{
 "generated_utc": "2026-08-17T17:27:32Z",
 "gfs_cycle_utc": "2026-08-17T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 487.5,
  "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_20260817_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260817_12Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 89190
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 09:08:40",
   "seed_lat": -54.125,
   "seed_lon": 105.20835,
   "seed_alt_m": 12270.0,
   "seed_age_h": 8.19,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": -48.82704,
    "lon": 121.37813,
    "alt_m": 12298.2
   },
   "member_spread_deg": {
    "lat": 20.77,
    "lon": 102.28
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 3.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:25:18",
   "seed_lat": 52.77083,
   "seed_lon": 116.91667,
   "seed_alt_m": 12570.0,
   "seed_age_h": 6.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:30:00",
    "lat": 78.35527,
    "lon": 137.99013,
    "alt_m": 12022.2
   },
   "member_spread_deg": {
    "lat": 27.04,
    "lon": 322.38
   },
   "member_spread_now_deg": {
    "lat": 2.39,
    "lon": 7.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 01:17:18",
   "seed_lat": 41.95833,
   "seed_lon": 177.125,
   "seed_alt_m": 14090.0,
   "seed_age_h": 16.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 47.70304,
    "lon": -86.70863,
    "alt_m": 13891.1
   },
   "member_spread_deg": {
    "lat": 17.89,
    "lon": 88.88
   },
   "member_spread_now_deg": {
    "lat": 1.8,
    "lon": 3.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 11:44:00",
   "seed_lat": 47.375,
   "seed_lon": 69.20833,
   "seed_alt_m": 12450.0,
   "seed_age_h": 5.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 34.37996,
    "lon": -130.32538,
    "alt_m": 12826.9
   },
   "member_spread_deg": {
    "lat": 23.03,
    "lon": 14.42
   },
   "member_spread_now_deg": {
    "lat": 0.75,
    "lon": 1.16
   },
   "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": 185.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 12.97153,
    "lon": -67.03334,
    "alt_m": 14083.6
   },
   "member_spread_deg": {
    "lat": 47.64,
    "lon": 135.72
   },
   "member_spread_now_deg": {
    "lat": 35.1,
    "lon": 84.13
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 324.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:30:00",
    "lat": 41.43826,
    "lon": 116.07993,
    "alt_m": 13501.8
   },
   "member_spread_deg": {
    "lat": 99.64,
    "lon": 279.78
   },
   "member_spread_now_deg": {
    "lat": 76.83,
    "lon": 225.82
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 16:46:00",
   "seed_lat": 49.5625,
   "seed_lon": -81.33333,
   "seed_alt_m": 12540.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 16:45:00",
    "lat": 52.09474,
    "lon": 136.14159,
    "alt_m": 12621.5
   },
   "member_spread_deg": {
    "lat": 11.8,
    "lon": 68.15
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 12:32:00",
   "seed_lat": 40.41667,
   "seed_lon": 26.29167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 28.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:30:00",
    "lat": 43.35559,
    "lon": -141.74721,
    "alt_m": 13181.3
   },
   "member_spread_deg": {
    "lat": 28.23,
    "lon": 51.24
   },
   "member_spread_now_deg": {
    "lat": 1.55,
    "lon": 14.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 15:28:00",
   "seed_lat": 84.60417,
   "seed_lon": -20.70833,
   "seed_alt_m": 11760.0,
   "seed_age_h": 1.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 15:00:00",
    "lat": 78.57176,
    "lon": -167.94562,
    "alt_m": 11655.4
   },
   "member_spread_deg": {
    "lat": 30.2,
    "lon": 339.36
   },
   "member_spread_now_deg": {
    "lat": 0.7,
    "lon": 2.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 16:43:00",
   "seed_lat": 59.27083,
   "seed_lon": -59.625,
   "seed_alt_m": 12500.0,
   "seed_age_h": 0.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 16:45:00",
    "lat": 57.90399,
    "lon": 52.14757,
    "alt_m": 12428.1
   },
   "member_spread_deg": {
    "lat": 30.56,
    "lon": 141.25
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.51
   },
   "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": 44.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 20.59921,
