{
 "generated_utc": "2026-09-08T11:27:05Z",
 "gfs_cycle_utc": "2026-09-08T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 488.0,
  "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_20260908_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260908_06Z.geojson.gz"
 },
 "counts": {
  "flights": 17,
  "members": 9,
  "rows": 75195
 },
 "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": 259.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": -58.57334,
    "lon": 4.71287,
    "alt_m": 11955.4
   },
   "member_spread_deg": {
    "lat": 31.41,
    "lon": 245.51
   },
   "member_spread_now_deg": {
    "lat": 23.27,
    "lon": 172.62
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 19:10:19",
   "seed_lat": 33.60417,
   "seed_lon": -62.70833,
   "seed_alt_m": 14540.0,
   "seed_age_h": 16.16,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 39.60756,
    "lon": -16.99466,
    "alt_m": 14434.5
   },
   "member_spread_deg": {
    "lat": 20.54,
    "lon": 53.14
   },
   "member_spread_now_deg": {
    "lat": 5.72,
    "lon": 10.25
   },
   "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": 325.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:30:00",
    "lat": -2.6157,
    "lon": -15.83906,
    "alt_m": 13177.3
   },
   "member_spread_deg": {
    "lat": 50.75,
    "lon": 98.3
   },
   "member_spread_now_deg": {
    "lat": 14.95,
    "lon": 72.19
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 78.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 83.72797,
    "lon": -133.16409,
    "alt_m": 11599.5
   },
   "member_spread_deg": {
    "lat": 30.03,
    "lon": 252.33
   },
   "member_spread_now_deg": {
    "lat": 15.33,
    "lon": 98.52
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:37:00",
   "seed_lat": 38.625,
   "seed_lon": -125.5,
   "seed_alt_m": 13290.0,
   "seed_age_h": 11.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:30:00",
    "lat": 28.48807,
    "lon": -30.15263,
    "alt_m": 13384.2
   },
   "member_spread_deg": {
    "lat": 44.13,
    "lon": 169.08
   },
   "member_spread_now_deg": {
    "lat": 1.03,
    "lon": 3.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 23:36:00",
   "seed_lat": 50.91667,
   "seed_lon": 151.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 11.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:30:00",
    "lat": 25.8685,
    "lon": 124.94778,
    "alt_m": 13993.4
   },
   "member_spread_deg": {
    "lat": 48.04,
    "lon": 248.66
   },
   "member_spread_now_deg": {
    "lat": 3.52,
    "lon": 4.29
   },
   "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": 193.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 05:30:00",
    "lat": 65.45962,
    "lon": -90.03653,
    "alt_m": 11663.4
   },
   "member_spread_deg": {
    "lat": 30.01,
    "lon": 254.83
   },
   "member_spread_now_deg": {
    "lat": 29.14,
    "lon": 295.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 06:11:23",
   "seed_lat": 45.72917,
   "seed_lon": 115.79167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 29.14,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 60.43556,
    "lon": -6.15648,
    "alt_m": 13535.9
   },
   "member_spread_deg": {
    "lat": 35.12,
    "lon": 229.53
   },
   "member_spread_now_deg": {
    "lat": 6.34,
    "lon": 13.86
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 08:15:00",
   "seed_lat": 40.16667,
   "seed_lon": 61.0,
   "seed_alt_m": 12620.0,
   "seed_age_h": 3.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 07:45:00",
    "lat": 47.79731,
    "lon": -62.33094,
    "alt_m": 12320.1
   },
   "member_spread_deg": {
    "lat": 17.08,
    "lon": 134.01
   },
   "member_spread_now_deg": {
    "lat": 0.81,
    "lon": 1.13
   },
   "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": 123.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:30:00",
    "lat": 30.21994,
    "lon": 157.82789,
    "alt_m": 12941.8
   },
   "member_spread_deg": {
    "lat": 29.33,
    "lon": 301.21
   },
   "member_spread_now_deg": {
    "lat": 21.0,
    "lon": 311.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 10:35:00",
   "seed_lat": 31.95833,
   "seed_lon": 7.66667,
   "seed_alt_m": 12960.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 10:00:00",
    "lat": 32.59666,
    "lon": -149.47494,
    "alt_m": 13046.7
   },
   "member_spread_deg": {
    "lat": 26.35,
    "lon": 298.05
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:46:00",
   "seed_lat": 64.5,
   "seed_lon": -98.625,
   "seed_alt_m": 12260.0,
   "seed_age_h": 17.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 57.91657,
    "lon": 52.85611,
    "alt_m": 12368.5
   },
   "member_spread_deg": {
    "lat": 22.31,
    "lon": 152.15
   },
   "member_spread_now_deg": {
    "lat": 9.41,
    "lon": 3.56
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 10:40:45",
   "seed_lat": 65.04161,
   "seed_lon": 64.41669,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 10:45:00",
    "lat": 57.47264,
    "lon": -52.43753,
    "alt_m": 12985.7
   },
   "member_spread_deg": {
    "lat": 14.61,
    "lon": 119.86
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.86
   },
   "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": 307.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 41.04625,
    "lon": -18.07465,
    "alt_m": 13373.0
   },
   "member_spread_deg": {
    "lat": 32.87,
    "lon": 221.87
   },
   "member_spread_now_deg": {
    "lat": 30.25,
    "lon": 102.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 02:11:00",
   "seed_lat": 33.04167,
   "seed_lon": -157.83333,
   "seed_alt_m": 16240.0,
   "seed_age_h": 9.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 05:45:00",
    "lat": 21.93849,
    "lon": -157.13265,
    "alt_m": 16344.4
   },
   "member_spread_deg": {
    "lat": 24.61,
    "lon": 80.14
   },
   "member_spread_now_deg": {
    "lat": 2.5,
    "lon": 3.77
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 10:31:00",
   "seed_lat": 40.1875,
   "seed_lon": -14.5,
   "seed_alt_m": 13680.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-15 10:00:00",
    "lat": 40.86654,
    "lon": 90.46805,
    "alt_m": 13479.8
   },
   "member_spread_deg": {
    "lat": 17.73,
    "lon": 114.34
   },
   "member_spread_now_deg": {
    "lat": 0.35,
    "lon": 0.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 10:21:00",
   "seed_lat": -18.0625,
   "seed_lon": 30.83333,
   "seed_alt_m": 15660.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-15 09:45:00",
    "lat": -17.30758,
    "lon": 128.69913,
    "alt_m": 15586.0
   },
   "member_spread_deg": {
    "lat": 19.95,
    "lon": 294.11
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.53
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}