{
 "generated_utc": "2026-08-13T17:27:15Z",
 "gfs_cycle_utc": "2026-08-13T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 487.0,
  "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_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260813_12Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 105210
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 16:53:40",
   "seed_lat": -53.64584,
   "seed_lon": -40.54165,
   "seed_alt_m": 12300.0,
   "seed_age_h": 0.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 17:00:00",
    "lat": -51.77705,
    "lon": -77.60209,
    "alt_m": 12471.0
   },
   "member_spread_deg": {
    "lat": 16.37,
    "lon": 73.26
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.29
   },
   "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": 8.83,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 70.94506,
    "lon": -168.56154,
    "alt_m": 12446.6
   },
   "member_spread_deg": {
    "lat": 28.86,
    "lon": 211.48
   },
   "member_spread_now_deg": {
    "lat": 1.25,
    "lon": 1.61
   },
   "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": 61.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 33.61876,
    "lon": -153.6918,
    "alt_m": 14431.4
   },
   "member_spread_deg": {
    "lat": 23.65,
    "lon": 355.74
   },
   "member_spread_now_deg": {
    "lat": 3.46,
    "lon": 10.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 16:04:00",
   "seed_lat": 52.14583,
   "seed_lon": 5.41667,
   "seed_alt_m": 12990.0,
   "seed_age_h": 1.27,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 15:30:00",
    "lat": 58.10426,
    "lon": -170.00731,
    "alt_m": 12833.1
   },
   "member_spread_deg": {
    "lat": 15.74,
    "lon": 351.69
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.16
   },
   "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": 89.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 20.75376,
    "lon": -90.3112,
    "alt_m": 14091.6
   },
   "member_spread_deg": {
    "lat": 37.47,
    "lon": 84.89
   },
   "member_spread_now_deg": {
    "lat": 27.26,
    "lon": 43.68
   },
   "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": 228.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 42.50506,
    "lon": 6.95624,
    "alt_m": 13359.8
   },
   "member_spread_deg": {
    "lat": 71.63,
    "lon": 224.94
   },
   "member_spread_now_deg": {
    "lat": 68.16,
    "lon": 238.57
   },
   "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": 11.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 52.42812,
    "lon": -0.49741,
    "alt_m": 12483.0
   },
   "member_spread_deg": {
    "lat": 15.54,
    "lon": 153.14
   },
   "member_spread_now_deg": {
    "lat": 1.55,
    "lon": 359.86
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 48.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 74.895,
    "lon": 162.73012,
    "alt_m": 11808.8
   },
   "member_spread_deg": {
    "lat": 39.15,
    "lon": 270.58
   },
   "member_spread_now_deg": {
    "lat": 11.2,
    "lon": 12.69
   },
   "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": 16.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 60.20474,
    "lon": -15.8928,
    "alt_m": 12432.6
   },
   "member_spread_deg": {
    "lat": 7.85,
    "lon": 73.83
   },
   "member_spread_now_deg": {
    "lat": 4.31,
    "lon": 22.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 16:50:37",
   "seed_lat": 23.27078,
   "seed_lon": -132.58333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 0.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 16:15:00",
    "lat": 24.66893,
    "lon": -48.79221,
    "alt_m": 13375.6
   },
   "member_spread_deg": {
    "lat": 25.66,
    "lon": 138.44
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 15:22:33",
   "seed_lat": 50.66667,
   "seed_lon": 25.54167,
   "seed_alt_m": 13700.0,
   "seed_age_h": 1.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 15:00:00",
    "lat": 49.08371,
    "lon": 74.56283,
    "alt_m": 13434.6
   },
   "member_spread_deg": {
    "lat": 17.88,
    "lon": 349.32
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.63
   },
   "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": 29.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 58.5212,
    "lon": 118.21818,
    "alt_m": 12730.7
   },
   "member_spread_deg": {
