{
 "generated_utc": "2026-08-20T23:26:35Z",
 "gfs_cycle_utc": "2026-08-20T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 425.5,
  "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_20260820_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260820_18Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 83088
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 13:13:40",
   "seed_lat": -54.16667,
   "seed_lon": -61.99999,
   "seed_alt_m": 12300.0,
   "seed_age_h": 10.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": -74.22669,
    "lon": -132.98425,
    "alt_m": 12509.3
   },
   "member_spread_deg": {
    "lat": 34.04,
    "lon": 306.24
   },
   "member_spread_now_deg": {
    "lat": 2.21,
    "lon": 7.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 06:13:49",
   "seed_lat": 67.79167,
   "seed_lon": -172.20833,
   "seed_alt_m": 12390.0,
   "seed_age_h": 17.1,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 70.47668,
    "lon": 7.29585,
    "alt_m": 12571.1
   },
   "member_spread_deg": {
    "lat": 26.07,
    "lon": 95.58
   },
   "member_spread_now_deg": {
    "lat": 4.16,
    "lon": 4.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 19:59:18",
   "seed_lat": 51.08333,
   "seed_lon": -140.58333,
   "seed_alt_m": 14060.0,
   "seed_age_h": 27.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 17:30:00",
    "lat": 56.99611,
    "lon": 18.19711,
    "alt_m": 13816.3
   },
   "member_spread_deg": {
    "lat": 37.74,
    "lon": 140.77
   },
   "member_spread_now_deg": {
    "lat": 11.8,
    "lon": 7.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 22:39:00",
   "seed_lat": 59.22917,
   "seed_lon": -176.54167,
   "seed_alt_m": 12650.0,
   "seed_age_h": 0.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 22:45:00",
    "lat": 40.81294,
    "lon": -6.92106,
    "alt_m": 12712.3
   },
   "member_spread_deg": {
    "lat": 15.54,
    "lon": 63.36
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.36
   },
   "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": 263.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 2.3426,
    "lon": -37.09803,
    "alt_m": 14060.0
   },
   "member_spread_deg": {
    "lat": 52.35,
    "lon": 128.7
   },
   "member_spread_now_deg": {
    "lat": 47.34,
    "lon": 118.95
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:01:00",
   "seed_lat": 54.91667,
   "seed_lon": 15.08333,
   "seed_alt_m": 12380.0,
   "seed_age_h": 7.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:30:00",
    "lat": 50.46763,
    "lon": -147.7841,
    "alt_m": 12543.5
   },
   "member_spread_deg": {
    "lat": 9.92,
    "lon": 39.28
   },
   "member_spread_now_deg": {
    "lat": 1.11,
    "lon": 9.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 07:22:00",
   "seed_lat": 46.85417,
   "seed_lon": 130.41667,
   "seed_alt_m": 13220.0,
   "seed_age_h": 15.97,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 47.24559,
    "lon": -84.78256,
    "alt_m": 13048.7
   },
   "member_spread_deg": {
    "lat": 17.44,
    "lon": 307.1
   },
   "member_spread_now_deg": {
    "lat": 4.45,
    "lon": 11.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:08:00",
   "seed_lat": 78.95833,
   "seed_lon": 117.79167,
   "seed_alt_m": 11880.0,
   "seed_age_h": 13.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 72.65113,
    "lon": 137.77477,
    "alt_m": 11964.9
   },
   "member_spread_deg": {
    "lat": 18.53,
    "lon": 191.63
   },
   "member_spread_now_deg": {
    "lat": 2.54,
    "lon": 6.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 17:48:00",
   "seed_lat": 58.08333,
   "seed_lon": -17.54167,
   "seed_alt_m": 12620.0,
   "seed_age_h": 5.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 63.96194,
    "lon": 75.02127,
    "alt_m": 12363.5
   },
   "member_spread_deg": {
    "lat": 19.14,
    "lon": 74.26
   },
   "member_spread_now_deg": {
    "lat": 2.47,
    "lon": 1.17
   },
   "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": 122.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 14.66629,
    "lon": -98.48403,
    "alt_m": 13411.2
   },
   "member_spread_deg": {
    "lat": 28.33,
    "lon": 186.75
   },
