{
 "generated_utc": "2026-08-29T11:27:03Z",
 "gfs_cycle_utc": "2026-08-29T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 489.0,
  "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_20260829_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260829_06Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 78129
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 19.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 05:45:00",
    "lat": -63.26445,
    "lon": -46.21746,
    "alt_m": 12158.8
   },
   "member_spread_deg": {
    "lat": 26.12,
    "lon": 97.92
   },
   "member_spread_now_deg": {
    "lat": 3.79,
    "lon": 20.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 09:54:48",
   "seed_lat": 48.89583,
   "seed_lon": 80.75,
   "seed_alt_m": 13930.0,
   "seed_age_h": 1.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-05 09:30:00",
    "lat": 36.61218,
    "lon": -54.02427,
    "alt_m": 14150.5
   },
   "member_spread_deg": {
    "lat": 31.22,
    "lon": 165.3
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:29:00",
   "seed_lat": 33.10417,
   "seed_lon": -84.75,
   "seed_alt_m": 13050.0,
   "seed_age_h": 85.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 41.04285,
    "lon": -88.16059,
    "alt_m": 13120.7
   },
   "member_spread_deg": {
    "lat": 23.84,
    "lon": 81.51
   },
   "member_spread_now_deg": {
    "lat": 12.87,
    "lon": 9.54
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:56:00",
   "seed_lat": 77.64583,
   "seed_lon": -74.79167,
   "seed_alt_m": 12270.0,
   "seed_age_h": 18.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 76.20715,
    "lon": -22.80144,
    "alt_m": 11837.0
   },
   "member_spread_deg": {
    "lat": 12.09,
    "lon": 192.25
   },
   "member_spread_now_deg": {
    "lat": 3.24,
    "lon": 10.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 10:27:00",
   "seed_lat": 44.5625,
   "seed_lon": -25.41667,
   "seed_alt_m": 13260.0,
   "seed_age_h": 0.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 10:00:00",
    "lat": 46.47545,
    "lon": 143.40211,
    "alt_m": 13271.5
   },
   "member_spread_deg": {
    "lat": 27.88,
    "lon": 70.14
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.98
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 10:53:00",
   "seed_lat": 68.08333,
   "seed_lon": 49.625,
   "seed_alt_m": 12020.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 11:00:00",
    "lat": 68.99807,
    "lon": 123.71711,
    "alt_m": 11694.6
   },
   "member_spread_deg": {
    "lat": 36.05,
    "lon": 316.77
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 117.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:45:00",
    "lat": 53.61474,
    "lon": 177.18161,
    "alt_m": 12503.1
   },
   "member_spread_deg": {
    "lat": 27.86,
    "lon": 329.21
   },
   "member_spread_now_deg": {
    "lat": 9.04,
    "lon": 341.8
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 326.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:45:00",
    "lat": 39.55828,
    "lon": 35.10108,
    "alt_m": 13084.9
   },
   "member_spread_deg": {
    "lat": 51.52,
    "lon": 238.52
   },
   "member_spread_now_deg": {
    "lat": 37.64,
    "lon": 253.79
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 06:33:48",
   "seed_lat": 61.6875,
   "seed_lon": -165.70833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 100.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 64.98033,
    "lon": 39.24779,
    "alt_m": 13061.8
   },
   "member_spread_deg": {
    "lat": 44.96,
    "lon": 195.46
   },
   "member_spread_now_deg": {
    "lat": 33.61,
    "lon": 141.95
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 14:29:00",
   "seed_lat": 28.5625,
   "seed_lon": 33.41667,
   "seed_alt_m": 12740.0,
   "seed_age_h": 20.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 33.81494,
    "lon": -147.4064,
    "alt_m": 12907.3
   },
   "member_spread_deg": {
    "lat": 29.85,
    "lon": 337.4
   },
   "member_spread_now_deg": {
    "lat": 2.44,
    "lon": 3.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 04:00:00",
   "seed_lat": 28.95833,
   "seed_lon": -157.75,
   "seed_alt_m": 12890.0,
   "seed_age_h": 7.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 28.19572,
    "lon": -20.76099,
    "alt_m": 12980.6
   },
   "member_spread_deg": {
    "lat": 20.07,
    "lon": 57.73
   },
   "member_spread_now_deg": {
    "lat": 1.93,
    "lon": 3.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 132.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 51.35583,
    "lon": 160.15655,
    "alt_m": 12025.1
   },
   "member_spread_deg": {
    "lat": 35.83,
    "lon": 324.92
   },
   "member_spread_now_deg": {
    "lat": 24.81,
    "lon": 234.33
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 03:35:45",
   "seed_lat": 73.54161,
   "seed_lon": -161.45831,
   "seed_alt_m": 12780.0,
   "seed_age_h": 7.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": 53.11039,
    "lon": 19.65203,
    "alt_m": 13062.7
   },
   "member_spread_deg": {
    "lat": 20.93,
    "lon": 53.54
   },
   "member_spread_now_deg": {
    "lat": 0.93,
    "lon": 1.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 67.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:45:00",
    "lat": 37.15336,
    "lon": -140.54511,
    "alt_m": 13388.4
   },
   "member_spread_deg": {
    "lat": 15.25,
    "lon": 110.19
   },
   "member_spread_now_deg": {
    "lat": 4.2,
    "lon": 19.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 10:31:00",
   "seed_lat": 32.25,
   "seed_lon": 35.95833,
   "seed_alt_m": 16200.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-05 10:00:00",
    "lat": 41.79784,
    "lon": -164.33683,
    "alt_m": 16350.7
   },
   "member_spread_deg": {
    "lat": 40.34,
    "lon": 336.17
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 0.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 08:26:00",
   "seed_lat": 44.58333,
   "seed_lon": 112.20833,
   "seed_alt_m": 12950.0,
   "seed_age_h": 2.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 08:00:00",
    "lat": 39.02812,
    "lon": -43.29432,
    "alt_m": 13548.6
   },
   "member_spread_deg": {
    "lat": 23.1,
    "lon": 106.69
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 1.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 10:47:53",
   "seed_lat": 37.37495,
   "seed_lon": 35.66669,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.54,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 10:15:00",
    "lat": 54.75004,
    "lon": -116.69069,
    "alt_m": 13426.0
   },
   "member_spread_deg": {
    "lat": 23.27,
    "lon": 52.51
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.13
   },
   "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": 278.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 05:30:00",
    "lat": -24.79112,
    "lon": -167.72776,
    "alt_m": 12154.1
   },
   "member_spread_deg": {
    "lat": 12.89,
    "lon": 254.76
   },
   "member_spread_now_deg": {
    "lat": 25.07,
    "lon": 104.48
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 01:21:00",
   "seed_lat": -25.875,
   "seed_lon": -135.66667,
   "seed_alt_m": 15340.0,
   "seed_age_h": 33.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 05:45:00",
    "lat": -9.83106,
    "lon": -63.62955,
    "alt_m": 15555.2
   },
   "member_spread_deg": {
    "lat": 47.0,
    "lon": 238.25
   },
   "member_spread_now_deg": {
    "lat": 11.14,
    "lon": 30.94
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}