{
 "generated_utc": "2026-08-13T05:26:58Z",
 "gfs_cycle_utc": "2026-08-13T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 475.0,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260813_00Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 103176
 },
 "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": 29.44,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": -62.29685,
    "lon": -98.84099,
    "alt_m": 12773.7
   },
   "member_spread_deg": {
    "lat": 35.65,
    "lon": 323.7
   },
   "member_spread_now_deg": {
    "lat": 10.4,
    "lon": 15.04
   },
   "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": 10.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 65.96012,
    "lon": -169.68234,
    "alt_m": 12475.8
   },
   "member_spread_deg": {
    "lat": 19.35,
    "lon": 344.78
   },
   "member_spread_now_deg": {
    "lat": 1.24,
    "lon": 1.75
   },
   "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": 49.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 30.01123,
    "lon": -140.23805,
    "alt_m": 14301.0
   },
   "member_spread_deg": {
    "lat": 37.65,
    "lon": 320.66
   },
   "member_spread_now_deg": {
    "lat": 4.04,
    "lon": 9.73
   },
   "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": 12.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 49.44266,
    "lon": 131.42,
    "alt_m": 12821.4
   },
   "member_spread_deg": {
    "lat": 6.71,
    "lon": 79.29
   },
   "member_spread_now_deg": {
    "lat": 1.28,
    "lon": 1.23
   },
   "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": 77.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 19.99925,
    "lon": -95.73931,
    "alt_m": 14069.2
   },
   "member_spread_deg": {
    "lat": 36.52,
    "lon": 54.58
   },
   "member_spread_now_deg": {
    "lat": 25.64,
    "lon": 39.18
   },
   "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": 216.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 30.74128,
    "lon": -29.92605,
    "alt_m": 13541.0
   },
   "member_spread_deg": {
    "lat": 77.75,
    "lon": 308.56
   },
   "member_spread_now_deg": {
    "lat": 65.92,
    "lon": 240.23
   },
   "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 04:41:00",
   "seed_lat": 48.33333,
   "seed_lon": 170.16667,
   "seed_alt_m": 12720.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 04:15:00",
    "lat": 53.87846,
    "lon": 3.67851,
    "alt_m": 12426.3
   },
   "member_spread_deg": {
    "lat": 7.92,
    "lon": 95.36
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.17
   },
   "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": 36.78,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 81.93832,
    "lon": 47.29778,
    "alt_m": 11943.1
   },
   "member_spread_deg": {
    "lat": 28.1,
    "lon": 249.51
   },
   "member_spread_now_deg": {
    "lat": 7.7,
    "lon": 14.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 00:53:00",
   "seed_lat": 74.79167,
   "seed_lon": -150.33333,
   "seed_alt_m": 12560.0,
   "seed_age_h": 4.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 00:30:00",
    "lat": 61.60273,
    "lon": -19.27895,
    "alt_m": 12575.5
   },
   "member_spread_deg": {
    "lat": 6.69,
    "lon": 93.53
   },
   "member_spread_now_deg": {
    "lat": 1.68,
    "lon": 3.94
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 01:05:37",
   "seed_lat": 24.45828,
   "seed_lon": -136.95833,
   "seed_alt_m": 13300.0,
   "seed_age_h": 4.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 00:30:00",
    "lat": 28.21351,
    "lon": -54.00994,
    "alt_m": 13388.0
   },
   "member_spread_deg": {
    "lat": 24.19,
    "lon": 133.45
   },
   "member_spread_now_deg": {
    "lat": 1.36,
    "lon": 1.75
   },
   "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": 9.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 63.61922,
    "lon": -178.50281,
    "alt_m": 13278.8
   },
   "member_spread_deg": {
    "lat": 14.54,
    "lon": 357.3
   },
   "member_spread_now_deg": {
    "lat": 1.28,
    "lon": 4.71
   },
   "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": 17.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 63.06659,
    "lon": 86.34311,
    "alt_m": 12568.0
   },
   "member_spread_deg": {
    "lat": 18.11,
