{
 "generated_utc": "2026-08-13T11:27:00Z",
 "gfs_cycle_utc": "2026-08-13T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 481.0,
  "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_20260813_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260813_06Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 104373
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 23:53:40",
   "seed_lat": -55.83334,
   "seed_lon": -115.37499,
   "seed_alt_m": 12390.0,
   "seed_age_h": 35.44,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": -62.26436,
    "lon": -83.40403,
    "alt_m": 12757.2
   },
   "member_spread_deg": {
    "lat": 27.54,
    "lon": 190.84
   },
   "member_spread_now_deg": {
    "lat": 14.05,
    "lon": 12.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:30:18",
   "seed_lat": 57.54167,
   "seed_lon": 19.20833,
   "seed_alt_m": 12870.0,
   "seed_age_h": 2.83,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 08:00:00",
    "lat": 63.71711,
    "lon": -167.31637,
    "alt_m": 12509.7
   },
   "member_spread_deg": {
    "lat": 16.21,
    "lon": 226.07
   },
   "member_spread_now_deg": {
    "lat": 0.59,
    "lon": 0.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 04:17:39",
   "seed_lat": 47.60417,
   "seed_lon": 117.45833,
   "seed_alt_m": 14140.0,
   "seed_age_h": 55.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 52.83358,
    "lon": -103.42939,
    "alt_m": 13914.1
   },
   "member_spread_deg": {
    "lat": 38.49,
    "lon": 348.14
   },
   "member_spread_now_deg": {
    "lat": 3.77,
    "lon": 9.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 09:49:00",
   "seed_lat": 51.89583,
   "seed_lon": 3.375,
   "seed_alt_m": 12970.0,
   "seed_age_h": 1.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 09:15:00",
    "lat": 59.07384,
    "lon": 173.22143,
    "alt_m": 12834.1
   },
   "member_spread_deg": {
    "lat": 17.62,
    "lon": 51.53
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.18
   },
   "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": 83.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 2.07542,
    "lon": -102.21847,
    "alt_m": 14088.1
   },
   "member_spread_deg": {
    "lat": 37.49,
    "lon": 78.15
   },
   "member_spread_now_deg": {
    "lat": 25.98,
    "lon": 41.08
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 222.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 33.85995,
    "lon": -15.99813,
    "alt_m": 13482.6
   },
   "member_spread_deg": {
    "lat": 68.13,
    "lon": 288.53
   },
   "member_spread_now_deg": {
    "lat": 66.42,
    "lon": 239.42
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 05:26:00",
   "seed_lat": 48.29167,
   "seed_lon": 170.66667,
   "seed_alt_m": 12730.0,
   "seed_age_h": 5.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 49.79998,
    "lon": 2.82815,
    "alt_m": 12423.9
   },
   "member_spread_deg": {
    "lat": 12.92,
    "lon": 98.55
   },
   "member_spread_now_deg": {
    "lat": 1.23,
    "lon": 1.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:33:00",
   "seed_lat": 63.0,
   "seed_lon": 3.91667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 42.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 77.85349,
    "lon": 93.76007,
    "alt_m": 11883.5
   },
   "member_spread_deg": {
    "lat": 22.51,
    "lon": 193.95
   },
   "member_spread_now_deg": {
    "lat": 9.88,
    "lon": 11.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 00:53:00",
   "seed_lat": 74.79167,
   "seed_lon": -150.33333,
   "seed_alt_m": 12560.0,
   "seed_age_h": 10.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 62.73775,
    "lon": -13.63236,
    "alt_m": 12480.5
   },
   "member_spread_deg": {
    "lat": 23.03,
    "lon": 130.18
   },
   "member_spread_now_deg": {
    "lat": 4.05,
    "lon": 12.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 01:05:37",
   "seed_lat": 24.45828,
   "seed_lon": -136.95833,
   "seed_alt_m": 13300.0,
   "seed_age_h": 10.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 56.44671,
    "lon": 50.71371,
    "alt_m": 12937.7
   },
   "member_spread_deg": {
    "lat": 36.62,
    "lon": 156.12
   },
   "member_spread_now_deg": {
    "lat": 3.01,
    "lon": 2.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 19:22:36",
   "seed_lat": 59.29167,
   "seed_lon": 6.5,
   "seed_alt_m": 13640.0,
   "seed_age_h": 15.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 59.17207,
    "lon": -178.01401,
    "alt_m": 13492.0
   },
   "member_spread_deg": {
    "lat": 18.85,
    "lon": 357.01
   },
   "member_spread_now_deg": {
    "lat": 1.68,
    "lon": 6.93
   },
   "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": 23.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 55.14245,
    "lon": 75.06757,
    "alt_m": 12503.3
   },
   "member_spread_deg": {
    "lat": 27.6,
    "lon": 270.11
   },
   "member_spread_now_deg": {
    "lat": 7.33,
