{
 "generated_utc": "2026-08-23T17:27:26Z",
 "gfs_cycle_utc": "2026-08-23T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 491.5,
  "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_20260823_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260823_12Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 99846
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 13:43:40",
   "seed_lat": -61.64583,
   "seed_lon": 25.04168,
   "seed_alt_m": 12480.0,
   "seed_age_h": 27.61,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": -55.62627,
    "lon": 80.7616,
    "alt_m": 12261.9
   },
   "member_spread_deg": {
    "lat": 18.76,
    "lon": 238.91
   },
   "member_spread_now_deg": {
    "lat": 11.49,
    "lon": 39.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 16:53:18",
   "seed_lat": 79.66667,
   "seed_lon": -76.70833,
   "seed_alt_m": 12300.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 17:00:00",
    "lat": 71.85468,
    "lon": 81.2864,
    "alt_m": 12058.8
   },
   "member_spread_deg": {
    "lat": 29.96,
    "lon": 101.64
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 16:57:18",
   "seed_lat": 43.89583,
   "seed_lon": -75.66667,
   "seed_alt_m": 13850.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 17:00:00",
    "lat": 49.58809,
    "lon": 111.4293,
    "alt_m": 13911.1
   },
   "member_spread_deg": {
    "lat": 14.67,
    "lon": 117.02
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 02:19:00",
   "seed_lat": 35.91667,
   "seed_lon": -146.25,
   "seed_alt_m": 13020.0,
   "seed_age_h": 15.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 63.95743,
    "lon": 38.30135,
    "alt_m": 12688.8
   },
   "member_spread_deg": {
    "lat": 27.9,
    "lon": 63.94
   },
   "member_spread_now_deg": {
    "lat": 3.15,
    "lon": 8.3
   },
   "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": 329.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": -4.12414,
    "lon": -13.06715,
    "alt_m": 14013.7
   },
   "member_spread_deg": {
    "lat": 70.43,
    "lon": 266.62
   },
   "member_spread_now_deg": {
    "lat": 57.49,
    "lon": 124.0
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 06:56:00",
   "seed_lat": 49.85417,
   "seed_lon": 87.375,
   "seed_alt_m": 12530.0,
   "seed_age_h": 10.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": 54.75847,
    "lon": -123.64941,
    "alt_m": 12429.1
   },
   "member_spread_deg": {
    "lat": 38.28,
    "lon": 211.39
   },
   "member_spread_now_deg": {
    "lat": 1.84,
    "lon": 7.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 02:47:00",
   "seed_lat": 55.54167,
   "seed_lon": -162.25,
   "seed_alt_m": 13120.0,
   "seed_age_h": 14.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 50.76458,
    "lon": -25.16669,
    "alt_m": 12906.4
   },
   "member_spread_deg": {
    "lat": 26.91,
    "lon": 89.15
   },
   "member_spread_now_deg": {
    "lat": 3.23,
    "lon": 2.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 04:13:00",
   "seed_lat": 69.47917,
   "seed_lon": -178.58333,
   "seed_alt_m": 11780.0,
   "seed_age_h": 13.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 61.34838,
    "lon": -27.2216,
    "alt_m": 11897.4
   },
   "member_spread_deg": {
    "lat": 29.71,
    "lon": 188.6
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 7.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 15:53:00",
   "seed_lat": 53.35417,
   "seed_lon": 17.375,
   "seed_alt_m": 12510.0,
   "seed_age_h": 25.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": 82.02115,
    "lon": 139.72455,
    "alt_m": 12475.9
   },
   "member_spread_deg": {
    "lat": 43.07,
    "lon": 171.52
   },
   "member_spread_now_deg": {
    "lat": 4.83,
    "lon": 15.54
   },
   "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": 188.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 12.67859,
    "lon": -51.72785,
    "alt_m": 13355.6
   },
   "member_spread_deg": {
    "lat": 29.83,
    "lon": 278.88
   },
   "member_spread_now_deg": {
    "lat": 19.8,
    "lon": 79.26
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 10:47:18",
   "seed_lat": 58.875,
   "seed_lon": 131.375,
   "seed_alt_m": 13220.0,
   "seed_age_h": 6.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 64.59751,
    "lon": -67.54341,
    "alt_m": 13342.3
   },
   "member_spread_deg": {
    "lat": 28.09,
    "lon": 112.77
   },
   "member_spread_now_deg": {
    "lat": 1.19,
    "lon": 3.36
   },
   "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": 269.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 59.18393,
    "lon": 172.63813,
    "alt_m": 12643.8
   },
   "member_spread_deg": {
    "lat": 37.43,
    "lon": 335.6
   },
   "member_spread_now_deg": {
