{
 "generated_utc": "2026-09-08T05:27:05Z",
 "gfs_cycle_utc": "2026-09-08T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 497.0,
  "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_20260908_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260908_00Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 84519
 },
 "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": 253.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": -58.42231,
    "lon": -1.9839,
    "alt_m": 11922.6
   },
   "member_spread_deg": {
    "lat": 28.26,
    "lon": 239.93
   },
   "member_spread_now_deg": {
    "lat": 25.41,
    "lon": 167.61
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 19:10:19",
   "seed_lat": 33.60417,
   "seed_lon": -62.70833,
   "seed_alt_m": 14540.0,
   "seed_age_h": 10.16,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": 43.70751,
    "lon": -20.85311,
    "alt_m": 14349.1
   },
   "member_spread_deg": {
    "lat": 17.41,
    "lon": 50.6
   },
   "member_spread_now_deg": {
    "lat": 3.62,
    "lon": 6.03
   },
   "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": 319.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": -1.01928,
    "lon": -23.85149,
    "alt_m": 13200.8
   },
   "member_spread_deg": {
    "lat": 43.6,
    "lon": 90.05
   },
   "member_spread_now_deg": {
    "lat": 15.11,
    "lon": 69.23
   },
   "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": 72.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": 77.68573,
    "lon": 141.9657,
    "alt_m": 11676.5
   },
   "member_spread_deg": {
    "lat": 20.58,
    "lon": 309.83
   },
   "member_spread_now_deg": {
    "lat": 13.35,
    "lon": 76.51
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:37:00",
   "seed_lat": 38.625,
   "seed_lon": -125.5,
   "seed_alt_m": 13290.0,
   "seed_age_h": 5.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 24.43244,
    "lon": -67.97954,
    "alt_m": 13594.1
   },
   "member_spread_deg": {
    "lat": 46.36,
    "lon": 132.94
   },
   "member_spread_now_deg": {
    "lat": 0.39,
    "lon": 1.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:36:00",
   "seed_lat": 50.91667,
   "seed_lon": 151.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 5.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 31.21547,
    "lon": 147.52071,
    "alt_m": 13879.9
   },
   "member_spread_deg": {
    "lat": 40.12,
    "lon": 250.84
   },
   "member_spread_now_deg": {
    "lat": 1.44,
    "lon": 2.69
   },
   "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": 187.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 63.69462,
    "lon": -104.63388,
    "alt_m": 11801.8
   },
   "member_spread_deg": {
    "lat": 33.14,
    "lon": 271.34
   },
   "member_spread_now_deg": {
    "lat": 26.01,
    "lon": 302.52
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 06:11:23",
   "seed_lat": 45.72917,
   "seed_lon": 115.79167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 23.14,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": 42.8456,
    "lon": -33.20907,
    "alt_m": 14134.1
   },
   "member_spread_deg": {
    "lat": 35.62,
    "lon": 272.48
   },
   "member_spread_now_deg": {
    "lat": 5.35,
    "lon": 9.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:25:00",
   "seed_lat": 38.8125,
   "seed_lon": 34.04167,
   "seed_alt_m": 12750.0,
   "seed_age_h": 15.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 33.54996,
    "lon": -144.92559,
    "alt_m": 12619.7
   },
   "member_spread_deg": {
    "lat": 15.82,
    "lon": 127.9
   },
   "member_spread_now_deg": {
    "lat": 2.33,
    "lon": 2.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 334.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 38.17614,
    "lon": 138.70418,
    "alt_m": 14180.1
   },
   "member_spread_deg": {
    "lat": 49.18,
    "lon": 304.98
   },
   "member_spread_now_deg": {
    "lat": 32.79,
    "lon": 226.47
   },
   "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": 117.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 28.40218,
    "lon": 154.15314,
    "alt_m": 12953.4
   },
   "member_spread_deg": {
    "lat": 30.97,
    "lon": 294.14
   },
   "member_spread_now_deg": {
    "lat": 20.54,
    "lon": 315.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:25:00",
   "seed_lat": 27.33333,
   "seed_lon": -0.875,
   "seed_alt_m": 12960.0,
   "seed_age_h": 11.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 42.29763,
    "lon": -159.3708,
    "alt_m": 12889.8
   },
   "member_spread_deg": {
    "lat": 13.85,
    "lon": 338.55
   },
   "member_spread_now_deg": {
    "lat": 3.75,
    "lon": 4.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:46:00",
   "seed_lat": 64.5,
   "seed_lon": -98.625,
   "seed_alt_m": 12260.0,
   "seed_age_h": 11.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": 50.95696,
    "lon": 87.22969,
    "alt_m": 12697.3
   },
   "member_spread_deg": {
    "lat": 7.69,
    "lon": 109.75
   },
   "member_spread_now_deg": {
    "lat": 5.16,
    "lon": 5.84
   },
   "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": 61.9,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 66.04978,
    "lon": -75.6116,
    "alt_m": 12922.4
   },
   "member_spread_deg": {
    "lat": 20.88,
    "lon": 174.03
   },
   "member_spread_now_deg": {
    "lat": 12.5,
    "lon": 24.02
   },
   "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": 301.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:45:00",
    "lat": 43.94388,
    "lon": -21.01058,
    "alt_m": 13326.2
   },
   "member_spread_deg": {
    "lat": 26.41,
    "lon": 168.47
   },
   "member_spread_now_deg": {
    "lat": 24.32,
    "lon": 110.44
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 02:11:00",
   "seed_lat": 33.04167,
   "seed_lon": -157.83333,
   "seed_alt_m": 16240.0,
   "seed_age_h": 3.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 02:15:00",
    "lat": 18.80837,
    "lon": -167.14053,
    "alt_m": 16390.9
   },
   "member_spread_deg": {
    "lat": 27.42,
    "lon": 88.76
   },
   "member_spread_now_deg": {
    "lat": 1.4,
    "lon": 1.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:26:00",
   "seed_lat": 49.125,
   "seed_lon": -38.79167,
   "seed_alt_m": 13430.0,
   "seed_age_h": 11.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": 40.46955,
    "lon": 123.77056,
    "alt_m": 13236.3
   },
   "member_spread_deg": {
    "lat": 15.95,
    "lon": 70.65
   },
   "member_spread_now_deg": {
    "lat": 4.56,
    "lon": 11.85
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:31:00",
   "seed_lat": -22.79167,
   "seed_lon": 25.625,
   "seed_alt_m": 15590.0,
   "seed_age_h": 15.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 23:30:00",
    "lat": -15.00747,
    "lon": 124.4331,
    "alt_m": 15681.0
   },
   "member_spread_deg": {
    "lat": 17.34,
    "lon": 303.57
   },
   "member_spread_now_deg": {
    "lat": 1.69,
    "lon": 6.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}