{
 "generated_utc": "2026-08-14T17:27:37Z",
 "gfs_cycle_utc": "2026-08-14T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 497.0,
  "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_20260814_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260814_12Z.geojson.gz"
 },
 "counts": {
  "flights": 25,
  "members": 9,
  "rows": 101862
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:43:40",
   "seed_lat": -43.75,
   "seed_lon": -10.91665,
   "seed_alt_m": 12150.0,
   "seed_age_h": 0.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 16:15:00",
    "lat": -40.75083,
    "lon": -58.89455,
    "alt_m": 12382.2
   },
   "member_spread_deg": {
    "lat": 22.69,
    "lon": 22.25
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 08:30:18",
   "seed_lat": 57.54167,
   "seed_lon": 19.20833,
   "seed_alt_m": 12870.0,
   "seed_age_h": 32.83,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 81.15435,
    "lon": -142.44841,
    "alt_m": 12362.1
   },
   "member_spread_deg": {
    "lat": 31.77,
    "lon": 280.89
   },
   "member_spread_now_deg": {
    "lat": 5.3,
    "lon": 24.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 02:55:18",
   "seed_lat": 49.58333,
   "seed_lon": 145.16667,
   "seed_alt_m": 14330.0,
   "seed_age_h": 14.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 37.17504,
    "lon": -132.60924,
    "alt_m": 14112.6
   },
   "member_spread_deg": {
    "lat": 21.31,
    "lon": 111.55
   },
   "member_spread_now_deg": {
    "lat": 1.85,
    "lon": 7.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:44:00",
   "seed_lat": 50.4375,
   "seed_lon": 16.625,
   "seed_alt_m": 12880.0,
   "seed_age_h": 1.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 15:15:00",
    "lat": 51.54117,
    "lon": -171.45911,
    "alt_m": 13009.1
   },
   "member_spread_deg": {
    "lat": 10.96,
    "lon": 341.43
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.2
   },
   "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": 113.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": 24.3593,
    "lon": -108.54624,
    "alt_m": 14062.2
   },
   "member_spread_deg": {
    "lat": 41.66,
    "lon": 130.17
   },
   "member_spread_now_deg": {
    "lat": 29.18,
    "lon": 54.96
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "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": 252.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 45.76887,
    "lon": 21.70854,
    "alt_m": 13381.2
   },
   "member_spread_deg": {
    "lat": 84.77,
    "lon": 263.76
   },
   "member_spread_now_deg": {
    "lat": 66.32,
    "lon": 233.25
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 03:01:00",
   "seed_lat": 48.25,
   "seed_lon": -163.70833,
   "seed_alt_m": 12760.0,
   "seed_age_h": 14.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 59.10898,
    "lon": 49.0655,
    "alt_m": 12305.9
   },
   "member_spread_deg": {
    "lat": 20.19,
    "lon": 186.93
   },
   "member_spread_now_deg": {
    "lat": 5.37,
    "lon": 8.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:47:00",
   "seed_lat": 44.10417,
   "seed_lon": 10.33333,
   "seed_alt_m": 13300.0,
   "seed_age_h": 1.55,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 15:15:00",
    "lat": 52.86893,
    "lon": -172.30762,
    "alt_m": 13335.9
   },
   "member_spread_deg": {
    "lat": 8.94,
    "lon": 348.43
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 12:43:00",
   "seed_lat": 70.72917,
   "seed_lon": 54.70833,
   "seed_alt_m": 12070.0,
   "seed_age_h": 4.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 12:15:00",
    "lat": 74.98696,
    "lon": -178.95827,
    "alt_m": 11650.4
   },
   "member_spread_deg": {
    "lat": 27.84,
    "lon": 358.24
   },
   "member_spread_now_deg": {
    "lat": 1.94,
    "lon": 2.67
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:13:00",
   "seed_lat": 65.08333,
   "seed_lon": -122.04167,
   "seed_alt_m": 12660.0,
   "seed_age_h": 1.12,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 15:45:00",
    "lat": 64.02401,
    "lon": 36.9937,
    "alt_m": 12345.3
   },
   "member_spread_deg": {
    "lat": 17.72,
    "lon": 210.47
   },
   "member_spread_now_deg": {
    "lat": 0.37,
    "lon": 1.05
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:55:37",
   "seed_lat": 32.79161,
   "seed_lon": -114.08333,
   "seed_alt_m": 13240.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 17:00:00",
    "lat": 13.00462,
    "lon": -64.79668,
    "alt_m": 13400.0
   },
   "member_spread_deg": {
    "lat": 29.07,
    "lon": 131.84
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 15:22:33",
   "seed_lat": 50.70833,
   "seed_lon": 58.5,
   "seed_alt_m": 13420.0,
   "seed_age_h": 1.96,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 15:00:00",
    "lat": 71.99571,
    "lon": 79.40448,
    "alt_m": 13343.6
   },
   "member_spread_deg": {
    "lat": 16.75,
