{
 "generated_utc": "2026-08-26T23:27:14Z",
 "gfs_cycle_utc": "2026-08-26T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 476.5,
  "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_20260826_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260826_18Z.geojson.gz"
 },
 "counts": {
  "flights": 20,
  "members": 9,
  "rows": 78318
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 22:48:40",
   "seed_lat": -70.39583,
   "seed_lon": -149.12499,
   "seed_alt_m": 12300.0,
   "seed_age_h": 0.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 22:45:00",
    "lat": -81.33068,
    "lon": -85.12066,
    "alt_m": 12059.9
   },
   "member_spread_deg": {
    "lat": 12.66,
    "lon": 330.15
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:43:18",
   "seed_lat": 35.89583,
   "seed_lon": -6.625,
   "seed_alt_m": 14390.0,
   "seed_age_h": 6.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 50.20765,
    "lon": -134.2868,
    "alt_m": 14079.7
   },
   "member_spread_deg": {
    "lat": 13.78,
    "lon": 323.68
   },
   "member_spread_now_deg": {
    "lat": 3.32,
    "lon": 5.49
   },
   "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": 25.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 29.49413,
    "lon": -35.87429,
    "alt_m": 13151.9
   },
   "member_spread_deg": {
    "lat": 15.26,
    "lon": 76.17
   },
   "member_spread_now_deg": {
    "lat": 2.66,
    "lon": 1.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 21:06:00",
   "seed_lat": 58.375,
   "seed_lon": -142.54167,
   "seed_alt_m": 12490.0,
   "seed_age_h": 2.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 20:30:00",
    "lat": 64.97347,
    "lon": -142.14551,
    "alt_m": 12190.9
   },
   "member_spread_deg": {
    "lat": 16.07,
    "lon": 335.94
   },
   "member_spread_now_deg": {
    "lat": 0.9,
    "lon": 1.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 21:52:00",
   "seed_lat": 43.79167,
   "seed_lon": -94.20833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 1.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 21:15:00",
    "lat": 43.03079,
    "lon": 63.36898,
    "alt_m": 13098.5
   },
   "member_spread_deg": {
    "lat": 23.62,
    "lon": 52.43
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:38:00",
   "seed_lat": 83.20833,
   "seed_lon": -24.91667,
   "seed_alt_m": 11920.0,
   "seed_age_h": 9.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 62.51834,
    "lon": 142.11041,
    "alt_m": 12339.5
   },
   "member_spread_deg": {
    "lat": 23.21,
    "lon": 101.4
   },
   "member_spread_now_deg": {
    "lat": 0.86,
    "lon": 15.86
   },
   "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": 57.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 63.25427,
    "lon": -148.16721,
    "alt_m": 12511.2
   },
   "member_spread_deg": {
    "lat": 38.63,
    "lon": 91.45
   },
   "member_spread_now_deg": {
    "lat": 20.73,
    "lon": 64.42
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 266.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 31.41346,
    "lon": 3.5402,
    "alt_m": 13190.0
   },
   "member_spread_deg": {
    "lat": 41.01,
    "lon": 253.33
   },
   "member_spread_now_deg": {
    "lat": 49.7,
    "lon": 175.38
   },
   "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": 40.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 51.23047,
    "lon": -33.40496,
    "alt_m": 13294.0
   },
   "member_spread_deg": {
    "lat": 26.18,
    "lon": 350.87
   },
   "member_spread_now_deg": {
    "lat": 17.61,
    "lon": 36.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:24:00",
   "seed_lat": 39.64583,
   "seed_lon": 8.25,
   "seed_alt_m": 12840.0,
   "seed_age_h": 9.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 59.1647,
    "lon": -169.23212,
    "alt_m": 12597.0
   },
   "member_spread_deg": {
    "lat": 28.82,
    "lon": 288.88
   },
   "member_spread_now_deg": {
    "lat": 2.63,
    "lon": 1.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 22:05:00",
   "seed_lat": 28.9375,
   "seed_lon": -170.125,
   "seed_alt_m": 12950.0,
   "seed_age_h": 1.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 21:30:00",
    "lat": 31.56442,
    "lon": -57.3158,
    "alt_m": 13079.2
   },
   "member_spread_deg": {
    "lat": 19.44,
    "lon": 65.42
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.44
   },
   "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": 72.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 69.56544,
    "lon": 144.51454,
    "alt_m": 12350.0
   },
   "member_spread_deg": {
    "lat": 20.38,
    "lon": 157.37
   },
   "member_spread_now_deg": {
    "lat": 16.17,
    "lon": 230.72
   },
   "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": 314.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 28.60691,
    "lon": -10.41386,
    "alt_m": 11208.1
   },
   "member_spread_deg": {
    "lat": 45.01,
    "lon": 349.62
   },
   "member_spread_now_deg": {
    "lat": 51.03,
    "lon": 226.91
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 07:50:45",
   "seed_lat": 81.70828,
   "seed_lon": 127.58335,
   "seed_alt_m": 12600.0,
   "seed_age_h": 15.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 68.0598,
    "lon": -27.94989,
    "alt_m": 12894.6
   },
   "member_spread_deg": {
    "lat": 24.61,
    "lon": 343.28
   },
   "member_spread_now_deg": {
    "lat": 1.88,
    "lon": 14.91
   },
   "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": 7.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 42.14493,
    "lon": -115.63753,
    "alt_m": 13120.8
   },
   "member_spread_deg": {
    "lat": 13.77,
    "lon": 36.87
   },
   "member_spread_now_deg": {
    "lat": 0.51,
    "lon": 1.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:11:00",
   "seed_lat": 29.6875,
   "seed_lon": -2.45833,
   "seed_alt_m": 16600.0,
   "seed_age_h": 7.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:45:00",
    "lat": 36.59944,
    "lon": 108.49849,
    "alt_m": 16406.9
   },
   "member_spread_deg": {
    "lat": 23.65,
    "lon": 356.88
   },
   "member_spread_now_deg": {
    "lat": 0.52,
    "lon": 2.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 14:31:00",
   "seed_lat": 46.83333,
   "seed_lon": 23.125,
   "seed_alt_m": 13050.0,
   "seed_age_h": 8.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 32.32168,
    "lon": -132.49087,
    "alt_m": 13279.4
   },
   "member_spread_deg": {
    "lat": 27.12,
    "lon": 329.62
   },
   "member_spread_now_deg": {
    "lat": 2.89,
    "lon": 3.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 15:25:23",
   "seed_lat": 50.93745,
   "seed_lon": 2.25002,
   "seed_alt_m": 13420.0,
   "seed_age_h": 7.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": 50.73447,
    "lon": 152.84264,
    "alt_m": 13350.2
   },
   "member_spread_deg": {
    "lat": 19.8,
    "lon": 357.11
   },
   "member_spread_now_deg": {
    "lat": 0.83,
    "lon": 4.43
   },
   "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": 218.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 17:30:00",
    "lat": -29.40586,
    "lon": 78.885,
    "alt_m": 12280.6
   },
   "member_spread_deg": {
    "lat": 18.37,
    "lon": 181.85
   },
   "member_spread_now_deg": {
    "lat": 24.64,
    "lon": 130.37
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 22:51:00",
   "seed_lat": -24.33333,
   "seed_lon": -164.54167,
   "seed_alt_m": 15380.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 22:45:00",
    "lat": -29.89132,
    "lon": -5.42093,
    "alt_m": 15393.1
   },
   "member_spread_deg": {
    "lat": 38.16,
    "lon": 97.03
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}