{
 "generated_utc": "2026-08-24T17:27:05Z",
 "gfs_cycle_utc": "2026-08-24T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 461.5,
  "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_20260824_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260824_12Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 90729
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-22 13:43:40",
   "seed_lat": -61.64583,
   "seed_lon": 25.04168,
   "seed_alt_m": 12480.0,
   "seed_age_h": 51.61,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": -64.30567,
    "lon": 131.17061,
    "alt_m": 12246.5
   },
   "member_spread_deg": {
    "lat": 20.49,
    "lon": 209.13
   },
   "member_spread_now_deg": {
    "lat": 9.48,
    "lon": 56.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:47:17",
   "seed_lat": 57.39583,
   "seed_lon": -60.0,
   "seed_alt_m": 13900.0,
   "seed_age_h": 0.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-31 16:15:00",
    "lat": 46.43214,
    "lon": 167.08,
    "alt_m": 13900.3
   },
   "member_spread_deg": {
    "lat": 5.98,
    "lon": 129.75
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 1.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:49:00",
   "seed_lat": 44.66667,
   "seed_lon": -110.79167,
   "seed_alt_m": 12970.0,
   "seed_age_h": 0.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 16:15:00",
    "lat": 45.70476,
    "lon": 67.00221,
    "alt_m": 12516.8
   },
   "member_spread_deg": {
    "lat": 27.99,
    "lon": 65.87
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.18
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 08:01:00",
   "seed_lat": 51.77083,
   "seed_lon": 124.25,
   "seed_alt_m": 12400.0,
   "seed_age_h": 9.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": 54.12299,
    "lon": -7.16813,
    "alt_m": 12198.1
   },
   "member_spread_deg": {
    "lat": 24.36,
    "lon": 110.27
   },
   "member_spread_now_deg": {
    "lat": 1.31,
    "lon": 3.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 23:47:00",
   "seed_lat": 40.66667,
   "seed_lon": -147.58333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 17.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 39.38047,
    "lon": -18.98052,
    "alt_m": 13478.4
   },
   "member_spread_deg": {
    "lat": 28.95,
    "lon": 93.8
   },
   "member_spread_now_deg": {
    "lat": 0.44,
    "lon": 4.72
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 02:23:00",
   "seed_lat": 72.83333,
   "seed_lon": -139.66667,
   "seed_alt_m": 11840.0,
   "seed_age_h": 14.95,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": 73.40858,
    "lon": 179.03017,
    "alt_m": 11810.6
   },
   "member_spread_deg": {
    "lat": 32.15,
    "lon": 239.75
   },
   "member_spread_now_deg": {
    "lat": 10.14,
    "lon": 19.89
   },
   "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": 3.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 13:45:00",
    "lat": 63.84756,
    "lon": 112.08157,
    "alt_m": 12871.6
   },
   "member_spread_deg": {
    "lat": 27.81,
    "lon": 351.87
   },
   "member_spread_now_deg": {
    "lat": 1.2,
    "lon": 2.74
   },
   "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": 212.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 26.33417,
    "lon": -39.50579,
    "alt_m": 13341.7
   },
   "member_spread_deg": {
    "lat": 41.39,
    "lon": 271.6
   },
   "member_spread_now_deg": {
    "lat": 30.45,
    "lon": 99.29
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 04:33:49",
   "seed_lat": 54.95833,
   "seed_lon": 154.16667,
   "seed_alt_m": 13250.0,
   "seed_age_h": 12.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": 61.13977,
    "lon": -50.67277,
    "alt_m": 13203.9
   },
   "member_spread_deg": {
    "lat": 34.08,
    "lon": 307.61
   },
   "member_spread_now_deg": {
    "lat": 4.53,
    "lon": 358.15
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 293.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 56.27142,
    "lon": 123.36152,
    "alt_m": 12720.0
   },
   "member_spread_deg": {
    "lat": 39.3,
    "lon": 306.12
   },
   "member_spread_now_deg": {
    "lat": 39.02,
    "lon": 301.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:19:00",
   "seed_lat": 25.33333,
   "seed_lon": -28.04167,
   "seed_alt_m": 12830.0,
