{
 "generated_utc": "2026-08-13T23:27:37Z",
 "gfs_cycle_utc": "2026-08-13T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 493.0,
  "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_20260813_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260813_18Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 106308
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 18:18:40",
   "seed_lat": -52.3125,
   "seed_lon": -39.20832,
   "seed_alt_m": 12270.0,
   "seed_age_h": 5.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": -53.9099,
    "lon": -80.1188,
    "alt_m": 12597.4
   },
   "member_spread_deg": {
    "lat": 23.0,
    "lon": 68.67
   },
   "member_spread_now_deg": {
    "lat": 0.47,
    "lon": 2.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:30:18",
   "seed_lat": 57.54167,
   "seed_lon": 19.20833,
   "seed_alt_m": 12870.0,
   "seed_age_h": 14.83,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 77.04981,
    "lon": -165.71996,
    "alt_m": 12358.6
   },
   "member_spread_deg": {
    "lat": 22.76,
    "lon": 232.57
   },
   "member_spread_now_deg": {
    "lat": 1.81,
    "lon": 5.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 04:17:39",
   "seed_lat": 47.60417,
   "seed_lon": 117.45833,
   "seed_alt_m": 14140.0,
   "seed_age_h": 67.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 41.6839,
    "lon": -124.35441,
    "alt_m": 14231.1
   },
   "member_spread_deg": {
    "lat": 29.95,
    "lon": 350.33
   },
   "member_spread_now_deg": {
    "lat": 4.11,
    "lon": 10.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 16:04:00",
   "seed_lat": 52.14583,
   "seed_lon": 5.41667,
   "seed_alt_m": 12990.0,
   "seed_age_h": 7.27,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 51.70436,
    "lon": -169.51961,
    "alt_m": 12945.9
   },
   "member_spread_deg": {
    "lat": 13.73,
    "lon": 356.05
   },
   "member_spread_now_deg": {
    "lat": 0.5,
    "lon": 0.56
   },
   "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": 95.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 7.83051,
    "lon": -80.63057,
    "alt_m": 14106.3
   },
   "member_spread_deg": {
    "lat": 37.54,
    "lon": 103.17
   },
   "member_spread_now_deg": {
    "lat": 27.84,
    "lon": 47.25
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 234.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 33.48756,
    "lon": -17.43906,
    "alt_m": 13552.9
   },
   "member_spread_deg": {
    "lat": 70.98,
    "lon": 243.19
   },
   "member_spread_now_deg": {
    "lat": 68.51,
    "lon": 238.36
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 22:41:00",
   "seed_lat": 48.77083,
   "seed_lon": -170.66667,
   "seed_alt_m": 12730.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 22:15:00",
    "lat": 57.46738,
    "lon": 22.60644,
    "alt_m": 12537.9
   },
   "member_spread_deg": {
    "lat": 28.18,
    "lon": 188.84
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:33:00",
   "seed_lat": 63.0,
   "seed_lon": 3.91667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 54.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 73.94559,
    "lon": 125.28208,
    "alt_m": 11860.6
   },
   "member_spread_deg": {
    "lat": 17.24,
    "lon": 330.5
   },
   "member_spread_now_deg": {
    "lat": 13.55,
    "lon": 12.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 22:38:00",
   "seed_lat": 70.1875,
   "seed_lon": -137.41667,
   "seed_alt_m": 12610.0,
   "seed_age_h": 0.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 22:15:00",
    "lat": 59.05684,
    "lon": -17.42357,
    "alt_m": 12555.6
   },
   "member_spread_deg": {
    "lat": 25.6,
    "lon": 99.26
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.66
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 22:55:37",
   "seed_lat": 24.37494,
   "seed_lon": -130.75,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 23:00:00",
    "lat": 31.35035,
    "lon": -95.05589,
    "alt_m": 13304.6
   },
   "member_spread_deg": {
    "lat": 28.48,
    "lon": 86.02
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 15:22:33",
   "seed_lat": 50.66667,
   "seed_lon": 25.54167,
   "seed_alt_m": 13700.0,
   "seed_age_h": 7.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 58.95899,
    "lon": 103.90734,
    "alt_m": 13446.7
   },
   "member_spread_deg": {
    "lat": 11.42,
    "lon": 336.14
   },
   "member_spread_now_deg": {
    "lat": 0.54,
    "lon": 3.19
   },
   "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": 35.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 53.51129,
    "lon": 79.73707,
    "alt_m": 12396.2
   },
   "member_spread_deg": {
    "lat": 22.04,
    "lon": 219.79
   },
   "member_spread_now_deg": {
    "lat": 7.49,
    "lon": 16.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 17:37:30",
   "seed_lat": 43.10417,
