{
 "generated_utc": "2026-08-25T11:27:19Z",
 "gfs_cycle_utc": "2026-08-25T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 479.5,
  "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_20260825_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260825_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 89244
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 05:58:40",
   "seed_lat": -63.97917,
   "seed_lon": 135.91668,
   "seed_alt_m": 12480.0,
   "seed_age_h": 5.36,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:30:00",
    "lat": -69.51766,
    "lon": 163.434,
    "alt_m": 11973.6
   },
   "member_spread_deg": {
    "lat": 20.69,
    "lon": 354.7
   },
   "member_spread_now_deg": {
    "lat": 2.43,
    "lon": 0.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:47:17",
   "seed_lat": 57.39583,
   "seed_lon": -60.0,
   "seed_alt_m": 13900.0,
   "seed_age_h": 18.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 54.15599,
    "lon": 178.47268,
    "alt_m": 13759.0
   },
   "member_spread_deg": {
    "lat": 14.43,
    "lon": 321.57
   },
   "member_spread_now_deg": {
    "lat": 19.24,
    "lon": 17.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 22:09:00",
   "seed_lat": 46.33333,
   "seed_lon": -102.45833,
   "seed_alt_m": 12920.0,
   "seed_age_h": 13.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 42.38272,
    "lon": 90.11664,
    "alt_m": 12772.3
   },
   "member_spread_deg": {
    "lat": 19.4,
    "lon": 68.35
   },
   "member_spread_now_deg": {
    "lat": 3.12,
    "lon": 5.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 07:46:00",
   "seed_lat": 54.16667,
   "seed_lon": 152.66667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 3.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 07:15:00",
    "lat": 80.54625,
    "lon": 142.17255,
    "alt_m": 11945.5
   },
   "member_spread_deg": {
    "lat": 34.51,
    "lon": 228.32
   },
   "member_spread_now_deg": {
    "lat": 0.46,
    "lon": 2.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 01:42:00",
   "seed_lat": 36.39583,
   "seed_lon": -131.75,
   "seed_alt_m": 13340.0,
   "seed_age_h": 9.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 55.5522,
    "lon": 41.26768,
    "alt_m": 13093.6
   },
   "member_spread_deg": {
    "lat": 15.39,
    "lon": 54.71
   },
   "member_spread_now_deg": {
    "lat": 1.67,
    "lon": 1.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 22:23:00",
   "seed_lat": 79.125,
   "seed_lon": -107.5,
   "seed_alt_m": 11860.0,
   "seed_age_h": 12.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 05:30:00",
    "lat": 74.77158,
    "lon": 89.01482,
    "alt_m": 12130.5
   },
   "member_spread_deg": {
    "lat": 35.72,
    "lon": 177.27
   },
   "member_spread_now_deg": {
    "lat": 3.46,
    "lon": 53.34
   },
   "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": 21.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 50.73637,
    "lon": 150.80182,
    "alt_m": 12766.5
   },
   "member_spread_deg": {
    "lat": 28.06,
    "lon": 334.59
   },
   "member_spread_now_deg": {
    "lat": 12.44,
    "lon": 16.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 230.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 25.91193,
    "lon": -35.07008,
    "alt_m": 13305.1
   },
   "member_spread_deg": {
    "lat": 41.78,
    "lon": 247.71
   },
   "member_spread_now_deg": {
    "lat": 40.3,
    "lon": 121.57
   },
   "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": 4.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 06:00:00",
    "lat": 60.61531,
    "lon": -63.5136,
    "alt_m": 13364.6
   },
   "member_spread_deg": {
    "lat": 30.97,
    "lon": 238.89
   },
   "member_spread_now_deg": {
    "lat": 2.49,
    "lon": 5.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 311.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 72.74527,
    "lon": 150.54411,
    "alt_m": 12379.0
   },
   "member_spread_deg": {
    "lat": 39.76,
    "lon": 286.23
   },
   "member_spread_now_deg": {
    "lat": 29.23,
    "lon": 291.83
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 09:19:00",
   "seed_lat": 25.52083,