    "lon": -85.00087,
    "alt_m": 13322.1
   },
   "member_spread_deg": {
    "lat": 14.38,
    "lon": 82.17
   },
   "member_spread_now_deg": {
    "lat": 8.48,
    "lon": 26.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 00:47:18",
   "seed_lat": 65.0,
   "seed_lon": 62.95833,
   "seed_alt_m": 13240.0,
   "seed_age_h": 16.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 57.07578,
    "lon": 158.17291,
    "alt_m": 13241.7
   },
   "member_spread_deg": {
    "lat": 24.52,
    "lon": 336.12
   },
   "member_spread_now_deg": {
    "lat": 1.77,
    "lon": 4.89
   },
   "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": 125.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 63.0678,
    "lon": 94.09886,
    "alt_m": 12688.9
   },
   "member_spread_deg": {
    "lat": 15.08,
    "lon": 209.52
   },
   "member_spread_now_deg": {
    "lat": 18.39,
    "lon": 240.06
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:45:00",
   "seed_lat": 43.72917,
   "seed_lon": 99.91667,
   "seed_alt_m": 12470.0,
   "seed_age_h": 6.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 32.24512,
    "lon": -170.25557,
    "alt_m": 12888.3
   },
   "member_spread_deg": {
    "lat": 44.66,
    "lon": 348.14
   },
   "member_spread_now_deg": {
    "lat": 0.71,
    "lon": 3.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 15:41:00",
   "seed_lat": 74.9375,
   "seed_lon": -39.20833,
   "seed_alt_m": 12260.0,
   "seed_age_h": 1.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 15:15:00",
    "lat": 82.17311,
    "lon": -113.41417,
    "alt_m": 11949.2
   },
   "member_spread_deg": {
    "lat": 17.25,
    "lon": 354.01
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.62
   },
   "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": 92.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 48.57535,
    "lon": 96.02322,
    "alt_m": 11059.1
   },
   "member_spread_deg": {
    "lat": 42.69,
    "lon": 158.27
   },
   "member_spread_now_deg": {
    "lat": 27.73,
    "lon": 24.88
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:13:15",
   "seed_lat": 64.74995,
   "seed_lon": 113.16669,
   "seed_alt_m": 13060.0,
   "seed_age_h": 7.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 79.0004,
    "lon": -71.89975,
    "alt_m": 12853.3
   },
   "member_spread_deg": {
    "lat": 28.84,
    "lon": 304.33
   },
   "member_spread_now_deg": {
    "lat": 1.41,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 07:46:00",
   "seed_lat": 12.54167,
   "seed_lon": 133.08333,
   "seed_alt_m": 16600.0,
   "seed_age_h": 9.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 9.28097,
    "lon": 20.17525,
    "alt_m": 16496.4
   },
   "member_spread_deg": {
    "lat": 42.71,
    "lon": 131.48
   },
   "member_spread_now_deg": {
    "lat": 4.17,
    "lon": 3.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 325.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:30:00",
    "lat": 52.06417,
    "lon": -133.66149,
    "alt_m": 12903.1
   },
   "member_spread_deg": {
    "lat": 37.57,
    "lon": 316.57
   },
   "member_spread_now_deg": {
    "lat": 30.7,
    "lon": 269.08
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 05:16:00",
   "seed_lat": 37.91667,
   "seed_lon": 177.08333,
   "seed_alt_m": 13420.0,
   "seed_age_h": 12.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": 43.71303,
    "lon": -20.35118,
    "alt_m": 13459.7
   },
   "member_spread_deg": {
    "lat": 44.74,
    "lon": 122.06
   },
   "member_spread_now_deg": {
    "lat": 2.43,
    "lon": 5.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 15:54:00",
   "seed_lat": -18.08333,
   "seed_lon": -81.54167,
   "seed_alt_m": 12290.0,
   "seed_age_h": 1.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 15:30:00",
    "lat": -27.13607,
    "lon": 173.5465,
    "alt_m": 11997.3
   },
   "member_spread_deg": {
    "lat": 46.67,
    "lon": 322.65
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 130.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 11:45:00",
    "lat": -1.16711,
    "lon": -33.82401,
    "alt_m": 16115.1
   },
   "member_spread_deg": {
    "lat": 31.12,
    "lon": 222.82
   },
   "member_spread_now_deg": {
    "lat": 13.06,
    "lon": 125.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}