   "seed_lon": -0.58333,
   "seed_alt_m": 13040.0,
   "seed_age_h": 5.71,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 47.32173,
    "lon": 177.80723,
    "alt_m": 13114.2
   },
   "member_spread_deg": {
    "lat": 22.5,
    "lon": 351.98
   },
   "member_spread_now_deg": {
    "lat": 0.98,
    "lon": 1.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 20:31:00",
   "seed_lat": 52.66667,
   "seed_lon": -65.0,
   "seed_alt_m": 12140.0,
   "seed_age_h": 2.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 20:00:00",
    "lat": 73.97769,
    "lon": -1.42675,
    "alt_m": 12208.6
   },
   "member_spread_deg": {
    "lat": 9.43,
    "lon": 72.65
   },
   "member_spread_now_deg": {
    "lat": 0.48,
    "lon": 0.35
   },
   "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": 2.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 20:45:00",
    "lat": 32.55295,
    "lon": -121.3634,
    "alt_m": 11244.8
   },
   "member_spread_deg": {
    "lat": 24.45,
    "lon": 96.78
   },
   "member_spread_now_deg": {
    "lat": 0.98,
    "lon": 1.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI1TEN-1",
   "flight_id": "KI1TEN-1_2026-07-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-01 22:55:27",
   "seed_lat": 23.95828,
   "seed_lon": -104.12496,
   "seed_alt_m": 12380.0,
   "seed_age_h": 288.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": -2.07965,
    "lon": -110.5902,
    "alt_m": 12350.9
   },
   "member_spread_deg": {
    "lat": 47.45,
    "lon": 149.94
   },
   "member_spread_now_deg": {
    "lat": 20.38,
    "lon": 61.31
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 13:50:45",
   "seed_lat": 74.62495,
   "seed_lon": 63.41669,
   "seed_alt_m": 13240.0,
   "seed_age_h": 9.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 60.8315,
    "lon": 173.59838,
    "alt_m": 13095.3
   },
   "member_spread_deg": {
    "lat": 26.62,
    "lon": 289.27
   },
   "member_spread_now_deg": {
    "lat": 1.28,
    "lon": 12.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 22:42:00",
   "seed_lat": 22.125,
   "seed_lon": 176.45833,
   "seed_alt_m": 16400.0,
   "seed_age_h": 0.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 22:15:00",
    "lat": 10.22546,
    "lon": 64.19007,
    "alt_m": 16520.5
   },
   "member_spread_deg": {
    "lat": 21.62,
    "lon": 75.88
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-34",
   "flight_id": "SP6MPL-34_2025-12-03",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 18:52:00",
   "seed_lat": 74.5625,
   "seed_lon": -160.0,
   "seed_alt_m": 12890.0,
   "seed_age_h": 316.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 48.33011,
    "lon": -27.86876,
    "alt_m": 13597.1
   },
   "member_spread_deg": {
    "lat": 35.65,
    "lon": 277.0
   },
   "member_spread_now_deg": {
    "lat": 14.09,
    "lon": 357.25
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 235.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": 40.49957,
    "lon": -175.7821,
    "alt_m": 13074.3
   },
   "member_spread_deg": {
    "lat": 35.8,
    "lon": 326.08
   },
   "member_spread_now_deg": {
    "lat": 36.95,
    "lon": 240.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:41:00",
   "seed_lat": 45.875,
   "seed_lon": 142.66667,
   "seed_alt_m": 13600.0,
   "seed_age_h": 24.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 45.9311,
    "lon": -82.03216,
    "alt_m": 13413.1
   },
   "member_spread_deg": {
    "lat": 44.08,
    "lon": 283.93
   },
   "member_spread_now_deg": {
    "lat": 10.12,
    "lon": 9.39
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:15:23",
   "seed_lat": 47.08328,
   "seed_lon": 122.37502,
   "seed_alt_m": 13540.0,
   "seed_age_h": 15.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": 60.26084,
    "lon": -121.86068,
    "alt_m": 13084.7
   },
   "member_spread_deg": {
    "lat": 29.02,
    "lon": 71.25
   },
   "member_spread_now_deg": {
    "lat": 7.67,
    "lon": 10.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-15",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 04:34:00",
   "seed_lat": -23.70833,
   "seed_lon": 149.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 330.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 17:30:00",
    "lat": -20.85676,
    "lon": -166.49708,
    "alt_m": 12666.4
   },
   "member_spread_deg": {
    "lat": 28.21,
    "lon": 338.65
   },
   "member_spread_now_deg": {
    "lat": 30.8,
    "lon": 267.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 40.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-20 17:45:00",
    "lat": -10.76455,
    "lon": -30.68148,
    "alt_m": 15961.1
   },
   "member_spread_deg": {
    "lat": 25.99,
    "lon": 147.13
   },
   "member_spread_now_deg": {
    "lat": 5.63,
    "lon": 358.1
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}