{
 "generated_utc": "2026-08-19T05:25:53Z",
 "gfs_cycle_utc": "2026-08-19T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 383.5,
  "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_20260819_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260819_00Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 78003
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 00:13:40",
   "seed_lat": -64.60417,
   "seed_lon": -143.74999,
   "seed_alt_m": 12240.0,
   "seed_age_h": 5.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": -58.01486,
    "lon": 174.94162,
    "alt_m": 12012.1
   },
   "member_spread_deg": {
    "lat": 28.65,
    "lon": 336.1
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 0.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 03:13:18",
   "seed_lat": 67.125,
   "seed_lon": 163.66667,
   "seed_alt_m": 12380.0,
   "seed_age_h": 2.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 02:45:00",
    "lat": 79.87889,
    "lon": 113.80145,
    "alt_m": 11993.0
   },
   "member_spread_deg": {
    "lat": 28.39,
    "lon": 201.01
   },
   "member_spread_now_deg": {
    "lat": 0.6,
    "lon": 1.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 03:48:18",
   "seed_lat": 43.79167,
   "seed_lon": -166.58333,
   "seed_alt_m": 14200.0,
   "seed_age_h": 25.53,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 54.63199,
    "lon": -45.91001,
    "alt_m": 13755.1
   },
   "member_spread_deg": {
    "lat": 39.44,
    "lon": 101.76
   },
   "member_spread_now_deg": {
    "lat": 5.74,
    "lon": 17.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 02:39:00",
   "seed_lat": 45.625,
   "seed_lon": 126.375,
   "seed_alt_m": 12610.0,
   "seed_age_h": 2.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 02:15:00",
    "lat": 43.81455,
    "lon": -68.16541,
    "alt_m": 12780.0
   },
   "member_spread_deg": {
    "lat": 20.3,
    "lon": 73.6
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.33
   },
   "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": 221.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": -0.12229,
    "lon": -69.74916,
    "alt_m": 14093.2
   },
   "member_spread_deg": {
    "lat": 51.36,
    "lon": 177.4
   },
   "member_spread_now_deg": {
    "lat": 46.68,
    "lon": 90.26
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 19:36:00",
   "seed_lat": 54.4375,
   "seed_lon": -45.375,
   "seed_alt_m": 12580.0,
   "seed_age_h": 9.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:30:00",
    "lat": 55.44322,
    "lon": 173.88105,
    "alt_m": 12574.9
   },
   "member_spread_deg": {
    "lat": 20.83,
    "lon": 304.06
   },
   "member_spread_now_deg": {
    "lat": 1.09,
    "lon": 8.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 01:52:00",
   "seed_lat": 45.54167,
   "seed_lon": 101.0,
   "seed_alt_m": 13040.0,
   "seed_age_h": 3.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 01:15:00",
    "lat": 61.96999,
    "lon": -96.93242,
    "alt_m": 12958.0
   },
   "member_spread_deg": {
    "lat": 22.87,
    "lon": 49.69
   },
   "member_spread_now_deg": {
    "lat": 1.01,
    "lon": 1.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 16:38:00",
   "seed_lat": 81.58333,
   "seed_lon": 14.95833,
   "seed_alt_m": 11970.0,
   "seed_age_h": 12.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 73.39841,
    "lon": -158.43282,
    "alt_m": 11608.0
   },
   "member_spread_deg": {
    "lat": 19.93,
    "lon": 319.52
   },
   "member_spread_now_deg": {
    "lat": 0.71,
    "lon": 13.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 19:28:00",
   "seed_lat": 64.0,
   "seed_lon": -37.41667,
   "seed_alt_m": 12680.0,
   "seed_age_h": 9.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:30:00",
    "lat": 63.00016,
    "lon": 75.91585,
    "alt_m": 12319.7
   },
   "member_spread_deg": {
    "lat": 24.36,
    "lon": 63.66
   },
   "member_spread_now_deg": {
    "lat": 0.84,
    "lon": 1.43
   },
   "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": 80.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 29.41922,
    "lon": -110.36421,
    "alt_m": 13355.6
