{
 "generated_utc": "2026-08-12T05:27:12Z",
 "gfs_cycle_utc": "2026-08-12T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 496.0,
  "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_20260812_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260812_00Z.geojson.gz"
 },
 "counts": {
  "flights": 25,
  "members": 9,
  "rows": 114723
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 23:53:40",
   "seed_lat": -55.83334,
   "seed_lon": -115.37499,
   "seed_alt_m": 12390.0,
   "seed_age_h": 5.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": -54.55025,
    "lon": -168.24665,
    "alt_m": 12495.1
   },
   "member_spread_deg": {
    "lat": 27.47,
    "lon": 285.22
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 1.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 20:01:18",
   "seed_lat": 57.52083,
   "seed_lon": -17.58333,
   "seed_alt_m": 12640.0,
   "seed_age_h": 9.31,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 63.59415,
    "lon": 172.35421,
    "alt_m": 12483.5
   },
   "member_spread_deg": {
    "lat": 7.75,
    "lon": 95.92
   },
   "member_spread_now_deg": {
    "lat": 2.95,
    "lon": 3.3
   },
   "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": 25.04,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 44.449,
    "lon": -141.59723,
    "alt_m": 13922.6
   },
   "member_spread_deg": {
    "lat": 32.6,
    "lon": 48.31
   },
   "member_spread_now_deg": {
    "lat": 6.37,
    "lon": 7.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 17:54:00",
   "seed_lat": 45.0,
   "seed_lon": -19.5,
   "seed_alt_m": 12870.0,
   "seed_age_h": 11.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 45.77697,
    "lon": 122.89739,
    "alt_m": 12693.8
   },
   "member_spread_deg": {
    "lat": 11.84,
    "lon": 79.43
   },
   "member_spread_now_deg": {
    "lat": 1.06,
    "lon": 1.82
   },
   "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": 53.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 2.952,
    "lon": -121.97399,
    "alt_m": 14071.8
   },
   "member_spread_deg": {
    "lat": 38.92,
    "lon": 55.92
   },
   "member_spread_now_deg": {
    "lat": 16.38,
    "lon": 27.32
   },
   "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": 192.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 29.5293,
    "lon": -17.28438,
    "alt_m": 13477.8
   },
   "member_spread_deg": {
    "lat": 77.1,
    "lon": 294.01
   },
   "member_spread_now_deg": {
    "lat": 70.68,
    "lon": 244.71
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 03:51:00",
   "seed_lat": 55.0625,
   "seed_lon": 152.41667,
   "seed_alt_m": 12780.0,
   "seed_age_h": 1.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 03:15:00",
    "lat": 50.61657,
    "lon": -15.54718,
    "alt_m": 12879.1
   },
   "member_spread_deg": {
    "lat": 38.26,
    "lon": 132.28
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.38
   },
   "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": 333.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 64.29575,
    "lon": 102.64161,
    "alt_m": 12077.9
   },
   "member_spread_deg": {
    "lat": 43.65,
    "lon": 346.07
   },
   "member_spread_now_deg": {
    "lat": 18.34,
    "lon": 277.36
   },
   "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": 333.88,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 52.33511,
    "lon": 10.07224,
    "alt_m": 12421.9
   },
   "member_spread_deg": {
    "lat": 48.99,
    "lon": 240.08
   },
   "member_spread_now_deg": {
    "lat": 32.74,
    "lon": 137.19
   },
   "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": 12.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 66.47912,
    "lon": -96.69976,
    "alt_m": 11990.5
   },
   "member_spread_deg": {
    "lat": 16.55,
    "lon": 267.76
   },
   "member_spread_now_deg": {
    "lat": 6.56,
    "lon": 3.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 00:18:00",
   "seed_lat": 74.52083,
   "seed_lon": -141.04167,
   "seed_alt_m": 12600.0,
   "seed_age_h": 5.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 61.75717,
    "lon": -36.79398,
    "alt_m": 12515.8
   },
   "member_spread_deg": {
    "lat": 11.79,
    "lon": 80.32
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 3.58
   },
   "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": 49.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 20.19496,
    "lon": -82.73983,
    "alt_m": 13524.1
   },
   "member_spread_deg": {
    "lat": 37.76,
    "lon": 293.12
   },
   "member_spread_now_deg": {
    "lat": 25.76,
    "lon": 341.18
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 20:47:18",
   "seed_lat": 53.9375,
   "seed_lon": -18.83333,
