{
 "generated_utc": "2026-09-16T11:26:52Z",
 "gfs_cycle_utc": "2026-09-16T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 477.5,
  "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_20260916_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260916_06Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 64989
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 10:30:48",
   "seed_lat": 33.9375,
   "seed_lon": -5.41667,
   "seed_alt_m": 14400.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 10:30:00",
    "lat": 47.1152,
    "lon": 67.3704,
    "alt_m": 14003.9
   },
   "member_spread_deg": {
    "lat": 7.61,
    "lon": 95.58
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 22:46:00",
   "seed_lat": 69.95833,
   "seed_lon": -127.66667,
   "seed_alt_m": 11950.0,
   "seed_age_h": 12.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 05:45:00",
    "lat": 61.06986,
    "lon": 34.00793,
    "alt_m": 12491.6
   },
   "member_spread_deg": {
    "lat": 16.28,
    "lon": 13.3
   },
   "member_spread_now_deg": {
    "lat": 5.63,
    "lon": 3.71
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 16:52:00",
   "seed_lat": 26.5,
   "seed_lon": -31.95833,
   "seed_alt_m": 13460.0,
   "seed_age_h": 18.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:45:00",
    "lat": 40.44529,
    "lon": 90.05193,
    "alt_m": 13276.8
   },
   "member_spread_deg": {
    "lat": 18.13,
    "lon": 179.71
   },
   "member_spread_now_deg": {
    "lat": 4.28,
    "lon": 4.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 09:16:00",
   "seed_lat": 47.41667,
   "seed_lon": 14.125,
   "seed_alt_m": 13650.0,
   "seed_age_h": 2.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 08:45:00",
    "lat": 46.14181,
    "lon": 140.43485,
    "alt_m": 13256.1
   },
   "member_spread_deg": {
    "lat": 12.22,
    "lon": 56.87
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 1.39
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 261.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 2.28128,
    "lon": 164.65575,
    "alt_m": 14612.5
   },
   "member_spread_deg": {
    "lat": 57.45,
    "lon": 335.8
   },
   "member_spread_now_deg": {
    "lat": 35.65,
    "lon": 139.4
   },
   "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": 149.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 21.11744,
    "lon": -46.22621,
    "alt_m": 12780.8
   },
   "member_spread_deg": {
    "lat": 55.07,
    "lon": 150.25
   },
   "member_spread_now_deg": {
    "lat": 32.28,
    "lon": 168.92
   },
   "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": 315.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 26.13812,
    "lon": -123.36603,
    "alt_m": 12726.0
   },
   "member_spread_deg": {
    "lat": 38.89,
    "lon": 302.54
   },
   "member_spread_now_deg": {
    "lat": 23.41,
    "lon": 286.2
   },
   "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": 101.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 48.47177,
    "lon": 104.33578,
    "alt_m": 12368.1
   },
   "member_spread_deg": {
    "lat": 31.19,
    "lon": 195.28
   },
   "member_spread_now_deg": {
    "lat": 20.82,
    "lon": 32.49
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 13:01:00",
   "seed_lat": 42.0625,
   "seed_lon": 28.04167,
   "seed_alt_m": 12700.0,
   "seed_age_h": 70.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 40.86385,
    "lon": -19.37819,
    "alt_m": 13043.1
   },
   "member_spread_deg": {
    "lat": 39.87,
    "lon": 101.88
   },
   "member_spread_now_deg": {
    "lat": 17.45,
    "lon": 16.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 19:15:45",
   "seed_lat": 70.16661,
   "seed_lon": -57.16665,
   "seed_alt_m": 12720.0,
   "seed_age_h": 16.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:45:00",
    "lat": 58.41769,
    "lon": -141.65945,
    "alt_m": 12829.6
   },
   "member_spread_deg": {
    "lat": 21.65,
    "lon": 336.45
   },
   "member_spread_now_deg": {
    "lat": 0.92,
    "lon": 11.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "NQ1W-6",
   "flight_id": "NQ1W-6_2026-09-11",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 10:21:00",
   "seed_lat": 29.3125,
   "seed_lon": 1.66667,
   "seed_alt_m": 13330.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 09:45:00",
    "lat": 46.18146,
    "lon": 149.6137,
    "alt_m": 12729.2
   },
   "member_spread_deg": {
    "lat": 5.11,
    "lon": 21.56
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 20:38:00",
   "seed_lat": 48.54167,
   "seed_lon": -74.83333,
   "seed_alt_m": 15900.0,
   "seed_age_h": 14.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 05:45:00",
    "lat": 58.99652,
    "lon": 68.22107,
    "alt_m": 15501.0
   },
   "member_spread_deg": {
    "lat": 47.91,
    "lon": 139.71
   },
   "member_spread_now_deg": {
    "lat": 2.44,
    "lon": 9.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 07:46:00",
   "seed_lat": 45.375,
   "seed_lon": 117.83333,
   "seed_alt_m": 13170.0,
   "seed_age_h": 3.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 07:15:00",
    "lat": 68.33763,
    "lon": 1.23819,
    "alt_m": 12487.4
   },
   "member_spread_deg": {
    "lat": 31.62,
    "lon": 104.76
   },
   "member_spread_now_deg": {
    "lat": 0.65,
    "lon": 0.83
   },
   "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": 181.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 05:30:00",
    "lat": 43.09344,
    "lon": -99.96259,
    "alt_m": 13431.0
   },
   "member_spread_deg": {
    "lat": 47.32,
    "lon": 326.73
   },
   "member_spread_now_deg": {
    "lat": 34.4,
    "lon": 349.49
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 09:28:30",
   "seed_lat": -18.9375,
   "seed_lon": 96.08333,
   "seed_alt_m": 15755.0,
   "seed_age_h": 1.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 09:00:00",
    "lat": -14.86158,
    "lon": -151.8106,
    "alt_m": 15671.2
   },
   "member_spread_deg": {
    "lat": 27.62,
    "lon": 348.33
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}