{
 "generated_utc": "2026-09-10T17:27:09Z",
 "gfs_cycle_utc": "2026-09-10T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 475.5,
  "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_20260910_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260910_12Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 67068
 },
 "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": 313.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 11:45:00",
    "lat": -58.82743,
    "lon": 97.95919,
    "alt_m": 12047.9
   },
   "member_spread_deg": {
    "lat": 27.97,
    "lon": 342.65
   },
   "member_spread_now_deg": {
    "lat": 16.88,
    "lon": 330.14
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 16:32:17",
   "seed_lat": 35.25,
   "seed_lon": -19.45833,
   "seed_alt_m": 14670.0,
   "seed_age_h": 0.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 16:30:00",
    "lat": 38.32724,
    "lon": 9.14887,
    "alt_m": 14230.2
   },
   "member_spread_deg": {
    "lat": 25.55,
    "lon": 76.4
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 132.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 11:45:00",
    "lat": 87.88068,
    "lon": 170.99637,
    "alt_m": 11580.5
   },
   "member_spread_deg": {
    "lat": 28.41,
    "lon": 346.63
   },
   "member_spread_now_deg": {
    "lat": 20.18,
    "lon": 345.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 16:07:00",
   "seed_lat": 32.4375,
   "seed_lon": -52.41667,
   "seed_alt_m": 13550.0,
   "seed_age_h": 1.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 15:30:00",
    "lat": 30.51531,
    "lon": -40.01587,
    "alt_m": 13519.6
   },
   "member_spread_deg": {
    "lat": 17.18,
    "lon": 71.02
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 03:16:00",
   "seed_lat": 52.33333,
   "seed_lon": -154.54167,
   "seed_alt_m": 13720.0,
   "seed_age_h": 14.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 11:45:00",
    "lat": 45.29139,
    "lon": 58.04545,
    "alt_m": 13577.9
   },
   "member_spread_deg": {
    "lat": 29.71,
    "lon": 120.36
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 14.07
   },
   "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": 247.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 67.52616,
    "lon": -102.78435,
    "alt_m": 11709.9
   },
   "member_spread_deg": {
    "lat": 47.08,
    "lon": 277.35
   },
   "member_spread_now_deg": {
    "lat": 47.82,
    "lon": 325.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 123.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 33.16586,
    "lon": 145.34964,
    "alt_m": 14597.7
   },
   "member_spread_deg": {
    "lat": 56.51,
    "lon": 140.72
   },
   "member_spread_now_deg": {
    "lat": 32.59,
    "lon": 293.88
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 05:25:00",
   "seed_lat": 48.52083,
   "seed_lon": 159.54167,
   "seed_alt_m": 12130.0,
   "seed_age_h": 11.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 42.67824,
    "lon": -140.61416,
    "alt_m": 12466.4
   },
   "member_spread_deg": {
    "lat": 33.83,
    "lon": 190.81
   },
   "member_spread_now_deg": {
    "lat": 8.27,
    "lon": 10.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 177.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 24.68691,
    "lon": 160.17332,
    "alt_m": 12890.2
   },
   "member_spread_deg": {
    "lat": 20.15,
    "lon": 273.23
   },
   "member_spread_now_deg": {
    "lat": 6.09,
    "lon": 331.96
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 12:25:00",
   "seed_lat": 42.45833,
   "seed_lon": 73.66667,
   "seed_alt_m": 12750.0,
   "seed_age_h": 4.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 12:00:00",
    "lat": 41.22734,
    "lon": -112.06747,
    "alt_m": 12719.9
   },
   "member_spread_deg": {
    "lat": 20.33,
    "lon": 97.9
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 3.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 16:26:00",
   "seed_lat": 50.83333,
   "seed_lon": -40.91667,
   "seed_alt_m": 12600.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 16:30:00",
    "lat": 49.89693,
    "lon": 134.09552,
    "alt_m": 12901.4
   },
   "member_spread_deg": {
    "lat": 7.0,
    "lon": 92.13
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 07:35:45",
   "seed_lat": 48.41661,
   "seed_lon": 121.04169,
   "seed_alt_m": 13390.0,
   "seed_age_h": 9.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 69.04842,
    "lon": -7.76682,
    "alt_m": 12837.8
   },
   "member_spread_deg": {
    "lat": 42.53,
    "lon": 63.5
   },
   "member_spread_now_deg": {
    "lat": 2.31,
    "lon": 2.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 02:08:00",
   "seed_lat": 35.14583,
   "seed_lon": -153.95833,
   "seed_alt_m": 16500.0,
   "seed_age_h": 15.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 11:45:00",
    "lat": 29.86115,
    "lon": -144.91389,
    "alt_m": 16351.3
   },
   "member_spread_deg": {
    "lat": 29.41,
    "lon": 340.01
   },
   "member_spread_now_deg": {
    "lat": 6.65,
    "lon": 6.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 16:31:00",
   "seed_lat": 31.3125,
   "seed_lon": 1.20833,
   "seed_alt_m": 13350.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 16:30:00",
    "lat": 39.59597,
    "lon": -162.15544,
    "alt_m": 13492.4
   },
   "member_spread_deg": {
    "lat": 14.82,
    "lon": 342.92
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 21:35:23",
   "seed_lat": 52.33328,
   "seed_lon": -95.95831,
   "seed_alt_m": 12860.0,
   "seed_age_h": 43.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 11:30:00",
    "lat": 46.02533,
    "lon": 88.80164,
    "alt_m": 13117.5
   },
   "member_spread_deg": {
    "lat": 24.37,
    "lon": 89.37
   },
   "member_spread_now_deg": {
    "lat": 7.6,
    "lon": 41.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 12:31:00",
   "seed_lat": -18.91667,
   "seed_lon": 54.125,
   "seed_alt_m": 15600.0,
   "seed_age_h": 4.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 12:00:00",
    "lat": -17.49028,
    "lon": 156.26689,
    "alt_m": 15714.6
   },
   "member_spread_deg": {
    "lat": 22.86,
    "lon": 321.52
   },
   "member_spread_now_deg": {
    "lat": 1.27,
    "lon": 5.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}