   "seed_alt_m": 13480.0,
   "seed_age_h": 8.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 64.08124,
    "lon": 157.08754,
    "alt_m": 13154.7
   },
   "member_spread_deg": {
    "lat": 19.66,
    "lon": 346.05
   },
   "member_spread_now_deg": {
    "lat": 1.82,
    "lon": 2.49
   },
   "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": 12.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 64.89824,
    "lon": 97.97811,
    "alt_m": 12659.8
   },
   "member_spread_deg": {
    "lat": 33.03,
    "lon": 260.07
   },
   "member_spread_now_deg": {
    "lat": 6.1,
    "lon": 7.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 18:12:30",
   "seed_lat": 38.97917,
   "seed_lon": -11.0,
   "seed_alt_m": 13112.0,
   "seed_age_h": 11.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 47.16815,
    "lon": 131.71088,
    "alt_m": 12892.8
   },
   "member_spread_deg": {
    "lat": 12.11,
    "lon": 108.27
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 2.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-11 21:06:00",
   "seed_lat": 54.45833,
   "seed_lon": -78.16667,
   "seed_alt_m": 12100.0,
   "seed_age_h": 8.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 70.98925,
    "lon": -15.71391,
    "alt_m": 12192.5
   },
   "member_spread_deg": {
    "lat": 18.34,
    "lon": 30.81
   },
   "member_spread_now_deg": {
    "lat": 1.38,
    "lon": 1.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 04:41:00",
   "seed_lat": 38.95833,
   "seed_lon": 106.83333,
   "seed_alt_m": 12240.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-19 04:45:00",
    "lat": 38.0911,
    "lon": -84.083,
    "alt_m": 12528.4
   },
   "member_spread_deg": {
    "lat": 50.91,
    "lon": 332.86
   },
   "member_spread_now_deg": {
    "lat": 0.24,
    "lon": 0.29
   },
   "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": 246.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 12.20118,
    "lon": -100.37392,
    "alt_m": 12368.1
   },
   "member_spread_deg": {
    "lat": 59.79,
    "lon": 130.67
   },
   "member_spread_now_deg": {
    "lat": 19.72,
    "lon": 49.64
   },
   "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": 22.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 64.71661,
    "lon": 147.06659,
    "alt_m": 12978.8
   },
   "member_spread_deg": {
    "lat": 25.44,
    "lon": 255.2
   },
   "member_spread_now_deg": {
    "lat": 7.81,
    "lon": 5.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 04:41:00",
   "seed_lat": 31.625,
   "seed_lon": 178.95833,
   "seed_alt_m": 16360.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 04:45:00",
    "lat": 6.42478,
    "lon": 96.45276,
    "alt_m": 16462.6
   },
   "member_spread_deg": {
    "lat": 38.25,
    "lon": 82.02
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 0.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 274.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:45:00",
    "lat": 59.40617,
    "lon": -49.75761,
    "alt_m": 12927.8
   },
   "member_spread_deg": {
    "lat": 38.77,
    "lon": 302.53
   },
   "member_spread_now_deg": {
    "lat": 10.68,
    "lon": 332.52
   },
   "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": 193.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": 59.91945,
    "lon": 144.5742,
    "alt_m": 12433.7
   },
   "member_spread_deg": {
    "lat": 39.82,
    "lon": 310.08
   },
   "member_spread_now_deg": {
    "lat": 30.31,
    "lon": 321.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 04:16:00",
   "seed_lat": 47.45833,
   "seed_lon": 145.91667,
   "seed_alt_m": 13650.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-19 03:45:00",
    "lat": 34.67467,
    "lon": -132.03023,
    "alt_m": 13424.0
   },
   "member_spread_deg": {
    "lat": 10.92,
    "lon": 340.38
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.34
   },
   "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": 288.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-18 23:30:00",
    "lat": -29.73092,
    "lon": 99.60964,
    "alt_m": 12176.8
   },
   "member_spread_deg": {
    "lat": 25.38,
    "lon": 222.2
   },
   "member_spread_now_deg": {
    "lat": 24.31,
    "lon": 254.54
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 04:26:00",
   "seed_lat": -21.3125,
   "seed_lon": 144.66667,
   "seed_alt_m": 15940.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-19 04:00:00",
    "lat": -30.3581,
    "lon": -45.64488,
    "alt_m": 15700.8
   },
   "member_spread_deg": {
    "lat": 26.87,
    "lon": 336.83
   },
   "member_spread_now_deg": {
    "lat": 0.4,
    "lon": 0.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}