{
 "generated_utc": "2026-08-14T23:27:15Z",
 "gfs_cycle_utc": "2026-08-14T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 474.5,
  "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_20260814_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260814_18Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 93249
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:58:40",
   "seed_lat": -43.83333,
   "seed_lon": -10.49999,
   "seed_alt_m": 12150.0,
   "seed_age_h": 6.36,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": -45.41087,
    "lon": -48.95648,
    "alt_m": 12184.4
   },
   "member_spread_deg": {
    "lat": 29.01,
    "lon": 37.2
   },
   "member_spread_now_deg": {
    "lat": 0.5,
    "lon": 2.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:30:18",
   "seed_lat": 57.54167,
   "seed_lon": 19.20833,
   "seed_alt_m": 12870.0,
   "seed_age_h": 38.83,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 73.3501,
    "lon": -140.07533,
    "alt_m": 12535.6
   },
   "member_spread_deg": {
    "lat": 35.19,
    "lon": 286.23
   },
   "member_spread_now_deg": {
    "lat": 8.09,
    "lon": 36.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:59:18",
   "seed_lat": 52.125,
   "seed_lon": 153.75,
   "seed_alt_m": 14180.0,
   "seed_age_h": 0.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 23:00:00",
    "lat": 57.20251,
    "lon": -112.68023,
    "alt_m": 13745.6
   },
   "member_spread_deg": {
    "lat": 29.04,
    "lon": 95.78
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:44:00",
   "seed_lat": 50.4375,
   "seed_lon": 16.625,
   "seed_alt_m": 12880.0,
   "seed_age_h": 7.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 48.80717,
    "lon": -165.6273,
    "alt_m": 12969.7
   },
   "member_spread_deg": {
    "lat": 15.64,
    "lon": 350.78
   },
   "member_spread_now_deg": {
    "lat": 0.73,
    "lon": 1.02
   },
   "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": 119.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 21.61905,
    "lon": -95.72101,
    "alt_m": 14111.8
   },
   "member_spread_deg": {
    "lat": 41.08,
    "lon": 106.26
   },
   "member_spread_now_deg": {
    "lat": 29.98,
    "lon": 56.74
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "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": 258.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 48.91544,
    "lon": 34.10452,
    "alt_m": 13288.2
   },
   "member_spread_deg": {
    "lat": 93.63,
    "lon": 299.02
   },
   "member_spread_now_deg": {
    "lat": 67.73,
    "lon": 229.24
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:11:00",
   "seed_lat": 37.27083,
   "seed_lon": -140.95833,
   "seed_alt_m": 13000.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 21:45:00",
    "lat": 45.95245,
    "lon": 58.41366,
    "alt_m": 12737.1
   },
   "member_spread_deg": {
    "lat": 23.77,
    "lon": 95.14
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:47:00",
   "seed_lat": 44.10417,
   "seed_lon": 10.33333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 7.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 46.8982,
    "lon": -171.8622,
    "alt_m": 13361.6
   },
   "member_spread_deg": {
    "lat": 17.81,
    "lon": 337.22
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 0.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 12:43:00",
   "seed_lat": 70.72917,
   "seed_lon": 54.70833,
   "seed_alt_m": 12070.0,
   "seed_age_h": 10.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 74.13336,
    "lon": 175.48266,
    "alt_m": 11487.3
   },
   "member_spread_deg": {
    "lat": 25.78,
    "lon": 348.64
   },
   "member_spread_now_deg": {
    "lat": 5.98,
    "lon": 9.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:28:00",
   "seed_lat": 63.91667,
   "seed_lon": -117.70833,
   "seed_alt_m": 12630.0,
   "seed_age_h": 0.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 22:00:00",
    "lat": 66.61352,
    "lon": 40.39643,
    "alt_m": 12290.3
   },
   "member_spread_deg": {
    "lat": 20.45,
    "lon": 227.58
   },
   "member_spread_now_deg": {
    "lat": 0.32,
    "lon": 1.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:55:37",
   "seed_lat": 38.79161,
   "seed_lon": -112.04167,
   "seed_alt_m": 13150.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 23:00:00",
    "lat": 30.5464,
    "lon": -10.78427,
    "alt_m": 13276.6
   },
   "member_spread_deg": {
    "lat": 30.6,
    "lon": 198.39
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:22:33",
   "seed_lat": 50.70833,
   "seed_lon": 58.5,
   "seed_alt_m": 13420.0,
   "seed_age_h": 7.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 55.133,
    "lon": 103.4519,
    "alt_m": 13343.0
   },
   "member_spread_deg": {
    "lat": 18.19,
    "lon": 290.45
   },
