{
 "generated_utc": "2026-08-10T23:27:39Z",
 "gfs_cycle_utc": "2026-08-10T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 488.5,
  "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_20260810_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260810_18Z.geojson.gz"
 },
 "counts": {
  "flights": 26,
  "members": 9,
  "rows": 123498
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 22:53:40",
   "seed_lat": -45.10417,
   "seed_lon": -141.24999,
   "seed_alt_m": 12330.0,
   "seed_age_h": 0.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 23:00:00",
    "lat": -60.40712,
    "lon": 148.35063,
    "alt_m": 12597.5
   },
   "member_spread_deg": {
    "lat": 28.99,
    "lon": 344.49
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.11
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 20:48:19",
   "seed_lat": 48.79167,
   "seed_lon": -33.95833,
   "seed_alt_m": 12620.0,
   "seed_age_h": 2.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 20:15:00",
    "lat": 55.62939,
    "lon": 118.45888,
    "alt_m": 12750.9
   },
   "member_spread_deg": {
    "lat": 34.87,
    "lon": 28.75
   },
   "member_spread_now_deg": {
    "lat": 0.78,
    "lon": 0.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 10:45:19",
   "seed_lat": 43.70833,
   "seed_lon": 98.83333,
   "seed_alt_m": 14180.0,
   "seed_age_h": 12.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 33.10864,
    "lon": 156.47993,
    "alt_m": 14699.1
   },
   "member_spread_deg": {
    "lat": 15.29,
    "lon": 27.65
   },
   "member_spread_now_deg": {
    "lat": 4.34,
    "lon": 5.79
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 18:54:00",
   "seed_lat": 41.20833,
   "seed_lon": -43.79167,
   "seed_alt_m": 12880.0,
   "seed_age_h": 4.43,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 18:30:00",
    "lat": 42.93873,
    "lon": 104.4908,
    "alt_m": 12639.9
   },
   "member_spread_deg": {
    "lat": 6.11,
    "lon": 85.7
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 1.57
   },
   "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": 23.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": -1.05203,
    "lon": -111.89175,
    "alt_m": 14091.2
   },
   "member_spread_deg": {
    "lat": 30.02,
    "lon": 36.17
   },
   "member_spread_now_deg": {
    "lat": 7.57,
    "lon": 7.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 162.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 31.50993,
    "lon": -39.87358,
    "alt_m": 13541.8
   },
   "member_spread_deg": {
    "lat": 70.39,
    "lon": 253.03
   },
   "member_spread_now_deg": {
    "lat": 48.21,
    "lon": 285.36
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DJ2DS-34",
   "flight_id": "DJ2DS-34_2026-04-22",
   "payload_type": "WSPR",
   "seed_time": "2026-07-28 14:41:00",
   "seed_lat": 30.70833,
   "seed_lon": -70.5,
   "seed_alt_m": 9190.0,
   "seed_age_h": 320.65,
   "float_reliable": false,
   "dead_reckoned": true,
   "levels_spanned": 4,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 18.8186,
    "lon": 96.26866,
    "alt_m": 9083.1
   },
   "member_spread_deg": {
    "lat": 59.66,
    "lon": 314.51
   },
   "member_spread_now_deg": {
    "lat": 58.96,
    "lon": 148.43
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DL0MZ-493",
   "flight_id": "DL0MZ-493_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-07-29 07:36:01",
   "seed_lat": 64.20833,
   "seed_lon": 58.16667,
   "seed_alt_m": 12170.0,
   "seed_age_h": 303.73,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 66.11184,
    "lon": 102.06542,
    "alt_m": 12217.8
   },
   "member_spread_deg": {
    "lat": 39.93,
    "lon": 319.51
   },
   "member_spread_now_deg": {
    "lat": 34.85,
    "lon": 245.6
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DL0MZ-493e",