    "lon": 270.43
   },
   "member_spread_now_deg": {
    "lat": 6.08,
    "lon": 7.47
   },
   "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": 12.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 55.91298,
    "lon": 161.78202,
    "alt_m": 12945.5
   },
   "member_spread_deg": {
    "lat": 26.55,
    "lon": 54.64
   },
   "member_spread_now_deg": {
    "lat": 2.06,
    "lon": 3.61
   },
   "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": 8.94,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 44.98458,
    "lon": 5.80007,
    "alt_m": 12948.9
   },
   "member_spread_deg": {
    "lat": 30.16,
    "lon": 63.93
   },
   "member_spread_now_deg": {
    "lat": 1.06,
    "lon": 2.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:11:00",
   "seed_lat": 47.5,
   "seed_lon": 126.29167,
   "seed_alt_m": 12180.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-20 03:45:00",
    "lat": 51.76071,
    "lon": -133.31637,
    "alt_m": 12450.1
   },
   "member_spread_deg": {
    "lat": 23.79,
    "lon": 74.79
   },
   "member_spread_now_deg": {
    "lat": 0.58,
    "lon": 0.28
   },
   "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": 270.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 4.80125,
    "lon": -103.31122,
    "alt_m": 12352.6
   },
   "member_spread_deg": {
    "lat": 61.86,
    "lon": 187.1
   },
   "member_spread_now_deg": {
    "lat": 21.78,
    "lon": 57.86
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:55:45",
   "seed_lat": 71.10411,
   "seed_lon": 55.33335,
   "seed_alt_m": 13240.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 05:00:00",
    "lat": 60.96638,
    "lon": 167.82564,
    "alt_m": 13258.8
   },
   "member_spread_deg": {
    "lat": 20.34,
    "lon": 338.99
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:11:00",
   "seed_lat": 26.08333,
   "seed_lon": 178.75,
   "seed_alt_m": 16470.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 03:45:00",
    "lat": 12.91934,
    "lon": 87.29375,
    "alt_m": 16656.1
   },
   "member_spread_deg": {
    "lat": 32.94,
    "lon": 47.07
   },
   "member_spread_now_deg": {
    "lat": 0.69,
    "lon": 0.14
   },
   "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": 298.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 50.44893,
    "lon": -56.89539,
    "alt_m": 13445.5
   },
   "member_spread_deg": {
    "lat": 26.84,
    "lon": 253.76
   },
   "member_spread_now_deg": {
    "lat": 12.62,
    "lon": 322.48
   },
   "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": 217.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": 55.93718,
    "lon": 142.12415,
    "alt_m": 12817.3
   },
   "member_spread_deg": {
    "lat": 42.76,
    "lon": 286.14
   },
   "member_spread_now_deg": {
    "lat": 28.54,
    "lon": 313.47
   },
   "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": 6.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": 48.2373,
    "lon": -91.25273,
    "alt_m": 13336.0
   },
   "member_spread_deg": {
    "lat": 24.65,
    "lon": 317.32
   },
   "member_spread_now_deg": {
    "lat": 2.73,
    "lon": 0.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 04:30:23",
   "seed_lat": 46.41661,
   "seed_lon": 119.41669,
   "seed_alt_m": 13540.0,
   "seed_age_h": 0.83,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-20 04:00:00",
    "lat": 64.12398,
    "lon": -145.41454,
    "alt_m": 12974.1
   },
   "member_spread_deg": {
    "lat": 28.17,
    "lon": 83.66
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.15
   },
   "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": 312.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 23:30:00",
    "lat": -23.09103,
    "lon": 160.02228,
    "alt_m": 12351.7
   },
   "member_spread_deg": {
    "lat": 19.55,
    "lon": 288.14
   },
   "member_spread_now_deg": {
    "lat": 28.16,
    "lon": 270.29
   },
   "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": 22.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 23:45:00",
    "lat": -12.73943,
    "lon": -30.19552,
    "alt_m": 15921.3
   },
   "member_spread_deg": {
    "lat": 22.86,
    "lon": 144.73
   },
   "member_spread_now_deg": {
    "lat": 3.57,
    "lon": 8.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}