{
 "generated_utc": "2026-08-30T11:27:00Z",
 "gfs_cycle_utc": "2026-08-30T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 464.5,
  "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_20260830_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260830_06Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 69606
 },
 "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": 43.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": -78.84019,
    "lon": 82.46747,
    "alt_m": 12170.6
   },
   "member_spread_deg": {
    "lat": 35.7,
    "lon": 151.32
   },
   "member_spread_now_deg": {
    "lat": 16.97,
    "lon": 43.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 05:39:27",
   "seed_lat": 43.35417,
   "seed_lon": 109.66667,
   "seed_alt_m": 13970.0,
   "seed_age_h": 5.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 43.65612,
    "lon": -93.88117,
    "alt_m": 14287.5
   },
   "member_spread_deg": {
    "lat": 31.68,
    "lon": 315.3
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 2.61
   },
   "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": 109.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": 23.37611,
    "lon": -95.13216,
    "alt_m": 13129.2
   },
   "member_spread_deg": {
    "lat": 23.88,
    "lon": 58.07
   },
   "member_spread_now_deg": {
    "lat": 13.61,
    "lon": 16.29
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 16:41:00",
   "seed_lat": 74.58333,
   "seed_lon": -39.79167,
   "seed_alt_m": 12140.0,
   "seed_age_h": 18.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 76.03372,
    "lon": -136.53749,
    "alt_m": 11731.3
   },
   "member_spread_deg": {
    "lat": 24.44,
    "lon": 311.17
   },
   "member_spread_now_deg": {
    "lat": 8.14,
    "lon": 5.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 10:32:00",
   "seed_lat": 49.85417,
   "seed_lon": 10.25,
   "seed_alt_m": 13100.0,
   "seed_age_h": 0.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 10:00:00",
    "lat": 52.5778,
    "lon": -173.4105,
    "alt_m": 12861.1
   },
   "member_spread_deg": {
    "lat": 31.2,
    "lon": 343.09
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 12:08:00",
   "seed_lat": 67.39583,
   "seed_lon": 49.5,
   "seed_alt_m": 12030.0,
   "seed_age_h": 23.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 67.26123,
    "lon": 119.34321,
    "alt_m": 11820.0
   },
   "member_spread_deg": {
    "lat": 24.74,
    "lon": 278.92
   },
   "member_spread_now_deg": {
    "lat": 4.65,
    "lon": 12.98
   },
   "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": 141.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 63.76905,
    "lon": -142.57535,
    "alt_m": 12523.7
   },
   "member_spread_deg": {
    "lat": 26.06,
    "lon": 246.99
   },
   "member_spread_now_deg": {
    "lat": 21.0,
    "lon": 287.97
   },
   "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": 124.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": 43.92349,
    "lon": 75.0127,
    "alt_m": 13554.9
   },
   "member_spread_deg": {
    "lat": 45.67,
    "lon": 242.85
   },
   "member_spread_now_deg": {
    "lat": 35.12,
    "lon": 190.09
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 06:59:00",
   "seed_lat": 44.97917,
   "seed_lon": 85.83333,
   "seed_alt_m": 12490.0,
   "seed_age_h": 4.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 06:30:00",
    "lat": 25.09925,
    "lon": 172.78739,
    "alt_m": 12857.6
   },
   "member_spread_deg": {
    "lat": 18.88,
    "lon": 353.58
   },
   "member_spread_now_deg": {
    "lat": 0.79,
    "lon": 1.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-4",
   "flight_id": "KC7RW-4_2026-08-26",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 17:55:00",
   "seed_lat": 22.08333,
   "seed_lon": -84.41667,
   "seed_alt_m": 11320.0,
   "seed_age_h": 17.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": 29.02278,
    "lon": -84.02246,
    "alt_m": 11255.0
   },
   "member_spread_deg": {
    "lat": 27.08,
    "lon": 26.39
   },
   "member_spread_now_deg": {
    "lat": 1.78,
    "lon": 1.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 02:00:00",
   "seed_lat": 34.0,
   "seed_lon": -129.16667,
   "seed_alt_m": 12780.0,
   "seed_age_h": 9.33,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": 27.65289,
    "lon": -30.94532,
    "alt_m": 12999.6
   },
   "member_spread_deg": {
    "lat": 25.4,
    "lon": 108.82
   },
   "member_spread_now_deg": {
    "lat": 0.7,
    "lon": 1.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 09:56:00",
   "seed_lat": 53.25,
   "seed_lon": 72.45833,
   "seed_alt_m": 12000.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 09:30:00",
    "lat": 60.0535,
    "lon": -176.739,
    "alt_m": 12035.1
   },
   "member_spread_deg": {
    "lat": 23.93,
    "lon": 345.08
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.59
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 02:10:45",
   "seed_lat": 77.16661,
   "seed_lon": -140.24998,
   "seed_alt_m": 12840.0,
   "seed_age_h": 9.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 65.21544,
    "lon": 15.08079,
    "alt_m": 12851.7
   },
   "member_spread_deg": {
    "lat": 35.14,
    "lon": 42.32
   },
   "member_spread_now_deg": {
    "lat": 1.47,
    "lon": 16.0
   },
   "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": 91.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 29.68611,
    "lon": -131.881,
    "alt_m": 13304.8
   },
   "member_spread_deg": {
    "lat": 15.42,
    "lon": 123.93
   },
   "member_spread_now_deg": {
    "lat": 2.86,
    "lon": 30.21
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 10:46:00",
   "seed_lat": 42.47917,
   "seed_lon": 56.625,
   "seed_alt_m": 16040.0,
   "seed_age_h": 0.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-06 10:45:00",
    "lat": 39.3478,
    "lon": -146.39792,
    "alt_m": 16306.6
   },
   "member_spread_deg": {
    "lat": 30.49,
    "lon": 330.41
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-30 06:21:00",
   "seed_lat": 45.10417,
   "seed_lon": 151.33333,
   "seed_alt_m": 12950.0,
   "seed_age_h": 4.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:45:00",
    "lat": 43.48164,
    "lon": -20.39707,
    "alt_m": 13332.7
   },
   "member_spread_deg": {
    "lat": 14.17,
    "lon": 189.11
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 2.48
   },
   "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": 302.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": -29.19093,
    "lon": -119.38155,
    "alt_m": 12047.1
   },
   "member_spread_deg": {
    "lat": 14.13,
    "lon": 249.54
   },
   "member_spread_now_deg": {
    "lat": 34.68,
    "lon": 112.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 21:01:00",
   "seed_lat": -23.125,
   "seed_lon": -76.0,
   "seed_alt_m": 15580.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-06 05:30:00",
    "lat": -1.81999,
    "lon": -66.26174,
    "alt_m": 15726.3
   },
   "member_spread_deg": {
    "lat": 34.23,
    "lon": 91.33
   },
   "member_spread_now_deg": {
    "lat": 2.14,
    "lon": 10.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}