{
 "generated_utc": "2026-08-19T17:26:09Z",
 "gfs_cycle_utc": "2026-08-19T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 395.5,
  "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_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260819_12Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 80019
 },
 "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": 17.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": -64.9054,
    "lon": -162.25965,
    "alt_m": 11982.4
   },
   "member_spread_deg": {
    "lat": 31.29,
    "lon": 319.67
   },
   "member_spread_now_deg": {
    "lat": 0.87,
    "lon": 0.42
   },
   "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": 11.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 72.3515,
    "lon": 30.92602,
    "alt_m": 12142.1
   },
   "member_spread_deg": {
    "lat": 32.73,
    "lon": 211.45
   },
   "member_spread_now_deg": {
    "lat": 3.83,
    "lon": 15.16
   },
   "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": 37.53,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 54.67105,
    "lon": -31.40864,
    "alt_m": 13993.4
   },
   "member_spread_deg": {
    "lat": 24.68,
    "lon": 137.0
   },
   "member_spread_now_deg": {
    "lat": 5.45,
    "lon": 27.88
   },
   "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": 10.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": 43.61003,
    "lon": -68.52642,
    "alt_m": 12710.6
   },
   "member_spread_deg": {
    "lat": 37.41,
    "lon": 110.42
   },
   "member_spread_now_deg": {
    "lat": 1.58,
    "lon": 7.98
   },
   "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": 233.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": -6.50219,
    "lon": -58.50802,
    "alt_m": 14037.1
   },
   "member_spread_deg": {
    "lat": 58.45,
    "lon": 189.42
   },
   "member_spread_now_deg": {
    "lat": 50.2,
    "lon": 102.61
   },
   "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 16:51:00",
   "seed_lat": 51.91667,
   "seed_lon": -17.79167,
   "seed_alt_m": 12520.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 16:15:00",
    "lat": 59.5512,
    "lon": -166.11737,
    "alt_m": 12723.9
   },
   "member_spread_deg": {
    "lat": 32.99,
    "lon": 331.19
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.23
   },
   "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": 9.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": 42.98627,
    "lon": -134.45046,
    "alt_m": 13070.7
   },
   "member_spread_deg": {
    "lat": 18.63,
    "lon": 44.71
   },
   "member_spread_now_deg": {
    "lat": 0.57,
    "lon": 6.86
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 14:13:00",
   "seed_lat": 83.8125,
   "seed_lon": 55.95833,
   "seed_alt_m": 11940.0,
   "seed_age_h": 3.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 13:45:00",
    "lat": 71.68706,
    "lon": -52.06486,
    "alt_m": 12011.5
   },
   "member_spread_deg": {
    "lat": 32.46,
    "lon": 125.96
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 4.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 16:48:00",
   "seed_lat": 63.83333,
   "seed_lon": -25.45833,
   "seed_alt_m": 12690.0,
   "seed_age_h": 0.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 16:15:00",
    "lat": 58.21748,
    "lon": 49.51748,
    "alt_m": 12470.0
   },
   "member_spread_deg": {
    "lat": 18.93,
    "lon": 121.19
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.04
   },
   "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": 92.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 22.94815,
    "lon": -60.15917,
    "alt_m": 13366.6
   },
   "member_spread_deg": {
    "lat": 42.09,
    "lon": 89.01
   },
   "member_spread_now_deg": {
    "lat": 22.0,
    "lon": 40.97
   },
   "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 16:57:03",
   "seed_lat": 76.97917,
   "seed_lon": 70.16667,
   "seed_alt_m": 13270.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 17:00:00",
    "lat": 64.25593,
    "lon": -144.10091,
    "alt_m": 13173.3
   },
   "member_spread_deg": {
    "lat": 23.9,
    "lon": 301.33
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.48
   },
   "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": 173.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 66.9081,
    "lon": -118.71917,
    "alt_m": 12786.3
   },
   "member_spread_deg": {
    "lat": 26.26,
    "lon": 310.74
   },
   "member_spread_now_deg": {
    "lat": 22.32,
    "lon": 281.57
   },
   "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": 11.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": 39.10022,
    "lon": -127.99906,
    "alt_m": 12961.4
   },
   "member_spread_deg": {
    "lat": 24.6,
    "lon": 351.22
   },
   "member_spread_now_deg": {
    "lat": 1.98,
    "lon": 4.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 11:06:00",
   "seed_lat": 80.66667,
   "seed_lon": -3.29167,
   "seed_alt_m": 12060.0,
   "seed_age_h": 6.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": 80.31514,
    "lon": 159.43112,
    "alt_m": 11743.9
   },
   "member_spread_deg": {
    "lat": 17.45,
    "lon": 302.78
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.94
   },
   "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": 140.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 50.63049,
    "lon": 79.61463,
    "alt_m": 11127.3
   },
   "member_spread_deg": {
    "lat": 35.36,
    "lon": 227.01
   },
   "member_spread_now_deg": {
    "lat": 19.1,
    "lon": 95.17
   },
   "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": 8.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": 82.2136,
    "lon": 147.72362,
    "alt_m": 12772.3
   },
   "member_spread_deg": {
    "lat": 20.91,
    "lon": 201.08
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 2.88
   },
   "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": 6.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 21.43657,
    "lon": -13.8433,
    "alt_m": 16606.7
   },
   "member_spread_deg": {
    "lat": 15.18,
    "lon": 5.58
   },
   "member_spread_now_deg": {
    "lat": 1.38,
    "lon": 2.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 16:51:00",
   "seed_lat": 41.77083,
   "seed_lon": -144.95833,
   "seed_alt_m": 13440.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 16:15:00",
    "lat": 45.55275,
    "lon": 18.43746,
    "alt_m": 13348.1
   },
   "member_spread_deg": {
    "lat": 18.7,
    "lon": 94.57
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.06
   },
   "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": 17.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": 70.23779,
    "lon": -42.16503,
    "alt_m": 12944.9
   },
   "member_spread_deg": {
    "lat": 20.25,
    "lon": 55.66
   },
   "member_spread_now_deg": {
    "lat": 0.97,
    "lon": 1.68
   },
   "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": 44.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-26 11:30:00",
    "lat": -16.56375,
    "lon": 42.2354,
    "alt_m": 12573.5
   },
   "member_spread_deg": {
    "lat": 15.69,
    "lon": 252.22
   },
   "member_spread_now_deg": {
    "lat": 30.0,
    "lon": 54.76
   },
   "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": 178.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-26 11:45:00",
    "lat": -37.69862,
    "lon": 20.23272,
    "alt_m": 15495.6
   },
   "member_spread_deg": {
    "lat": 31.26,
    "lon": 292.62
   },
   "member_spread_now_deg": {
    "lat": 25.6,
    "lon": 148.42
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}