{
 "generated_utc": "2026-09-16T23:27:00Z",
 "gfs_cycle_utc": "2026-09-16T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 489.5,
  "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_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260916_18Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 66114
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 14:26:18",
   "seed_lat": 33.6875,
   "seed_lon": -3.33333,
   "seed_alt_m": 14260.0,
   "seed_age_h": 8.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 44.80713,
    "lon": 69.20081,
    "alt_m": 13896.8
   },
   "member_spread_deg": {
    "lat": 12.95,
    "lon": 111.47
   },
   "member_spread_now_deg": {
    "lat": 1.53,
    "lon": 3.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 21:16:00",
   "seed_lat": 56.29167,
   "seed_lon": -98.04167,
   "seed_alt_m": 11980.0,
   "seed_age_h": 2.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 21:15:00",
    "lat": 42.83375,
    "lon": 30.71192,
    "alt_m": 12293.3
   },
   "member_spread_deg": {
    "lat": 27.64,
    "lon": 86.84
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 17:07:00",
   "seed_lat": 33.04167,
   "seed_lon": -21.91667,
   "seed_alt_m": 13610.0,
   "seed_age_h": 6.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 41.09233,
    "lon": 137.79176,
    "alt_m": 13216.1
   },
   "member_spread_deg": {
    "lat": 10.21,
    "lon": 93.1
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 0.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 15:36:00",
   "seed_lat": 47.35417,
   "seed_lon": 18.125,
   "seed_alt_m": 13600.0,
   "seed_age_h": 7.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 45.42517,
    "lon": 154.4007,
    "alt_m": 13208.9
   },
   "member_spread_deg": {
    "lat": 34.19,
    "lon": 355.41
   },
   "member_spread_now_deg": {
    "lat": 3.93,
    "lon": 1.64
   },
   "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": 273.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 2.68619,
    "lon": 145.11346,
    "alt_m": 14598.2
   },
   "member_spread_deg": {
    "lat": 55.7,
    "lon": 303.68
   },
   "member_spread_now_deg": {
    "lat": 43.86,
    "lon": 340.65
   },
   "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": 161.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 11.57166,
    "lon": -60.06938,
    "alt_m": 12796.0
   },
   "member_spread_deg": {
    "lat": 47.29,
    "lon": 240.0
   },
   "member_spread_now_deg": {
    "lat": 39.84,
    "lon": 176.53
   },
   "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": 327.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 28.02247,
    "lon": -120.79876,
    "alt_m": 12733.8
   },
   "member_spread_deg": {
    "lat": 28.12,
    "lon": 283.0
   },
   "member_spread_now_deg": {
    "lat": 23.75,
    "lon": 284.41
   },
   "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": 113.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 52.15872,
    "lon": 69.14498,
    "alt_m": 12627.1
   },
   "member_spread_deg": {
    "lat": 35.85,
    "lon": 177.31
   },
   "member_spread_now_deg": {
    "lat": 20.31,
    "lon": 38.28
   },
   "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": 82.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 49.94582,
    "lon": -56.88282,
    "alt_m": 12648.4
   },
   "member_spread_deg": {
    "lat": 33.0,
    "lon": 161.96
   },
   "member_spread_now_deg": {
    "lat": 18.07,
    "lon": 25.64
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 16:35:45",
   "seed_lat": 76.41661,
   "seed_lon": -30.16665,
   "seed_alt_m": 12780.0,
   "seed_age_h": 6.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 57.92434,
    "lon": -121.09253,
    "alt_m": 13077.2
   },
   "member_spread_deg": {
    "lat": 23.7,
    "lon": 93.9
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 3.92
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "NQ1W-6",
   "flight_id": "NQ1W-6_2026-09-11",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 13:26:00",
   "seed_lat": 29.875,
   "seed_lon": 3.41667,
   "seed_alt_m": 13310.0,
   "seed_age_h": 9.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 50.20022,
    "lon": 169.72334,
    "alt_m": 12536.4
   },
   "member_spread_deg": {
    "lat": 17.9,
    "lon": 355.01
   },
   "member_spread_now_deg": {
    "lat": 2.78,
    "lon": 1.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 18:11:00",
   "seed_lat": 54.0,
   "seed_lon": -52.45833,
   "seed_alt_m": 15660.0,
   "seed_age_h": 5.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 17:45:00",
    "lat": 55.56965,
    "lon": 75.19688,
    "alt_m": 15451.5
   },
   "member_spread_deg": {
    "lat": 38.49,
    "lon": 76.18
   },
   "member_spread_now_deg": {
    "lat": 1.15,
    "lon": 5.41
   },
   "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": 15.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:45:00",
    "lat": 52.33627,
    "lon": 8.42915,
    "alt_m": 12933.5
   },
   "member_spread_deg": {
    "lat": 34.43,
    "lon": 135.01
   },
   "member_spread_now_deg": {
    "lat": 2.14,
    "lon": 3.94
   },
   "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": 193.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": 43.78891,
    "lon": -105.5209,
    "alt_m": 13352.0
   },
   "member_spread_deg": {
    "lat": 44.02,
    "lon": 328.06
   },
   "member_spread_now_deg": {
    "lat": 35.23,
    "lon": 283.38
   },
   "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": 13.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 17:30:00",
    "lat": -11.25367,
    "lon": 173.09916,
    "alt_m": 15709.9
   },
   "member_spread_deg": {
    "lat": 27.93,
    "lon": 344.49
   },
   "member_spread_now_deg": {
    "lat": 2.37,
    "lon": 4.86
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}