   "flight_id": "DL0MZ-493e_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-07-29 07:27:02",
   "seed_lat": 64.15625,
   "seed_lon": 58.08889,
   "seed_alt_m": 12170.0,
   "seed_age_h": 303.88,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 13.23282,
    "lon": -66.53488,
    "alt_m": 12728.7
   },
   "member_spread_deg": {
    "lat": 57.0,
    "lon": 178.21
   },
   "member_spread_now_deg": {
    "lat": 30.11,
    "lon": 100.04
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 19:28:00",
   "seed_lat": 61.41667,
   "seed_lon": -27.58333,
   "seed_alt_m": 12260.0,
   "seed_age_h": 3.87,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 19:00:00",
    "lat": 84.49725,
    "lon": -55.79929,
    "alt_m": 11876.4
   },
   "member_spread_deg": {
    "lat": 27.82,
    "lon": 172.69
   },
   "member_spread_now_deg": {
    "lat": 1.96,
    "lon": 4.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 21:50:30",
   "seed_lat": 71.52083,
   "seed_lon": -119.54167,
   "seed_alt_m": 12640.0,
   "seed_age_h": 1.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 21:15:00",
    "lat": 59.95716,
    "lon": -64.5672,
    "alt_m": 12365.6
   },
   "member_spread_deg": {
    "lat": 16.14,
    "lon": 67.86
   },
   "member_spread_now_deg": {
    "lat": 0.51,
    "lon": 0.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 03:45:37",
   "seed_lat": 33.04161,
   "seed_lon": 175.83333,
   "seed_alt_m": 13420.0,
   "seed_age_h": 19.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 23.93085,
    "lon": -78.76488,
    "alt_m": 13525.1
   },
   "member_spread_deg": {
    "lat": 38.39,
    "lon": 290.63
   },
   "member_spread_now_deg": {
    "lat": 4.83,
    "lon": 12.95
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 21:47:18",
   "seed_lat": 48.875,
   "seed_lon": -36.33333,
   "seed_alt_m": 13470.0,
   "seed_age_h": 1.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 21:15:00",
    "lat": 55.93712,
    "lon": 106.53309,
    "alt_m": 13373.7
   },
   "member_spread_deg": {
    "lat": 25.08,
    "lon": 80.48
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-485",
   "flight_id": "KC3LBR-485_2026-03-19",
   "payload_type": "WSPR",
   "seed_time": "2026-07-28 09:08:18",
   "seed_lat": 50.14583,
   "seed_lon": 23.375,
   "seed_alt_m": 12850.0,
   "seed_age_h": 326.2,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 61.2742,
    "lon": 36.98968,
    "alt_m": 12867.4
   },
   "member_spread_deg": {
    "lat": 59.58,
    "lon": 234.4
   },
   "member_spread_now_deg": {
    "lat": 42.33,
    "lon": 322.72
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 16:58:13",
   "seed_lat": 63.49995,
   "seed_lon": -28.5833,
   "seed_alt_m": 12660.0,
   "seed_age_h": 6.36,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 55.63504,
    "lon": 55.2478,
    "alt_m": 12407.2
   },
   "member_spread_deg": {
    "lat": 26.16,
    "lon": 206.6
   },
   "member_spread_now_deg": {
    "lat": 0.52,
    "lon": 4.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 19:30:00",
   "seed_lat": 37.70833,
   "seed_lon": -17.875,
   "seed_alt_m": 13130.0,
   "seed_age_h": 3.83,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 19:00:00",
    "lat": 45.79771,
    "lon": 78.41205,
    "alt_m": 12682.8
   },
   "member_spread_deg": {
    "lat": 6.25,
    "lon": 70.5
   },
   "member_spread_now_deg": {
    "lat": 0.42,
    "lon": 0.81
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 22:16:00",
   "seed_lat": 54.5625,
   "seed_lon": -84.79167,
   "seed_alt_m": 12000.0,
   "seed_age_h": 1.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 21:45:00",
    "lat": 42.57348,
    "lon": -6.37217,
    "alt_m": 12489.8
   },
   "member_spread_deg": {
    "lat": 24.38,
    "lon": 79.27
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 12:21:00",
