{
 "generated_utc": "2026-08-27T17:27:37Z",
 "gfs_cycle_utc": "2026-08-27T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 494.5,
  "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_20260827_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260827_12Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 79029
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 23:18:40",
   "seed_lat": -70.79167,
   "seed_lon": -148.58332,
   "seed_alt_m": 12300.0,
   "seed_age_h": 18.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": -80.18888,
    "lon": 131.98856,
    "alt_m": 12256.3
   },
   "member_spread_deg": {
    "lat": 10.49,
    "lon": 289.34
   },
   "member_spread_now_deg": {
    "lat": 2.16,
    "lon": 19.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 14:01:48",
   "seed_lat": 43.125,
   "seed_lon": 21.54167,
   "seed_alt_m": 14180.0,
   "seed_age_h": 3.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 13:30:00",
    "lat": 32.46763,
    "lon": -128.52799,
    "alt_m": 14419.4
   },
   "member_spread_deg": {
    "lat": 31.01,
    "lon": 327.64
   },
   "member_spread_now_deg": {
    "lat": 1.26,
    "lon": 1.71
   },
   "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": 43.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 26.98062,
    "lon": -99.32391,
    "alt_m": 13098.2
   },
   "member_spread_deg": {
    "lat": 13.37,
    "lon": 67.39
   },
   "member_spread_now_deg": {
    "lat": 5.15,
    "lon": 5.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:06:00",
   "seed_lat": 59.25,
   "seed_lon": -136.5,
   "seed_alt_m": 12380.0,
   "seed_age_h": 15.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 73.49261,
    "lon": -177.13884,
    "alt_m": 12011.7
   },
   "member_spread_deg": {
    "lat": 34.74,
    "lon": 341.05
   },
   "member_spread_now_deg": {
    "lat": 10.57,
    "lon": 21.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 16:17:00",
   "seed_lat": 42.14583,
   "seed_lon": -75.20833,
   "seed_alt_m": 13140.0,
   "seed_age_h": 1.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 16:15:00",
    "lat": 46.36393,
    "lon": 91.01623,
    "alt_m": 13087.3
   },
   "member_spread_deg": {
    "lat": 17.87,
    "lon": 178.96
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 0.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:38:00",
   "seed_lat": 83.20833,
   "seed_lon": -24.91667,
   "seed_alt_m": 11920.0,
   "seed_age_h": 27.7,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 51.24185,
    "lon": 165.85573,
    "alt_m": 11848.4
   },
   "member_spread_deg": {
    "lat": 30.89,
    "lon": 280.13
   },
   "member_spread_now_deg": {
    "lat": 6.29,
    "lon": 11.65
   },
   "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": 75.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 49.31324,
    "lon": 168.68164,
    "alt_m": 12294.7
   },
   "member_spread_deg": {
    "lat": 28.26,
    "lon": 314.78
   },
   "member_spread_now_deg": {
    "lat": 21.4,
    "lon": 95.44
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 284.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 30.43972,
    "lon": 13.6672,
    "alt_m": 13096.8
   },
   "member_spread_deg": {
    "lat": 49.57,
    "lon": 196.68
   },
   "member_spread_now_deg": {
    "lat": 45.76,
    "lon": 196.69
   },
   "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": 58.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 62.46849,
    "lon": -0.24746,
    "alt_m": 13259.4
   },
   "member_spread_deg": {
    "lat": 30.49,
    "lon": 170.39
   },
   "member_spread_now_deg": {
    "lat": 30.78,
    "lon": 45.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 11:49:00",
   "seed_lat": 31.89583,
   "seed_lon": 23.625,
   "seed_alt_m": 12710.0,
   "seed_age_h": 5.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 30.3522,
    "lon": -163.80481,
    "alt_m": 12826.3
   },
   "member_spread_deg": {
    "lat": 22.06,
    "lon": 290.24
   },
   "member_spread_now_deg": {
    "lat": 1.07,
    "lon": 0.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 04:25:00",
   "seed_lat": 28.08333,
   "seed_lon": -169.5,
   "seed_alt_m": 12940.0,
   "seed_age_h": 12.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 25.49571,
    "lon": -58.71721,
    "alt_m": 13115.9
   },
   "member_spread_deg": {
    "lat": 7.06,
    "lon": 20.55
   },
   "member_spread_now_deg": {
    "lat": 2.64,
    "lon": 2.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 90.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 58.71703,
    "lon": 163.08042,
    "alt_m": 11994.2
   },
   "member_spread_deg": {
    "lat": 23.41,
    "lon": 217.25
   },
   "member_spread_now_deg": {
    "lat": 20.42,
    "lon": 239.78
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 332.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 25.88774,
    "lon": -3.96298,
    "alt_m": 11237.5
   },
   "member_spread_deg": {
    "lat": 26.54,
    "lon": 247.65
   },
   "member_spread_now_deg": {
    "lat": 38.67,
    "lon": 320.96
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 03:00:45",
   "seed_lat": 77.66661,
   "seed_lon": 155.16669,
   "seed_alt_m": 12690.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 64.22507,
    "lon": -25.48233,
    "alt_m": 12735.9
   },
   "member_spread_deg": {
    "lat": 18.07,
    "lon": 86.46
   },
   "member_spread_now_deg": {
    "lat": 3.37,
    "lon": 7.23
   },
   "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": 25.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:45:00",
    "lat": 48.3646,
    "lon": -149.62575,
    "alt_m": 13396.9
   },
   "member_spread_deg": {
    "lat": 24.48,
    "lon": 54.16
   },
   "member_spread_now_deg": {
    "lat": 3.4,
    "lon": 6.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 15:48:00",
   "seed_lat": 37.375,
   "seed_lon": 9.16667,
   "seed_alt_m": 16440.0,
   "seed_age_h": 1.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 15:15:00",
    "lat": 36.10888,
    "lon": 174.9144,
    "alt_m": 16449.3
   },
   "member_spread_deg": {
    "lat": 22.79,
    "lon": 352.3
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 1.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 14:31:00",
   "seed_lat": 46.83333,
   "seed_lon": 23.125,
   "seed_alt_m": 13050.0,
   "seed_age_h": 26.82,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": 48.27918,
    "lon": -79.09097,
    "alt_m": 13092.4
   },
   "member_spread_deg": {
    "lat": 24.84,
    "lon": 75.94
   },
   "member_spread_now_deg": {
    "lat": 2.94,
    "lon": 8.23
   },
   "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": 236.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": -30.08436,
    "lon": 105.07705,
    "alt_m": 12107.7
   },
   "member_spread_deg": {
    "lat": 29.74,
    "lon": 348.86
   },
   "member_spread_now_deg": {
    "lat": 13.42,
    "lon": 133.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:56:00",
   "seed_lat": -23.45833,
   "seed_lon": -160.20833,
   "seed_alt_m": 15500.0,
   "seed_age_h": 14.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:30:00",
    "lat": -15.19523,
    "lon": -26.71197,
    "alt_m": 15753.8
   },
   "member_spread_deg": {
    "lat": 35.29,
    "lon": 134.06
   },
   "member_spread_now_deg": {
    "lat": 2.51,
    "lon": 15.38
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}