{
 "generated_utc": "2026-09-12T05:26:27Z",
 "gfs_cycle_utc": "2026-09-12T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 445.5,
  "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_20260912_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260912_00Z.geojson.gz"
 },
 "counts": {
  "flights": 15,
  "members": 9,
  "rows": 62586
 },
 "flights": [
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 15:35:48",
   "seed_lat": 41.47917,
   "seed_lon": -16.95833,
   "seed_alt_m": 14600.0,
   "seed_age_h": 13.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 41.53087,
    "lon": 12.88436,
    "alt_m": 13995.2
   },
   "member_spread_deg": {
    "lat": 20.46,
    "lon": 88.25
   },
   "member_spread_now_deg": {
    "lat": 5.62,
    "lon": 3.92
   },
   "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": 168.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 23:45:00",
    "lat": 60.94365,
    "lon": -22.25425,
    "alt_m": 11719.2
   },
   "member_spread_deg": {
    "lat": 22.0,
    "lon": 350.13
   },
   "member_spread_now_deg": {
    "lat": 9.88,
    "lon": 197.52
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 19:02:00",
   "seed_lat": 29.3125,
   "seed_lon": -43.54167,
   "seed_alt_m": 13720.0,
   "seed_age_h": 10.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 38.9914,
    "lon": 48.34128,
    "alt_m": 13414.2
   },
   "member_spread_deg": {
    "lat": 15.48,
    "lon": 86.41
   },
   "member_spread_now_deg": {
    "lat": 1.31,
    "lon": 2.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 22:36:00",
   "seed_lat": 51.33333,
   "seed_lon": -81.83333,
   "seed_alt_m": 13260.0,
   "seed_age_h": 6.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 46.35046,
    "lon": 50.90394,
    "alt_m": 13218.6
   },
   "member_spread_deg": {
    "lat": 27.7,
    "lon": 155.95
   },
   "member_spread_now_deg": {
    "lat": 2.63,
    "lon": 4.62
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 283.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 60.59296,
    "lon": -84.86897,
    "alt_m": 11933.8
   },
   "member_spread_deg": {
    "lat": 42.67,
    "lon": 312.72
   },
   "member_spread_now_deg": {
    "lat": 46.98,
    "lon": 323.55
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 159.8,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 12.0481,
    "lon": 160.63157,
    "alt_m": 14627.9
   },
   "member_spread_deg": {
    "lat": 34.38,
    "lon": 334.87
   },
   "member_spread_now_deg": {
    "lat": 30.73,
    "lon": 226.46
   },
   "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": 47.92,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 28.5313,
    "lon": -69.28823,
    "alt_m": 12825.1
   },
   "member_spread_deg": {
    "lat": 36.33,
    "lon": 245.68
   },
   "member_spread_now_deg": {
    "lat": 9.01,
    "lon": 50.07
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 213.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 32.74619,
    "lon": -175.55499,
    "alt_m": 12886.3
   },
   "member_spread_deg": {
    "lat": 20.46,
    "lon": 174.65
   },
   "member_spread_now_deg": {
    "lat": 22.94,
    "lon": 310.93
   },
   "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 04:15:00",
   "seed_lat": 45.125,
   "seed_lon": 154.20833,
   "seed_alt_m": 12660.0,
   "seed_age_h": 1.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 04:15:00",
    "lat": 51.06635,
    "lon": -140.36999,
    "alt_m": 12602.2
   },
   "member_spread_deg": {
    "lat": 37.85,
    "lon": 145.66
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.75
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 12:36:00",
   "seed_lat": 55.875,
   "seed_lon": -6.45833,
   "seed_alt_m": 12800.0,
   "seed_age_h": 16.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 50.70903,
    "lon": -157.87249,
    "alt_m": 12655.7
   },
   "member_spread_deg": {
    "lat": 15.65,
    "lon": 329.4
   },
   "member_spread_now_deg": {
    "lat": 12.99,
    "lon": 2.69
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 03:55:45",
   "seed_lat": 60.18745,
   "seed_lon": -174.66665,
   "seed_alt_m": 13120.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 03:30:00",
    "lat": 71.08662,
    "lon": 18.724,
    "alt_m": 12843.3
   },
   "member_spread_deg": {
    "lat": 17.01,
    "lon": 144.66
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.82
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 01:21:00",
   "seed_lat": 23.89583,
   "seed_lon": -142.91667,
   "seed_alt_m": 16440.0,
   "seed_age_h": 3.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-19 00:45:00",
    "lat": 53.90218,
    "lon": 5.87732,
    "alt_m": 15659.4
   },
   "member_spread_deg": {
    "lat": 36.52,
    "lon": 150.92
   },
   "member_spread_now_deg": {
    "lat": 1.76,
    "lon": 3.9
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-11 15:46:00",
   "seed_lat": 38.6875,
   "seed_lon": 9.54167,
   "seed_alt_m": 13310.0,
   "seed_age_h": 13.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:45:00",
    "lat": 36.92044,
    "lon": -149.93265,
    "alt_m": 13272.1
   },
   "member_spread_deg": {
    "lat": 28.85,
    "lon": 58.8
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 3.17
   },
   "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": 79.74,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-18 23:30:00",
    "lat": 43.22258,
    "lon": 156.45256,
    "alt_m": 13303.5
   },
   "member_spread_deg": {
    "lat": 30.17,
    "lon": 272.94
   },
   "member_spread_now_deg": {
    "lat": 14.44,
    "lon": 81.54
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-12 04:21:00",
   "seed_lat": -20.39583,
   "seed_lon": 84.29167,
   "seed_alt_m": 15650.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-19 04:15:00",
    "lat": -19.7915,
    "lon": -142.77864,
    "alt_m": 15623.8
   },
   "member_spread_deg": {
    "lat": 31.42,
    "lon": 309.65
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.94
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}