{
 "generated_utc": "2026-08-17T11:27:15Z",
 "gfs_cycle_utc": "2026-08-17T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 481.5,
  "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_20260817_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260817_06Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 88479
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 09:08:40",
   "seed_lat": -54.125,
   "seed_lon": 105.20835,
   "seed_alt_m": 12270.0,
   "seed_age_h": 2.19,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 08:45:00",
    "lat": -60.46728,
    "lon": 135.66129,
    "alt_m": 12514.0
   },
   "member_spread_deg": {
    "lat": 25.05,
    "lon": 56.86
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:25:18",
   "seed_lat": 52.77083,
   "seed_lon": 116.91667,
   "seed_alt_m": 12570.0,
   "seed_age_h": 0.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 10:00:00",
    "lat": 84.83391,
    "lon": 0.52182,
    "alt_m": 12103.8
   },
   "member_spread_deg": {
    "lat": 21.96,
    "lon": 228.6
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 1.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 01:17:18",
   "seed_lat": 41.95833,
   "seed_lon": 177.125,
   "seed_alt_m": 14090.0,
   "seed_age_h": 10.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 46.91469,
    "lon": -67.22864,
    "alt_m": 13939.6
   },
   "member_spread_deg": {
    "lat": 20.31,
    "lon": 103.63
   },
   "member_spread_now_deg": {
    "lat": 0.94,
    "lon": 2.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:24:00",
   "seed_lat": 47.54167,
   "seed_lon": 66.08333,
   "seed_alt_m": 12420.0,
   "seed_age_h": 0.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 10:00:00",
    "lat": 41.67908,
    "lon": -126.40846,
    "alt_m": 12911.8
   },
   "member_spread_deg": {
    "lat": 34.83,
    "lon": 52.01
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 179.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": -4.13355,
    "lon": -78.59543,
    "alt_m": 14047.6
   },
   "member_spread_deg": {
    "lat": 50.31,
    "lon": 151.19
   },
   "member_spread_now_deg": {
    "lat": 33.79,
    "lon": 84.02
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 318.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": 46.88751,
    "lon": 90.2791,
    "alt_m": 13294.3
   },
   "member_spread_deg": {
    "lat": 105.95,
    "lon": 277.13
   },
   "member_spread_now_deg": {
    "lat": 72.13,
    "lon": 216.08
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 23:31:00",
   "seed_lat": 49.47917,
   "seed_lon": -107.5,
   "seed_alt_m": 12730.0,
   "seed_age_h": 11.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": 55.88954,
    "lon": 100.83139,
    "alt_m": 12482.4
   },
   "member_spread_deg": {
    "lat": 30.79,
    "lon": 80.34
   },
   "member_spread_now_deg": {
    "lat": 1.15,
    "lon": 4.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 12:32:00",
   "seed_lat": 40.41667,
   "seed_lon": 26.29167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 22.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": 58.75591,
    "lon": -175.14248,
    "alt_m": 13184.4
   },
   "member_spread_deg": {
    "lat": 25.31,
    "lon": 56.11
   },
   "member_spread_now_deg": {
    "lat": 2.93,
    "lon": 8.46
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:18:00",
   "seed_lat": 87.5,
   "seed_lon": -76.08333,
   "seed_alt_m": 11730.0,
   "seed_age_h": 13.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 62.52811,
    "lon": 163.85958,
    "alt_m": 11860.5
   },
   "member_spread_deg": {
    "lat": 34.66,
    "lon": 329.13
   },
   "member_spread_now_deg": {
    "lat": 2.24,
    "lon": 36.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:08:00",
   "seed_lat": 59.16667,
   "seed_lon": -78.625,
   "seed_alt_m": 12500.0,
   "seed_age_h": 13.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 62.48646,
    "lon": 21.67316,
    "alt_m": 12427.2
   },
   "member_spread_deg": {
    "lat": 27.56,
    "lon": 123.05
   },
   "member_spread_now_deg": {
    "lat": 0.54,
    "lon": 6.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 38.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 20.57691,
    "lon": -88.0095,
