{
 "generated_utc": "2026-09-14T05:27:00Z",
 "gfs_cycle_utc": "2026-09-14T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 493.5,
  "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_20260914_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260914_00Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 71703
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 17:29:48",
   "seed_lat": 34.0625,
   "seed_lon": -14.41667,
   "seed_alt_m": 14590.0,
   "seed_age_h": 11.84,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 41.76926,
    "lon": 31.93853,
    "alt_m": 14154.1
   },
   "member_spread_deg": {
    "lat": 12.7,
    "lon": 111.31
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 1.57
   },
   "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": 216.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 23:45:00",
    "lat": 69.23669,
    "lon": 18.02651,
    "alt_m": 11885.9
   },
   "member_spread_deg": {
    "lat": 38.93,
    "lon": 196.7
   },
   "member_spread_now_deg": {
    "lat": 14.17,
    "lon": 320.13
   },
   "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 17:52:00",
   "seed_lat": 24.625,
   "seed_lon": -25.70833,
   "seed_alt_m": 13460.0,
   "seed_age_h": 11.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:45:00",
    "lat": 31.44758,
    "lon": -27.06354,
    "alt_m": 13408.7
   },
   "member_spread_deg": {
    "lat": 24.12,
    "lon": 84.44
   },
   "member_spread_now_deg": {
    "lat": 1.64,
    "lon": 1.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 16:21:00",
   "seed_lat": 56.14583,
   "seed_lon": -9.83333,
   "seed_alt_m": 13500.0,
   "seed_age_h": 12.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:45:00",
    "lat": 48.6268,
    "lon": 115.13565,
    "alt_m": 13283.5
   },
   "member_spread_deg": {
    "lat": 6.87,
    "lon": 67.46
   },
   "member_spread_now_deg": {
    "lat": 9.73,
    "lon": 2.44
   },
   "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": 331.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 75.68018,
    "lon": -176.84565,
    "alt_m": 11476.5
   },
   "member_spread_deg": {
    "lat": 46.27,
    "lon": 304.32
   },
   "member_spread_now_deg": {
    "lat": 42.0,
    "lon": 321.03
   },
   "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": 207.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": -20.64265,
    "lon": -99.22403,
    "alt_m": 14425.5
   },
   "member_spread_deg": {
    "lat": 78.66,
    "lon": 334.97
   },
   "member_spread_now_deg": {
    "lat": 35.61,
    "lon": 154.31
   },
   "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": 95.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 29.22898,
    "lon": -92.45006,
    "alt_m": 12722.0
   },
   "member_spread_deg": {
    "lat": 44.8,
    "lon": 265.97
   },
   "member_spread_now_deg": {
    "lat": 9.41,
    "lon": 121.62
   },
   "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": 261.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": -6.85301,
    "lon": 167.50279,
    "alt_m": 12888.4
   },
   "member_spread_deg": {
    "lat": 50.57,
    "lon": 336.19
   },
   "member_spread_now_deg": {
    "lat": 22.3,
    "lon": 294.49
   },
   "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": 47.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 46.14851,
    "lon": -115.72089,
    "alt_m": 12824.2
   },
   "member_spread_deg": {
    "lat": 8.04,
    "lon": 141.41
   },
   "member_spread_now_deg": {
    "lat": 4.66,
    "lon": 17.98
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 16.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 50.66889,
    "lon": -122.50114,
    "alt_m": 12720.5
   },
   "member_spread_deg": {
    "lat": 8.86,
    "lon": 48.46
   },
   "member_spread_now_deg": {
    "lat": 3.52,
    "lon": 8.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 22:25:45",
   "seed_lat": 65.14578,
   "seed_lon": -92.37498,
   "seed_alt_m": 12720.0,
   "seed_age_h": 6.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 78.6967,
    "lon": -146.40263,
    "alt_m": 12425.0
   },
   "member_spread_deg": {
    "lat": 28.91,
    "lon": 285.78
   },
   "member_spread_now_deg": {
    "lat": 0.66,
    "lon": 0.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "NQ1W-6",
   "flight_id": "NQ1W-6_2026-09-11",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 14:41:00",
   "seed_lat": 41.4375,
   "seed_lon": -4.29167,
   "seed_alt_m": 13460.0,
   "seed_age_h": 14.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:45:00",
    "lat": 41.34623,
    "lon": 80.6709,
    "alt_m": 13117.5
   },
   "member_spread_deg": {
    "lat": 3.22,
    "lon": 90.23
   },
   "member_spread_now_deg": {
    "lat": 1.48,
    "lon": 0.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 23:01:00",
   "seed_lat": 40.54167,
   "seed_lon": -114.95833,
   "seed_alt_m": 15880.0,
   "seed_age_h": 6.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 51.64648,
    "lon": 35.28569,
    "alt_m": 15490.4
   },
   "member_spread_deg": {
    "lat": 61.33,
    "lon": 201.04
   },
   "member_spread_now_deg": {
    "lat": 3.71,
    "lon": 7.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 04:11:00",
   "seed_lat": 48.10417,
   "seed_lon": 68.79167,
   "seed_alt_m": 13230.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 03:45:00",
    "lat": 50.49259,
    "lon": -68.5011,
    "alt_m": 12782.6
   },
   "member_spread_deg": {
    "lat": 13.56,
    "lon": 78.37
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.7
   },
   "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": 127.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-20 23:30:00",
    "lat": 56.97327,
    "lon": -105.55467,
    "alt_m": 12962.3
   },
   "member_spread_deg": {
    "lat": 31.19,
    "lon": 329.94
   },
   "member_spread_now_deg": {
    "lat": 35.82,
    "lon": 38.7
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 04:51:00",
   "seed_lat": -14.20833,
   "seed_lon": 97.5,
   "seed_alt_m": 15870.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 04:45:00",
    "lat": -34.72736,
    "lon": 162.92114,
    "alt_m": 15215.5
   },
   "member_spread_deg": {
    "lat": 20.87,
    "lon": 69.59
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}