{
 "generated_utc": "2026-09-07T05:27:05Z",
 "gfs_cycle_utc": "2026-09-07T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 489.5,
  "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_20260907_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260907_00Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 89811
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 229.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": -73.55438,
    "lon": 2.30329,
    "alt_m": 12077.1
   },
   "member_spread_deg": {
    "lat": 33.45,
    "lon": 321.28
   },
   "member_spread_now_deg": {
    "lat": 36.41,
    "lon": 112.3
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 19:02:18",
   "seed_lat": 32.0,
   "seed_lon": -77.625,
   "seed_alt_m": 14580.0,
   "seed_age_h": 10.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 35.25764,
    "lon": 14.60362,
    "alt_m": 14213.2
   },
   "member_spread_deg": {
    "lat": 23.53,
    "lon": 43.16
   },
   "member_spread_now_deg": {
    "lat": 0.9,
    "lon": 5.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:29:00",
   "seed_lat": 33.10417,
   "seed_lon": -84.75,
   "seed_alt_m": 13050.0,
   "seed_age_h": 295.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 9.25415,
    "lon": -48.81239,
    "alt_m": 13171.7
   },
   "member_spread_deg": {
    "lat": 31.85,
    "lon": 102.28
   },
   "member_spread_now_deg": {
    "lat": 14.88,
    "lon": 60.3
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 04:41:00",
   "seed_lat": 86.0,
   "seed_lon": 110.20833,
   "seed_alt_m": 11660.0,
   "seed_age_h": 48.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": 77.5322,
    "lon": 145.07157,
    "alt_m": 11720.7
   },
   "member_spread_deg": {
    "lat": 17.32,
    "lon": 331.23
   },
   "member_spread_now_deg": {
    "lat": 3.71,
    "lon": 30.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 01:52:00",
   "seed_lat": 41.85417,
   "seed_lon": -141.29167,
   "seed_alt_m": 13380.0,
   "seed_age_h": 3.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 01:15:00",
    "lat": 23.59217,
    "lon": -48.74322,
    "alt_m": 13550.4
   },
   "member_spread_deg": {
    "lat": 41.21,
    "lon": 126.99
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 0.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 04:01:00",
   "seed_lat": 45.10417,
   "seed_lon": 117.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 04:00:00",
    "lat": 37.00759,
    "lon": 149.43369,
    "alt_m": 14104.6
   },
   "member_spread_deg": {
    "lat": 44.94,
    "lon": 319.14
   },
   "member_spread_now_deg": {
    "lat": 0.23,
    "lon": 1.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 163.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 64.8847,
    "lon": 157.44781,
    "alt_m": 11972.3
   },
   "member_spread_deg": {
    "lat": 43.36,
    "lon": 324.44
   },
   "member_spread_now_deg": {
    "lat": 21.69,
    "lon": 311.81
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 39.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 32.03808,
    "lon": 150.94742,
    "alt_m": 14650.0
   },
   "member_spread_deg": {
    "lat": 42.16,
    "lon": 175.9
   },
   "member_spread_now_deg": {
    "lat": 1.1,
    "lon": 15.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 327.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": 37.36249,
    "lon": -145.98194,
    "alt_m": 12973.2
   },
   "member_spread_deg": {
    "lat": 39.27,
    "lon": 303.68
   },
   "member_spread_now_deg": {
    "lat": 29.03,
    "lon": 236.63
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 06:33:48",
   "seed_lat": 61.6875,
   "seed_lon": -165.70833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 310.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 25.01765,
    "lon": 155.92994,
    "alt_m": 14241.4
   },
   "member_spread_deg": {
    "lat": 56.54,
    "lon": 324.14
   },
   "member_spread_now_deg": {
    "lat": 35.96,
    "lon": 232.2
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 93.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 35.45445,
    "lon": 154.0267,
    "alt_m": 12934.2
   },
   "member_spread_deg": {
    "lat": 66.11,
    "lon": 304.89
   },
   "member_spread_now_deg": {
    "lat": 25.54,
    "lon": 324.14
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 17:05:00",
   "seed_lat": 28.66667,
   "seed_lon": -4.45833,
   "seed_alt_m": 13010.0,
   "seed_age_h": 12.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 33.50062,
    "lon": -158.43374,
    "alt_m": 12789.9
   },
   "member_spread_deg": {
    "lat": 26.59,
    "lon": 332.13
   },
   "member_spread_now_deg": {
    "lat": 4.87,
    "lon": 1.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 22:56:00",
   "seed_lat": 62.79167,
   "seed_lon": -124.54167,
   "seed_alt_m": 12340.0,
   "seed_age_h": 6.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 45.8292,
    "lon": 73.00711,
    "alt_m": 12766.5
   },
   "member_spread_deg": {
    "lat": 22.68,
    "lon": 124.78
   },
   "member_spread_now_deg": {
    "lat": 1.82,
    "lon": 8.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 37.91,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:30:00",
    "lat": 70.13659,
    "lon": -100.97905,
    "alt_m": 12944.0
   },
   "member_spread_deg": {
    "lat": 17.96,
    "lon": 213.95
   },
   "member_spread_now_deg": {
    "lat": 3.24,
    "lon": 3.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 277.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": 33.94081,
    "lon": 16.87545,
    "alt_m": 13237.4
   },
   "member_spread_deg": {
    "lat": 42.75,
    "lon": 229.63
   },
   "member_spread_now_deg": {
    "lat": 16.04,
    "lon": 113.94
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 02:41:00",
   "seed_lat": 24.25,
   "seed_lon": -159.45833,
   "seed_alt_m": 16160.0,
   "seed_age_h": 2.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 02:15:00",
    "lat": 18.67799,
    "lon": -160.15274,
    "alt_m": 16451.1
   },
   "member_spread_deg": {
    "lat": 36.39,
    "lon": 175.83
   },
   "member_spread_now_deg": {
    "lat": 0.78,
    "lon": 2.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 20:41:00",
   "seed_lat": 38.10417,
   "seed_lon": -70.29167,
   "seed_alt_m": 13280.0,
   "seed_age_h": 8.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": 44.97645,
    "lon": 99.23007,
    "alt_m": 13298.1
   },
   "member_spread_deg": {
    "lat": 41.47,
    "lon": 134.38
   },
   "member_spread_now_deg": {
    "lat": 5.05,
    "lon": 8.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 00:15:23",
   "seed_lat": 35.22911,
   "seed_lon": -126.08331,
   "seed_alt_m": 13840.0,
   "seed_age_h": 5.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": 58.54548,
    "lon": 60.9291,
    "alt_m": 13305.4
   },
   "member_spread_deg": {
    "lat": 40.45,
    "lon": 131.46
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.93
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 14:41:00",
   "seed_lat": -26.25,
   "seed_lon": 20.70833,
   "seed_alt_m": 15570.0,
   "seed_age_h": 14.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-13 23:45:00",
    "lat": -22.49171,
    "lon": 113.31771,
    "alt_m": 15664.5
   },
   "member_spread_deg": {
    "lat": 13.76,
    "lon": 345.38
   },
   "member_spread_now_deg": {
    "lat": 0.92,
    "lon": 3.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}