{
 "generated_utc": "2026-08-12T23:26:51Z",
 "gfs_cycle_utc": "2026-08-12T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 469.0,
  "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_20260812_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260812_18Z.geojson.gz"
 },
 "counts": {
  "flights": 23,
  "members": 9,
  "rows": 99189
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 23:53:40",
   "seed_lat": -55.83334,
   "seed_lon": -115.37499,
   "seed_alt_m": 12390.0,
   "seed_age_h": 23.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": -57.80121,
    "lon": -146.89921,
    "alt_m": 12623.7
   },
   "member_spread_deg": {
    "lat": 38.22,
    "lon": 307.21
   },
   "member_spread_now_deg": {
    "lat": 5.94,
    "lon": 15.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 19:12:18",
   "seed_lat": 63.25,
   "seed_lon": 4.70833,
   "seed_alt_m": 12760.0,
   "seed_age_h": 4.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 18:45:00",
    "lat": 67.52232,
    "lon": 174.59628,
    "alt_m": 12384.6
   },
   "member_spread_deg": {
    "lat": 14.84,
    "lon": 357.93
   },
   "member_spread_now_deg": {
    "lat": 0.48,
    "lon": 0.99
   },
   "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": 43.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 36.91546,
    "lon": -148.41589,
    "alt_m": 14177.8
   },
   "member_spread_deg": {
    "lat": 28.69,
    "lon": 346.11
   },
   "member_spread_now_deg": {
    "lat": 4.63,
    "lon": 9.85
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:49:00",
   "seed_lat": 51.20833,
   "seed_lon": -4.16667,
   "seed_alt_m": 12980.0,
   "seed_age_h": 6.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 47.94808,
    "lon": 121.30617,
    "alt_m": 12690.2
   },
   "member_spread_deg": {
    "lat": 4.87,
    "lon": 80.11
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 0.98
   },
   "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": 71.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 9.20897,
    "lon": -96.26312,
    "alt_m": 14106.8
   },
   "member_spread_deg": {
    "lat": 38.12,
    "lon": 54.06
   },
   "member_spread_now_deg": {
    "lat": 24.72,
    "lon": 37.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 210.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 52.06449,
    "lon": 7.63024,
    "alt_m": 13175.0
   },
   "member_spread_deg": {
    "lat": 74.23,
    "lon": 281.19
   },
   "member_spread_now_deg": {
    "lat": 66.45,
    "lon": 241.03
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:26:00",
   "seed_lat": 48.89583,
   "seed_lon": 166.5,
   "seed_alt_m": 12700.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 22:00:00",
    "lat": 53.3241,
    "lon": 1.50833,
    "alt_m": 12591.1
   },
   "member_spread_deg": {
    "lat": 19.63,
    "lon": 166.3
   },
   "member_spread_now_deg": {
    "lat": 0.39,
    "lon": 0.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:33:00",
   "seed_lat": 63.0,
   "seed_lon": 3.91667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 30.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 70.20843,
    "lon": -102.25103,
    "alt_m": 11950.2
   },
   "member_spread_deg": {
    "lat": 21.45,
    "lon": 249.67
   },
   "member_spread_now_deg": {
    "lat": 4.43,
    "lon": 14.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 19:08:00",
   "seed_lat": 75.08333,
   "seed_lon": -150.75,
   "seed_alt_m": 12580.0,
   "seed_age_h": 4.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 18:45:00",
    "lat": 61.21699,
    "lon": -41.44924,
    "alt_m": 12673.0
   },
   "member_spread_deg": {
    "lat": 12.96,
    "lon": 44.56
   },
   "member_spread_now_deg": {
    "lat": 0.7,
    "lon": 0.85
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:55:37",
   "seed_lat": 25.35411,
   "seed_lon": -137.41667,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:00:00",
    "lat": 37.42213,
    "lon": -83.03229,
    "alt_m": 13496.2
   },
   "member_spread_deg": {
    "lat": 20.05,
    "lon": 97.25
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 19:22:36",
   "seed_lat": 59.29167,
   "seed_lon": 6.5,
   "seed_alt_m": 13640.0,
   "seed_age_h": 3.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 19:00:00",
    "lat": 58.31296,
    "lon": 176.53202,
    "alt_m": 13281.9
   },
   "member_spread_deg": {