    "lon": 9.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 10:15:00",
   "seed_lat": 42.72917,
   "seed_lon": -2.83333,
   "seed_alt_m": 13060.0,
   "seed_age_h": 1.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 09:45:00",
    "lat": 44.1718,
    "lon": 177.73079,
    "alt_m": 13082.7
   },
   "member_spread_deg": {
    "lat": 24.96,
    "lon": 54.3
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 20:23:30",
   "seed_lat": 52.45833,
   "seed_lon": -72.58333,
   "seed_alt_m": 12140.0,
   "seed_age_h": 14.94,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 48.36634,
    "lon": 31.8281,
    "alt_m": 12789.3
   },
   "member_spread_deg": {
    "lat": 25.55,
    "lon": 55.62
   },
   "member_spread_now_deg": {
    "lat": 0.79,
    "lon": 7.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:51:00",
   "seed_lat": 48.20833,
   "seed_lon": 127.45833,
   "seed_alt_m": 12160.0,
   "seed_age_h": 6.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 48.16265,
    "lon": -96.95105,
    "alt_m": 12261.3
   },
   "member_spread_deg": {
    "lat": 26.88,
    "lon": 76.42
   },
   "member_spread_now_deg": {
    "lat": 5.19,
    "lon": 4.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI1TEN-1",
   "flight_id": "KI1TEN-1_2026-07-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-01 22:55:27",
   "seed_lat": 23.95828,
   "seed_lon": -104.12496,
   "seed_alt_m": 12380.0,
   "seed_age_h": 276.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": -1.89801,
    "lon": -105.52386,
    "alt_m": 12357.4
   },
   "member_spread_deg": {
    "lat": 59.03,
    "lon": 189.97
   },
   "member_spread_now_deg": {
    "lat": 20.99,
    "lon": 59.53
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 10:55:45",
   "seed_lat": 73.58328,
   "seed_lon": 59.95835,
   "seed_alt_m": 13240.0,
   "seed_age_h": 0.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:00:00",
    "lat": 61.86191,
    "lon": 156.16226,
    "alt_m": 13100.2
   },
   "member_spread_deg": {
    "lat": 27.03,
    "lon": 243.04
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:41:00",
   "seed_lat": 26.02083,
   "seed_lon": 178.66667,
   "seed_alt_m": 16470.0,
   "seed_age_h": 6.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 11.02733,
    "lon": 63.37043,
    "alt_m": 16634.6
   },
   "member_spread_deg": {
    "lat": 39.79,
    "lon": 58.25
   },
   "member_spread_now_deg": {
    "lat": 4.57,
    "lon": 1.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-34",
   "flight_id": "SP6MPL-34_2025-12-03",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 18:52:00",
   "seed_lat": 74.5625,
   "seed_lon": -160.0,
   "seed_alt_m": 12890.0,
   "seed_age_h": 304.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 59.09534,
    "lon": -28.6662,
    "alt_m": 13194.2
   },
   "member_spread_deg": {
    "lat": 38.05,
    "lon": 232.32
   },
   "member_spread_now_deg": {
    "lat": 12.93,
    "lon": 320.93
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 223.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": 49.93494,
    "lon": -179.7224,
    "alt_m": 12993.2
   },
   "member_spread_deg": {
    "lat": 30.21,
    "lon": 302.33
   },
   "member_spread_now_deg": {
    "lat": 30.87,
    "lon": 254.87
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:41:00",
   "seed_lat": 45.875,
   "seed_lon": 142.66667,
   "seed_alt_m": 13600.0,
   "seed_age_h": 12.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": 44.54059,
    "lon": -93.20422,
    "alt_m": 13494.4
   },
   "member_spread_deg": {
    "lat": 27.59,
    "lon": 336.54
   },
   "member_spread_now_deg": {
    "lat": 5.27,
    "lon": 1.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:15:23",
   "seed_lat": 47.08328,
   "seed_lon": 122.37502,
   "seed_alt_m": 13540.0,
   "seed_age_h": 3.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 07:45:00",
    "lat": 69.19499,
    "lon": -148.29359,
    "alt_m": 12990.8
   },
   "member_spread_deg": {
    "lat": 37.03,
    "lon": 58.83
   },
   "member_spread_now_deg": {
    "lat": 0.68,
    "lon": 0.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-15",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 04:34:00",
   "seed_lat": -23.70833,
   "seed_lon": 149.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 318.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 05:30:00",
    "lat": -24.27885,
    "lon": 161.29153,
    "alt_m": 12270.2
   },
   "member_spread_deg": {
    "lat": 18.4,
    "lon": 281.38
   },
   "member_spread_now_deg": {
    "lat": 30.73,
    "lon": 273.28
   },
   "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": 28.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 05:45:00",
    "lat": -10.04079,
    "lon": -28.24455,
    "alt_m": 15898.7
   },
   "member_spread_deg": {
    "lat": 25.13,
    "lon": 136.76
   },
   "member_spread_now_deg": {
    "lat": 3.75,
    "lon": 10.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}