{
 "generated_utc": "2026-08-21T11:26:41Z",
 "gfs_cycle_utc": "2026-08-21T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 437.5,
  "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_20260821_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260821_06Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 87687
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 09:43:40",
   "seed_lat": -53.5,
   "seed_lon": -19.49999,
   "seed_alt_m": 12210.0,
   "seed_age_h": 1.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 09:15:00",
    "lat": -79.28769,
    "lon": -69.45671,
    "alt_m": 12422.7
   },
   "member_spread_deg": {
    "lat": 35.36,
    "lon": 217.61
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.75
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 23:54:48",
   "seed_lat": 69.52083,
   "seed_lon": -158.91667,
   "seed_alt_m": 12300.0,
   "seed_age_h": 11.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 76.94442,
    "lon": -21.36238,
    "alt_m": 12292.2
   },
   "member_spread_deg": {
    "lat": 22.21,
    "lon": 93.69
   },
   "member_spread_now_deg": {
    "lat": 2.9,
    "lon": 9.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 19:59:18",
   "seed_lat": 51.08333,
   "seed_lon": -140.58333,
   "seed_alt_m": 14060.0,
   "seed_age_h": 39.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 48.82416,
    "lon": 28.03124,
    "alt_m": 13993.5
   },
   "member_spread_deg": {
    "lat": 24.79,
    "lon": 171.42
   },
   "member_spread_now_deg": {
    "lat": 21.18,
    "lon": 12.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 03:24:00",
   "seed_lat": 55.64583,
   "seed_lon": -168.45833,
   "seed_alt_m": 12690.0,
   "seed_age_h": 7.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 44.35421,
    "lon": -12.08347,
    "alt_m": 12750.5
   },
   "member_spread_deg": {
    "lat": 22.27,
    "lon": 81.69
   },
   "member_spread_now_deg": {
    "lat": 4.22,
    "lon": 0.46
   },
   "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": 275.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": 0.19914,
    "lon": -38.00674,
    "alt_m": 14009.9
   },
   "member_spread_deg": {
    "lat": 51.81,
    "lon": 139.19
   },
   "member_spread_now_deg": {
    "lat": 48.0,
    "lon": 115.65
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:01:00",
   "seed_lat": 54.91667,
   "seed_lon": 15.08333,
   "seed_alt_m": 12380.0,
   "seed_age_h": 19.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 50.6513,
    "lon": -124.74422,
    "alt_m": 12446.6
   },
   "member_spread_deg": {
    "lat": 23.45,
    "lon": 66.85
   },
   "member_spread_now_deg": {
    "lat": 5.98,
    "lon": 13.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 06:09:30",
   "seed_lat": 45.72917,
   "seed_lon": 146.75,
   "seed_alt_m": 13135.0,
   "seed_age_h": 5.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": 45.1044,
    "lon": -61.60526,
    "alt_m": 13291.8
   },
   "member_spread_deg": {
    "lat": 8.41,
    "lon": 51.48
   },
   "member_spread_now_deg": {
    "lat": 1.72,
    "lon": 1.63
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 07:38:00",
   "seed_lat": 71.3125,
   "seed_lon": 136.125,
   "seed_alt_m": 11880.0,
   "seed_age_h": 3.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 07:15:00",
    "lat": 77.67232,
    "lon": 36.08016,
    "alt_m": 11632.9
   },
   "member_spread_deg": {
    "lat": 19.64,
    "lon": 351.83
   },
   "member_spread_now_deg": {
    "lat": 0.51,
    "lon": 0.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 10:28:00",
   "seed_lat": 52.10417,
   "seed_lon": -11.16667,
   "seed_alt_m": 12590.0,
   "seed_age_h": 0.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 10:00:00",
    "lat": 77.41565,
    "lon": 95.38533,
    "alt_m": 12442.0
   },
   "member_spread_deg": {
    "lat": 21.14,
    "lon": 52.23
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 0.25
   },
   "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": 134.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": 25.17434,
    "lon": -75.6046,
    "alt_m": 13366.1
   },
   "member_spread_deg": {
    "lat": 45.1,
    "lon": 203.4
   },
   "member_spread_now_deg": {
    "lat": 32.18,
    "lon": 51.14
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 10:57:03",
   "seed_lat": 67.875,
   "seed_lon": 108.0,
