{
 "generated_utc": "2026-08-11T17:27:22Z",
 "gfs_cycle_utc": "2026-08-11T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 484.0,
  "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_20260811_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260811_12Z.geojson.gz"
 },
 "counts": {
  "flights": 26,
  "members": 9,
  "rows": 115308
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 01:23:40",
   "seed_lat": -45.1875,
   "seed_lon": -138.20832,
   "seed_alt_m": 12300.0,
   "seed_age_h": 15.94,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": -64.93522,
    "lon": 163.55185,
    "alt_m": 12597.6
   },
   "member_spread_deg": {
    "lat": 29.81,
    "lon": 341.36
   },
   "member_spread_now_deg": {
    "lat": 2.53,
    "lon": 5.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:51:18",
   "seed_lat": 55.39583,
   "seed_lon": -19.04167,
   "seed_alt_m": 12640.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 16:15:00",
    "lat": 52.72585,
    "lon": 178.19557,
    "alt_m": 12632.2
   },
   "member_spread_deg": {
    "lat": 14.35,
    "lon": 356.04
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 04:17:39",
   "seed_lat": 47.60417,
   "seed_lon": 117.45833,
   "seed_alt_m": 14140.0,
   "seed_age_h": 13.04,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 40.40419,
    "lon": -154.33884,
    "alt_m": 14288.7
   },
   "member_spread_deg": {
    "lat": 30.48,
    "lon": 359.02
   },
   "member_spread_now_deg": {
    "lat": 0.77,
    "lon": 10.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:24:00",
   "seed_lat": 44.54167,
   "seed_lon": -20.75,
   "seed_alt_m": 12920.0,
   "seed_age_h": 0.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 16:00:00",
    "lat": 48.35427,
    "lon": 113.9507,
    "alt_m": 12729.0
   },
   "member_spread_deg": {
    "lat": 10.27,
    "lon": 72.62
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 41.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": -8.14047,
    "lon": -116.05919,
    "alt_m": 14044.4
   },
   "member_spread_deg": {
    "lat": 50.01,
    "lon": 65.06
   },
   "member_spread_now_deg": {
    "lat": 13.62,
    "lon": 19.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 180.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 33.10624,
    "lon": -11.80285,
    "alt_m": 13482.1
   },
   "member_spread_deg": {
    "lat": 71.58,
    "lon": 274.16
   },
   "member_spread_now_deg": {
    "lat": 57.49,
    "lon": 260.31
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 08:36:00",
   "seed_lat": 56.08333,
   "seed_lon": 129.625,
   "seed_alt_m": 12630.0,
   "seed_age_h": 8.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 48.87071,
    "lon": -50.35422,
    "alt_m": 12716.8
   },
   "member_spread_deg": {
    "lat": 56.89,
    "lon": 118.4
   },
   "member_spread_now_deg": {
    "lat": 1.16,
    "lon": 3.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DL0MZ-493",
   "flight_id": "DL0MZ-493_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-07-29 07:36:01",
   "seed_lat": 64.20833,
   "seed_lon": 58.16667,
   "seed_alt_m": 12170.0,
   "seed_age_h": 321.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 62.85717,
    "lon": 131.62408,
    "alt_m": 11878.7
   },
   "member_spread_deg": {
    "lat": 54.17,
    "lon": 312.72
   },
   "member_spread_now_deg": {
    "lat": 29.41,
    "lon": 272.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DL0MZ-493e",
   "flight_id": "DL0MZ-493e_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-07-29 07:27:02",
   "seed_lat": 64.15625,
   "seed_lon": 58.08889,
   "seed_alt_m": 12170.0,
   "seed_age_h": 321.88,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 18.6013,
    "lon": -94.97155,
    "alt_m": 12753.0
   },
   "member_spread_deg": {
    "lat": 56.26,
    "lon": 264.64
   },
   "member_spread_now_deg": {
    "lat": 31.26,
    "lon": 111.4
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:33:00",
   "seed_lat": 63.0,
   "seed_lon": 3.91667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 0.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 16:00:00",
    "lat": 59.56271,
    "lon": -104.42652,
    "alt_m": 12187.4
   },
   "member_spread_deg": {
    "lat": 18.37,
    "lon": 251.19
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 0.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:13:00",
   "seed_lat": 73.8125,
   "seed_lon": -132.45833,
   "seed_alt_m": 12620.0,
   "seed_age_h": 1.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 15:45:00",
    "lat": 59.06804,
    "lon": -37.36088,
    "alt_m": 12498.0
   },
   "member_spread_deg": {
    "lat": 7.17,
    "lon": 42.1
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 1.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 03:45:37",
   "seed_lat": 33.04161,
   "seed_lon": 175.83333,
   "seed_alt_m": 13420.0,
   "seed_age_h": 37.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 28.77077,
    "lon": -58.44377,
    "alt_m": 13463.5
   },
   "member_spread_deg": {
    "lat": 35.32,
    "lon": 275.6
   },
   "member_spread_now_deg": {
    "lat": 20.85,
    "lon": 29.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:57:04",
   "seed_lat": 52.3125,
   "seed_lon": -21.70833,
   "seed_alt_m": 13520.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 17:00:00",
    "lat": 55.19852,
    "lon": 166.19242,
    "alt_m": 13536.2
   },
   "member_spread_deg": {
    "lat": 14.21,