   "seed_lon": -19.5,
   "seed_alt_m": 12820.0,
   "seed_age_h": 2.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 08:45:00",
    "lat": 42.40997,
    "lon": 163.37163,
    "alt_m": 12548.9
   },
   "member_spread_deg": {
    "lat": 24.44,
    "lon": 339.32
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 04:10:00",
   "seed_lat": 30.70833,
   "seed_lon": -167.58333,
   "seed_alt_m": 13010.0,
   "seed_age_h": 7.17,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 40.98679,
    "lon": -59.62957,
    "alt_m": 12998.8
   },
   "member_spread_deg": {
    "lat": 23.39,
    "lon": 62.69
   },
   "member_spread_now_deg": {
    "lat": 1.41,
    "lon": 1.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 36.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 05:30:00",
    "lat": 72.38374,
    "lon": 123.33071,
    "alt_m": 12347.6
   },
   "member_spread_deg": {
    "lat": 28.91,
    "lon": 209.1
   },
   "member_spread_now_deg": {
    "lat": 6.54,
    "lon": 205.67
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 278.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 24.45094,
    "lon": -6.43502,
    "alt_m": 11143.4
   },
   "member_spread_deg": {
    "lat": 56.61,
    "lon": 355.53
   },
   "member_spread_now_deg": {
    "lat": 35.54,
    "lon": 152.54
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 01:45:45",
   "seed_lat": 81.20828,
   "seed_lon": -145.74998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 57.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": 65.46822,
    "lon": -43.25562,
    "alt_m": 12812.2
   },
   "member_spread_deg": {
    "lat": 13.83,
    "lon": 150.73
   },
   "member_spread_now_deg": {
    "lat": 9.69,
    "lon": 121.93
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-25 11:04:58",
   "seed_lat": 40.67366,
   "seed_lon": -5.47767,
   "seed_alt_m": 13177.0,
   "seed_age_h": 0.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:00:00",
    "lat": 34.31915,
    "lon": -138.83979,
    "alt_m": 13251.3
   },
   "member_spread_deg": {
    "lat": 24.5,
    "lon": 355.89
   },
   "member_spread_now_deg": {
    "lat": 0.0,
    "lon": 0.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 10:36:00",
   "seed_lat": 22.27083,
   "seed_lon": -5.125,
   "seed_alt_m": 16700.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 10:00:00",
    "lat": 49.10559,
    "lon": 108.49783,
    "alt_m": 15872.8
   },
   "member_spread_deg": {
    "lat": 21.73,
    "lon": 207.07
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 09:51:00",
   "seed_lat": 36.5,
   "seed_lon": -12.95833,
   "seed_alt_m": 13350.0,
   "seed_age_h": 1.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 09:15:00",
    "lat": 39.56812,
    "lon": -137.65303,
    "alt_m": 13359.4
   },
   "member_spread_deg": {
    "lat": 20.31,
    "lon": 340.19
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 0.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 20:59:00",
   "seed_lat": -20.58333,
   "seed_lon": -72.33333,
   "seed_alt_m": 12210.0,
   "seed_age_h": 182.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 05:30:00",
    "lat": -16.25452,
    "lon": 8.40144,
    "alt_m": 12647.8
   },
   "member_spread_deg": {
    "lat": 33.85,
    "lon": 177.94
   },
   "member_spread_now_deg": {
    "lat": 11.51,
    "lon": 348.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 316.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-01 05:45:00",
    "lat": -28.53738,
    "lon": 131.45234,
    "alt_m": 15955.8
   },
   "member_spread_deg": {
    "lat": 41.17,
    "lon": 231.65
   },
   "member_spread_now_deg": {
    "lat": 32.85,
    "lon": 259.35
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 05:26:00",
   "seed_lat": -27.04167,
   "seed_lon": 152.16667,
   "seed_alt_m": 15550.0,
   "seed_age_h": 5.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 05:30:00",
    "lat": -29.25357,
    "lon": -20.10915,
    "alt_m": 15439.6
   },
   "member_spread_deg": {
    "lat": 48.75,
    "lon": 68.54
   },
   "member_spread_now_deg": {
    "lat": 0.48,
    "lon": 5.63
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}