   "member_spread_now_deg": {
    "lat": 2.74,
    "lon": 1.75
   },
   "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": 59.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 52.12497,
    "lon": 97.41522,
    "alt_m": 12489.2
   },
   "member_spread_deg": {
    "lat": 25.32,
    "lon": 235.93
   },
   "member_spread_now_deg": {
    "lat": 26.95,
    "lon": 47.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 17:15:00",
   "seed_lat": 40.35417,
   "seed_lon": 8.16667,
   "seed_alt_m": 12920.0,
   "seed_age_h": 6.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 34.33227,
    "lon": 160.14088,
    "alt_m": 13015.2
   },
   "member_spread_deg": {
    "lat": 16.08,
    "lon": 354.62
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 2.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 18:56:00",
   "seed_lat": 55.5625,
   "seed_lon": -55.125,
   "seed_alt_m": 12260.0,
   "seed_age_h": 4.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 18:30:00",
    "lat": 66.98087,
    "lon": 134.71095,
    "alt_m": 12193.3
   },
   "member_spread_deg": {
    "lat": 34.55,
    "lon": 167.67
   },
   "member_spread_now_deg": {
    "lat": 1.02,
    "lon": 0.68
   },
   "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": 26.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": 34.16064,
    "lon": -66.50294,
    "alt_m": 11196.4
   },
   "member_spread_deg": {
    "lat": 26.16,
    "lon": 139.88
   },
   "member_spread_now_deg": {
    "lat": 9.3,
    "lon": 5.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI1TEN-1",
   "flight_id": "KI1TEN-1_2026-07-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-01 22:55:27",
   "seed_lat": 23.95828,
   "seed_lon": -104.12496,
   "seed_alt_m": 12380.0,
   "seed_age_h": 312.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": -7.09441,
    "lon": -103.24308,
    "alt_m": 12385.7
   },
   "member_spread_deg": {
    "lat": 38.96,
    "lon": 141.93
   },
   "member_spread_now_deg": {
    "lat": 24.69,
    "lon": 68.07
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 11:05:45",
   "seed_lat": 78.43745,
   "seed_lon": 94.75002,
   "seed_alt_m": 13240.0,
   "seed_age_h": 12.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 70.28248,
    "lon": -166.20919,
    "alt_m": 12840.5
   },
   "member_spread_deg": {
    "lat": 28.32,
    "lon": 342.92
   },
   "member_spread_now_deg": {
    "lat": 2.69,
    "lon": 3.57
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:08:00",
   "seed_lat": 17.39583,
   "seed_lon": 166.95833,
   "seed_alt_m": 17520.0,
   "seed_age_h": 1.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 21:45:00",
    "lat": 11.33289,
    "lon": 53.29805,
    "alt_m": 17466.1
   },
   "member_spread_deg": {
    "lat": 19.91,
    "lon": 64.53
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.23
   },
   "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": 259.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 36.58226,
    "lon": -163.70075,
    "alt_m": 13006.6
   },
   "member_spread_deg": {
    "lat": 43.8,
    "lon": 323.57
   },
   "member_spread_now_deg": {
    "lat": 35.26,
    "lon": 234.88
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 22:26:00",
   "seed_lat": 48.85417,
   "seed_lon": 148.125,
   "seed_alt_m": 13480.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 22:00:00",
    "lat": 46.89486,
    "lon": -75.34456,
    "alt_m": 13259.4
   },
   "member_spread_deg": {
    "lat": 37.73,
    "lon": 312.68
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.56
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 02:05:23",
   "seed_lat": 54.52078,
   "seed_lon": 141.29169,
   "seed_alt_m": 13630.0,
   "seed_age_h": 21.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:30:00",
    "lat": 65.56191,
    "lon": -102.37685,
    "alt_m": 13059.0
   },
   "member_spread_deg": {
    "lat": 30.09,
    "lon": 67.59
   },
   "member_spread_now_deg": {
    "lat": 8.35,
    "lon": 356.61
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 05:39:00",
   "seed_lat": -23.64583,
   "seed_lon": 119.66667,
   "seed_alt_m": 12290.0,
   "seed_age_h": 17.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": -7.28451,
    "lon": -46.98741,
    "alt_m": 12589.3
   },
   "member_spread_deg": {
    "lat": 25.43,
    "lon": 320.81
   },
   "member_spread_now_deg": {
    "lat": 8.4,
    "lon": 15.35
   },
   "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": 64.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-21 17:45:00",
    "lat": -12.23234,
    "lon": -12.11458,
    "alt_m": 15896.8
   },
   "member_spread_deg": {
    "lat": 27.37,
    "lon": 191.59
   },
   "member_spread_now_deg": {
    "lat": 8.67,
    "lon": 348.4
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}