{
 "generated_utc": "2026-08-29T17:27:05Z",
 "gfs_cycle_utc": "2026-08-29T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 495.0,
  "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_20260829_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260829_12Z.geojson.gz"
 },
 "counts": {
  "flights": 18,
  "members": 9,
  "rows": 75105
 },
 "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": 25.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 11:45:00",
    "lat": -61.55253,
    "lon": -25.02018,
    "alt_m": 12034.8
   },
   "member_spread_deg": {
    "lat": 21.08,
    "lon": 89.25
   },
   "member_spread_now_deg": {
    "lat": 5.59,
    "lon": 33.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 09:54:48",
   "seed_lat": 48.89583,
   "seed_lon": 80.75,
   "seed_alt_m": 13930.0,
   "seed_age_h": 7.42,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 39.61139,
    "lon": -90.46098,
    "alt_m": 14500.0
   },
   "member_spread_deg": {
    "lat": 36.53,
    "lon": 87.34
   },
   "member_spread_now_deg": {
    "lat": 0.68,
    "lon": 4.05
   },
   "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": 91.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 24.0795,
    "lon": -92.12219,
    "alt_m": 13033.9
   },
   "member_spread_deg": {
    "lat": 12.39,
    "lon": 87.6
   },
   "member_spread_now_deg": {
    "lat": 13.67,
    "lon": 9.74
   },
   "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 15:26:00",
   "seed_lat": 75.125,
   "seed_lon": -40.29167,
   "seed_alt_m": 12150.0,
   "seed_age_h": 1.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 15:00:00",
    "lat": 71.02881,
    "lon": 115.28128,
    "alt_m": 12004.9
   },
   "member_spread_deg": {
    "lat": 23.23,
    "lon": 256.78
   },
   "member_spread_now_deg": {
    "lat": 1.03,
    "lon": 0.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 15:17:00",
   "seed_lat": 45.27083,
   "seed_lon": -17.95833,
   "seed_alt_m": 13210.0,
   "seed_age_h": 2.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 14:45:00",
    "lat": 59.58157,
    "lon": 151.52635,
    "alt_m": 13016.6
   },
   "member_spread_deg": {
    "lat": 20.24,
    "lon": 325.05
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 1.93
   },
   "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": 5.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 11:45:00",
    "lat": 73.35783,
    "lon": 144.71755,
    "alt_m": 11912.1
   },
   "member_spread_deg": {
    "lat": 22.33,
    "lon": 349.2
   },
   "member_spread_now_deg": {
    "lat": 2.82,
    "lon": 0.69
   },
   "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": 123.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:45:00",
    "lat": 60.41798,
    "lon": -153.32667,
    "alt_m": 12640.9
   },
   "member_spread_deg": {
    "lat": 29.89,
    "lon": 201.59
   },
   "member_spread_now_deg": {
    "lat": 12.32,
    "lon": 354.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 332.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:45:00",
    "lat": 38.85417,
    "lon": 58.93609,
    "alt_m": 12988.9
   },
   "member_spread_deg": {
    "lat": 46.14,
    "lon": 225.99
   },
   "member_spread_now_deg": {
    "lat": 39.97,
    "lon": 254.13
   },
   "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": 106.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 69.29433,
    "lon": 47.99612,
    "alt_m": 13047.5
   },
   "member_spread_deg": {
    "lat": 41.65,
    "lon": 207.57
   },
   "member_spread_now_deg": {
    "lat": 33.45,
    "lon": 158.9
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 12:29:00",
   "seed_lat": 42.33333,
   "seed_lon": 53.91667,
   "seed_alt_m": 12550.0,
   "seed_age_h": 4.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 12:00:00",
    "lat": 31.85415,
    "lon": 168.68504,
    "alt_m": 12845.1
   },
   "member_spread_deg": {
    "lat": 32.04,
    "lon": 348.82
   },
   "member_spread_now_deg": {
    "lat": 0.65,
    "lon": 1.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 16:45:00",
   "seed_lat": 34.58333,
   "seed_lon": -143.375,
   "seed_alt_m": 12810.0,
   "seed_age_h": 0.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 16:45:00",
    "lat": 25.0161,
    "lon": -39.53144,
    "alt_m": 12984.4
   },
   "member_spread_deg": {
    "lat": 32.07,
    "lon": 112.6
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:01:00",
   "seed_lat": 73.33333,
   "seed_lon": -150.25,
   "seed_alt_m": 11900.0,
   "seed_age_h": 138.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 58.24033,
    "lon": 179.83864,
    "alt_m": 11997.1
   },
   "member_spread_deg": {
    "lat": 38.0,
    "lon": 140.46
   },
   "member_spread_now_deg": {
    "lat": 26.31,
    "lon": 230.01
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 03:35:45",
   "seed_lat": 73.54161,
   "seed_lon": -161.45831,
   "seed_alt_m": 12780.0,
   "seed_age_h": 13.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 58.83077,
    "lon": 30.66536,
    "alt_m": 12976.4
   },
   "member_spread_deg": {
    "lat": 28.8,
    "lon": 43.66
   },
   "member_spread_now_deg": {
    "lat": 1.31,
    "lon": 3.4
   },
   "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": 73.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:45:00",
    "lat": 47.95727,
    "lon": -102.0912,
    "alt_m": 13218.0
   },
   "member_spread_deg": {
    "lat": 12.56,
    "lon": 129.11
   },
   "member_spread_now_deg": {
    "lat": 3.52,
    "lon": 23.98
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 13:46:00",
   "seed_lat": 32.70833,
   "seed_lon": 38.875,
   "seed_alt_m": 16300.0,
   "seed_age_h": 3.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-05 13:15:00",
    "lat": 32.82638,
    "lon": -172.30384,
    "alt_m": 16355.8
   },
   "member_spread_deg": {
    "lat": 37.37,
    "lon": 331.01
   },
   "member_spread_now_deg": {
    "lat": 2.36,
    "lon": 3.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-29 08:26:00",
   "seed_lat": 44.58333,
   "seed_lon": 112.20833,
   "seed_alt_m": 12950.0,
   "seed_age_h": 8.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": 41.12295,
    "lon": -26.02269,
    "alt_m": 13378.5
   },
   "member_spread_deg": {
    "lat": 21.18,
    "lon": 133.64
   },
   "member_spread_now_deg": {
    "lat": 0.98,
    "lon": 5.45
   },
   "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": 284.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-05 11:30:00",
    "lat": -29.93962,
    "lon": -152.31179,
    "alt_m": 12220.2
   },
   "member_spread_deg": {
    "lat": 23.73,
    "lon": 243.72
   },
   "member_spread_now_deg": {
    "lat": 24.12,
    "lon": 97.16
   },
   "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 14:11:00",
   "seed_lat": -23.60417,
   "seed_lon": -83.91667,
   "seed_alt_m": 15600.0,
   "seed_age_h": 3.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-05 13:45:00",
    "lat": -7.20385,
    "lon": -65.96721,
    "alt_m": 15771.4
   },
   "member_spread_deg": {
    "lat": 34.15,
    "lon": 78.71
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 3.02
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}