{
 "generated_utc": "2026-08-25T23:27:32Z",
 "gfs_cycle_utc": "2026-08-25T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 491.5,
  "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_20260825_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260825_18Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 93717
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 22:53:40",
   "seed_lat": -56.08333,
   "seed_lon": 179.45834,
   "seed_alt_m": 11930.0,
   "seed_age_h": 0.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 23:00:00",
    "lat": -66.16969,
    "lon": 158.86593,
    "alt_m": 12277.3
   },
   "member_spread_deg": {
    "lat": 32.33,
    "lon": 325.24
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 18:24:19",
   "seed_lat": 37.58333,
   "seed_lon": -26.25,
   "seed_alt_m": 14390.0,
   "seed_age_h": 4.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 18:00:00",
    "lat": 55.42289,
    "lon": -150.67966,
    "alt_m": 14015.2
   },
   "member_spread_deg": {
    "lat": 12.68,
    "lon": 321.98
   },
   "member_spread_now_deg": {
    "lat": 2.06,
    "lon": 1.5
   },
   "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": 1.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 21:00:00",
    "lat": 26.56065,
    "lon": -36.28378,
    "alt_m": 13113.3
   },
   "member_spread_deg": {
    "lat": 9.06,
    "lon": 65.5
   },
   "member_spread_now_deg": {
    "lat": 0.45,
    "lon": 0.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 22:06:00",
   "seed_lat": 57.58333,
   "seed_lon": 172.5,
   "seed_alt_m": 12480.0,
   "seed_age_h": 1.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 21:30:00",
    "lat": 67.33979,
    "lon": -16.99011,
    "alt_m": 11923.7
   },
   "member_spread_deg": {
    "lat": 13.02,
    "lon": 156.31
   },
   "member_spread_now_deg": {
    "lat": 0.2,
    "lon": 0.99
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 22:02:00",
   "seed_lat": 47.875,
   "seed_lon": -117.41667,
   "seed_alt_m": 13320.0,
   "seed_age_h": 1.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 21:30:00",
    "lat": 49.83062,
    "lon": 53.20554,
    "alt_m": 13027.9
   },
   "member_spread_deg": {
    "lat": 16.15,
    "lon": 42.09
   },
   "member_spread_now_deg": {
    "lat": 0.03,
    "lon": 0.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 17:03:00",
   "seed_lat": 82.20833,
   "seed_lon": -72.08333,
   "seed_alt_m": 11970.0,
   "seed_age_h": 6.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": 72.41216,
    "lon": 105.02553,
    "alt_m": 12317.0
   },
   "member_spread_deg": {
    "lat": 25.69,
    "lon": 315.5
   },
   "member_spread_now_deg": {
    "lat": 1.09,
    "lon": 3.92
   },
   "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": 33.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 56.52605,
    "lon": 148.79025,
    "alt_m": 12878.8
   },
   "member_spread_deg": {
    "lat": 30.34,
    "lon": 322.53
   },
   "member_spread_now_deg": {
    "lat": 14.77,
    "lon": 24.43
   },
   "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": 242.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 21.9885,
    "lon": -27.72069,
    "alt_m": 13350.9
   },
   "member_spread_deg": {
    "lat": 32.8,
    "lon": 192.22
   },
   "member_spread_now_deg": {
    "lat": 38.25,
    "lon": 135.11
   },
   "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": 16.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": 57.24665,
    "lon": -59.25393,
    "alt_m": 13305.4
   },
   "member_spread_deg": {
    "lat": 29.61,
    "lon": 209.24
   },
   "member_spread_now_deg": {
    "lat": 6.13,
    "lon": 26.49
   },
   "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": 323.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 60.5435,
    "lon": 169.19085,
    "alt_m": 12524.6
   },
   "member_spread_deg": {
    "lat": 21.75,
    "lon": 347.36
   },
   "member_spread_now_deg": {
    "lat": 30.47,
    "lon": 281.38
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 15:19:00",
   "seed_lat": 26.95833,
   "seed_lon": -16.45833,
   "seed_alt_m": 12860.0,
   "seed_age_h": 8.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 55.68812,
    "lon": -156.89366,
    "alt_m": 12582.3
   },