    "alt_m": 13330.2
   },
   "member_spread_deg": {
    "lat": 22.49,
    "lon": 68.74
   },
   "member_spread_now_deg": {
    "lat": 6.63,
    "lon": 21.75
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 00:47:18",
   "seed_lat": 65.0,
   "seed_lon": 62.95833,
   "seed_alt_m": 13240.0,
   "seed_age_h": 10.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 57.10159,
    "lon": 159.80245,
    "alt_m": 13136.8
   },
   "member_spread_deg": {
    "lat": 16.03,
    "lon": 333.65
   },
   "member_spread_now_deg": {
    "lat": 0.78,
    "lon": 3.98
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 119.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 57.05822,
    "lon": 120.49424,
    "alt_m": 12507.9
   },
   "member_spread_deg": {
    "lat": 19.17,
    "lon": 240.79
   },
   "member_spread_now_deg": {
    "lat": 19.37,
    "lon": 239.94
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:45:00",
   "seed_lat": 43.72917,
   "seed_lon": 99.91667,
   "seed_alt_m": 12470.0,
   "seed_age_h": 0.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 10:45:00",
    "lat": 23.19929,
    "lon": -128.49435,
    "alt_m": 12891.2
   },
   "member_spread_deg": {
    "lat": 57.67,
    "lon": 350.3
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 19:31:00",
   "seed_lat": 70.25,
   "seed_lon": -41.83333,
   "seed_alt_m": 12260.0,
   "seed_age_h": 15.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": 80.37352,
    "lon": 166.08935,
    "alt_m": 11756.8
   },
   "member_spread_deg": {
    "lat": 32.53,
    "lon": 316.33
   },
   "member_spread_now_deg": {
    "lat": 2.07,
    "lon": 4.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 86.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 44.04745,
    "lon": 35.44547,
    "alt_m": 11145.1
   },
   "member_spread_deg": {
    "lat": 23.19,
    "lon": 151.56
   },
   "member_spread_now_deg": {
    "lat": 34.66,
    "lon": 20.09
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 10:13:15",
   "seed_lat": 64.74995,
   "seed_lon": 113.16669,
   "seed_alt_m": 13060.0,
   "seed_age_h": 1.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 09:45:00",
    "lat": 85.52463,
    "lon": -46.69953,
    "alt_m": 12805.9
   },
   "member_spread_deg": {
    "lat": 27.24,
    "lon": 309.3
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 07:46:00",
   "seed_lat": 12.54167,
   "seed_lon": 133.08333,
   "seed_alt_m": 16600.0,
   "seed_age_h": 3.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 07:15:00",
    "lat": 10.16961,
    "lon": 11.60446,
    "alt_m": 16417.9
   },
   "member_spread_deg": {
    "lat": 43.0,
    "lon": 124.36
   },
   "member_spread_now_deg": {
    "lat": 1.91,
    "lon": 1.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 319.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": 29.32773,
    "lon": -129.54572,
    "alt_m": 13199.0
   },
   "member_spread_deg": {
    "lat": 49.27,
    "lon": 321.94
   },
   "member_spread_now_deg": {
    "lat": 30.7,
    "lon": 262.6
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 05:16:00",
   "seed_lat": 37.91667,
   "seed_lon": 177.08333,
   "seed_alt_m": 13420.0,
   "seed_age_h": 6.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": 48.99617,
    "lon": -69.18287,
    "alt_m": 12884.1
   },
   "member_spread_deg": {
    "lat": 26.02,
    "lon": 120.34
   },
   "member_spread_now_deg": {
    "lat": 0.69,
    "lon": 359.65
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:59:00",
   "seed_lat": -25.85417,
   "seed_lon": -110.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 12.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-24 05:30:00",
    "lat": -28.68722,
    "lon": 156.09081,
    "alt_m": 12023.2
   },
   "member_spread_deg": {
    "lat": 12.08,
    "lon": 134.11
   },
   "member_spread_now_deg": {
    "lat": 4.65,
    "lon": 9.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 124.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-24 05:45:00",
    "lat": -12.89121,
    "lon": -3.06418,
    "alt_m": 15963.9
   },
   "member_spread_deg": {
    "lat": 22.32,
    "lon": 230.84
   },
   "member_spread_now_deg": {
    "lat": 10.34,
    "lon": 114.6
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}