{
 "generated_utc": "2026-08-29T05:27:00Z",
 "gfs_cycle_utc": "2026-08-29T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 483.0,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260829_00Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 78174
 },
 "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": 13.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": -77.80531,
    "lon": 8.92883,
    "alt_m": 12207.9
   },
   "member_spread_deg": {
    "lat": 26.03,
    "lon": 128.87
   },
   "member_spread_now_deg": {
    "lat": 2.23,
    "lon": 8.94
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 14:01:48",
   "seed_lat": 43.125,
   "seed_lon": 21.54167,
   "seed_alt_m": 14180.0,
   "seed_age_h": 39.3,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 44.26276,
    "lon": -81.424,
    "alt_m": 14270.3
   },
   "member_spread_deg": {
    "lat": 36.28,
    "lon": 327.14
   },
   "member_spread_now_deg": {
    "lat": 9.7,
    "lon": 39.63
   },
   "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": 79.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 25.04854,
    "lon": -105.96573,
    "alt_m": 13075.4
   },
   "member_spread_deg": {
    "lat": 9.3,
    "lon": 66.77
   },
   "member_spread_now_deg": {
    "lat": 11.88,
    "lon": 9.91
   },
   "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": 12.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 69.66256,
    "lon": -25.18845,
    "alt_m": 11758.1
   },
   "member_spread_deg": {
    "lat": 24.93,
    "lon": 269.23
   },
   "member_spread_now_deg": {
    "lat": 1.0,
    "lon": 14.91
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 19:07:00",
   "seed_lat": 45.75,
   "seed_lon": -44.625,
   "seed_alt_m": 13360.0,
   "seed_age_h": 10.22,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 50.54307,
    "lon": 128.53332,
    "alt_m": 13403.2
   },
   "member_spread_deg": {
    "lat": 17.04,
    "lon": 317.29
   },
   "member_spread_now_deg": {
    "lat": 1.15,
    "lon": 5.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 11:53:00",
   "seed_lat": 76.5,
   "seed_lon": 46.625,
   "seed_alt_m": 11980.0,
   "seed_age_h": 17.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 49.04354,
    "lon": 155.69291,
    "alt_m": 12103.8
   },
   "member_spread_deg": {
    "lat": 27.94,
    "lon": 339.98
   },
   "member_spread_now_deg": {
    "lat": 6.36,
    "lon": 2.87
   },
   "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": 111.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": 55.63198,
    "lon": -156.74486,
    "alt_m": 12954.7
   },
   "member_spread_deg": {
    "lat": 24.83,
    "lon": 329.54
   },
   "member_spread_now_deg": {
    "lat": 7.17,
    "lon": 341.76
   },
   "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": 320.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": 33.21589,
    "lon": 23.40366,
    "alt_m": 13142.2
   },
   "member_spread_deg": {
    "lat": 58.43,
    "lon": 275.34
   },
   "member_spread_now_deg": {
    "lat": 35.57,
    "lon": 252.03
   },
   "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": 94.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 64.688,
    "lon": 28.63471,
    "alt_m": 13053.0
   },
   "member_spread_deg": {
    "lat": 39.13,
    "lon": 200.41
   },
   "member_spread_now_deg": {
    "lat": 38.85,
    "lon": 123.34
   },
   "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": 14.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 50.1385,
    "lon": -129.40711,
    "alt_m": 12745.5
   },
   "member_spread_deg": {
    "lat": 44.95,
    "lon": 352.66
   },
   "member_spread_now_deg": {
    "lat": 1.74,
    "lon": 1.49
   },
   "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": 1.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 03:30:00",
    "lat": 34.80687,
    "lon": -10.86942,
    "alt_m": 12926.3
   },
   "member_spread_deg": {
    "lat": 9.82,
    "lon": 43.0
   },
   "member_spread_now_deg": {
    "lat": 0.59,
    "lon": 0.86
   },
   "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": 126.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": 62.86136,
    "lon": 161.55276,
    "alt_m": 12365.0
   },
   "member_spread_deg": {
    "lat": 25.49,
    "lon": 295.13
   },
   "member_spread_now_deg": {
    "lat": 21.69,
    "lon": 235.5
   },
   "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": 1.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 03:00:00",
    "lat": 55.4213,
    "lon": 15.34131,
    "alt_m": 12938.6
   },
   "member_spread_deg": {
    "lat": 27.11,
    "lon": 58.12
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.32
   },
   "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": 61.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": 45.58578,
    "lon": -113.38888,
    "alt_m": 13132.5
   },
   "member_spread_deg": {
    "lat": 17.34,
    "lon": 56.84
   },
   "member_spread_now_deg": {
    "lat": 3.69,
    "lon": 17.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 15:08:00",
   "seed_lat": 33.45833,
   "seed_lon": 22.66667,
   "seed_alt_m": 16470.0,
   "seed_age_h": 14.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": 36.84568,
    "lon": 137.81382,
    "alt_m": 16485.7
   },
   "member_spread_deg": {
    "lat": 39.03,
    "lon": 338.07
   },
   "member_spread_now_deg": {
    "lat": 3.19,
    "lon": 6.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 04:11:00",
   "seed_lat": 46.25,
   "seed_lon": 105.95833,
   "seed_alt_m": 13010.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 04:15:00",
    "lat": 33.80683,
    "lon": -66.09787,
    "alt_m": 13604.5
   },
   "member_spread_deg": {
    "lat": 18.66,
    "lon": 71.39
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 11:20:23",
   "seed_lat": 45.58328,
   "seed_lon": 27.04169,
   "seed_alt_m": 13540.0,
   "seed_age_h": 17.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": 68.65268,
    "lon": -157.16007,
    "alt_m": 13197.4
   },
   "member_spread_deg": {
    "lat": 38.01,
    "lon": 341.68
   },
   "member_spread_now_deg": {
    "lat": 1.99,
    "lon": 5.59
   },
   "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": 272.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 23:30:00",
    "lat": -28.00208,
    "lon": 177.55295,
    "alt_m": 12130.6
   },
   "member_spread_deg": {
    "lat": 14.99,
    "lon": 334.53
   },
   "member_spread_now_deg": {
    "lat": 24.09,
    "lon": 111.65
   },
   "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": 27.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 23:45:00",
    "lat": -10.95534,
    "lon": -67.69733,
    "alt_m": 15628.4
   },
   "member_spread_deg": {
    "lat": 52.75,
    "lon": 217.89
   },
   "member_spread_now_deg": {
    "lat": 8.32,
    "lon": 28.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}