   "seed_alt_m": 13260.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 11:00:00",
    "lat": 76.64146,
    "lon": -111.87227,
    "alt_m": 12974.3
   },
   "member_spread_deg": {
    "lat": 31.38,
    "lon": 158.74
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.17
   },
   "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": 215.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": 54.46659,
    "lon": 100.87646,
    "alt_m": 12502.1
   },
   "member_spread_deg": {
    "lat": 27.94,
    "lon": 320.49
   },
   "member_spread_now_deg": {
    "lat": 30.02,
    "lon": 321.2
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 05:25:00",
   "seed_lat": 48.27083,
   "seed_lon": 176.70833,
   "seed_alt_m": 13020.0,
   "seed_age_h": 5.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 26.34069,
    "lon": -158.64946,
    "alt_m": 12983.8
   },
   "member_spread_deg": {
    "lat": 21.26,
    "lon": 99.82
   },
   "member_spread_now_deg": {
    "lat": 1.09,
    "lon": 359.51
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:01:00",
   "seed_lat": 85.25,
   "seed_lon": 45.875,
   "seed_alt_m": 11960.0,
   "seed_age_h": 25.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 69.99144,
    "lon": 40.90057,
    "alt_m": 11886.6
   },
   "member_spread_deg": {
    "lat": 21.63,
    "lon": 345.43
   },
   "member_spread_now_deg": {
    "lat": 9.47,
    "lon": 23.15
   },
   "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": 182.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": 26.87946,
    "lon": -49.94327,
    "alt_m": 11207.7
   },
   "member_spread_deg": {
    "lat": 20.33,
    "lon": 335.78
   },
   "member_spread_now_deg": {
    "lat": 22.04,
    "lon": 100.32
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 04:30:45",
   "seed_lat": 68.79161,
   "seed_lon": 179.37502,
   "seed_alt_m": 12870.0,
   "seed_age_h": 6.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 75.76672,
    "lon": 150.81283,
    "alt_m": 12820.0
   },
   "member_spread_deg": {
    "lat": 13.41,
    "lon": 330.86
   },
   "member_spread_now_deg": {
    "lat": 0.89,
    "lon": 1.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 10:36:00",
   "seed_lat": 12.72917,
   "seed_lon": 52.5,
   "seed_alt_m": 16560.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 10:00:00",
    "lat": 16.29525,
    "lon": -29.34998,
    "alt_m": 16445.2
   },
   "member_spread_deg": {
    "lat": 22.93,
    "lon": 27.89
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 01:31:00",
   "seed_lat": 37.04167,
   "seed_lon": -128.45833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 9.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 48.69634,
    "lon": 69.35168,
    "alt_m": 12951.8
   },
   "member_spread_deg": {
    "lat": 13.58,
    "lon": 118.95
   },
   "member_spread_now_deg": {
    "lat": 6.96,
    "lon": 2.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 22:05:23",
   "seed_lat": 63.66661,
   "seed_lon": -102.70831,
   "seed_alt_m": 12930.0,
   "seed_age_h": 13.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": 46.58636,
    "lon": 30.84416,
    "alt_m": 13498.8
   },
   "member_spread_deg": {
    "lat": 23.49,
    "lon": 75.83
   },
   "member_spread_now_deg": {
    "lat": 1.26,
    "lon": 3.9
   },
   "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": 86.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-28 05:30:00",
    "lat": -21.55315,
    "lon": 105.49022,
    "alt_m": 12454.3
   },
   "member_spread_deg": {
    "lat": 21.46,
    "lon": 299.11
   },
   "member_spread_now_deg": {
    "lat": 26.85,
    "lon": 119.69
   },
   "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": 220.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 05:45:00",
    "lat": -29.81096,
    "lon": 128.00377,
    "alt_m": 15358.7
   },
   "member_spread_deg": {
    "lat": 32.83,
    "lon": 256.27
   },
   "member_spread_now_deg": {
    "lat": 19.24,
    "lon": 175.37
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-21 10:16:00",
   "seed_lat": -20.72917,
   "seed_lon": 71.95833,
   "seed_alt_m": 15680.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-28 09:45:00",
    "lat": -29.51966,
    "lon": -88.03834,
    "alt_m": 15114.8
   },
   "member_spread_deg": {
    "lat": 28.59,
    "lon": 88.16
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}