{
 "generated_utc": "2026-09-01T11:25:12Z",
 "gfs_cycle_utc": "2026-09-01T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 351.5,
  "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_20260901_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260901_06Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 63783
 },
 "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": 91.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": -70.12367,
    "lon": 70.68155,
    "alt_m": 12182.9
   },
   "member_spread_deg": {
    "lat": 32.65,
    "lon": 111.44
   },
   "member_spread_now_deg": {
    "lat": 12.85,
    "lon": 116.21
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 23:04:18",
   "seed_lat": 53.97917,
   "seed_lon": 172.375,
   "seed_alt_m": 13860.0,
   "seed_age_h": 12.26,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": 28.35241,
    "lon": -97.32292,
    "alt_m": 14448.6
   },
   "member_spread_deg": {
    "lat": 27.21,
    "lon": 106.69
   },
   "member_spread_now_deg": {
    "lat": 2.58,
    "lon": 19.01
   },
   "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": 157.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": 20.70691,
    "lon": -96.03246,
    "alt_m": 13204.8
   },
   "member_spread_deg": {
    "lat": 12.05,
    "lon": 74.38
   },
   "member_spread_now_deg": {
    "lat": 16.42,
    "lon": 27.75
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 09:31:00",
   "seed_lat": 66.08333,
   "seed_lon": -0.5,
   "seed_alt_m": 12050.0,
   "seed_age_h": 1.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 09:00:00",
    "lat": 71.31123,
    "lon": 44.93723,
    "alt_m": 11983.9
   },
   "member_spread_deg": {
    "lat": 42.06,
    "lon": 222.23
   },
   "member_spread_now_deg": {
    "lat": 0.81,
    "lon": 0.95
   },
   "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": 43.55,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": 69.77543,
    "lon": -127.03067,
    "alt_m": 13005.9
   },
   "member_spread_deg": {
    "lat": 31.8,
    "lon": 59.0
   },
   "member_spread_now_deg": {
    "lat": 3.41,
    "lon": 7.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 25.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": 62.18277,
    "lon": 150.20834,
    "alt_m": 11793.2
   },
   "member_spread_deg": {
    "lat": 22.96,
    "lon": 342.56
   },
   "member_spread_now_deg": {
    "lat": 6.8,
    "lon": 32.15
   },
   "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": 189.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": 43.33332,
    "lon": -124.80869,
    "alt_m": 13084.0
   },
   "member_spread_deg": {
    "lat": 31.47,
    "lon": 288.66
   },
   "member_spread_now_deg": {
    "lat": 12.39,
    "lon": 297.22
   },
   "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": 172.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": 51.56862,
    "lon": 142.17846,
    "alt_m": 13228.9
   },
   "member_spread_deg": {
    "lat": 34.57,
    "lon": 150.16
   },
   "member_spread_now_deg": {
    "lat": 34.91,
    "lon": 221.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 08:21:30",
   "seed_lat": 31.8125,
   "seed_lon": 109.91667,
   "seed_alt_m": 12640.0,
   "seed_age_h": 2.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 07:45:00",
    "lat": 36.22598,
    "lon": 147.12599,
    "alt_m": 12802.7
   },
   "member_spread_deg": {
    "lat": 33.68,
    "lon": 334.6
   },
   "member_spread_now_deg": {
    "lat": 0.71,
    "lon": 0.57
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 22:00:00",
   "seed_lat": 38.02083,
   "seed_lon": -70.91667,
   "seed_alt_m": 13060.0,
   "seed_age_h": 13.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": 30.25674,
    "lon": -23.0552,
    "alt_m": 12993.8
   },
   "member_spread_deg": {
    "lat": 5.69,
    "lon": 46.47
   },
   "member_spread_now_deg": {
    "lat": 0.86,
    "lon": 3.04
   },
   "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": 48.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": 75.27826,
    "lon": -165.0211,
    "alt_m": 12011.7
   },
   "member_spread_deg": {
    "lat": 22.78,
    "lon": 101.05
   },
   "member_spread_now_deg": {
    "lat": 4.82,
    "lon": 33.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 10:55:45",
   "seed_lat": 69.74995,
   "seed_lon": -46.62498,
   "seed_alt_m": 13000.0,
   "seed_age_h": 0.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 11:00:00",
    "lat": 66.91571,
    "lon": 58.48835,
    "alt_m": 13056.1
   },
   "member_spread_deg": {
    "lat": 15.13,
    "lon": 87.37
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.09
   },
   "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": 139.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": 32.17718,
    "lon": -63.15982,
    "alt_m": 13489.7
   },
   "member_spread_deg": {
    "lat": 31.81,
    "lon": 75.85
   },
   "member_spread_now_deg": {
    "lat": 22.19,
    "lon": 327.38
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 08:28:00",
   "seed_lat": 40.875,
   "seed_lon": 114.45833,
   "seed_alt_m": 16040.0,
   "seed_age_h": 2.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 08:00:00",
    "lat": 62.97859,
    "lon": -100.28436,
    "alt_m": 15366.0
   },
   "member_spread_deg": {
    "lat": 33.99,
    "lon": 325.82
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 3.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-01 02:21:00",
   "seed_lat": 41.58333,
   "seed_lon": -150.16667,
   "seed_alt_m": 13610.0,
   "seed_age_h": 8.98,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-08 05:45:00",
    "lat": 40.93021,
    "lon": -52.28823,
    "alt_m": 13160.6
   },
   "member_spread_deg": {
    "lat": 43.43,
    "lon": 134.41
   },
   "member_spread_now_deg": {
    "lat": 1.45,
    "lon": 1.77
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 20:01:00",
   "seed_lat": -20.58333,
   "seed_lon": -53.125,
   "seed_alt_m": 15810.0,
   "seed_age_h": 15.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-08 05:30:00",
    "lat": -21.75109,
    "lon": 17.36879,
    "alt_m": 15715.5
   },
   "member_spread_deg": {
    "lat": 42.71,
    "lon": 80.61
   },
   "member_spread_now_deg": {
    "lat": 4.95,
    "lon": 3.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}