{
 "generated_utc": "2026-09-16T17:27:10Z",
 "gfs_cycle_utc": "2026-09-16T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 483.5,
  "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_20260916_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260916_12Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 65016
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 14:26:18",
   "seed_lat": 33.6875,
   "seed_lon": -3.33333,
   "seed_alt_m": 14260.0,
   "seed_age_h": 2.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 14:00:00",
    "lat": 48.52358,
    "lon": 67.91317,
    "alt_m": 13892.3
   },
   "member_spread_deg": {
    "lat": 17.24,
    "lon": 118.61
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 0.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 16:01:00",
   "seed_lat": 57.70833,
   "seed_lon": -104.75,
   "seed_alt_m": 12010.0,
   "seed_age_h": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 15:30:00",
    "lat": 63.98454,
    "lon": 35.44666,
    "alt_m": 12454.2
   },
   "member_spread_deg": {
    "lat": 20.78,
    "lon": 73.33
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 0.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 16:27:00",
   "seed_lat": 33.08333,
   "seed_lon": -22.25,
   "seed_alt_m": 13610.0,
   "seed_age_h": 0.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 16:00:00",
    "lat": 43.90183,
    "lon": 149.84562,
    "alt_m": 13050.2
   },
   "member_spread_deg": {
    "lat": 12.0,
    "lon": 92.28
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 15:36:00",
   "seed_lat": 47.35417,
   "seed_lon": 18.125,
   "seed_alt_m": 13600.0,
   "seed_age_h": 1.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 15:00:00",
    "lat": 42.50727,
    "lon": 140.48383,
    "alt_m": 13360.1
   },
   "member_spread_deg": {
    "lat": 27.08,
    "lon": 346.43
   },
   "member_spread_now_deg": {
    "lat": 0.49,
    "lon": 0.96
   },
   "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": 267.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 8.41265,
    "lon": 136.48688,
    "alt_m": 14651.6
   },
   "member_spread_deg": {
    "lat": 60.56,
    "lon": 326.16
   },
   "member_spread_now_deg": {
    "lat": 41.36,
    "lon": 142.76
   },
   "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": 155.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 16.68717,
    "lon": -55.5171,
    "alt_m": 12780.9
   },
   "member_spread_deg": {
    "lat": 34.26,
    "lon": 239.46
   },
   "member_spread_now_deg": {
    "lat": 36.9,
    "lon": 172.29
   },
   "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": 321.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 40.89207,
    "lon": -125.24457,
    "alt_m": 12744.3
   },
   "member_spread_deg": {
    "lat": 34.85,
    "lon": 276.41
   },
   "member_spread_now_deg": {
    "lat": 24.26,
    "lon": 285.74
   },
   "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": 107.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 47.9844,
    "lon": 78.76698,
    "alt_m": 12609.2
   },
   "member_spread_deg": {
    "lat": 46.83,
    "lon": 185.76
   },
   "member_spread_now_deg": {
    "lat": 22.17,
    "lon": 35.79
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "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": 76.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 45.88419,
    "lon": -12.01412,
    "alt_m": 12928.7
   },
   "member_spread_deg": {
    "lat": 41.96,
    "lon": 170.26
   },
   "member_spread_now_deg": {
    "lat": 17.61,
    "lon": 21.99
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 16:35:45",
   "seed_lat": 76.41661,
   "seed_lon": -30.16665,
   "seed_alt_m": 12780.0,
   "seed_age_h": 0.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 16:00:00",
    "lat": 57.2247,
    "lon": -132.88396,
    "alt_m": 13122.0
   },
   "member_spread_deg": {
    "lat": 25.54,
    "lon": 97.12
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "NQ1W-6",
   "flight_id": "NQ1W-6_2026-09-11",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 13:26:00",
   "seed_lat": 29.875,
   "seed_lon": 3.41667,
   "seed_alt_m": 13310.0,
   "seed_age_h": 3.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 13:00:00",
    "lat": 49.65385,
    "lon": 163.94927,
    "alt_m": 12542.8
   },
   "member_spread_deg": {
    "lat": 11.26,
    "lon": 30.34
   },
   "member_spread_now_deg": {
    "lat": 1.03,
    "lon": 0.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 16:51:00",
   "seed_lat": 53.52083,
   "seed_lon": -53.75,
   "seed_alt_m": 15660.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 16:45:00",
    "lat": 59.04542,
    "lon": 71.81479,
    "alt_m": 15412.6
   },
   "member_spread_deg": {
    "lat": 40.31,
    "lon": 91.29
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 07:46:00",
   "seed_lat": 45.375,
   "seed_lon": 117.83333,
   "seed_alt_m": 13170.0,
   "seed_age_h": 9.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 11:45:00",
    "lat": 66.67493,
    "lon": 7.1284,
    "alt_m": 12690.5
   },
   "member_spread_deg": {
    "lat": 37.85,
    "lon": 84.55
   },
   "member_spread_now_deg": {
    "lat": 1.46,
    "lon": 2.32
   },
   "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": 187.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": 35.9712,
    "lon": -115.05817,
    "alt_m": 13156.1
   },
   "member_spread_deg": {
    "lat": 46.63,
    "lon": 331.11
   },
   "member_spread_now_deg": {
    "lat": 34.84,
    "lon": 289.7
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-16 09:28:30",
   "seed_lat": -18.9375,
   "seed_lon": 96.08333,
   "seed_alt_m": 15755.0,
   "seed_age_h": 7.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-23 11:30:00",
    "lat": -7.74475,
    "lon": 177.4508,
    "alt_m": 15749.2
   },
   "member_spread_deg": {
    "lat": 25.3,
    "lon": 350.52
   },
   "member_spread_now_deg": {
    "lat": 1.48,
    "lon": 2.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}