    "lat": 16.83,
    "lon": 90.24
   },
   "member_spread_now_deg": {
    "lat": 0.52,
    "lon": 2.08
   },
   "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": 11.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 73.85915,
    "lon": 57.57336,
    "alt_m": 12646.2
   },
   "member_spread_deg": {
    "lat": 33.2,
    "lon": 236.78
   },
   "member_spread_now_deg": {
    "lat": 5.45,
    "lon": 4.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 17:15:00",
   "seed_lat": 41.47917,
   "seed_lon": -7.5,
   "seed_alt_m": 13090.0,
   "seed_age_h": 6.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 55.15025,
    "lon": 155.96437,
    "alt_m": 12961.2
   },
   "member_spread_deg": {
    "lat": 24.12,
    "lon": 39.18
   },
   "member_spread_now_deg": {
    "lat": 0.92,
    "lon": 2.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 20:23:30",
   "seed_lat": 52.45833,
   "seed_lon": -72.58333,
   "seed_alt_m": 12140.0,
   "seed_age_h": 2.94,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 20:00:00",
    "lat": 73.48782,
    "lon": -6.34718,
    "alt_m": 12266.2
   },
   "member_spread_deg": {
    "lat": 22.4,
    "lon": 140.51
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 08:48:30",
   "seed_lat": 38.77083,
   "seed_lon": 107.91667,
   "seed_alt_m": 12330.0,
   "seed_age_h": 14.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 45.1824,
    "lon": -132.48244,
    "alt_m": 12531.5
   },
   "member_spread_deg": {
    "lat": 24.01,
    "lon": 298.84
   },
   "member_spread_now_deg": {
    "lat": 10.54,
    "lon": 15.37
   },
   "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": 264.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 3.77863,
    "lon": -98.1333,
    "alt_m": 12350.7
   },
   "member_spread_deg": {
    "lat": 53.9,
    "lon": 183.03
   },
   "member_spread_now_deg": {
    "lat": 22.62,
    "lon": 55.82
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 06:35:45",
   "seed_lat": 54.72911,
   "seed_lon": 24.66669,
   "seed_alt_m": 13360.0,
   "seed_age_h": 40.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 62.8124,
    "lon": 124.7307,
    "alt_m": 13215.2
   },
   "member_spread_deg": {
    "lat": 12.67,
    "lon": 302.0
   },
   "member_spread_now_deg": {
    "lat": 15.55,
    "lon": 23.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:51:00",
   "seed_lat": 27.10417,
   "seed_lon": 179.5,
   "seed_alt_m": 16440.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 22:15:00",
    "lat": 8.75765,
    "lon": 85.153,
    "alt_m": 16369.8
   },
   "member_spread_deg": {
    "lat": 42.06,
    "lon": 80.18
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.04
   },
   "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": 292.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": 45.71048,
    "lon": -51.1556,
    "alt_m": 13477.4
   },
   "member_spread_deg": {
    "lat": 27.62,
    "lon": 235.32
   },
   "member_spread_now_deg": {
    "lat": 12.75,
    "lon": 324.29
   },
   "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": 211.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 53.10256,
    "lon": -172.13613,
    "alt_m": 12574.8
   },
   "member_spread_deg": {
    "lat": 32.35,
    "lon": 299.02
   },
   "member_spread_now_deg": {
    "lat": 27.96,
    "lon": 314.76
   },
   "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": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 22:15:00",
    "lat": 24.0879,
    "lon": -146.06858,
    "alt_m": 13719.8
   },
   "member_spread_deg": {
    "lat": 28.48,
    "lon": 346.32
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.16
   },
   "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": 306.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 17:30:00",
    "lat": 0.67708,
    "lon": 39.2896,
    "alt_m": 12685.0
   },
   "member_spread_deg": {
    "lat": 34.04,
    "lon": 291.08
   },
   "member_spread_now_deg": {
    "lat": 28.5,
    "lon": 265.75
   },
   "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": 16.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 17:45:00",
    "lat": -16.19871,
    "lon": -32.90426,
    "alt_m": 15795.0
   },
   "member_spread_deg": {
    "lat": 21.93,
    "lon": 146.44
   },
   "member_spread_now_deg": {
    "lat": 3.08,
    "lon": 6.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}