{
 "generated_utc": "2026-08-17T23:27:32Z",
 "gfs_cycle_utc": "2026-08-17T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 493.5,
  "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_20260817_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260817_18Z.geojson.gz"
 },
 "counts": {
  "flights": 23,
  "members": 9,
  "rows": 93267
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 09:08:40",
   "seed_lat": -54.125,
   "seed_lon": 105.20835,
   "seed_alt_m": 12270.0,
   "seed_age_h": 14.19,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": -46.23567,
    "lon": 115.18198,
    "alt_m": 12396.6
   },
   "member_spread_deg": {
    "lat": 16.17,
    "lon": 47.97
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 9.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 22:47:47",
   "seed_lat": 57.125,
   "seed_lon": 131.29167,
   "seed_alt_m": 12490.0,
   "seed_age_h": 0.54,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 22:15:00",
    "lat": 68.40752,
    "lon": 152.43988,
    "alt_m": 12233.8
   },
   "member_spread_deg": {
    "lat": 22.08,
    "lon": 324.65
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 22:41:18",
   "seed_lat": 42.6875,
   "seed_lon": -170.66667,
   "seed_alt_m": 14160.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 22:15:00",
    "lat": 55.02997,
    "lon": -89.81354,
    "alt_m": 13742.8
   },
   "member_spread_deg": {
    "lat": 30.84,
    "lon": 121.52
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 11:44:00",
   "seed_lat": 47.375,
   "seed_lon": 69.20833,
   "seed_alt_m": 12450.0,
   "seed_age_h": 11.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 48.18482,
    "lon": -125.51664,
    "alt_m": 12780.9
   },
   "member_spread_deg": {
    "lat": 32.75,
    "lon": 19.49
   },
   "member_spread_now_deg": {
    "lat": 2.19,
    "lon": 2.7
   },
   "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": 191.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": -4.04346,
    "lon": -77.60745,
    "alt_m": 14074.2
   },
   "member_spread_deg": {
    "lat": 59.27,
    "lon": 150.42
   },
   "member_spread_now_deg": {
    "lat": 36.08,
    "lon": 84.37
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 330.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:30:00",
    "lat": 44.30955,
    "lon": 89.89874,
    "alt_m": 13189.8
   },
   "member_spread_deg": {
    "lat": 90.06,
    "lon": 284.39
   },
   "member_spread_now_deg": {
    "lat": 82.04,
    "lon": 235.12
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 21:56:00",
   "seed_lat": 49.95833,
   "seed_lon": -74.0,
   "seed_alt_m": 12440.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 21:30:00",
    "lat": 50.67341,
    "lon": 128.86486,
    "alt_m": 12311.5
   },
   "member_spread_deg": {
    "lat": 16.37,
    "lon": 64.14
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 12:32:00",
   "seed_lat": 40.41667,
   "seed_lon": 26.29167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 34.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:30:00",
    "lat": 42.68603,
    "lon": 172.39622,
    "alt_m": 13412.1
   },
   "member_spread_deg": {
    "lat": 41.19,
    "lon": 322.96
   },
   "member_spread_now_deg": {
    "lat": 2.89,
    "lon": 21.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 16:53:00",
   "seed_lat": 84.27083,
   "seed_lon": -18.25,
   "seed_alt_m": 11790.0,
   "seed_age_h": 6.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 17:30:00",
    "lat": 69.04102,
    "lon": -85.63825,
    "alt_m": 11983.4
   },
   "member_spread_deg": {
    "lat": 23.44,
    "lon": 285.68
   },
   "member_spread_now_deg": {
    "lat": 2.25,
    "lon": 4.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 19:58:00",
   "seed_lat": 59.8125,
   "seed_lon": -56.625,
   "seed_alt_m": 12540.0,
   "seed_age_h": 3.37,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 19:30:00",
    "lat": 62.34558,
    "lon": 36.67748,
    "alt_m": 12546.3
   },
   "member_spread_deg": {
    "lat": 16.02,
    "lon": 162.26
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 3.24
   },
   "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": 50.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 23.65419,
    "lon": -103.16433,
    "alt_m": 13418.2
   },
   "member_spread_deg": {
    "lat": 18.33,
    "lon": 73.78
   },
   "member_spread_now_deg": {
    "lat": 10.58,
    "lon": 29.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 00:47:18",
