{
 "generated_utc": "2026-09-13T11:26:47Z",
 "gfs_cycle_utc": "2026-09-13T06:00:00Z",
 "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_20260913_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260913_06Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 66339
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 10:47:19",
   "seed_lat": 34.83333,
   "seed_lon": -11.5,
   "seed_alt_m": 14570.0,
   "seed_age_h": 0.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 10:45:00",
    "lat": 54.38067,
    "lon": 54.33278,
    "alt_m": 14003.1
   },
   "member_spread_deg": {
    "lat": 23.55,
    "lon": 101.79
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.14
   },
   "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": 198.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 05:45:00",
    "lat": 62.70159,
    "lon": 6.23428,
    "alt_m": 11768.7
   },
   "member_spread_deg": {
    "lat": 23.62,
    "lon": 330.28
   },
   "member_spread_now_deg": {
    "lat": 13.15,
    "lon": 300.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 09:42:00",
   "seed_lat": 25.04167,
   "seed_lon": -29.54167,
   "seed_alt_m": 13580.0,
   "seed_age_h": 1.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 09:15:00",
    "lat": 39.92156,
    "lon": 41.15082,
    "alt_m": 13375.2
   },
   "member_spread_deg": {
    "lat": 13.03,
    "lon": 85.78
   },
   "member_spread_now_deg": {
    "lat": 0.65,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 18:01:00",
   "seed_lat": 42.83333,
   "seed_lon": -53.66667,
   "seed_alt_m": 13540.0,
   "seed_age_h": 17.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 44.93139,
    "lon": 80.72739,
    "alt_m": 13412.7
   },
   "member_spread_deg": {
    "lat": 10.73,
    "lon": 87.59
   },
   "member_spread_now_deg": {
    "lat": 11.6,
    "lon": 22.39
   },
   "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": 313.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 68.0034,
    "lon": -72.24253,
    "alt_m": 11726.4
   },
   "member_spread_deg": {
    "lat": 32.07,
    "lon": 278.41
   },
   "member_spread_now_deg": {
    "lat": 37.78,
    "lon": 314.2
   },
   "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": 189.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 8.55359,
    "lon": 165.16591,
    "alt_m": 14622.4
   },
   "member_spread_deg": {
    "lat": 48.04,
    "lon": 329.47
   },
   "member_spread_now_deg": {
    "lat": 39.94,
    "lon": 170.81
   },
   "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": 77.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 27.11891,
    "lon": -88.21207,
    "alt_m": 12526.2
   },
   "member_spread_deg": {
    "lat": 32.4,
    "lon": 227.26
   },
   "member_spread_now_deg": {
    "lat": 13.48,
    "lon": 97.98
   },
   "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": 243.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 15.39185,
    "lon": 165.30999,
    "alt_m": 12882.5
   },
   "member_spread_deg": {
    "lat": 26.9,
    "lon": 313.22
   },
   "member_spread_now_deg": {
    "lat": 27.23,
    "lon": 293.0
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 06:05:00",
   "seed_lat": 45.47917,
   "seed_lon": 159.375,
   "seed_alt_m": 12660.0,
   "seed_age_h": 29.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 51.338,
    "lon": -88.24556,
    "alt_m": 12439.9
   },
   "member_spread_deg": {
    "lat": 20.16,
    "lon": 151.47
   },
   "member_spread_now_deg": {
    "lat": 4.86,
    "lon": 8.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 10:31:00",
   "seed_lat": 41.125,
   "seed_lon": 25.125,
   "seed_alt_m": 12700.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 10:00:00",
    "lat": 52.20216,
    "lon": -119.00801,
    "alt_m": 12816.5
   },
   "member_spread_deg": {
    "lat": 15.2,
    "lon": 314.99
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 00:40:45",
   "seed_lat": 68.31245,
   "seed_lon": -130.12498,
   "seed_alt_m": 12900.0,
   "seed_age_h": 10.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:45:00",
    "lat": 66.50327,
    "lon": 112.36363,
    "alt_m": 13006.1
   },
   "member_spread_deg": {
    "lat": 28.93,
    "lon": 352.8
   },
   "member_spread_now_deg": {
    "lat": 0.55,
    "lon": 5.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 00:16:00",
   "seed_lat": 35.5625,
   "seed_lon": -132.58333,
   "seed_alt_m": 16200.0,
   "seed_age_h": 11.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 05:45:00",
    "lat": 58.24564,
    "lon": 30.19096,
    "alt_m": 15444.4
   },
   "member_spread_deg": {
    "lat": 49.05,
    "lon": 130.29
   },
   "member_spread_now_deg": {
    "lat": 4.14,
    "lon": 13.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 13:51:00",
   "seed_lat": 44.95833,
   "seed_lon": 27.79167,
   "seed_alt_m": 13240.0,
   "seed_age_h": 21.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:45:00",
    "lat": 41.07695,
    "lon": -129.45624,
    "alt_m": 13064.9
   },
   "member_spread_deg": {
    "lat": 29.54,
    "lon": 17.98
   },
   "member_spread_now_deg": {
    "lat": 4.52,
    "lon": 10.27
   },
   "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": 109.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 05:30:00",
    "lat": 52.66812,
    "lon": -134.92077,
    "alt_m": 13096.6
   },
   "member_spread_deg": {
    "lat": 33.53,
    "lon": 284.71
   },
   "member_spread_now_deg": {
    "lat": 32.2,
    "lon": 51.4
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 09:36:00",
   "seed_lat": -14.16667,
   "seed_lon": 95.54167,
   "seed_alt_m": 15770.0,
   "seed_age_h": 1.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 09:00:00",
    "lat": -22.84244,
    "lon": 109.15423,
    "alt_m": 15625.9
   },
   "member_spread_deg": {
    "lat": 25.13,
    "lon": 64.36
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}