{
 "generated_utc": "2026-09-13T05:26:38Z",
 "gfs_cycle_utc": "2026-09-13T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 469.5,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260913_00Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 65583
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 17:46:19",
   "seed_lat": 39.47917,
   "seed_lon": -7.66667,
   "seed_alt_m": 14590.0,
   "seed_age_h": 11.56,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:45:00",
    "lat": 49.9955,
    "lon": 51.94689,
    "alt_m": 14023.8
   },
   "member_spread_deg": {
    "lat": 18.9,
    "lon": 74.02
   },
   "member_spread_now_deg": {
    "lat": 0.82,
    "lon": 2.03
   },
   "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": 192.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 23:45:00",
    "lat": 66.89091,
    "lon": -22.13474,
    "alt_m": 11811.6
   },
   "member_spread_deg": {
    "lat": 23.06,
    "lon": 296.02
   },
   "member_spread_now_deg": {
    "lat": 16.11,
    "lon": 284.8
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 17:27:00",
   "seed_lat": 30.79167,
   "seed_lon": -37.04167,
   "seed_alt_m": 13760.0,
   "seed_age_h": 11.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 37.41013,
    "lon": -31.7854,
    "alt_m": 13518.5
   },
   "member_spread_deg": {
    "lat": 27.5,
    "lon": 82.69
   },
   "member_spread_now_deg": {
    "lat": 1.98,
    "lon": 2.3
   },
   "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": 11.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 46.18536,
    "lon": 75.68873,
    "alt_m": 13441.6
   },
   "member_spread_deg": {
    "lat": 17.26,
    "lon": 95.51
   },
   "member_spread_now_deg": {
    "lat": 7.13,
    "lon": 11.9
   },
   "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": 307.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 64.47289,
    "lon": -79.24226,
    "alt_m": 11695.7
   },
   "member_spread_deg": {
    "lat": 29.32,
    "lon": 297.83
   },
   "member_spread_now_deg": {
    "lat": 36.36,
    "lon": 308.45
   },
   "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": 183.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 19.34651,
    "lon": -161.70559,
    "alt_m": 14545.1
   },
   "member_spread_deg": {
    "lat": 41.95,
    "lon": 336.81
   },
   "member_spread_now_deg": {
    "lat": 40.33,
    "lon": 182.08
   },
   "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": 71.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 35.89845,
    "lon": -62.57261,
    "alt_m": 12740.3
   },
   "member_spread_deg": {
    "lat": 28.18,
    "lon": 209.82
   },
   "member_spread_now_deg": {
    "lat": 18.54,
    "lon": 87.46
   },
   "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": 237.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 22.12803,
    "lon": -175.12815,
    "alt_m": 12855.5
   },
   "member_spread_deg": {
    "lat": 37.61,
    "lon": 296.74
   },
   "member_spread_now_deg": {
    "lat": 25.26,
    "lon": 294.94
   },
   "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": 23.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 48.85185,
    "lon": -102.73657,
    "alt_m": 12803.9
   },
   "member_spread_deg": {
    "lat": 18.78,
    "lon": 146.07
   },
   "member_spread_now_deg": {
    "lat": 4.99,
    "lon": 6.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 13:46:00",
   "seed_lat": 39.72917,
   "seed_lon": 7.875,
   "seed_alt_m": 12800.0,
   "seed_age_h": 15.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:45:00",
    "lat": 41.14401,
    "lon": -169.31938,
    "alt_m": 12763.2
   },
   "member_spread_deg": {
    "lat": 23.29,
    "lon": 349.1
   },
   "member_spread_now_deg": {
    "lat": 1.22,
    "lon": 5.6
   },
   "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": 4.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 00:15:00",
    "lat": 72.04978,
    "lon": 122.85811,
    "alt_m": 12929.8
   },
   "member_spread_deg": {
    "lat": 13.85,
    "lon": 331.12
   },
   "member_spread_now_deg": {
    "lat": 0.57,
    "lon": 2.6
   },
   "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": 5.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-19 23:45:00",
    "lat": 43.02735,
    "lon": -7.06393,
    "alt_m": 16259.0
   },
   "member_spread_deg": {
    "lat": 46.97,
    "lon": 113.05
   },
   "member_spread_now_deg": {
    "lat": 1.87,
    "lon": 6.13
   },
   "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": 15.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:45:00",
    "lat": 40.27325,
    "lon": -130.78689,
    "alt_m": 13013.5
   },
   "member_spread_deg": {
    "lat": 21.35,
    "lon": 40.19
   },
   "member_spread_now_deg": {
    "lat": 4.69,
    "lon": 4.28
   },
   "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": 103.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 23:30:00",
    "lat": 41.31797,
    "lon": -173.96754,
    "alt_m": 13186.6
   },
   "member_spread_deg": {
    "lat": 40.05,
    "lon": 350.54
   },
   "member_spread_now_deg": {
    "lat": 29.43,
    "lon": 59.61
   },
   "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 04:01:00",
   "seed_lat": -14.52083,
   "seed_lon": 95.0,
   "seed_alt_m": 15780.0,
   "seed_age_h": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 04:00:00",
    "lat": -19.39112,
    "lon": 99.12622,
    "alt_m": 15716.4
   },
   "member_spread_deg": {
    "lat": 21.43,
    "lon": 68.58
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.66
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}