{
 "generated_utc": "2026-09-06T11:26:47Z",
 "gfs_cycle_utc": "2026-09-06T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 471.5,
  "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_20260906_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260906_06Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 83547
 },
 "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": 211.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 05:45:00",
    "lat": -65.11277,
    "lon": -70.10922,
    "alt_m": 12259.8
   },
   "member_spread_deg": {
    "lat": 21.58,
    "lon": 251.55
   },
   "member_spread_now_deg": {
    "lat": 21.19,
    "lon": 63.19
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 22:12:18",
   "seed_lat": 37.70833,
   "seed_lon": -86.91667,
   "seed_alt_m": 14440.0,
   "seed_age_h": 13.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:45:00",
    "lat": 42.24226,
    "lon": 11.36062,
    "alt_m": 14225.6
   },
   "member_spread_deg": {
    "lat": 20.13,
    "lon": 70.4
   },
   "member_spread_now_deg": {
    "lat": 1.55,
    "lon": 2.65
   },
   "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": 277.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 16.39132,
    "lon": -52.8745,
    "alt_m": 13160.0
   },
   "member_spread_deg": {
    "lat": 33.15,
    "lon": 122.2
   },
   "member_spread_now_deg": {
    "lat": 16.52,
    "lon": 55.85
   },
   "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": 30.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 05:45:00",
    "lat": 84.68445,
    "lon": -82.96032,
    "alt_m": 11829.3
   },
   "member_spread_deg": {
    "lat": 24.7,
    "lon": 253.08
   },
   "member_spread_now_deg": {
    "lat": 0.88,
    "lon": 40.53
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 02:37:00",
   "seed_lat": 50.3125,
   "seed_lon": -174.08333,
   "seed_alt_m": 13010.0,
   "seed_age_h": 8.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 45.59696,
    "lon": -48.72631,
    "alt_m": 13522.0
   },
   "member_spread_deg": {
    "lat": 22.9,
    "lon": 158.0
   },
   "member_spread_now_deg": {
    "lat": 8.73,
    "lon": 8.93
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 07:36:00",
   "seed_lat": 43.02083,
   "seed_lon": 80.875,
   "seed_alt_m": 13360.0,
   "seed_age_h": 3.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 07:00:00",
    "lat": 33.63979,
    "lon": -179.79143,
    "alt_m": 13736.0
   },
   "member_spread_deg": {
    "lat": 43.43,
    "lon": 353.07
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 1.29
   },
   "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": 145.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 67.25364,
    "lon": 166.26849,
    "alt_m": 11941.0
   },
   "member_spread_deg": {
    "lat": 30.73,
    "lon": 334.99
   },
   "member_spread_now_deg": {
    "lat": 17.99,
    "lon": 330.48
   },
   "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": 21.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 35.05308,
    "lon": -178.37732,
    "alt_m": 14272.2
   },
   "member_spread_deg": {
    "lat": 38.73,
    "lon": 357.29
   },
   "member_spread_now_deg": {
    "lat": 1.02,
    "lon": 7.13
   },
   "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": 309.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:45:00",
    "lat": 44.42175,
    "lon": -142.55065,
    "alt_m": 12930.5
   },
   "member_spread_deg": {
    "lat": 23.73,
    "lon": 298.81
   },
   "member_spread_now_deg": {
    "lat": 25.55,
    "lon": 220.63
   },
   "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": 292.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 59.09639,
    "lon": -128.63811,
    "alt_m": 13457.3
   },
   "member_spread_deg": {
    "lat": 28.01,
    "lon": 298.41
   },
   "member_spread_now_deg": {
    "lat": 39.2,
    "lon": 228.93
   },
   "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": 75.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 30.65036,
    "lon": 160.40287,
    "alt_m": 12934.4
   },
   "member_spread_deg": {
    "lat": 41.88,
    "lon": 306.35
   },
   "member_spread_now_deg": {
    "lat": 19.3,
    "lon": 356.67
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 09:20:00",
   "seed_lat": 30.52083,
   "seed_lon": -6.0,
   "seed_alt_m": 13050.0,
   "seed_age_h": 2.0,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 08:45:00",
    "lat": 34.97057,
    "lon": 104.79281,
    "alt_m": 12693.4
   },
   "member_spread_deg": {
    "lat": 12.48,
    "lon": 345.44
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.36
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 02:01:00",
   "seed_lat": 62.91667,
   "seed_lon": -150.16667,
   "seed_alt_m": 12300.0,
   "seed_age_h": 9.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 70.34559,
    "lon": 66.95448,
    "alt_m": 12369.7
   },
   "member_spread_deg": {
    "lat": 29.9,
    "lon": 107.12
   },
   "member_spread_now_deg": {
    "lat": 2.23,
    "lon": 17.32
   },
   "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": 19.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 65.99976,
    "lon": -136.96395,
    "alt_m": 13097.7
   },
   "member_spread_deg": {
    "lat": 8.37,
    "lon": 316.27
   },
   "member_spread_now_deg": {
    "lat": 1.13,
    "lon": 2.18
   },
   "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": 259.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:45:00",
    "lat": 42.32939,
    "lon": 1.12557,
    "alt_m": 13359.2
   },
   "member_spread_deg": {
    "lat": 29.0,
    "lon": 153.97
   },
   "member_spread_now_deg": {
    "lat": 23.67,
    "lon": 95.74
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 03:03:00",
   "seed_lat": 28.04167,
   "seed_lon": -162.5,
   "seed_alt_m": 16300.0,
   "seed_age_h": 8.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 19.72044,
    "lon": -154.50429,
    "alt_m": 16570.8
   },
   "member_spread_deg": {
    "lat": 31.8,
    "lon": 339.04
   },
   "member_spread_now_deg": {
    "lat": 2.59,
    "lon": 4.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 22:26:00",
   "seed_lat": 52.83333,
   "seed_lon": -93.54167,
   "seed_alt_m": 13200.0,
   "seed_age_h": 12.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 05:30:00",
    "lat": 56.82749,
    "lon": 79.94873,
    "alt_m": 13189.4
   },
   "member_spread_deg": {
    "lat": 34.71,
    "lon": 98.66
   },
   "member_spread_now_deg": {
    "lat": 5.18,
    "lon": 5.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 10:36:00",
   "seed_lat": -26.9375,
   "seed_lon": 19.91667,
   "seed_alt_m": 15520.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 10:30:00",
    "lat": -26.14135,
    "lon": 108.22839,
    "alt_m": 15528.9
   },
   "member_spread_deg": {
    "lat": 20.1,
    "lon": 334.1
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}