{
 "generated_utc": "2026-08-27T05:27:20Z",
 "gfs_cycle_utc": "2026-08-27T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 482.5,
  "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_20260827_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260827_00Z.geojson.gz"
 },
 "counts": {
  "flights": 20,
  "members": 9,
  "rows": 79695
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 23:18:40",
   "seed_lat": -70.79167,
   "seed_lon": -148.58332,
   "seed_alt_m": 12300.0,
   "seed_age_h": 6.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": -81.5422,
    "lon": -85.56247,
    "alt_m": 12122.2
   },
   "member_spread_deg": {
    "lat": 28.29,
    "lon": 242.78
   },
   "member_spread_now_deg": {
    "lat": 1.34,
    "lon": 4.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:43:18",
   "seed_lat": 35.89583,
   "seed_lon": -6.625,
   "seed_alt_m": 14390.0,
   "seed_age_h": 12.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 45.02387,
    "lon": -122.24172,
    "alt_m": 13970.2
   },
   "member_spread_deg": {
    "lat": 22.47,
    "lon": 327.19
   },
   "member_spread_now_deg": {
    "lat": 2.57,
    "lon": 12.43
   },
   "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": 31.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 36.26588,
    "lon": -18.39797,
    "alt_m": 13055.7
   },
   "member_spread_deg": {
    "lat": 16.35,
    "lon": 74.52
   },
   "member_spread_now_deg": {
    "lat": 3.42,
    "lon": 3.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:06:00",
   "seed_lat": 59.25,
   "seed_lon": -136.5,
   "seed_alt_m": 12380.0,
   "seed_age_h": 3.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 01:30:00",
    "lat": 73.01658,
    "lon": 19.81973,
    "alt_m": 12097.3
   },
   "member_spread_deg": {
    "lat": 29.71,
    "lon": 221.3
   },
   "member_spread_now_deg": {
    "lat": 1.85,
    "lon": 0.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 21:52:00",
   "seed_lat": 43.79167,
   "seed_lon": -94.20833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 7.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 41.94993,
    "lon": 65.94022,
    "alt_m": 13109.5
   },
   "member_spread_deg": {
    "lat": 31.16,
    "lon": 138.7
   },
   "member_spread_now_deg": {
    "lat": 1.32,
    "lon": 2.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:38:00",
   "seed_lat": 83.20833,
   "seed_lon": -24.91667,
   "seed_alt_m": 11920.0,
   "seed_age_h": 15.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 59.32427,
    "lon": 149.81155,
    "alt_m": 12250.6
   },
   "member_spread_deg": {
    "lat": 26.48,
    "lon": 309.92
   },
   "member_spread_now_deg": {
    "lat": 2.25,
    "lon": 18.79
   },
   "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": 63.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 58.87554,
    "lon": 139.41794,
    "alt_m": 12795.5
   },
   "member_spread_deg": {
    "lat": 20.05,
    "lon": 318.31
   },
   "member_spread_now_deg": {
    "lat": 21.2,
    "lon": 79.84
   },
   "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": 272.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 29.82406,
    "lon": 3.41551,
    "alt_m": 13191.8
   },
   "member_spread_deg": {
    "lat": 43.49,
    "lon": 240.82
   },
   "member_spread_now_deg": {
    "lat": 51.3,
    "lon": 182.84
   },
   "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": 46.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 54.25795,
    "lon": -6.38307,
    "alt_m": 13224.3
   },
   "member_spread_deg": {
    "lat": 27.66,
    "lon": 189.95
   },
   "member_spread_now_deg": {
    "lat": 24.63,
    "lon": 39.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:24:00",
   "seed_lat": 39.64583,
   "seed_lon": 8.25,
   "seed_alt_m": 12840.0,
   "seed_age_h": 15.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 36.96141,
    "lon": -166.81053,
    "alt_m": 12863.3
   },
   "member_spread_deg": {
