{
 "generated_utc": "2026-09-14T23:26:27Z",
 "gfs_cycle_utc": "2026-09-14T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 441.5,
  "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_20260914_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260914_18Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 64899
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 16:42:18",
   "seed_lat": 35.27083,
   "seed_lon": -19.16667,
   "seed_alt_m": 14510.0,
   "seed_age_h": 6.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:45:00",
    "lat": 42.53089,
    "lon": 35.59026,
    "alt_m": 13996.4
   },
   "member_spread_deg": {
    "lat": 8.0,
    "lon": 121.84
   },
   "member_spread_now_deg": {
    "lat": 0.86,
    "lon": 1.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 234.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-21 17:45:00",
    "lat": 79.20716,
    "lon": 81.22278,
    "alt_m": 11907.8
   },
   "member_spread_deg": {
    "lat": 40.2,
    "lon": 257.11
   },
   "member_spread_now_deg": {
    "lat": 23.1,
    "lon": 310.46
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 18:27:00",
   "seed_lat": 30.9375,
   "seed_lon": -31.70833,
   "seed_alt_m": 13420.0,
   "seed_age_h": 4.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 18:00:00",
    "lat": 35.50121,
    "lon": -6.02093,
    "alt_m": 13459.6
   },
   "member_spread_deg": {
    "lat": 33.41,
    "lon": 99.74
   },
   "member_spread_now_deg": {
    "lat": 1.33,
    "lon": 0.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 16:06:00",
   "seed_lat": 40.08333,
   "seed_lon": -0.95833,
   "seed_alt_m": 13940.0,
   "seed_age_h": 7.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 47.19746,
    "lon": 106.99697,
    "alt_m": 13370.6
   },
   "member_spread_deg": {
    "lat": 8.01,
    "lon": 133.23
   },
   "member_spread_now_deg": {
    "lat": 1.11,
    "lon": 2.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 13:31:52",
   "seed_lat": 46.04167,
   "seed_lon": 61.70833,
   "seed_alt_m": 13960.0,
   "seed_age_h": 225.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": -29.95657,
    "lon": -88.26305,
    "alt_m": 14228.7
   },
   "member_spread_deg": {
    "lat": 89.7,
    "lon": 330.55
   },
   "member_spread_now_deg": {
    "lat": 35.34,
    "lon": 145.9
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-10 05:25:00",
   "seed_lat": 48.52083,
   "seed_lon": 159.54167,
   "seed_alt_m": 12130.0,
   "seed_age_h": 113.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 32.80307,
    "lon": -68.78112,
    "alt_m": 12814.0
   },
   "member_spread_deg": {
    "lat": 30.5,
    "lon": 194.99
   },
   "member_spread_now_deg": {
    "lat": 26.38,
    "lon": 164.5
   },
   "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": 279.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 21.94312,
    "lon": -168.57234,
    "alt_m": 12852.3
   },
   "member_spread_deg": {
    "lat": 37.34,
    "lon": 336.86
   },
   "member_spread_now_deg": {
    "lat": 31.27,
    "lon": 299.21
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 06:05:00",
   "seed_lat": 45.47917,
   "seed_lon": 159.375,
   "seed_alt_m": 12660.0,
   "seed_age_h": 65.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 59.53116,
    "lon": 61.35614,
    "alt_m": 12547.6
   },
   "member_spread_deg": {
    "lat": 21.83,
    "lon": 155.3
   },
   "member_spread_now_deg": {
    "lat": 1.8,
    "lon": 23.36
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-13 13:01:00",
   "seed_lat": 42.0625,
   "seed_lon": 28.04167,
   "seed_alt_m": 12700.0,
   "seed_age_h": 34.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 55.16467,
    "lon": -86.1165,
    "alt_m": 12602.6
   },
   "member_spread_deg": {
    "lat": 16.18,
    "lon": 71.66
   },
   "member_spread_now_deg": {
    "lat": 6.7,
    "lon": 15.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 20:45:45",
   "seed_lat": 65.83328,
   "seed_lon": -74.24998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 2.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 20:15:00",
    "lat": 59.16855,
    "lon": -167.88855,
    "alt_m": 12821.5
   },
   "member_spread_deg": {
    "lat": 25.0,
    "lon": 320.63
   },
   "member_spread_now_deg": {
    "lat": 0.23,
    "lon": 1.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "NQ1W-6",
   "flight_id": "NQ1W-6_2026-09-11",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 14:28:30",
   "seed_lat": 36.52083,
   "seed_lon": -7.625,
   "seed_alt_m": 13387.0,
   "seed_age_h": 8.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 42.26966,
    "lon": 93.49665,
    "alt_m": 12916.4
   },
   "member_spread_deg": {
    "lat": 4.22,
    "lon": 31.57
   },
   "member_spread_now_deg": {
    "lat": 0.76,
    "lon": 1.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 22:03:00",
   "seed_lat": 46.5,
   "seed_lon": -94.625,
   "seed_alt_m": 15880.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 22:00:00",
    "lat": 39.97199,
    "lon": 4.66589,
    "alt_m": 15908.9
   },
   "member_spread_deg": {
    "lat": 66.29,
    "lon": 134.09
   },
   "member_spread_now_deg": {
    "lat": 0.66,
    "lon": 1.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 10:56:00",
   "seed_lat": 47.875,
   "seed_lon": 75.58333,
   "seed_alt_m": 13200.0,
   "seed_age_h": 12.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 48.09254,
    "lon": -64.75847,
    "alt_m": 12660.6
   },
   "member_spread_deg": {
    "lat": 14.4,
    "lon": 88.11
   },
   "member_spread_now_deg": {
    "lat": 2.87,
    "lon": 6.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-08 21:35:23",
   "seed_lat": 52.33328,
   "seed_lon": -95.95831,
   "seed_alt_m": 12860.0,
   "seed_age_h": 145.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": 47.75448,
    "lon": -82.15611,
    "alt_m": 13201.0
   },
   "member_spread_deg": {
    "lat": 27.72,
    "lon": 316.4
   },
   "member_spread_now_deg": {
    "lat": 35.32,
    "lon": 77.59
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-14 09:01:00",
   "seed_lat": -13.52083,
   "seed_lon": 97.83333,
   "seed_alt_m": 15850.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 17:30:00",
    "lat": -22.28989,
    "lon": -178.0298,
    "alt_m": 15549.5
   },
   "member_spread_deg": {
    "lat": 27.73,
    "lon": 333.32
   },
   "member_spread_now_deg": {
    "lat": 2.03,
    "lon": 7.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}