{
 "generated_utc": "2026-08-22T23:27:09Z",
 "gfs_cycle_utc": "2026-08-22T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 473.5,
  "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_20260822_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260822_18Z.geojson.gz"
 },
 "counts": {
  "flights": 23,
  "members": 9,
  "rows": 94590
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 13:43:40",
   "seed_lat": -61.64583,
   "seed_lon": 25.04168,
   "seed_alt_m": 12480.0,
   "seed_age_h": 9.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": -68.49197,
    "lon": 53.57708,
    "alt_m": 12367.7
   },
   "member_spread_deg": {
    "lat": 24.97,
    "lon": 304.18
   },
   "member_spread_now_deg": {
    "lat": 2.06,
    "lon": 15.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 22:48:47",
   "seed_lat": 81.0625,
   "seed_lon": -103.41667,
   "seed_alt_m": 12330.0,
   "seed_age_h": 0.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 22:15:00",
    "lat": 55.23866,
    "lon": 64.01878,
    "alt_m": 12381.4
   },
   "member_spread_deg": {
    "lat": 16.36,
    "lon": 94.21
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 21:42:18",
   "seed_lat": 41.04167,
   "seed_lon": -89.125,
   "seed_alt_m": 14010.0,
   "seed_age_h": 1.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 21:15:00",
    "lat": 57.89203,
    "lon": 29.19767,
    "alt_m": 13847.7
   },
   "member_spread_deg": {
    "lat": 14.76,
    "lon": 86.35
   },
   "member_spread_now_deg": {
    "lat": 0.6,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 22:04:00",
   "seed_lat": 37.5,
   "seed_lon": -153.91667,
   "seed_alt_m": 12980.0,
   "seed_age_h": 1.27,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 21:30:00",
    "lat": 41.1993,
    "lon": 39.60977,
    "alt_m": 12737.5
   },
   "member_spread_deg": {
    "lat": 28.62,
    "lon": 62.85
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 1.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 311.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": -3.95446,
    "lon": -30.46923,
    "alt_m": 14031.8
   },
   "member_spread_deg": {
    "lat": 68.79,
    "lon": 166.54
   },
   "member_spread_now_deg": {
    "lat": 57.35,
    "lon": 122.16
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 11:26:00",
   "seed_lat": 49.08333,
   "seed_lon": 69.16667,
   "seed_alt_m": 12560.0,
   "seed_age_h": 11.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:30:00",
    "lat": 56.78644,
    "lon": -120.80117,
    "alt_m": 12290.6
   },
   "member_spread_deg": {
    "lat": 25.46,
    "lon": 155.77
   },
   "member_spread_now_deg": {
    "lat": 2.48,
    "lon": 1.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 21:37:00",
   "seed_lat": 58.72917,
   "seed_lon": -171.75,
   "seed_alt_m": 13020.0,
   "seed_age_h": 1.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 21:00:00",
    "lat": 47.43601,
    "lon": -15.39142,
    "alt_m": 13073.9
   },
   "member_spread_deg": {
    "lat": 11.97,
    "lon": 116.16
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 22:53:00",
   "seed_lat": 68.97917,
   "seed_lon": 171.04167,
   "seed_alt_m": 11840.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 23:00:00",
    "lat": 62.56807,
    "lon": -39.00341,
    "alt_m": 12128.6
   },
   "member_spread_deg": {
    "lat": 32.03,
    "lon": 323.49
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 15:53:00",
   "seed_lat": 53.35417,
   "seed_lon": 17.375,
   "seed_alt_m": 12510.0,
   "seed_age_h": 7.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:30:00",
    "lat": 46.76615,
    "lon": 125.035,
    "alt_m": 12601.2
   },
   "member_spread_deg": {
    "lat": 31.36,
    "lon": 75.49
   },
   "member_spread_now_deg": {
    "lat": 1.23,
    "lon": 0.94
   },
   "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": 170.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": 22.48586,
    "lon": -60.15372,
    "alt_m": 13409.3
   },
   "member_spread_deg": {
    "lat": 48.16,
    "lon": 256.34
   },
   "member_spread_now_deg": {
    "lat": 17.01,
    "lon": 65.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 12:13:33",
   "seed_lat": 62.72917,
   "seed_lon": 114.16667,
   "seed_alt_m": 13210.0,
   "seed_age_h": 11.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": 59.97028,
    "lon": -91.85179,
    "alt_m": 13368.8
   },
   "member_spread_deg": {
    "lat": 32.34,
    "lon": 120.96
   },
   "member_spread_now_deg": {
    "lat": 0.57,
    "lon": 2.73
   },
