{
 "generated_utc": "2026-08-30T17:27:03Z",
 "gfs_cycle_utc": "2026-08-30T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 470.5,
  "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_20260830_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260830_12Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 70425
 },
 "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": 49.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": -60.59876,
    "lon": 42.37731,
    "alt_m": 12428.5
   },
   "member_spread_deg": {
    "lat": 22.2,
    "lon": 83.19
   },
   "member_spread_now_deg": {
    "lat": 18.56,
    "lon": 41.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 05:39:27",
   "seed_lat": 43.35417,
   "seed_lon": 109.66667,
   "seed_alt_m": 13970.0,
   "seed_age_h": 11.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 31.43035,
    "lon": -66.89862,
    "alt_m": 14529.4
   },
   "member_spread_deg": {
    "lat": 39.61,
    "lon": 262.81
   },
   "member_spread_now_deg": {
    "lat": 2.56,
    "lon": 8.05
   },
   "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": 115.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:30:00",
    "lat": 10.53449,
    "lon": -104.24808,
    "alt_m": 13174.4
   },
   "member_spread_deg": {
    "lat": 18.23,
    "lon": 78.69
   },
   "member_spread_now_deg": {
    "lat": 13.66,
    "lon": 19.02
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 16:31:00",
   "seed_lat": 63.04167,
   "seed_lon": -38.83333,
   "seed_alt_m": 12130.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 16:30:00",
    "lat": 73.38319,
    "lon": -129.13413,
    "alt_m": 12038.9
   },
   "member_spread_deg": {
    "lat": 37.89,
    "lon": 310.27
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 15:47:00",
   "seed_lat": 50.16667,
   "seed_lon": 16.875,
   "seed_alt_m": 13220.0,
   "seed_age_h": 1.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 15:15:00",
    "lat": 50.75884,
    "lon": -149.06151,
    "alt_m": 12977.9
   },
   "member_spread_deg": {
    "lat": 18.92,
    "lon": 329.1
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 1.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 12:08:00",
   "seed_lat": 67.39583,
   "seed_lon": 49.5,
   "seed_alt_m": 12030.0,
   "seed_age_h": 29.2,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 82.53589,
    "lon": -130.66927,
    "alt_m": 11663.8
   },
   "member_spread_deg": {
    "lat": 31.3,
    "lon": 294.7
   },
   "member_spread_now_deg": {
    "lat": 0.81,
    "lon": 19.82
   },
   "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": 147.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 64.81693,
    "lon": -134.35512,
    "alt_m": 12605.4
   },
   "member_spread_deg": {
    "lat": 29.21,
    "lon": 190.15
   },
   "member_spread_now_deg": {
    "lat": 26.0,
    "lon": 289.76
   },
   "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": 130.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:30:00",
    "lat": 48.92926,
    "lon": 76.11139,
    "alt_m": 13442.6
   },
   "member_spread_deg": {
    "lat": 50.18,
    "lon": 238.92
   },
   "member_spread_now_deg": {
    "lat": 34.98,
    "lon": 198.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 06:59:00",
   "seed_lat": 44.97917,
   "seed_lon": 85.83333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 10.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:30:00",
    "lat": 31.24435,
    "lon": 160.1347,
    "alt_m": 12807.1
   },
   "member_spread_deg": {
    "lat": 19.46,
    "lon": 338.71
   },
   "member_spread_now_deg": {
    "lat": 1.75,
    "lon": 1.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-4",
   "flight_id": "KC7RW-4_2026-08-26",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 17:55:00",
   "seed_lat": 22.08333,
   "seed_lon": -84.41667,
   "seed_alt_m": 11320.0,
   "seed_age_h": 23.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:30:00",
    "lat": 13.69674,
    "lon": -101.9101,
    "alt_m": 11269.4
   },
   "member_spread_deg": {
    "lat": 30.07,
    "lon": 23.87
   },
   "member_spread_now_deg": {
    "lat": 1.68,
    "lon": 1.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 15:20:00",
   "seed_lat": 39.22917,
   "seed_lon": -110.875,
   "seed_alt_m": 12800.0,
   "seed_age_h": 2.0,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 14:45:00",
    "lat": 28.67702,
    "lon": -12.03002,
    "alt_m": 12907.9
   },
   "member_spread_deg": {
    "lat": 24.49,
    "lon": 83.42
   },
   "member_spread_now_deg": {
    "lat": 0.46,
    "lon": 0.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 11:11:00",
   "seed_lat": 53.6875,
   "seed_lon": 74.70833,
   "seed_alt_m": 12000.0,
   "seed_age_h": 6.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 64.42761,
    "lon": -155.17897,
    "alt_m": 12024.6
   },
   "member_spread_deg": {
    "lat": 27.99,
    "lon": 110.82
   },
   "member_spread_now_deg": {
    "lat": 1.78,
    "lon": 0.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 02:10:45",
   "seed_lat": 77.16661,
   "seed_lon": -140.24998,
   "seed_alt_m": 12840.0,
   "seed_age_h": 15.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 62.34061,
    "lon": 22.89934,
    "alt_m": 12929.7
   },
   "member_spread_deg": {
    "lat": 18.9,
    "lon": 247.67
   },
   "member_spread_now_deg": {
    "lat": 0.8,
    "lon": 37.39
   },
   "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": 97.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 35.01638,
    "lon": -68.89186,
    "alt_m": 13272.5
   },
   "member_spread_deg": {
    "lat": 23.01,
    "lon": 116.95
   },
   "member_spread_now_deg": {
    "lat": 4.43,
    "lon": 29.55
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 12:33:00",
   "seed_lat": 43.375,
   "seed_lon": 58.79167,
   "seed_alt_m": 15960.0,
   "seed_age_h": 4.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 12:00:00",
    "lat": 37.21107,
    "lon": -152.25112,
    "alt_m": 16251.8
   },
   "member_spread_deg": {
    "lat": 42.82,
    "lon": 320.72
   },
   "member_spread_now_deg": {
    "lat": 1.26,
    "lon": 7.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 06:21:00",
   "seed_lat": 45.10417,
   "seed_lon": 151.33333,
   "seed_alt_m": 12950.0,
   "seed_age_h": 10.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 11:45:00",
    "lat": 30.77142,
    "lon": -31.88184,
    "alt_m": 13694.6
   },
   "member_spread_deg": {
    "lat": 18.35,
    "lon": 139.12
   },
   "member_spread_now_deg": {
    "lat": 2.73,
    "lon": 1.98
   },
   "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": 308.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 11:30:00",
    "lat": -24.9815,
    "lon": -100.41022,
    "alt_m": 12026.3
   },
   "member_spread_deg": {
    "lat": 18.34,
    "lon": 278.91
   },
   "member_spread_now_deg": {
    "lat": 25.64,
    "lon": 119.99
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 16:06:00",
   "seed_lat": -18.5,
   "seed_lon": -60.25,
   "seed_alt_m": 15770.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 15:30:00",
    "lat": -10.17736,
    "lon": -70.83469,
    "alt_m": 15711.9
   },
   "member_spread_deg": {
    "lat": 31.84,
    "lon": 76.16
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 0.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}