   "member_spread_deg": {
    "lat": 30.61,
    "lon": 342.91
   },
   "member_spread_now_deg": {
    "lat": 1.45,
    "lon": 1.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 21:35:00",
   "seed_lat": 32.83333,
   "seed_lon": -168.625,
   "seed_alt_m": 13010.0,
   "seed_age_h": 1.75,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 21:00:00",
    "lat": 44.67711,
    "lon": -42.26898,
    "alt_m": 12776.1
   },
   "member_spread_deg": {
    "lat": 26.51,
    "lon": 87.6
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 0.27
   },
   "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": 48.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": 75.61605,
    "lon": 70.25525,
    "alt_m": 12150.2
   },
   "member_spread_deg": {
    "lat": 31.85,
    "lon": 156.87
   },
   "member_spread_now_deg": {
    "lat": 4.66,
    "lon": 232.63
   },
   "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": 290.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 23.95591,
    "lon": -54.22032,
    "alt_m": 11158.4
   },
   "member_spread_deg": {
    "lat": 32.26,
    "lon": 324.26
   },
   "member_spread_now_deg": {
    "lat": 40.04,
    "lon": 173.18
   },
   "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": 69.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 82.21431,
    "lon": -53.08768,
    "alt_m": 12693.4
   },
   "member_spread_deg": {
    "lat": 19.85,
    "lon": 138.07
   },
   "member_spread_now_deg": {
    "lat": 9.17,
    "lon": 147.03
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-25 17:24:41",
   "seed_lat": 43.69967,
   "seed_lon": 2.45866,
   "seed_alt_m": 13253.0,
   "seed_age_h": 5.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": 38.89297,
    "lon": -138.51701,
    "alt_m": 13309.5
   },
   "member_spread_deg": {
    "lat": 17.93,
    "lon": 40.05
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 2.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:53:00",
   "seed_lat": 22.9375,
   "seed_lon": -5.91667,
   "seed_alt_m": 16640.0,
   "seed_age_h": 6.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": 41.33806,
    "lon": 62.42995,
    "alt_m": 16285.1
   },
   "member_spread_deg": {
    "lat": 18.15,
    "lon": 194.38
   },
   "member_spread_now_deg": {
    "lat": 0.99,
    "lon": 0.66
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 15:51:00",
   "seed_lat": 41.27083,
   "seed_lon": -5.66667,
   "seed_alt_m": 13320.0,
   "seed_age_h": 7.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 44.13652,
    "lon": -139.31031,
    "alt_m": 13553.5
   },
   "member_spread_deg": {
    "lat": 21.37,
    "lon": 335.33
   },
   "member_spread_now_deg": {
    "lat": 1.72,
    "lon": 6.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 17:15:23",
   "seed_lat": 37.66661,
   "seed_lon": -15.70831,
   "seed_alt_m": 13540.0,
   "seed_age_h": 6.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": 45.59172,
    "lon": 119.47138,
    "alt_m": 13575.5
   },
   "member_spread_deg": {
    "lat": 15.93,
    "lon": 333.52
   },
   "member_spread_now_deg": {
    "lat": 2.79,
    "lon": 1.77
   },
   "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": 194.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 17:30:00",
    "lat": -20.42393,
    "lon": 31.38511,
    "alt_m": 12604.7
   },
   "member_spread_deg": {
    "lat": 23.8,
    "lon": 275.66
   },
   "member_spread_now_deg": {
    "lat": 9.79,
    "lon": 343.34
   },
   "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": 328.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-01 17:45:00",
    "lat": -28.51832,
    "lon": 140.63141,
    "alt_m": 15975.8
   },
   "member_spread_deg": {
    "lat": 36.35,
    "lon": 232.89
   },
   "member_spread_now_deg": {
    "lat": 33.26,
    "lon": 270.57
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 22:26:00",
   "seed_lat": -27.0625,
   "seed_lon": 172.04167,
   "seed_alt_m": 15510.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 22:00:00",
    "lat": -13.06693,
    "lon": -47.61736,
    "alt_m": 15736.0
   },
   "member_spread_deg": {
    "lat": 39.01,
    "lon": 65.7
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 0.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}