   },
   "member_spread_deg": {
    "lat": 39.88,
    "lon": 128.85
   },
   "member_spread_now_deg": {
    "lat": 22.07,
    "lon": 37.72
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 04:52:34",
   "seed_lat": 76.0,
   "seed_lon": 54.375,
   "seed_alt_m": 13270.0,
   "seed_age_h": 0.46,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:00:00",
    "lat": 63.51623,
    "lon": -158.41132,
    "alt_m": 13232.5
   },
   "member_spread_deg": {
    "lat": 25.46,
    "lon": 252.98
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.34
   },
   "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": 161.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 87.32847,
    "lon": -96.49414,
    "alt_m": 12302.5
   },
   "member_spread_deg": {
    "lat": 41.5,
    "lon": 261.79
   },
   "member_spread_now_deg": {
    "lat": 22.55,
    "lon": 347.64
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 04:35:00",
   "seed_lat": 55.83333,
   "seed_lon": 160.83333,
   "seed_alt_m": 13050.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 04:00:00",
    "lat": 32.19464,
    "lon": -134.3986,
    "alt_m": 13052.0
   },
   "member_spread_deg": {
    "lat": 21.0,
    "lon": 71.38
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 17:46:00",
   "seed_lat": 78.58333,
   "seed_lon": -21.91667,
   "seed_alt_m": 12200.0,
   "seed_age_h": 11.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 83.74522,
    "lon": 43.02301,
    "alt_m": 11926.9
   },
   "member_spread_deg": {
    "lat": 26.2,
    "lon": 285.47
   },
   "member_spread_now_deg": {
    "lat": 2.72,
    "lon": 9.56
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 128.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 30.11859,
    "lon": -48.38996,
    "alt_m": 11261.1
   },
   "member_spread_deg": {
    "lat": 41.48,
    "lon": 206.74
   },
   "member_spread_now_deg": {
    "lat": 21.91,
    "lon": 82.87
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 23:20:45",
   "seed_lat": 61.49995,
   "seed_lon": 126.29169,
   "seed_alt_m": 13000.0,
   "seed_age_h": 5.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 78.45812,
    "lon": -49.69177,
    "alt_m": 12915.4
   },
   "member_spread_deg": {
    "lat": 15.11,
    "lon": 349.35
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 2.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 04:31:00",
   "seed_lat": 9.8125,
   "seed_lon": 94.25,
   "seed_alt_m": 16470.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 04:00:00",
    "lat": 16.32144,
    "lon": -13.49677,
    "alt_m": 16471.2
   },
   "member_spread_deg": {
    "lat": 12.1,
    "lon": 33.44
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 03:06:00",
   "seed_lat": 45.47917,
   "seed_lon": -147.04167,
   "seed_alt_m": 13500.0,
   "seed_age_h": 2.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 02:30:00",
    "lat": 37.58757,
    "lon": -3.60707,
    "alt_m": 13442.6
   },
   "member_spread_deg": {
    "lat": 15.46,
    "lon": 103.99
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 23:45:23",
   "seed_lat": 66.70828,
   "seed_lon": -132.62498,
   "seed_alt_m": 12900.0,
   "seed_age_h": 5.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": 52.21302,
    "lon": -24.61124,
    "alt_m": 13223.0
   },
   "member_spread_deg": {
    "lat": 15.18,
    "lon": 58.69
   },
   "member_spread_now_deg": {
    "lat": 0.45,
    "lon": 1.11
   },
   "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": 32.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-25 23:30:00",
    "lat": -23.33794,
    "lon": -166.17982,
    "alt_m": 12044.7
   },
   "member_spread_deg": {
    "lat": 29.18,
    "lon": 303.89
   },
   "member_spread_now_deg": {
    "lat": 19.59,
    "lon": 33.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 166.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-25 23:45:00",
    "lat": -25.06411,
    "lon": -1.6182,
    "alt_m": 15702.6
   },
   "member_spread_deg": {
    "lat": 26.17,
    "lon": 258.02
   },
   "member_spread_now_deg": {
    "lat": 18.88,
    "lon": 144.63
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}