    "lon": 353.64
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:35:43",
   "seed_lat": 64.79161,
   "seed_lon": -4.79163,
   "seed_alt_m": 12660.0,
   "seed_age_h": 0.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 16:00:00",
    "lat": 61.57698,
    "lon": 86.70183,
    "alt_m": 12691.4
   },
   "member_spread_deg": {
    "lat": 19.36,
    "lon": 246.62
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:05:00",
   "seed_lat": 39.0625,
   "seed_lon": -11.54167,
   "seed_alt_m": 13120.0,
   "seed_age_h": 1.25,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 15:30:00",
    "lat": 42.54763,
    "lon": 122.67759,
    "alt_m": 12901.2
   },
   "member_spread_deg": {
    "lat": 8.89,
    "lon": 105.52
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 16:26:00",
   "seed_lat": 54.3125,
   "seed_lon": -79.08333,
   "seed_alt_m": 12060.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 16:00:00",
    "lat": 67.92566,
    "lon": -79.29935,
    "alt_m": 11944.2
   },
   "member_spread_deg": {
    "lat": 11.87,
    "lon": 35.72
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 10:51:00",
   "seed_lat": 50.22917,
   "seed_lon": 92.08333,
   "seed_alt_m": 12160.0,
   "seed_age_h": 6.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 33.95625,
    "lon": -125.99499,
    "alt_m": 12356.3
   },
   "member_spread_deg": {
    "lat": 27.7,
    "lon": 57.53
   },
   "member_spread_now_deg": {
    "lat": 2.04,
    "lon": 1.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI1TEN-1",
   "flight_id": "KI1TEN-1_2026-07-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-01 22:55:27",
   "seed_lat": 23.95828,
   "seed_lon": -104.12496,
   "seed_alt_m": 12380.0,
   "seed_age_h": 234.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 1.67056,
    "lon": -100.94019,
    "alt_m": 12386.0
   },
   "member_spread_deg": {
    "lat": 44.34,
    "lon": 121.15
   },
   "member_spread_now_deg": {
    "lat": 18.46,
    "lon": 45.08
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 06:35:45",
   "seed_lat": 54.72911,
   "seed_lon": 24.66669,
   "seed_alt_m": 13360.0,
   "seed_age_h": 10.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 63.22614,
    "lon": 122.08941,
    "alt_m": 13259.3
   },
   "member_spread_deg": {
    "lat": 34.1,
    "lon": 254.65
   },
   "member_spread_now_deg": {
    "lat": 2.58,
    "lon": 4.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 04:48:30",
   "seed_lat": 37.41667,
   "seed_lon": 178.70833,
   "seed_alt_m": 16270.0,
   "seed_age_h": 12.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 7.30405,
    "lon": 90.6491,
    "alt_m": 16493.9
   },
   "member_spread_deg": {
    "lat": 44.58,
    "lon": 342.59
   },
   "member_spread_now_deg": {
    "lat": 6.93,
    "lon": 358.78
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP6MPL-34",
   "flight_id": "SP6MPL-34_2025-12-03",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 18:52:00",
   "seed_lat": 74.5625,
   "seed_lon": -160.0,
   "seed_alt_m": 12890.0,
   "seed_age_h": 262.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 47.46166,
    "lon": -71.10885,
    "alt_m": 13202.7
   },
   "member_spread_deg": {
    "lat": 21.56,
    "lon": 209.43
   },
   "member_spread_now_deg": {
    "lat": 24.07,
    "lon": 336.21
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 181.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": 50.6281,
    "lon": 117.61374,
    "alt_m": 12894.0
   },
   "member_spread_deg": {
    "lat": 29.45,
    "lon": 282.71
   },
   "member_spread_now_deg": {
    "lat": 25.58,
    "lon": 326.04
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 00:51:00",
   "seed_lat": 49.16667,
   "seed_lon": 117.375,
   "seed_alt_m": 13220.0,
   "seed_age_h": 16.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 33.28151,
    "lon": 175.34219,
    "alt_m": 13599.6
   },
   "member_spread_deg": {
    "lat": 49.36,
    "lon": 355.31
   },
   "member_spread_now_deg": {
    "lat": 4.71,
    "lon": 12.86
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 06:40:23",
   "seed_lat": 52.79161,
   "seed_lon": 83.50002,
   "seed_alt_m": 13540.0,
   "seed_age_h": 10.66,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": 65.5753,
    "lon": -179.47258,
    "alt_m": 12980.4
   },
   "member_spread_deg": {
    "lat": 31.76,
    "lon": 355.41
   },
   "member_spread_now_deg": {
    "lat": 0.96,
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   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-15",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 04:34:00",
   "seed_lat": -23.70833,
   "seed_lon": 149.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 276.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 11:30:00",
    "lat": -4.22378,
    "lon": 30.22892,
    "alt_m": 12670.9
   },
   "member_spread_deg": {
    "lat": 33.98,
    "lon": 250.79
   },
   "member_spread_now_deg": {
    "lat": 25.01,
    "lon": 351.87
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 06:46:00",
   "seed_lat": -17.70833,
   "seed_lon": 133.83333,
   "seed_alt_m": 15910.0,
   "seed_age_h": 10.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 11:45:00",
    "lat": -19.87523,
    "lon": 96.78256,
    "alt_m": 15827.4
   },
   "member_spread_deg": {
    "lat": 21.91,
    "lon": 97.22
   },
   "member_spread_now_deg": {
    "lat": 4.33,
    "lon": 2.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}