{
 "generated_utc": "2026-09-15T05:26:23Z",
 "gfs_cycle_utc": "2026-09-15T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 447.5,
  "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_20260915_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260915_00Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 65889
 },
 "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": 12.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:45:00",
    "lat": 46.52562,
    "lon": 55.85001,
    "alt_m": 14001.8
   },
   "member_spread_deg": {
    "lat": 11.73,
    "lon": 123.68
   },
   "member_spread_now_deg": {
    "lat": 1.57,
    "lon": 3.72
   },
   "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": 240.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-21 23:45:00",
    "lat": 59.63097,
    "lon": 15.34015,
    "alt_m": 12312.8
   },
   "member_spread_deg": {
    "lat": 30.13,
    "lon": 207.42
   },
   "member_spread_now_deg": {
    "lat": 27.81,
    "lon": 292.9
   },
   "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": 10.88,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 27.18048,
    "lon": 3.52192,
    "alt_m": 13473.4
   },
   "member_spread_deg": {
    "lat": 35.02,
    "lon": 93.17
   },
   "member_spread_now_deg": {
    "lat": 4.01,
    "lon": 0.85
   },
   "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": 13.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 46.24035,
    "lon": 80.81153,
    "alt_m": 13437.1
   },
   "member_spread_deg": {
    "lat": 4.4,
    "lon": 105.33
   },
   "member_spread_now_deg": {
    "lat": 3.11,
    "lon": 3.43
   },
   "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": 231.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 2.94471,
    "lon": -166.38457,
    "alt_m": 14581.6
   },
   "member_spread_deg": {
    "lat": 52.47,
    "lon": 345.63
   },
   "member_spread_now_deg": {
    "lat": 36.64,
    "lon": 143.88
   },
   "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": 119.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 14.46078,
    "lon": -61.72928,
    "alt_m": 12803.1
   },
   "member_spread_deg": {
    "lat": 43.6,
    "lon": 204.44
   },
   "member_spread_now_deg": {
    "lat": 23.33,
    "lon": 176.7
   },
   "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": 285.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 37.22412,
    "lon": -151.99713,
    "alt_m": 12814.4
   },
   "member_spread_deg": {
    "lat": 30.17,
    "lon": 302.74
   },
   "member_spread_now_deg": {
    "lat": 30.24,
    "lon": 297.34
   },
   "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": 71.25,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 59.95315,
    "lon": 47.05953,
    "alt_m": 12553.6
   },
   "member_spread_deg": {
    "lat": 35.31,
    "lon": 162.87
   },
   "member_spread_now_deg": {
    "lat": 2.78,
    "lon": 23.93
   },
   "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": 40.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 54.95413,
    "lon": -109.99846,
    "alt_m": 12611.0
   },
   "member_spread_deg": {
    "lat": 32.41,
    "lon": 108.73
   },
   "member_spread_now_deg": {
    "lat": 7.51,
    "lon": 16.08
   },
   "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": 8.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:45:00",
    "lat": 58.55542,
    "lon": 171.67283,
    "alt_m": 13224.1
   },
   "member_spread_deg": {
    "lat": 23.2,
    "lon": 348.75
   },
   "member_spread_now_deg": {
    "lat": 0.77,
    "lon": 3.86
   },
   "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": 14.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 41.5924,
    "lon": 86.14542,
    "alt_m": 12984.1
   },
   "member_spread_deg": {
    "lat": 6.08,
    "lon": 75.1
   },
   "member_spread_now_deg": {
    "lat": 1.98,
    "lon": 1.51
   },
   "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": 7.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 55.94614,
    "lon": 40.4863,
    "alt_m": 15361.0
   },
   "member_spread_deg": {
    "lat": 65.33,
    "lon": 138.91
   },
   "member_spread_now_deg": {
    "lat": 1.64,
    "lon": 9.97
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 04:51:00",
   "seed_lat": 49.70833,
   "seed_lon": 93.125,
   "seed_alt_m": 13230.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-22 04:45:00",
    "lat": 46.01015,
    "lon": -41.43183,
    "alt_m": 12997.4
   },
   "member_spread_deg": {
    "lat": 19.71,
    "lon": 107.81
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.27
   },
   "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": 151.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-21 23:30:00",
    "lat": 47.96415,
    "lon": -75.11509,
    "alt_m": 13243.3
   },
   "member_spread_deg": {
    "lat": 23.49,
    "lon": 340.41
   },
   "member_spread_now_deg": {
    "lat": 33.08,
    "lon": 88.61
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-15 04:21:00",
   "seed_lat": -13.9375,
   "seed_lon": 95.04167,
   "seed_alt_m": 15840.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-22 03:45:00",
    "lat": -9.61483,
    "lon": 171.42112,
    "alt_m": 15854.8
   },
   "member_spread_deg": {
    "lat": 25.8,
    "lon": 346.79
   },
   "member_spread_now_deg": {
    "lat": 0.16,
    "lon": 0.52
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}