{
 "generated_utc": "2026-09-05T17:26:35Z",
 "gfs_cycle_utc": "2026-09-05T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 453.5,
  "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_20260905_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260905_12Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 83664
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 193.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 11:45:00",
    "lat": -53.79396,
    "lon": -112.46513,
    "alt_m": 12379.4
   },
   "member_spread_deg": {
    "lat": 34.15,
    "lon": 229.62
   },
   "member_spread_now_deg": {
    "lat": 19.45,
    "lon": 55.69
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 16:59:18",
   "seed_lat": 39.16667,
   "seed_lon": -89.625,
   "seed_alt_m": 14480.0,
   "seed_age_h": 0.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 17:00:00",
    "lat": 37.05555,
    "lon": -11.00524,
    "alt_m": 14484.3
   },
   "member_spread_deg": {
    "lat": 31.87,
    "lon": 83.23
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:29:00",
   "seed_lat": 33.10417,
   "seed_lon": -84.75,
   "seed_alt_m": 13050.0,
   "seed_age_h": 259.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 1.3482,
    "lon": -49.75614,
    "alt_m": 13181.1
   },
   "member_spread_deg": {
    "lat": 26.33,
    "lon": 107.42
   },
   "member_spread_now_deg": {
    "lat": 19.85,
    "lon": 52.36
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "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": 12.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 11:45:00",
    "lat": 84.37792,
    "lon": -22.57635,
    "alt_m": 11572.1
   },
   "member_spread_deg": {
    "lat": 14.06,
    "lon": 295.24
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 11.77
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 06:27:00",
   "seed_lat": 41.83333,
   "seed_lon": 143.0,
   "seed_alt_m": 13010.0,
   "seed_age_h": 10.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 37.61241,
    "lon": -35.38154,
    "alt_m": 13398.5
   },
   "member_spread_deg": {
    "lat": 33.93,
    "lon": 186.88
   },
   "member_spread_now_deg": {
    "lat": 3.97,
    "lon": 6.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 09:41:00",
   "seed_lat": 46.375,
   "seed_lon": 57.29167,
   "seed_alt_m": 13450.0,
   "seed_age_h": 7.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:45:00",
    "lat": 39.7642,
    "lon": -151.60794,
    "alt_m": 13646.3
   },
   "member_spread_deg": {
    "lat": 44.76,
    "lon": 300.37
   },
   "member_spread_now_deg": {
    "lat": 1.78,
    "lon": 3.23
   },
   "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": 127.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 62.33232,
    "lon": -171.64856,
    "alt_m": 11788.8
   },
   "member_spread_deg": {
    "lat": 28.16,
    "lon": 194.14
   },
   "member_spread_now_deg": {
    "lat": 34.29,
    "lon": 319.82
   },
   "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": 3.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-12 13:00:00",
    "lat": 32.67852,
    "lon": -135.44281,
    "alt_m": 14186.4
   },
   "member_spread_deg": {
    "lat": 46.72,
    "lon": 326.44
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 1.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 291.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:45:00",
    "lat": 22.97712,
    "lon": -56.17155,
    "alt_m": 13416.4
   },
   "member_spread_deg": {
    "lat": 41.81,
    "lon": 234.99
   },
   "member_spread_now_deg": {
    "lat": 18.75,
    "lon": 268.99
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 06:33:48",
   "seed_lat": 61.6875,
   "seed_lon": -165.70833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 274.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 45.38688,
    "lon": -79.66881,
    "alt_m": 13781.3
   },
   "member_spread_deg": {
    "lat": 36.1,
    "lon": 318.27
   },
   "member_spread_now_deg": {
    "lat": 38.05,
    "lon": 184.01
   },
   "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": 57.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 40.05142,
    "lon": 167.43121,
    "alt_m": 12870.2
   },
   "member_spread_deg": {
    "lat": 37.03,
    "lon": 319.87
   },
   "member_spread_now_deg": {
    "lat": 4.66,
    "lon": 14.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 16:25:00",
   "seed_lat": 29.70833,
   "seed_lon": -14.33333,
   "seed_alt_m": 12960.0,
   "seed_age_h": 0.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 16:00:00",
    "lat": 44.89347,
    "lon": 93.31674,
    "alt_m": 12758.8
   },
   "member_spread_deg": {
    "lat": 10.78,
    "lon": 62.48
   },
   "member_spread_now_deg": {
    "lat": 0.37,
    "lon": 0.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 02:36:00",
   "seed_lat": 55.70833,
   "seed_lon": -173.95833,
   "seed_alt_m": 12060.0,
   "seed_age_h": 14.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 51.18242,
    "lon": 44.88512,
    "alt_m": 12834.0
   },
   "member_spread_deg": {
    "lat": 17.63,
    "lon": 179.74
   },
   "member_spread_now_deg": {
    "lat": 0.32,
    "lon": 11.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 1.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 15:00:00",
    "lat": 62.76181,
    "lon": -160.32776,
    "alt_m": 13114.0
   },
   "member_spread_deg": {
    "lat": 14.68,
    "lon": 334.7
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 241.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:45:00",
    "lat": 44.78556,
    "lon": 4.78969,
    "alt_m": 13324.3
   },
   "member_spread_deg": {
    "lat": 18.99,
    "lon": 229.28
   },
   "member_spread_now_deg": {
    "lat": 12.41,
    "lon": 77.32
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 03:01:00",
   "seed_lat": 35.79167,
   "seed_lon": -162.375,
   "seed_alt_m": 16200.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 28.03645,
    "lon": -166.67103,
    "alt_m": 16420.4
   },
   "member_spread_deg": {
    "lat": 22.46,
    "lon": 349.85
   },
   "member_spread_now_deg": {
    "lat": 5.21,
    "lon": 2.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 16:51:00",
   "seed_lat": 52.41667,
   "seed_lon": -103.125,
   "seed_alt_m": 13260.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 16:15:00",
    "lat": 54.47875,
    "lon": 85.30744,
    "alt_m": 13283.4
   },
   "member_spread_deg": {
    "lat": 20.74,
    "lon": 81.97
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-04 23:05:23",
   "seed_lat": 65.56245,
   "seed_lon": -134.08331,
   "seed_alt_m": 13180.0,
   "seed_age_h": 18.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 11:30:00",
    "lat": 47.0192,
    "lon": 8.31861,
    "alt_m": 13492.3
   },
   "member_spread_deg": {
    "lat": 52.26,
    "lon": 124.7
   },
   "member_spread_now_deg": {
    "lat": 11.7,
    "lon": 15.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:21:00",
   "seed_lat": -31.45833,
   "seed_lon": 12.45833,
   "seed_alt_m": 15480.0,
   "seed_age_h": 3.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-12 12:45:00",
    "lat": -27.27357,
    "lon": 81.94423,
    "alt_m": 15456.2
   },
   "member_spread_deg": {
    "lat": 15.89,
    "lon": 296.29
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 0.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}