "lon": 127.58
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 00:15:23",
   "seed_lat": 35.22911,
   "seed_lon": -126.08331,
   "seed_alt_m": 13840.0,
   "seed_age_h": 11.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 05:45:00",
    "lat": 45.59221,
    "lon": 53.79011,
    "alt_m": 13497.7
   },
   "member_spread_deg": {
    "lat": 39.41,
    "lon": 108.76
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 1.57
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 10:46:00",
   "seed_lat": -23.25,
   "seed_lon": 24.83333,
   "seed_alt_m": 15600.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 10:45:00",
    "lat": -19.73197,
    "lon": 122.62109,
    "alt_m": 15635.1
   },
   "member_spread_deg": {
    "lat": 19.86,
    "lon": 325.61
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}