{
 "generated_utc": "2026-08-30T05:26:56Z",
 "gfs_cycle_utc": "2026-08-30T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 458.5,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260830_00Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 71118
 },
 "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": 37.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": -73.80321,
    "lon": 18.09874,
    "alt_m": 12135.0
   },
   "member_spread_deg": {
    "lat": 34.36,
    "lon": 155.66
   },
   "member_spread_now_deg": {
    "lat": 12.93,
    "lon": 50.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 05:01:18",
   "seed_lat": 43.58333,
   "seed_lon": 108.83333,
   "seed_alt_m": 13980.0,
   "seed_age_h": 0.31,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 05:00:00",
    "lat": 43.51393,
    "lon": -82.29607,
    "alt_m": 14262.5
   },
   "member_spread_deg": {
    "lat": 9.55,
    "lon": 61.58
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.19
   },
   "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": 103.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": 28.00636,
    "lon": -91.77524,
    "alt_m": 13035.3
   },
   "member_spread_deg": {
    "lat": 15.4,
    "lon": 91.93
   },
   "member_spread_now_deg": {
    "lat": 13.53,
    "lon": 13.68
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 16:41:00",
   "seed_lat": 74.58333,
   "seed_lon": -39.79167,
   "seed_alt_m": 12140.0,
   "seed_age_h": 12.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": 77.09909,
    "lon": -157.08853,
    "alt_m": 11761.4
   },
   "member_spread_deg": {
    "lat": 35.14,
    "lon": 286.05
   },
   "member_spread_now_deg": {
    "lat": 6.62,
    "lon": 6.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 16:47:00",
   "seed_lat": 45.72917,
   "seed_lon": -15.54167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 12.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": 39.15132,
    "lon": 152.0082,
    "alt_m": 13050.9
   },
   "member_spread_deg": {
    "lat": 24.97,
    "lon": 63.87
   },
   "member_spread_now_deg": {
    "lat": 0.82,
    "lon": 9.51
   },
   "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": 17.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": 76.70561,
    "lon": 176.50913,
    "alt_m": 11753.5
   },
   "member_spread_deg": {
    "lat": 25.57,
    "lon": 345.68
   },
   "member_spread_now_deg": {
    "lat": 6.6,
    "lon": 6.13
   },
   "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": 135.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": 57.82102,
    "lon": -131.22111,
    "alt_m": 12815.7
   },
   "member_spread_deg": {
    "lat": 39.85,
    "lon": 309.51
   },
   "member_spread_now_deg": {
    "lat": 15.49,
    "lon": 347.54
   },
   "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": 118.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": 45.93661,
    "lon": 69.40951,
    "alt_m": 13445.4
   },
   "member_spread_deg": {
    "lat": 33.68,
    "lon": 232.7
   },
   "member_spread_now_deg": {
    "lat": 34.74,
    "lon": 180.43
   },
   "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 03:29:00",
   "seed_lat": 44.97917,
   "seed_lon": 80.08333,
   "seed_alt_m": 12470.0,
   "seed_age_h": 1.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 03:00:00",
    "lat": 25.6676,
    "lon": 149.03883,
    "alt_m": 12730.4
   },
   "member_spread_deg": {
    "lat": 18.98,
    "lon": 336.76
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.59
   },
   "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": 11.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": 23.98181,
    "lon": -81.24279,
    "alt_m": 11304.9
   },
   "member_spread_deg": {
    "lat": 12.11,
    "lon": 29.76
   },
   "member_spread_now_deg": {
    "lat": 1.76,
    "lon": 1.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 02:00:00",
   "seed_lat": 34.0,
   "seed_lon": -129.16667,
   "seed_alt_m": 12780.0,
   "seed_age_h": 3.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 01:30:00",
    "lat": 27.41682,
    "lon": -24.15476,
    "alt_m": 12953.6
   },
   "member_spread_deg": {
    "lat": 19.92,
    "lon": 102.3
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.96
   },
   "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": 150.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": 56.71221,
    "lon": 178.76489,
    "alt_m": 12076.7
   },
   "member_spread_deg": {
    "lat": 26.56,
    "lon": 193.11
   },
   "member_spread_now_deg": {
    "lat": 24.62,
    "lon": 223.27
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 3.16,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 01:45:00",
    "lat": 63.53776,
    "lon": 36.95496,
    "alt_m": 12790.3
   },
   "member_spread_deg": {
    "lat": 15.17,
    "lon": 30.11
   },
   "member_spread_now_deg": {
    "lat": 0.54,
    "lon": 2.85
   },
   "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": 85.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:45:00",
    "lat": 52.21965,
    "lon": -94.92429,
    "alt_m": 13121.3
   },
   "member_spread_deg": {
    "lat": 22.23,
    "lon": 137.97
   },
   "member_spread_now_deg": {
    "lat": 5.3,
    "lon": 31.63
   },
   "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 04:43:00",
   "seed_lat": 40.47917,
   "seed_lon": 50.66667,
   "seed_alt_m": 16000.0,
   "seed_age_h": 0.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 04:15:00",
    "lat": 64.85239,
    "lon": -115.93393,
    "alt_m": 15235.5
   },
   "member_spread_deg": {
    "lat": 34.62,
    "lon": 342.4
   },
   "member_spread_now_deg": {
    "lat": 0.36,
    "lon": 0.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 04:16:00",
   "seed_lat": 45.625,
   "seed_lon": 147.79167,
   "seed_alt_m": 13000.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 03:45:00",
    "lat": 38.74656,
    "lon": -84.45124,
    "alt_m": 13579.3
   },
   "member_spread_deg": {
    "lat": 17.9,
    "lon": 134.77
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.45
   },
   "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": 296.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": -31.34802,
    "lon": -136.64765,
    "alt_m": 12129.8
   },
   "member_spread_deg": {
    "lat": 22.21,
    "lon": 243.82
   },
   "member_spread_now_deg": {
    "lat": 39.24,
    "lon": 91.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 21:01:00",
   "seed_lat": -23.125,
   "seed_lon": -76.0,
   "seed_alt_m": 15580.0,
   "seed_age_h": 8.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 23:30:00",
    "lat": -5.43874,
    "lon": -62.60347,
    "alt_m": 15729.4
   },
   "member_spread_deg": {
    "lat": 37.83,
    "lon": 86.58
   },
   "member_spread_now_deg": {
    "lat": 0.77,
    "lon": 7.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}