   "seed_lat": 44.04167,
   "seed_lon": 64.29167,
   "seed_alt_m": 12010.0,
   "seed_age_h": 10.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 66.19021,
    "lon": -148.16556,
    "alt_m": 12367.2
   },
   "member_spread_deg": {
    "lat": 39.82,
    "lon": 347.34
   },
   "member_spread_now_deg": {
    "lat": 2.48,
    "lon": 5.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI1TEN-1",
   "flight_id": "KI1TEN-1_2026-07-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-01 22:55:27",
   "seed_lat": 23.95828,
   "seed_lon": -104.12496,
   "seed_alt_m": 12380.0,
   "seed_age_h": 216.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 6.94975,
    "lon": -106.4853,
    "alt_m": 12378.3
   },
   "member_spread_deg": {
    "lat": 28.85,
    "lon": 99.22
   },
   "member_spread_now_deg": {
    "lat": 20.26,
    "lon": 40.17
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 17:35:45",
   "seed_lat": 55.70828,
   "seed_lon": 5.41669,
   "seed_alt_m": 13480.0,
   "seed_age_h": 5.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 62.49346,
    "lon": 125.52288,
    "alt_m": 13119.0
   },
   "member_spread_deg": {
    "lat": 34.8,
    "lon": 317.24
   },
   "member_spread_now_deg": {
    "lat": 2.06,
    "lon": 5.78
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 22:51:00",
   "seed_lat": 38.79167,
   "seed_lon": 179.33333,
   "seed_alt_m": 15880.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-17 22:15:00",
    "lat": 0.20748,
    "lon": 113.61069,
    "alt_m": 16167.7
   },
   "member_spread_deg": {
    "lat": 47.87,
    "lon": 333.41
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-34",
   "flight_id": "SP6MPL-34_2025-12-03",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 18:52:00",
   "seed_lat": 74.5625,
   "seed_lon": -160.0,
   "seed_alt_m": 12890.0,
   "seed_age_h": 244.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": 50.98636,
    "lon": -80.49354,
    "alt_m": 13150.6
   },
   "member_spread_deg": {
    "lat": 26.8,
    "lon": 291.93
   },
   "member_spread_now_deg": {
    "lat": 26.51,
    "lon": 338.15
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 163.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 56.39719,
    "lon": 87.49635,
    "alt_m": 12730.1
   },
   "member_spread_deg": {
    "lat": 38.32,
    "lon": 237.21
   },
   "member_spread_now_deg": {
    "lat": 23.13,
    "lon": 329.82
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 10:36:00",
   "seed_lat": 44.64583,
   "seed_lon": 102.29167,
   "seed_alt_m": 13110.0,
   "seed_age_h": 12.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": 36.15942,
    "lon": -115.52578,
    "alt_m": 13531.0
   },
   "member_spread_deg": {
    "lat": 24.73,
    "lon": 284.11
   },
   "member_spread_now_deg": {
    "lat": 3.73,
    "lon": 1.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-15",
   "payload_type": "WSPR",
   "seed_time": "2026-07-31 04:34:00",
   "seed_lat": -23.70833,
   "seed_lon": 149.29167,
   "seed_alt_m": 12380.0,
   "seed_age_h": 258.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-17 17:30:00",
    "lat": -4.80824,
    "lon": 40.78577,
    "alt_m": 12671.5
   },
   "member_spread_deg": {
    "lat": 29.96,
    "lon": 227.16
   },
   "member_spread_now_deg": {
    "lat": 25.64,
    "lon": 204.27
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 06:11:00",
   "seed_lat": -23.0,
   "seed_lon": 114.875,
   "seed_alt_m": 15730.0,
   "seed_age_h": 17.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-17 17:45:00",
    "lat": -19.75303,
    "lon": -101.04464,
    "alt_m": 15727.5
   },
   "member_spread_deg": {
    "lat": 32.78,
    "lon": 354.43
   },
   "member_spread_now_deg": {
    "lat": 2.68,
    "lon": 22.31
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}