   "member_spread_now_deg": {
    "lat": 29.32,
    "lon": 49.41
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 21:03:04",
   "seed_lat": 71.91667,
   "seed_lon": 103.16667,
   "seed_alt_m": 13220.0,
   "seed_age_h": 2.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 20:30:00",
    "lat": 57.88716,
    "lon": -145.31496,
    "alt_m": 13326.9
   },
   "member_spread_deg": {
    "lat": 35.67,
    "lon": 332.45
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 1.1
   },
   "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": 203.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 53.32401,
    "lon": 103.22071,
    "alt_m": 12564.3
   },
   "member_spread_deg": {
    "lat": 28.28,
    "lon": 324.71
   },
   "member_spread_now_deg": {
    "lat": 28.44,
    "lon": 304.65
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 20:15:00",
   "seed_lat": 48.97917,
   "seed_lon": 171.625,
   "seed_alt_m": 13040.0,
   "seed_age_h": 3.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 19:45:00",
    "lat": 34.23693,
    "lon": -137.52975,
    "alt_m": 12865.4
   },
   "member_spread_deg": {
    "lat": 14.61,
    "lon": 93.83
   },
   "member_spread_now_deg": {
    "lat": 0.97,
    "lon": 0.77
   },
   "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": 13.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:30:00",
    "lat": 66.84401,
    "lon": 151.58102,
    "alt_m": 12055.3
   },
   "member_spread_deg": {
    "lat": 24.37,
    "lon": 335.67
   },
   "member_spread_now_deg": {
    "lat": 5.44,
    "lon": 32.43
   },
   "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": 170.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": 30.44644,
    "lon": -32.6135,
    "alt_m": 11243.2
   },
   "member_spread_deg": {
    "lat": 24.75,
    "lon": 342.69
   },
   "member_spread_now_deg": {
    "lat": 19.77,
    "lon": 103.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 20:25:45",
   "seed_lat": 68.10411,
   "seed_lon": 169.83335,
   "seed_alt_m": 12900.0,
   "seed_age_h": 2.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 20:00:00",
    "lat": 64.52562,
    "lon": 159.72196,
    "alt_m": 12916.5
   },
   "member_spread_deg": {
    "lat": 17.22,
    "lon": 342.79
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 1.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 11:01:00",
   "seed_lat": 8.70833,
   "seed_lon": 71.20833,
   "seed_alt_m": 16270.0,
   "seed_age_h": 12.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 17:30:00",
    "lat": -3.72624,
    "lon": -5.9774,
    "alt_m": 16369.1
   },
   "member_spread_deg": {
    "lat": 17.05,
    "lon": 62.36
   },
   "member_spread_now_deg": {
    "lat": 1.28,
    "lon": 7.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 22:36:00",
   "seed_lat": 34.4375,
   "seed_lon": -129.83333,
   "seed_alt_m": 13250.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 22:00:00",
    "lat": 36.82886,
    "lon": 24.41982,
    "alt_m": 13451.8
   },
   "member_spread_deg": {
    "lat": 21.25,
    "lon": 117.99
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 22:05:23",
   "seed_lat": 63.66661,
   "seed_lon": -102.70831,
   "seed_alt_m": 12930.0,
   "seed_age_h": 1.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 21:30:00",
    "lat": 58.59727,
    "lon": 26.42381,
    "alt_m": 13306.9
   },
   "member_spread_deg": {
    "lat": 17.23,
    "lon": 69.71
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.28
   },
   "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": 74.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 17:30:00",
    "lat": -25.3507,
    "lon": -169.22823,
    "alt_m": 12162.1
   },
   "member_spread_deg": {
    "lat": 13.67,
    "lon": 323.9
   },
   "member_spread_now_deg": {
    "lat": 20.42,
    "lon": 113.93
   },
   "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": 208.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 17:45:00",
    "lat": -29.37197,
    "lon": 106.41514,
    "alt_m": 15615.6
   },
   "member_spread_deg": {
    "lat": 27.69,
    "lon": 267.39
   },
   "member_spread_now_deg": {
    "lat": 21.53,
    "lon": 171.72
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}