{
 "generated_utc": "2026-08-19T11:25:54Z",
 "gfs_cycle_utc": "2026-08-19T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 389.5,
  "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_20260819_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260819_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 78615
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 00:13:40",
   "seed_lat": -64.60417,
   "seed_lon": -143.74999,
   "seed_alt_m": 12240.0,
   "seed_age_h": 11.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": -65.38956,
    "lon": 137.87644,
    "alt_m": 12134.4
   },
   "member_spread_deg": {
    "lat": 34.08,
    "lon": 283.47
   },
   "member_spread_now_deg": {
    "lat": 0.82,
    "lon": 1.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 05:41:19",
   "seed_lat": 67.33333,
   "seed_lon": 165.91667,
   "seed_alt_m": 12380.0,
   "seed_age_h": 5.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 80.13444,
    "lon": 108.07789,
    "alt_m": 12054.6
   },
   "member_spread_deg": {
    "lat": 24.58,
    "lon": 197.56
   },
   "member_spread_now_deg": {
    "lat": 1.43,
    "lon": 6.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 03:48:18",
   "seed_lat": 43.79167,
   "seed_lon": -166.58333,
   "seed_alt_m": 14200.0,
   "seed_age_h": 31.53,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 51.96738,
    "lon": -50.61784,
    "alt_m": 13713.3
   },
   "member_spread_deg": {
    "lat": 20.09,
    "lon": 149.23
   },
   "member_spread_now_deg": {
    "lat": 5.49,
    "lon": 22.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 06:59:00",
   "seed_lat": 46.29167,
   "seed_lon": 130.91667,
   "seed_alt_m": 12620.0,
   "seed_age_h": 4.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 06:30:00",
    "lat": 42.42966,
    "lon": -76.75634,
    "alt_m": 12734.3
   },
   "member_spread_deg": {
    "lat": 36.74,
    "lon": 87.05
   },
   "member_spread_now_deg": {
    "lat": 0.37,
    "lon": 4.39
   },
   "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": 227.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": -3.19711,
    "lon": -55.40232,
    "alt_m": 14010.9
   },
   "member_spread_deg": {
    "lat": 55.25,
    "lon": 187.54
   },
   "member_spread_now_deg": {
    "lat": 49.39,
    "lon": 97.0
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:46:00",
   "seed_lat": 54.14583,
   "seed_lon": -25.83333,
   "seed_alt_m": 12550.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 10:15:00",
    "lat": 57.70247,
    "lon": -169.27113,
    "alt_m": 12680.9
   },
   "member_spread_deg": {
    "lat": 14.45,
    "lon": 348.45
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 07:32:00",
   "seed_lat": 45.77083,
   "seed_lon": 107.54167,
   "seed_alt_m": 13210.0,
   "seed_age_h": 3.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 07:00:00",
    "lat": 70.27469,
    "lon": -87.23898,
    "alt_m": 12702.2
   },
   "member_spread_deg": {
    "lat": 35.86,
    "lon": 58.61
   },
   "member_spread_now_deg": {
    "lat": 0.5,
    "lon": 2.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:53:00",
   "seed_lat": 83.64583,
   "seed_lon": 43.58333,
   "seed_alt_m": 11960.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:00:00",
    "lat": 72.89175,
    "lon": -56.68612,
    "alt_m": 11873.7
   },
   "member_spread_deg": {
    "lat": 12.36,
    "lon": 299.84
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:03:00",
   "seed_lat": 64.4375,
   "seed_lon": -28.66667,
   "seed_alt_m": 12680.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 09:30:00",
    "lat": 63.01569,
    "lon": 103.04035,
    "alt_m": 12628.2
   },
   "member_spread_deg": {
    "lat": 8.9,
    "lon": 87.21
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.07
   },
   "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": 86.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 12.92886,
    "lon": -63.19362,
    "alt_m": 13383.6
   },
   "member_spread_deg": {
    "lat": 27.07,
    "lon": 113.64
   },
   "member_spread_now_deg": {
    "lat": 22.52,
    "lon": 39.32
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:57:04",