    "lon": 341.63
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.73
   },
   "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": 53.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": 64.39379,
    "lon": 78.16943,
    "alt_m": 12680.6
   },
   "member_spread_deg": {
    "lat": 10.74,
    "lon": 209.43
   },
   "member_spread_now_deg": {
    "lat": 18.82,
    "lon": 33.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:35:00",
   "seed_lat": 40.45833,
   "seed_lon": 7.91667,
   "seed_alt_m": 12950.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 16:00:00",
    "lat": 46.20227,
    "lon": 175.05326,
    "alt_m": 13093.7
   },
   "member_spread_deg": {
    "lat": 18.32,
    "lon": 350.33
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.18
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 16:41:00",
   "seed_lat": 55.04167,
   "seed_lon": -56.33333,
   "seed_alt_m": 12200.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 16:15:00",
    "lat": 73.87835,
    "lon": 126.62112,
    "alt_m": 12015.8
   },
   "member_spread_deg": {
    "lat": 25.78,
    "lon": 228.26
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.04
   },
   "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": 20.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": 45.0399,
    "lon": -10.33444,
    "alt_m": 11092.5
   },
   "member_spread_deg": {
    "lat": 21.33,
    "lon": 115.72
   },
   "member_spread_now_deg": {
    "lat": 10.57,
    "lon": 8.43
   },
   "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": 306.41,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 4.15624,
    "lon": -110.60171,
    "alt_m": 12343.4
   },
   "member_spread_deg": {
    "lat": 41.47,
    "lon": 145.98
   },
   "member_spread_now_deg": {
    "lat": 22.26,
    "lon": 66.15
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 11:05:45",
   "seed_lat": 78.43745,
   "seed_lon": 94.75002,
   "seed_alt_m": 13240.0,
   "seed_age_h": 6.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 65.02338,
    "lon": -158.75674,
    "alt_m": 12895.6
   },
   "member_spread_deg": {
    "lat": 20.75,
    "lon": 324.85
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 5.37
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 05:03:00",
   "seed_lat": 21.10417,
   "seed_lon": 174.5,
   "seed_alt_m": 16470.0,
   "seed_age_h": 12.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 8.45944,
    "lon": 53.84957,
    "alt_m": 16488.7
   },
   "member_spread_deg": {
    "lat": 37.68,
    "lon": 67.02
   },
   "member_spread_now_deg": {
    "lat": 4.01,
    "lon": 2.38
   },
   "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": 334.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": 50.52752,
    "lon": -125.79166,
    "alt_m": 13402.5
   },
   "member_spread_deg": {
    "lat": 38.23,
    "lon": 293.68
   },
   "member_spread_now_deg": {
    "lat": 18.41,
    "lon": 350.65
   },
   "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": 253.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 41.27814,
    "lon": -166.60078,
    "alt_m": 12819.8
   },
   "member_spread_deg": {
    "lat": 45.28,
    "lon": 352.51
   },
   "member_spread_now_deg": {
    "lat": 38.47,
    "lon": 233.06
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 22:41:00",
   "seed_lat": 45.875,
   "seed_lon": 142.66667,
   "seed_alt_m": 13600.0,
   "seed_age_h": 42.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": 46.2937,
    "lon": -78.81097,
    "alt_m": 13218.1
   },
   "member_spread_deg": {
    "lat": 25.23,
    "lon": 254.68
   },
   "member_spread_now_deg": {
    "lat": 11.13,
    "lon": 20.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 02:05:23",
   "seed_lat": 54.52078,
   "seed_lon": 141.29169,
   "seed_alt_m": 13630.0,
   "seed_age_h": 15.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-21 11:30:00",
    "lat": 60.17993,
    "lon": -104.75319,
    "alt_m": 13274.6
   },
   "member_spread_deg": {
    "lat": 31.71,
    "lon": 90.92
   },
   "member_spread_now_deg": {
    "lat": 9.2,
    "lon": 16.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-14 05:39:00",
   "seed_lat": -23.64583,
   "seed_lon": 119.66667,
   "seed_alt_m": 12290.0,
   "seed_age_h": 11.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": -10.97672,
    "lon": -15.63907,
    "alt_m": 12671.4
   },
   "member_spread_deg": {
    "lat": 29.61,
    "lon": 292.8
   },
   "member_spread_now_deg": {
    "lat": 6.28,
    "lon": 8.57
   },
   "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": 58.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-21 11:45:00",
    "lat": -9.1145,
    "lon": -19.99319,
    "alt_m": 15972.8
   },
   "member_spread_deg": {
    "lat": 22.79,
    "lon": 170.47
   },
   "member_spread_now_deg": {
    "lat": 8.67,
    "lon": 349.94
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}