{
 "generated_utc": "2026-08-27T23:26:37Z",
 "gfs_cycle_utc": "2026-08-27T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 453.0,
  "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_20260827_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260827_18Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 70785
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 23:18:40",
   "seed_lat": -70.79167,
   "seed_lon": -148.58332,
   "seed_alt_m": 12300.0,
   "seed_age_h": 24.02,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": -82.35122,
    "lon": -16.10712,
    "alt_m": 12071.5
   },
   "member_spread_deg": {
    "lat": 17.26,
    "lon": 268.47
   },
   "member_spread_now_deg": {
    "lat": 2.26,
    "lon": 12.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 14:01:48",
   "seed_lat": 43.125,
   "seed_lon": 21.54167,
   "seed_alt_m": 14180.0,
   "seed_age_h": 9.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": 40.4116,
    "lon": -114.65268,
    "alt_m": 14234.1
   },
   "member_spread_deg": {
    "lat": 35.21,
    "lon": 327.99
   },
   "member_spread_now_deg": {
    "lat": 2.28,
    "lon": 5.29
   },
   "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": 49.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": 27.68488,
    "lon": -92.68068,
    "alt_m": 13144.7
   },
   "member_spread_deg": {
    "lat": 9.95,
    "lon": 68.73
   },
   "member_spread_now_deg": {
    "lat": 5.24,
    "lon": 6.27
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 22:06:00",
   "seed_lat": 69.14583,
   "seed_lon": -115.5,
   "seed_alt_m": 12310.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 21:30:00",
    "lat": 69.65321,
    "lon": -128.17544,
    "alt_m": 12125.1
   },
   "member_spread_deg": {
    "lat": 28.18,
    "lon": 274.58
   },
   "member_spread_now_deg": {
    "lat": 0.47,
    "lon": 1.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 21:37:00",
   "seed_lat": 44.35417,
   "seed_lon": -69.45833,
   "seed_alt_m": 13180.0,
   "seed_age_h": 1.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 21:00:00",
    "lat": 47.77707,
    "lon": 97.2793,
    "alt_m": 13078.6
   },
   "member_spread_deg": {
    "lat": 37.31,
    "lon": 79.6
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 1.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:38:00",
   "seed_lat": 83.20833,
   "seed_lon": -24.91667,
   "seed_alt_m": 11920.0,
   "seed_age_h": 33.7,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 50.91329,
    "lon": 173.43944,
    "alt_m": 11852.0
   },
   "member_spread_deg": {
    "lat": 29.92,
    "lon": 99.03
   },
   "member_spread_now_deg": {
    "lat": 9.78,
    "lon": 8.98
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 14:13:00",
   "seed_lat": 65.52083,
   "seed_lon": 37.33333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 81.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 50.33322,
    "lon": 172.85471,
    "alt_m": 12339.7
   },
   "member_spread_deg": {
    "lat": 35.39,
    "lon": 305.25
   },
   "member_spread_now_deg": {
    "lat": 23.23,
    "lon": 94.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 290.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 34.78903,
    "lon": 19.69269,
    "alt_m": 13031.3
   },
   "member_spread_deg": {
    "lat": 52.45,
    "lon": 244.11
   },
   "member_spread_now_deg": {
    "lat": 43.81,
    "lon": 206.2
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 64.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": 46.77385,
    "lon": 15.01429,
    "alt_m": 13514.9
   },
   "member_spread_deg": {
    "lat": 35.16,
    "lon": 346.86
   },
   "member_spread_now_deg": {
    "lat": 35.41,
    "lon": 49.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 11:49:00",
   "seed_lat": 31.89583,
   "seed_lon": 23.625,
   "seed_alt_m": 12710.0,
   "seed_age_h": 11.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 39.12835,
    "lon": -126.34656,
    "alt_m": 12718.4
   },
   "member_spread_deg": {
    "lat": 42.38,
    "lon": 322.55
   },
   "member_spread_now_deg": {
    "lat": 2.04,
    "lon": 2.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 22:45:00",
   "seed_lat": 26.625,
   "seed_lon": -165.75,
   "seed_alt_m": 12930.0,
   "seed_age_h": 0.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 22:15:00",
    "lat": 32.18534,
    "lon": -102.7994,
    "alt_m": 12942.7
   },
   "member_spread_deg": {
    "lat": 13.74,
    "lon": 115.95
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 96.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": 53.01512,
    "lon": 165.15272,
    "alt_m": 12054.8
   },
   "member_spread_deg": {
    "lat": 28.41,
    "lon": 209.28
   },
   "member_spread_now_deg": {
    "lat": 18.84,
    "lon": 238.13
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 22:55:45",
   "seed_lat": 73.83328,
   "seed_lon": 174.58335,
   "seed_alt_m": 12780.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 23:00:00",
    "lat": 68.85806,
    "lon": -19.50548,
    "alt_m": 12849.4
   },
   "member_spread_deg": {
    "lat": 28.85,
    "lon": 97.0
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.1
   },
   "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": 31.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 39.05114,
    "lon": -151.02344,
    "alt_m": 13363.5
   },
   "member_spread_deg": {
    "lat": 17.85,
    "lon": 82.68
   },
   "member_spread_now_deg": {
    "lat": 3.72,
    "lon": 9.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 15:48:00",
   "seed_lat": 37.375,
   "seed_lon": 9.16667,
   "seed_alt_m": 16440.0,
   "seed_age_h": 7.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:45:00",
    "lat": 37.70521,
    "lon": 175.65164,
    "alt_m": 16263.5
   },
   "member_spread_deg": {
    "lat": 22.43,
    "lon": 355.41
   },
   "member_spread_now_deg": {
    "lat": 2.14,
    "lon": 5.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 14:31:00",
   "seed_lat": 46.83333,
   "seed_lon": 23.125,
   "seed_alt_m": 13050.0,
   "seed_age_h": 32.82,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": 35.67587,
    "lon": -122.51992,
    "alt_m": 13410.3
   },
   "member_spread_deg": {
    "lat": 32.67,
    "lon": 311.66
   },
   "member_spread_now_deg": {
    "lat": 3.23,
    "lon": 13.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 20:59:00",
   "seed_lat": -20.58333,
   "seed_lon": -72.33333,
   "seed_alt_m": 12210.0,
   "seed_age_h": 242.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 17:30:00",
    "lat": -36.93178,
    "lon": 142.47138,
    "alt_m": 11962.7
   },
   "member_spread_deg": {
    "lat": 25.35,
    "lon": 346.51
   },
   "member_spread_now_deg": {
    "lat": 11.7,
    "lon": 135.66
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 21:46:00",
   "seed_lat": -24.22917,
   "seed_lon": -139.95833,
   "seed_alt_m": 15500.0,
   "seed_age_h": 1.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 21:15:00",
    "lat": -13.19727,
    "lon": -78.58834,
    "alt_m": 15714.1
   },
   "member_spread_deg": {
    "lat": 47.75,
    "lon": 192.59
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}