{
 "generated_utc": "2026-08-12T17:26:46Z",
 "gfs_cycle_utc": "2026-08-12T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 463.0,
  "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_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260812_12Z.geojson.gz"
 },
 "counts": {
  "flights": 23,
  "members": 9,
  "rows": 99234
 },
 "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": 17.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": -53.78251,
    "lon": -158.27438,
    "alt_m": 12519.7
   },
   "member_spread_deg": {
    "lat": 27.69,
    "lon": 294.09
   },
   "member_spread_now_deg": {
    "lat": 2.59,
    "lon": 11.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:50:18",
   "seed_lat": 63.54167,
   "seed_lon": 1.95833,
   "seed_alt_m": 12740.0,
   "seed_age_h": 0.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 16:15:00",
    "lat": 51.7258,
    "lon": -172.863,
    "alt_m": 12584.8
   },
   "member_spread_deg": {
    "lat": 14.39,
    "lon": 345.98
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.08
   },
   "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": 37.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 34.03341,
    "lon": -149.44059,
    "alt_m": 14298.9
   },
   "member_spread_deg": {
    "lat": 25.92,
    "lon": 339.19
   },
   "member_spread_now_deg": {
    "lat": 5.77,
    "lon": 8.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:09:00",
   "seed_lat": 51.14583,
   "seed_lon": -4.58333,
   "seed_alt_m": 12990.0,
   "seed_age_h": 1.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 15:45:00",
    "lat": 49.77124,
    "lon": 140.25624,
    "alt_m": 12795.3
   },
   "member_spread_deg": {
    "lat": 6.76,
    "lon": 91.55
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.15
   },
   "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": 65.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 1.59772,
    "lon": -121.85222,
    "alt_m": 14077.8
   },
   "member_spread_deg": {
    "lat": 33.04,
    "lon": 62.17
   },
   "member_spread_now_deg": {
    "lat": 21.94,
    "lon": 34.77
   },
   "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": 204.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 42.84605,
    "lon": -13.45874,
    "alt_m": 13492.8
   },
   "member_spread_deg": {
    "lat": 80.49,
    "lon": 292.82
   },
   "member_spread_now_deg": {
    "lat": 70.53,
    "lon": 241.04
   },
   "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 05:16:00",
   "seed_lat": 54.60417,
   "seed_lon": 154.08333,
   "seed_alt_m": 12810.0,
   "seed_age_h": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 48.86149,
    "lon": -13.75918,
    "alt_m": 12856.1
   },
   "member_spread_deg": {
    "lat": 13.23,
    "lon": 61.97
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 1.78
   },
   "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": 24.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 58.03127,
    "lon": -78.10169,
    "alt_m": 11878.3
   },
   "member_spread_deg": {
    "lat": 27.52,
    "lon": 230.29
   },
   "member_spread_now_deg": {
    "lat": 4.19,
    "lon": 11.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 00:18:00",
   "seed_lat": 74.52083,
   "seed_lon": -141.04167,
   "seed_alt_m": 12600.0,
   "seed_age_h": 17.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 63.78215,
    "lon": -40.82705,
    "alt_m": 12426.5
   },
   "member_spread_deg": {
    "lat": 22.56,
    "lon": 36.09
   },
   "member_spread_now_deg": {
    "lat": 1.82,
    "lon": 3.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 03:45:37",
   "seed_lat": 33.04161,
   "seed_lon": 175.83333,
   "seed_alt_m": 13420.0,
   "seed_age_h": 61.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 19.64463,
    "lon": -67.26778,
    "alt_m": 13572.4
   },
   "member_spread_deg": {
    "lat": 32.74,
    "lon": 299.14
   },
   "member_spread_now_deg": {
    "lat": 26.11,
    "lon": 328.85
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:57:03",
   "seed_lat": 59.70833,
   "seed_lon": 3.125,
   "seed_alt_m": 13650.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 17:00:00",
    "lat": 64.8027,
    "lon": 169.22348,
    "alt_m": 13137.7
   },
   "member_spread_deg": {
    "lat": 17.67,