   "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": 251.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": 69.11161,
    "lon": 109.1491,
    "alt_m": 12549.5
   },
   "member_spread_deg": {
    "lat": 31.67,
    "lon": 277.98
   },
   "member_spread_now_deg": {
    "lat": 31.62,
    "lon": 301.82
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 14:59:00",
   "seed_lat": 47.54167,
   "seed_lon": -29.75,
   "seed_alt_m": 11670.0,
   "seed_age_h": 8.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 17:30:00",
    "lat": 41.06756,
    "lon": 109.1539,
    "alt_m": 11340.7
   },
   "member_spread_deg": {
    "lat": 22.09,
    "lon": 146.7
   },
   "member_spread_now_deg": {
    "lat": 3.0,
    "lon": 0.63
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 22:35:00",
   "seed_lat": 34.33333,
   "seed_lon": -178.08333,
   "seed_alt_m": 13020.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 22:00:00",
    "lat": 21.9619,
    "lon": -171.33133,
    "alt_m": 13023.3
   },
   "member_spread_deg": {
    "lat": 21.14,
    "lon": 78.58
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:01:00",
   "seed_lat": 85.25,
   "seed_lon": 45.875,
   "seed_alt_m": 11960.0,
   "seed_age_h": 61.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 17:30:00",
    "lat": 64.25877,
    "lon": 69.44972,
    "alt_m": 11740.8
   },
   "member_spread_deg": {
    "lat": 45.63,
    "lon": 260.16
   },
   "member_spread_now_deg": {
    "lat": 4.74,
    "lon": 343.08
   },
   "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": 218.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": 30.0644,
    "lon": -65.17003,
    "alt_m": 11237.8
   },
   "member_spread_deg": {
    "lat": 50.78,
    "lon": 326.79
   },
   "member_spread_now_deg": {
    "lat": 15.04,
    "lon": 100.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 22:45:45",
   "seed_lat": 79.93745,
   "seed_lon": -146.70831,
   "seed_alt_m": 12780.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 22:15:00",
    "lat": 68.65274,
    "lon": -172.42926,
    "alt_m": 12847.4
   },
   "member_spread_deg": {
    "lat": 22.54,
    "lon": 337.99
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 14:18:00",
   "seed_lat": 13.52083,
   "seed_lon": 30.0,
   "seed_alt_m": 16560.0,
   "seed_age_h": 9.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": 34.61046,
    "lon": 40.70613,
    "alt_m": 16243.8
   },
   "member_spread_deg": {
    "lat": 22.01,
    "lon": 103.39
   },
   "member_spread_now_deg": {
    "lat": 1.82,
    "lon": 2.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 21:41:00",
   "seed_lat": 39.3125,
   "seed_lon": -89.625,
   "seed_alt_m": 13250.0,
   "seed_age_h": 1.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 21:15:00",
    "lat": 45.14722,
    "lon": 113.71927,
    "alt_m": 12965.2
   },
   "member_spread_deg": {
    "lat": 7.25,
    "lon": 117.46
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 0.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 21:40:23",
   "seed_lat": 56.83328,
   "seed_lon": -87.12498,
   "seed_alt_m": 13000.0,
   "seed_age_h": 1.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 21:15:00",
    "lat": 43.36881,
    "lon": 45.83816,
    "alt_m": 13299.0
   },
   "member_spread_deg": {
    "lat": 27.69,
    "lon": 56.02
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.48
   },
   "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": 122.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-29 17:30:00",
    "lat": -16.40225,
    "lon": -38.80592,
    "alt_m": 12520.7
   },
   "member_spread_deg": {
    "lat": 30.9,
    "lon": 117.54
   },
   "member_spread_now_deg": {
    "lat": 17.93,
    "lon": 143.23
   },
   "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": 256.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": -22.95688,
    "lon": 119.65878,
    "alt_m": 15914.0
   },
   "member_spread_deg": {
    "lat": 38.79,
    "lon": 246.35
   },
   "member_spread_now_deg": {
    "lat": 24.72,
    "lon": 190.35
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 09:41:00",
   "seed_lat": -27.0625,
   "seed_lon": 95.04167,
   "seed_alt_m": 15530.0,
   "seed_age_h": 13.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-29 17:45:00",
    "lat": -27.09512,
    "lon": -53.25585,
    "alt_m": 15397.1
   },
   "member_spread_deg": {
    "lat": 25.3,
    "lon": 50.07
   },
   "member_spread_now_deg": {
    "lat": 3.75,
    "lon": 12.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}