{
 "generated_utc": "2026-09-07T23:27:02Z",
 "gfs_cycle_utc": "2026-09-07T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 491.0,
  "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_20260907_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260907_18Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 82899
 },
 "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": 247.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 17:45:00",
    "lat": -71.26878,
    "lon": 25.82764,
    "alt_m": 12088.3
   },
   "member_spread_deg": {
    "lat": 33.69,
    "lon": 238.36
   },
   "member_spread_now_deg": {
    "lat": 26.9,
    "lon": 160.25
   },
   "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": 4.16,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 18:45:00",
    "lat": 44.6668,
    "lon": -19.01098,
    "alt_m": 14263.2
   },
   "member_spread_deg": {
    "lat": 15.28,
    "lon": 48.41
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 1.99
   },
   "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": 313.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 7.10562,
    "lon": -36.60719,
    "alt_m": 13191.6
   },
   "member_spread_deg": {
    "lat": 46.59,
    "lon": 108.6
   },
   "member_spread_now_deg": {
    "lat": 14.15,
    "lon": 66.11
   },
   "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": 66.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 17:45:00",
    "lat": 83.31236,
    "lon": 154.00138,
    "alt_m": 11741.2
   },
   "member_spread_deg": {
    "lat": 15.89,
    "lon": 237.65
   },
   "member_spread_now_deg": {
    "lat": 11.05,
    "lon": 57.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 20:42:00",
   "seed_lat": 38.375,
   "seed_lon": -127.66667,
   "seed_alt_m": 13290.0,
   "seed_age_h": 2.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 20:15:00",
    "lat": 24.34468,
    "lon": -77.92408,
    "alt_m": 13609.3
   },
   "member_spread_deg": {
    "lat": 51.82,
    "lon": 133.99
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 22:31:00",
   "seed_lat": 50.5,
   "seed_lon": 149.5,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 22:00:00",
    "lat": 54.29871,
    "lon": 25.55454,
    "alt_m": 13430.7
   },
   "member_spread_deg": {
    "lat": 60.57,
    "lon": 122.62
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 0.43
   },
   "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": 181.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 61.6514,
    "lon": 177.23141,
    "alt_m": 11725.0
   },
   "member_spread_deg": {
    "lat": 49.55,
    "lon": 315.37
   },
   "member_spread_now_deg": {
    "lat": 21.0,
    "lon": 314.5
   },
   "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": 17.14,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 17:45:00",
    "lat": 59.5187,
    "lon": -7.94363,
    "alt_m": 13785.9
   },
   "member_spread_deg": {
    "lat": 39.69,
    "lon": 171.48
   },
   "member_spread_now_deg": {
    "lat": 3.21,
    "lon": 8.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:25:00",
   "seed_lat": 38.8125,
   "seed_lon": 34.04167,
   "seed_alt_m": 12750.0,
   "seed_age_h": 9.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 36.02484,
    "lon": -152.61095,
    "alt_m": 12707.4
   },
   "member_spread_deg": {
    "lat": 24.7,
    "lon": 113.33
   },
   "member_spread_now_deg": {
    "lat": 0.99,
    "lon": 1.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 328.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 34.16232,
    "lon": 147.91342,
    "alt_m": 14297.4
   },
   "member_spread_deg": {
    "lat": 38.63,
    "lon": 284.51
   },
   "member_spread_now_deg": {
    "lat": 31.6,
    "lon": 222.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 111.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 20.96189,
    "lon": 165.20823,
    "alt_m": 12834.0
   },
   "member_spread_deg": {
    "lat": 21.85,
    "lon": 316.56
   },
   "member_spread_now_deg": {
    "lat": 24.61,
    "lon": 318.84
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:25:00",
   "seed_lat": 27.33333,
   "seed_lon": -0.875,
   "seed_alt_m": 12960.0,
   "seed_age_h": 5.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 44.06382,
    "lon": -143.27163,
    "alt_m": 12976.4
   },
   "member_spread_deg": {
    "lat": 11.82,
    "lon": 352.24
   },
   "member_spread_now_deg": {
    "lat": 2.09,
    "lon": 2.49
   },
   "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": 5.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 17:45:00",
    "lat": 64.66477,
    "lon": 68.92396,
    "alt_m": 12011.4
   },
   "member_spread_deg": {
    "lat": 18.06,
    "lon": 134.92
   },
   "member_spread_now_deg": {
    "lat": 1.78,
    "lon": 6.53
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 55.9,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 66.05651,
    "lon": -74.32198,
    "alt_m": 12988.8
   },
   "member_spread_deg": {
    "lat": 13.88,
    "lon": 171.62
   },
   "member_spread_now_deg": {
    "lat": 10.59,
    "lon": 12.11
   },
   "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": 295.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:45:00",
    "lat": 48.99792,
    "lon": -13.03756,
    "alt_m": 13185.1
   },
   "member_spread_deg": {
    "lat": 39.33,
    "lon": 158.62
   },
   "member_spread_now_deg": {
    "lat": 20.7,
    "lon": 116.78
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 22:51:00",
   "seed_lat": 31.66667,
   "seed_lon": -157.54167,
   "seed_alt_m": 16170.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 22:45:00",
    "lat": 19.54101,
    "lon": -162.67785,
    "alt_m": 16318.7
   },
   "member_spread_deg": {
    "lat": 26.64,
    "lon": 136.49
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 17:26:00",
   "seed_lat": 49.125,
   "seed_lon": -38.79167,
   "seed_alt_m": 13430.0,
   "seed_age_h": 5.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": 36.41958,
    "lon": 113.89293,
    "alt_m": 13300.4
   },
   "member_spread_deg": {
    "lat": 11.45,
    "lon": 89.27
   },
   "member_spread_now_deg": {
    "lat": 1.68,
    "lon": 7.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:31:00",
   "seed_lat": -22.79167,
   "seed_lon": 25.625,
   "seed_alt_m": 15590.0,
   "seed_age_h": 9.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:30:00",
    "lat": -20.33936,
    "lon": 107.39412,
    "alt_m": 15713.1
   },
   "member_spread_deg": {
    "lat": 23.09,
    "lon": 282.69
   },
   "member_spread_now_deg": {
    "lat": 1.14,
    "lon": 3.35
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}