    "lon": 348.5
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.31
   },
   "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": 5.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 48.94109,
    "lon": 80.96097,
    "alt_m": 12475.3
   },
   "member_spread_deg": {
    "lat": 11.37,
    "lon": 226.94
   },
   "member_spread_now_deg": {
    "lat": 3.49,
    "lon": 2.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:25:00",
   "seed_lat": 41.35417,
   "seed_lon": -7.66667,
   "seed_alt_m": 13110.0,
   "seed_age_h": 0.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 16:00:00",
    "lat": 51.69101,
    "lon": 157.73253,
    "alt_m": 13086.6
   },
   "member_spread_deg": {
    "lat": 23.91,
    "lon": 59.59
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 16:41:00",
   "seed_lat": 52.625,
   "seed_lon": -73.54167,
   "seed_alt_m": 12140.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 16:15:00",
    "lat": 70.33983,
    "lon": -6.15834,
    "alt_m": 12189.3
   },
   "member_spread_deg": {
    "lat": 11.37,
    "lon": 28.72
   },
   "member_spread_now_deg": {
    "lat": 0.01,
    "lon": 0.02
   },
   "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": 8.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 47.7154,
    "lon": -127.98481,
    "alt_m": 12367.4
   },
   "member_spread_deg": {
    "lat": 36.78,
    "lon": 332.99
   },
   "member_spread_now_deg": {
    "lat": 4.39,
    "lon": 6.73
   },
   "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": 258.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 11.57227,
    "lon": -75.86481,
    "alt_m": 12384.7
   },
   "member_spread_deg": {
    "lat": 64.35,
    "lon": 165.46
   },
   "member_spread_now_deg": {
    "lat": 22.0,
    "lon": 54.22
   },
   "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": 34.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 67.26011,
    "lon": 164.84472,
    "alt_m": 13043.4
   },
   "member_spread_deg": {
    "lat": 20.36,
    "lon": 315.0
   },
   "member_spread_now_deg": {
    "lat": 13.58,
    "lon": 12.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 04:41:00",
   "seed_lat": 31.625,
   "seed_lon": 178.95833,
   "seed_alt_m": 16360.0,
   "seed_age_h": 12.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 8.69103,
    "lon": 97.31192,
    "alt_m": 16537.5
   },
   "member_spread_deg": {
    "lat": 54.42,
    "lon": 80.58
   },
   "member_spread_now_deg": {
    "lat": 8.61,
    "lon": 359.43
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 286.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 56.89816,
    "lon": -40.21618,
    "alt_m": 13071.8
   },
   "member_spread_deg": {
    "lat": 30.44,
    "lon": 328.88
   },
   "member_spread_now_deg": {
    "lat": 11.29,
    "lon": 326.62
   },
   "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": 205.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 60.06707,
    "lon": 151.83324,
    "alt_m": 12581.2
   },
   "member_spread_deg": {
    "lat": 44.09,
    "lon": 273.74
   },
   "member_spread_now_deg": {
    "lat": 27.23,
    "lon": 316.42
   },
   "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 06:51:00",
   "seed_lat": 47.125,
   "seed_lon": 146.33333,
   "seed_alt_m": 13700.0,
   "seed_age_h": 10.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": 33.80159,
    "lon": -144.85949,
    "alt_m": 13582.1
   },
   "member_spread_deg": {
    "lat": 33.51,
    "lon": 344.85
   },
   "member_spread_now_deg": {
    "lat": 1.58,
    "lon": 5.63
   },
   "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": 300.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 11:30:00",
    "lat": 1.84014,
    "lon": 33.88486,
    "alt_m": 12678.4
   },
   "member_spread_deg": {
    "lat": 35.58,
    "lon": 219.12
   },
   "member_spread_now_deg": {
    "lat": 25.81,
    "lon": 261.22
   },
   "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": 10.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 11:45:00",
    "lat": -19.52206,
    "lon": -31.84299,
    "alt_m": 15706.3
   },
   "member_spread_deg": {
    "lat": 20.32,
    "lon": 148.01
   },
   "member_spread_now_deg": {
    "lat": 2.95,
    "lon": 5.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}