   "seed_lat": 76.83333,
   "seed_lon": 61.375,
   "seed_alt_m": 13260.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:00:00",
    "lat": 63.14902,
    "lon": -145.34495,
    "alt_m": 13174.7
   },
   "member_spread_deg": {
    "lat": 29.05,
    "lon": 337.71
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.34
   },
   "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": 167.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 66.85339,
    "lon": 124.1826,
    "alt_m": 12414.9
   },
   "member_spread_deg": {
    "lat": 31.93,
    "lon": 300.33
   },
   "member_spread_now_deg": {
    "lat": 21.01,
    "lon": 278.31
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 06:00:00",
   "seed_lat": 55.20833,
   "seed_lon": 162.70833,
   "seed_alt_m": 13090.0,
   "seed_age_h": 5.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:30:00",
    "lat": 43.50369,
    "lon": -120.87132,
    "alt_m": 13035.0
   },
   "member_spread_deg": {
    "lat": 27.13,
    "lon": 63.13
   },
   "member_spread_now_deg": {
    "lat": 1.79,
    "lon": 0.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 09:36:00",
   "seed_lat": 80.5,
   "seed_lon": -5.125,
   "seed_alt_m": 12060.0,
   "seed_age_h": 1.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 09:00:00",
    "lat": 73.89356,
    "lon": 165.74502,
    "alt_m": 11750.8
   },
   "member_spread_deg": {
    "lat": 12.84,
    "lon": 257.51
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.88
   },
   "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": 134.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 30.81323,
    "lon": -43.03497,
    "alt_m": 11256.2
   },
   "member_spread_deg": {
    "lat": 32.45,
    "lon": 227.18
   },
   "member_spread_now_deg": {
    "lat": 20.76,
    "lon": 91.0
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 08:25:45",
   "seed_lat": 62.85411,
   "seed_lon": 132.87502,
   "seed_alt_m": 13000.0,
   "seed_age_h": 2.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 08:00:00",
    "lat": 80.23886,
    "lon": -36.02045,
    "alt_m": 12928.3
   },
   "member_spread_deg": {
    "lat": 14.08,
    "lon": 342.41
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 1.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 10:38:00",
   "seed_lat": 10.89583,
   "seed_lon": 88.58333,
   "seed_alt_m": 16500.0,
   "seed_age_h": 0.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 10:15:00",
    "lat": 17.30488,
    "lon": -12.70064,
    "alt_m": 16591.6
   },
   "member_spread_deg": {
    "lat": 7.22,
    "lon": 5.32
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 03:06:00",
   "seed_lat": 45.47917,
   "seed_lon": -147.04167,
   "seed_alt_m": 13500.0,
   "seed_age_h": 8.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:30:00",
    "lat": 31.83726,
    "lon": -14.40096,
    "alt_m": 13663.2
   },
   "member_spread_deg": {
    "lat": 25.57,
    "lon": 136.86
   },
   "member_spread_now_deg": {
    "lat": 1.33,
    "lon": 0.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-18 23:45:23",
   "seed_lat": 66.70828,
   "seed_lon": -132.62498,
   "seed_alt_m": 12900.0,
   "seed_age_h": 11.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": 57.81758,
    "lon": -55.14324,
    "alt_m": 12810.6
   },
   "member_spread_deg": {
    "lat": 15.32,
    "lon": 67.06
   },
   "member_spread_now_deg": {
    "lat": 0.63,
    "lon": 1.61
   },
   "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": 38.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 05:30:00",
    "lat": -21.95589,
    "lon": -162.20896,
    "alt_m": 12206.9
   },
   "member_spread_deg": {
    "lat": 39.69,
    "lon": 203.16
   },
   "member_spread_now_deg": {
    "lat": 24.78,
    "lon": 40.01
   },
   "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": 172.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 05:45:00",
    "lat": -38.58551,
    "lon": 21.18661,
    "alt_m": 15516.7
   },
   "member_spread_deg": {
    "lat": 32.13,
    "lon": 305.51
   },
   "member_spread_now_deg": {
    "lat": 22.94,
    "lon": 146.02
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}