   "seed_lat": 65.0,
   "seed_lon": 62.95833,
   "seed_alt_m": 13240.0,
   "seed_age_h": 22.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 60.92095,
    "lon": 162.33987,
    "alt_m": 13043.7
   },
   "member_spread_deg": {
    "lat": 19.82,
    "lon": 336.61
   },
   "member_spread_now_deg": {
    "lat": 2.92,
    "lon": 4.69
   },
   "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": 131.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 65.1142,
    "lon": 72.4503,
    "alt_m": 12485.5
   },
   "member_spread_deg": {
    "lat": 28.28,
    "lon": 289.66
   },
   "member_spread_now_deg": {
    "lat": 22.64,
    "lon": 241.67
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 22:45:00",
   "seed_lat": 43.0,
   "seed_lon": 117.125,
   "seed_alt_m": 12570.0,
   "seed_age_h": 0.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 22:15:00",
    "lat": 36.71837,
    "lon": -163.88912,
    "alt_m": 13008.6
   },
   "member_spread_deg": {
    "lat": 25.8,
    "lon": 321.74
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 17:11:00",
   "seed_lat": 75.10417,
   "seed_lon": -39.04167,
   "seed_alt_m": 12260.0,
   "seed_age_h": 6.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 71.52225,
    "lon": -87.5594,
    "alt_m": 12023.3
   },
   "member_spread_deg": {
    "lat": 32.45,
    "lon": 328.14
   },
   "member_spread_now_deg": {
    "lat": 0.83,
    "lon": 3.55
   },
   "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": 98.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 50.44216,
    "lon": 63.91799,
    "alt_m": 11011.3
   },
   "member_spread_deg": {
    "lat": 35.85,
    "lon": 219.88
   },
   "member_spread_now_deg": {
    "lat": 23.57,
    "lon": 27.93
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:13:15",
   "seed_lat": 64.74995,
   "seed_lon": 113.16669,
   "seed_alt_m": 13060.0,
   "seed_age_h": 13.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 69.22196,
    "lon": -74.22563,
    "alt_m": 12866.9
   },
   "member_spread_deg": {
    "lat": 34.02,
    "lon": 325.92
   },
   "member_spread_now_deg": {
    "lat": 2.39,
    "lon": 0.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 07:46:00",
   "seed_lat": 12.54167,
   "seed_lon": 133.08333,
   "seed_alt_m": 16600.0,
   "seed_age_h": 15.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": 9.24506,
    "lon": 15.94826,
    "alt_m": 16473.7
   },
   "member_spread_deg": {
    "lat": 45.34,
    "lon": 143.54
   },
   "member_spread_now_deg": {
    "lat": 6.55,
    "lon": 4.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 331.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 17:30:00",
    "lat": 25.47427,
    "lon": -118.22723,
    "alt_m": 13277.2
   },
   "member_spread_deg": {
    "lat": 32.02,
    "lon": 321.52
   },
   "member_spread_now_deg": {
    "lat": 32.3,
    "lon": 275.25
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 21:46:00",
   "seed_lat": 38.79167,
   "seed_lon": -172.41667,
   "seed_alt_m": 13490.0,
   "seed_age_h": 1.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 21:15:00",
    "lat": 43.9336,
    "lon": -30.56338,
    "alt_m": 13611.2
   },
   "member_spread_deg": {
    "lat": 23.42,
    "lon": 135.64
   },
   "member_spread_now_deg": {
    "lat": 1.16,
    "lon": 1.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 22:55:23",
   "seed_lat": 67.95828,
   "seed_lon": -149.87498,
   "seed_alt_m": 13000.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 23:00:00",
    "lat": 55.62583,
    "lon": -68.73852,
    "alt_m": 12871.5
   },
   "member_spread_deg": {
    "lat": 17.44,
    "lon": 70.71
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.7
   },
   "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": 2.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 20:30:00",
    "lat": -25.99332,
    "lon": 170.80813,
    "alt_m": 12198.5
   },
   "member_spread_deg": {
    "lat": 20.11,
    "lon": 328.53
   },
   "member_spread_now_deg": {
    "lat": 1.68,
    "lon": 0.65
   },
   "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": 136.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 17:45:00",
    "lat": -14.63372,
    "lon": -28.86803,
    "alt_m": 15889.6
   },
   "member_spread_deg": {
    "lat": 31.84,
    "lon": 209.71
   },
   "member_spread_now_deg": {
    "lat": 14.86,
    "lon": 135.21
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}