    "lat": 17.77,
    "lon": 347.91
   },
   "member_spread_now_deg": {
    "lat": 3.61,
    "lon": 4.93
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 04:25:00",
   "seed_lat": 28.08333,
   "seed_lon": -169.5,
   "seed_alt_m": 12940.0,
   "seed_age_h": 0.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 04:30:00",
    "lat": 25.50618,
    "lon": -57.60488,
    "alt_m": 13103.8
   },
   "member_spread_deg": {
    "lat": 14.32,
    "lon": 46.21
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.46
   },
   "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": 78.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 69.22293,
    "lon": 143.66758,
    "alt_m": 12442.0
   },
   "member_spread_deg": {
    "lat": 21.18,
    "lon": 178.56
   },
   "member_spread_now_deg": {
    "lat": 19.03,
    "lon": 345.79
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 320.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 28.135,
    "lon": -14.12193,
    "alt_m": 11201.8
   },
   "member_spread_deg": {
    "lat": 36.99,
    "lon": 313.61
   },
   "member_spread_now_deg": {
    "lat": 47.06,
    "lon": 326.45
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 03:00:45",
   "seed_lat": 77.66661,
   "seed_lon": 155.16669,
   "seed_alt_m": 12690.0,
   "seed_age_h": 2.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 02:30:00",
    "lat": 64.72054,
    "lon": -24.20108,
    "alt_m": 12778.0
   },
   "member_spread_deg": {
    "lat": 21.06,
    "lon": 144.24
   },
   "member_spread_now_deg": {
    "lat": 0.59,
    "lon": 2.33
   },
   "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": 13.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 46.92448,
    "lon": -147.59018,
    "alt_m": 13482.7
   },
   "member_spread_deg": {
    "lat": 11.94,
    "lon": 52.43
   },
   "member_spread_now_deg": {
    "lat": 1.19,
    "lon": 2.91
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:11:00",
   "seed_lat": 29.6875,
   "seed_lon": -2.45833,
   "seed_alt_m": 16600.0,
   "seed_age_h": 13.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:45:00",
    "lat": 52.25719,
    "lon": 117.3695,
    "alt_m": 15850.5
   },
   "member_spread_deg": {
    "lat": 18.84,
    "lon": 334.07
   },
   "member_spread_now_deg": {
    "lat": 2.87,
    "lon": 6.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 14:31:00",
   "seed_lat": 46.83333,
   "seed_lon": 23.125,
   "seed_alt_m": 13050.0,
   "seed_age_h": 14.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 35.50043,
    "lon": -123.05658,
    "alt_m": 13137.7
   },
   "member_spread_deg": {
    "lat": 28.13,
    "lon": 57.82
   },
   "member_spread_now_deg": {
    "lat": 3.57,
    "lon": 4.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 15:25:23",
   "seed_lat": 50.93745,
   "seed_lon": 2.25002,
   "seed_alt_m": 13420.0,
   "seed_age_h": 13.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": 39.97602,
    "lon": 177.55593,
    "alt_m": 13520.4
   },
   "member_spread_deg": {
    "lat": 32.91,
    "lon": 353.84
   },
   "member_spread_now_deg": {
    "lat": 2.79,
    "lon": 7.01
   },
   "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": 224.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 23:30:00",
    "lat": -28.55022,
    "lon": 91.1812,
    "alt_m": 12157.1
   },
   "member_spread_deg": {
    "lat": 21.33,
    "lon": 319.55
   },
   "member_spread_now_deg": {
    "lat": 22.82,
    "lon": 128.83
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:56:00",
   "seed_lat": -23.45833,
   "seed_lon": -160.20833,
   "seed_alt_m": 15500.0,
   "seed_age_h": 2.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 02:30:00",
    "lat": -16.97048,
    "lon": -19.37151,
    "alt_m": 15677.9
   },
   "member_spread_deg": {
    "lat": 44.14,
    "lon": 125.4
   },
   "member_spread_now_deg": {
    "lat": 0.32,
    "lon": 2.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}