    "lat": 25.31,
    "lon": 311.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 15:54:00",
   "seed_lat": 33.91667,
   "seed_lon": -26.16667,
   "seed_alt_m": 12750.0,
   "seed_age_h": 1.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 15:30:00",
    "lat": 39.29134,
    "lon": 114.19745,
    "alt_m": 12410.8
   },
   "member_spread_deg": {
    "lat": 22.51,
    "lon": 177.9
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 04:55:00",
   "seed_lat": 31.64583,
   "seed_lon": -179.04167,
   "seed_alt_m": 13060.0,
   "seed_age_h": 12.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": 42.06186,
    "lon": -120.32269,
    "alt_m": 12867.9
   },
   "member_spread_deg": {
    "lat": 20.47,
    "lon": 131.51
   },
   "member_spread_now_deg": {
    "lat": 5.11,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 05:06:00",
   "seed_lat": 70.6875,
   "seed_lon": 178.08333,
   "seed_alt_m": 11840.0,
   "seed_age_h": 12.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": 56.45453,
    "lon": 90.20346,
    "alt_m": 12128.1
   },
   "member_spread_deg": {
    "lat": 27.77,
    "lon": 268.16
   },
   "member_spread_now_deg": {
    "lat": 1.05,
    "lon": 8.62
   },
   "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": 236.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 31.05157,
    "lon": -48.51642,
    "alt_m": 11268.3
   },
   "member_spread_deg": {
    "lat": 39.66,
    "lon": 325.36
   },
   "member_spread_now_deg": {
    "lat": 24.93,
    "lon": 110.59
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 01:45:45",
   "seed_lat": 81.20828,
   "seed_lon": -145.74998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 15.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": 78.39872,
    "lon": -126.58071,
    "alt_m": 12952.8
   },
   "member_spread_deg": {
    "lat": 15.74,
    "lon": 348.9
   },
   "member_spread_now_deg": {
    "lat": 3.5,
    "lon": 7.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-23 17:04:04",
   "seed_lat": 51.38984,
   "seed_lon": -64.00742,
   "seed_alt_m": 13026.0,
   "seed_age_h": 0.27,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:00:00",
    "lat": 38.32454,
    "lon": 164.59273,
    "alt_m": 13168.7
   },
   "member_spread_deg": {
    "lat": 22.93,
    "lon": 59.12
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 0.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 15:23:00",
   "seed_lat": 17.52083,
   "seed_lon": 13.625,
   "seed_alt_m": 16640.0,
   "seed_age_h": 1.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 15:00:00",
    "lat": 44.88287,
    "lon": 60.94118,
    "alt_m": 15979.9
   },
   "member_spread_deg": {
    "lat": 25.61,
    "lon": 152.83
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.39
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 15:31:00",
   "seed_lat": 45.3125,
   "seed_lon": -73.375,
   "seed_alt_m": 13050.0,
   "seed_age_h": 1.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 15:00:00",
    "lat": 46.31041,
    "lon": 158.04801,
    "alt_m": 13051.1
   },
   "member_spread_deg": {
    "lat": 14.65,
    "lon": 135.23
   },
   "member_spread_now_deg": {
    "lat": 1.3,
    "lon": 0.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 16:55:23",
   "seed_lat": 56.79161,
   "seed_lon": -78.87498,
   "seed_alt_m": 13120.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-30 17:00:00",
    "lat": 44.35955,
    "lon": 51.05337,
    "alt_m": 13420.1
   },
   "member_spread_deg": {
    "lat": 22.21,
    "lon": 63.82
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 0.28
   },
   "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": 140.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": -15.71132,
    "lon": -28.17454,
    "alt_m": 12475.3
   },
   "member_spread_deg": {
    "lat": 20.54,
    "lon": 134.94
   },
   "member_spread_now_deg": {
    "lat": 13.9,
    "lon": 329.06
   },
   "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": 274.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 11:45:00",
    "lat": -18.91828,
    "lon": 105.13291,
    "alt_m": 16014.9
   },
   "member_spread_deg": {
    "lat": 34.27,
    "lon": 226.21
   },
   "member_spread_now_deg": {
    "lat": 30.42,
    "lon": 206.17
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 08:01:00",
   "seed_lat": -21.5,
   "seed_lon": 112.91667,
   "seed_alt_m": 15710.0,
   "seed_age_h": 9.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-30 11:30:00",
    "lat": -31.64057,
    "lon": -40.96882,
    "alt_m": 15185.7
   },
   "member_spread_deg": {
    "lat": 30.53,
    "lon": 52.66
   },
   "member_spread_now_deg": {
    "lat": 3.28,
    "lon": 6.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}