   "seed_age_h": 1.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 15:45:00",
    "lat": 40.43449,
    "lon": 165.51646,
    "alt_m": 12478.1
   },
   "member_spread_deg": {
    "lat": 14.48,
    "lon": 146.54
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 04:20:00",
   "seed_lat": 22.60417,
   "seed_lon": -175.375,
   "seed_alt_m": 13080.0,
   "seed_age_h": 13.0,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 42.30513,
    "lon": -39.11263,
    "alt_m": 13197.4
   },
   "member_spread_deg": {
    "lat": 10.81,
    "lon": 84.8
   },
   "member_spread_now_deg": {
    "lat": 3.11,
    "lon": 3.26
   },
   "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": 18.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": 64.0483,
    "lon": 91.0522,
    "alt_m": 12173.9
   },
   "member_spread_deg": {
    "lat": 29.53,
    "lon": 197.22
   },
   "member_spread_now_deg": {
    "lat": 7.85,
    "lon": 15.3
   },
   "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": 260.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 21.87145,
    "lon": -17.77553,
    "alt_m": 11201.7
   },
   "member_spread_deg": {
    "lat": 56.73,
    "lon": 305.59
   },
   "member_spread_now_deg": {
    "lat": 42.16,
    "lon": 134.57
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-23 01:45:45",
   "seed_lat": 81.20828,
   "seed_lon": -145.74998,
   "seed_alt_m": 12720.0,
   "seed_age_h": 39.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": 74.61541,
    "lon": -35.70213,
    "alt_m": 12934.2
   },
   "member_spread_deg": {
    "lat": 21.11,
    "lon": 148.74
   },
   "member_spread_now_deg": {
    "lat": 4.2,
    "lon": 142.4
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-24 16:57:38",
   "seed_lat": 35.22266,
   "seed_lon": -24.3055,
   "seed_alt_m": 13436.0,
   "seed_age_h": 0.37,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:00:00",
    "lat": 52.31411,
    "lon": -139.55342,
    "alt_m": 12938.3
   },
   "member_spread_deg": {
    "lat": 19.26,
    "lon": 358.86
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:03:30",
   "seed_lat": 18.77083,
   "seed_lon": 0.75,
   "seed_alt_m": 16715.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 15:30:00",
    "lat": 22.48733,
    "lon": -30.01815,
    "alt_m": 16450.9
   },
   "member_spread_deg": {
    "lat": 18.19,
    "lon": 23.18
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 15:51:00",
   "seed_lat": 42.33333,
   "seed_lon": -31.875,
   "seed_alt_m": 13530.0,
   "seed_age_h": 1.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 15:15:00",
    "lat": 51.21444,
    "lon": 170.7535,
    "alt_m": 13228.5
   },
   "member_spread_deg": {
    "lat": 17.13,
    "lon": 349.89
   },
   "member_spread_now_deg": {
    "lat": 0.64,
    "lon": 0.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 16:55:23",
   "seed_lat": 55.87495,
   "seed_lon": -43.54164,
   "seed_alt_m": 13300.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 17:00:00",
    "lat": 43.71252,
    "lon": 120.40836,
    "alt_m": 13240.0
   },
   "member_spread_deg": {
    "lat": 22.26,
    "lon": 77.31
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.79
   },
   "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": 164.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": -18.85528,
    "lon": 0.92336,
    "alt_m": 12636.9
   },
   "member_spread_deg": {
    "lat": 29.68,
    "lon": 149.04
   },
   "member_spread_now_deg": {
    "lat": 8.75,
    "lon": 307.02
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 298.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-31 11:45:00",
    "lat": -18.40785,
    "lon": 118.07918,
    "alt_m": 16131.1
   },
   "member_spread_deg": {
    "lat": 33.55,
    "lon": 237.19
   },
   "member_spread_now_deg": {
    "lat": 35.62,
    "lon": 237.54
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-24 08:06:00",
   "seed_lat": -23.4375,
   "seed_lon": 133.08333,
   "seed_alt_m": 15530.0,
   "seed_age_h": 9.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-31 11:30:00",
    "lat": -25.76839,
    "lon": -30.68583,
    "alt_m": 15565.7
   },
   "member_spread_deg": {
    "lat": 48.53,
    "lon": 48.89
   },
   "member_spread_now_deg": {
    "lat": 1.15,
    "lon": 6.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}