{
 "generated_utc": "2026-09-10T05:26:48Z",
 "gfs_cycle_utc": "2026-09-10T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 463.5,
  "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_20260910_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260910_00Z.geojson.gz"
 },
 "counts": {
  "flights": 16,
  "members": 9,
  "rows": 65664
 },
 "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": 301.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 23:45:00",
    "lat": -65.65603,
    "lon": 75.76265,
    "alt_m": 12073.1
   },
   "member_spread_deg": {
    "lat": 23.83,
    "lon": 212.5
   },
   "member_spread_now_deg": {
    "lat": 18.69,
    "lon": 201.51
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 16:43:48",
   "seed_lat": 39.45833,
   "seed_lon": -15.41667,
   "seed_alt_m": 14620.0,
   "seed_age_h": 12.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:45:00",
    "lat": 49.85909,
    "lon": 10.3481,
    "alt_m": 13853.4
   },
   "member_spread_deg": {
    "lat": 24.16,
    "lon": 65.85
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 4.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 04:41:00",
   "seed_lat": 86.0,
   "seed_lon": 110.20833,
   "seed_alt_m": 11660.0,
   "seed_age_h": 120.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 23:45:00",
    "lat": 78.25214,
    "lon": -83.03006,
    "alt_m": 11550.1
   },
   "member_spread_deg": {
    "lat": 28.59,
    "lon": 334.2
   },
   "member_spread_now_deg": {
    "lat": 22.77,
    "lon": 347.68
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 19:57:00",
   "seed_lat": 44.4375,
   "seed_lon": -63.625,
   "seed_alt_m": 13290.0,
   "seed_age_h": 9.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:30:00",
    "lat": 20.03082,
    "lon": -49.84623,
    "alt_m": 13677.1
   },
   "member_spread_deg": {
    "lat": 31.65,
    "lon": 167.99
   },
   "member_spread_now_deg": {
    "lat": 2.48,
    "lon": 3.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 03:16:00",
   "seed_lat": 52.33333,
   "seed_lon": -154.54167,
   "seed_alt_m": 13720.0,
   "seed_age_h": 2.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 02:45:00",
    "lat": 49.7762,
    "lon": 48.92755,
    "alt_m": 13344.6
   },
   "member_spread_deg": {
    "lat": 22.99,
    "lon": 96.77
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 1.88
   },
   "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": 235.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-16 23:30:00",
    "lat": 67.14646,
    "lon": -153.55836,
    "alt_m": 11678.9
   },
   "member_spread_deg": {
    "lat": 41.48,
    "lon": 298.06
   },
   "member_spread_now_deg": {
    "lat": 42.03,
    "lon": 314.16
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 111.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-16 23:30:00",
    "lat": 32.8264,
    "lon": 152.45709,
    "alt_m": 14637.0
   },
   "member_spread_deg": {
    "lat": 42.69,
    "lon": 118.85
   },
   "member_spread_now_deg": {
    "lat": 27.12,
    "lon": 316.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 04:50:00",
   "seed_lat": 47.875,
   "seed_lon": 157.54167,
   "seed_alt_m": 12140.0,
   "seed_age_h": 0.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-17 04:15:00",
    "lat": 39.86142,
    "lon": -36.6381,
    "alt_m": 12824.2
   },
   "member_spread_deg": {
    "lat": 30.65,
    "lon": 115.0
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 165.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:30:00",
    "lat": 29.14232,
    "lon": 162.86192,
    "alt_m": 12904.8
   },
   "member_spread_deg": {
    "lat": 17.77,
    "lon": 264.16
   },
   "member_spread_now_deg": {
    "lat": 14.01,
    "lon": 325.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 03:55:00",
   "seed_lat": 39.08333,
   "seed_lon": 62.20833,
   "seed_alt_m": 12700.0,
   "seed_age_h": 1.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 03:30:00",
    "lat": 42.65922,
    "lon": -110.55629,
    "alt_m": 12768.5
   },
   "member_spread_deg": {
    "lat": 14.66,
    "lon": 121.44
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 18:21:00",
   "seed_lat": 42.75,
   "seed_lon": -52.91667,
   "seed_alt_m": 12370.0,
   "seed_age_h": 10.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:45:00",
    "lat": 44.31596,
    "lon": 90.8774,
    "alt_m": 12777.9
   },
   "member_spread_deg": {
    "lat": 30.63,
    "lon": 115.22
   },
   "member_spread_now_deg": {
    "lat": 2.07,
    "lon": 2.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 04:55:45",
   "seed_lat": 49.24995,
   "seed_lon": 118.87502,
   "seed_alt_m": 13480.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 05:00:00",
    "lat": 78.12526,
    "lon": -23.40366,
    "alt_m": 12833.9
   },
   "member_spread_deg": {
    "lat": 34.39,
    "lon": 67.45
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 02:08:00",
   "seed_lat": 35.14583,
   "seed_lon": -153.95833,
   "seed_alt_m": 16500.0,
   "seed_age_h": 3.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 01:45:00",
    "lat": 28.943,
    "lon": -149.59407,
    "alt_m": 16367.3
   },
   "member_spread_deg": {
    "lat": 29.22,
    "lon": 327.81
   },
   "member_spread_now_deg": {
    "lat": 1.7,
    "lon": 0.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-09 16:46:00",
   "seed_lat": 30.02083,
   "seed_lon": -7.54167,
   "seed_alt_m": 13420.0,
   "seed_age_h": 12.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:45:00",
    "lat": 45.47904,
    "lon": 151.19476,
    "alt_m": 13295.9
   },
   "member_spread_deg": {
    "lat": 16.02,
    "lon": 344.05
   },
   "member_spread_now_deg": {
    "lat": 1.25,
    "lon": 1.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 21:35:23",
   "seed_lat": 52.33328,
   "seed_lon": -95.95831,
   "seed_alt_m": 12860.0,
   "seed_age_h": 31.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-16 23:30:00",
    "lat": 45.15691,
    "lon": 80.74052,
    "alt_m": 13147.8
   },
   "member_spread_deg": {
    "lat": 24.05,
    "lon": 118.61
   },
   "member_spread_now_deg": {
    "lat": 6.72,
    "lon": 18.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 04:41:00",
   "seed_lat": -17.6875,
   "seed_lon": 48.08333,
   "seed_alt_m": 15580.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-17 04:15:00",
    "lat": -18.14241,
    "lon": 149.73807,
    "alt_m": 15674.5
   },
   "member_spread_deg": {
    "lat": 30.32,
    "lon": 318.2
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 0.47
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}