    "lat": 25.82,
    "lon": 269.07
   },
   "member_spread_now_deg": {
    "lat": 6.21,
    "lon": 11.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 15:35:00",
   "seed_lat": 43.04167,
   "seed_lon": -1.41667,
   "seed_alt_m": 13070.0,
   "seed_age_h": 1.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 15:00:00",
    "lat": 44.68389,
    "lon": -176.65955,
    "alt_m": 13100.2
   },
   "member_spread_deg": {
    "lat": 27.13,
    "lon": 350.09
   },
   "member_spread_now_deg": {
    "lat": 0.42,
    "lon": 0.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 16:33:30",
   "seed_lat": 52.25,
   "seed_lon": -66.04167,
   "seed_alt_m": 12100.0,
   "seed_age_h": 0.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 16:00:00",
    "lat": 71.3224,
    "lon": -24.29948,
    "alt_m": 12102.1
   },
   "member_spread_deg": {
    "lat": 29.54,
    "lon": 121.88
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.06
   },
   "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": 12.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 15.73889,
    "lon": 170.08951,
    "alt_m": 12497.9
   },
   "member_spread_deg": {
    "lat": 36.24,
    "lon": 319.45
   },
   "member_spread_now_deg": {
    "lat": 6.28,
    "lon": 9.57
   },
   "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": 282.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 1.18202,
    "lon": -108.83259,
    "alt_m": 12317.9
   },
   "member_spread_deg": {
    "lat": 46.49,
    "lon": 141.09
   },
   "member_spread_now_deg": {
    "lat": 19.91,
    "lon": 60.23
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 13:50:45",
   "seed_lat": 74.62495,
   "seed_lon": 63.41669,
   "seed_alt_m": 13240.0,
   "seed_age_h": 3.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 13:15:00",
    "lat": 57.08719,
    "lon": 161.32483,
    "alt_m": 13165.4
   },
   "member_spread_deg": {
    "lat": 36.17,
    "lon": 296.83
   },
   "member_spread_now_deg": {
    "lat": 0.87,
    "lon": 3.91
   },
   "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": 12.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 8.81989,
    "lon": 64.14222,
    "alt_m": 16577.7
   },
   "member_spread_deg": {
    "lat": 42.47,
    "lon": 70.78
   },
   "member_spread_now_deg": {
    "lat": 8.41,
    "lon": 3.22
   },
   "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": 310.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 55.04558,
    "lon": -22.19831,
    "alt_m": 13096.7
   },
   "member_spread_deg": {
    "lat": 35.2,
    "lon": 249.84
   },
   "member_spread_now_deg": {
    "lat": 13.91,
    "lon": 319.39
   },
   "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": 229.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": 44.81162,
    "lon": -172.85596,
    "alt_m": 13111.5
   },
   "member_spread_deg": {
    "lat": 25.57,
    "lon": 307.21
   },
   "member_spread_now_deg": {
    "lat": 33.99,
    "lon": 245.88
   },
   "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": 18.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 34.64905,
    "lon": -152.17963,
    "alt_m": 13669.8
   },
   "member_spread_deg": {
    "lat": 29.6,
    "lon": 323.49
   },
   "member_spread_now_deg": {
    "lat": 7.69,
    "lon": 4.97
   },
   "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": 9.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": 67.34081,
    "lon": -88.39982,
    "alt_m": 13090.1
   },
   "member_spread_deg": {
    "lat": 38.43,
    "lon": 92.13
   },
   "member_spread_now_deg": {
    "lat": 3.0,
    "lon": 4.44
   },
   "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": 324.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 11:30:00",
    "lat": -11.82154,
    "lon": 157.52485,
    "alt_m": 12662.6
   },
   "member_spread_deg": {
    "lat": 19.51,
    "lon": 291.11
   },
   "member_spread_now_deg": {
    "lat": 32.07,
    "lon": 272.45
   },
   "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": 34.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 11:45:00",
    "lat": -10.88342,
    "lon": -29.1223,
    "alt_m": 15975.3
   },
   "member_spread_deg": {
    "lat": 25.6,
    "lon": 131.8
   },
   "member_spread_now_deg": {
    "lat": 4.69,
    "lon": 13.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}