{
 "generated_utc": "2026-08-25T17:27:37Z",
 "gfs_cycle_utc": "2026-08-25T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 485.5,
  "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_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260825_12Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 93240
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 05:58:40",
   "seed_lat": -63.97917,
   "seed_lon": 135.91668,
   "seed_alt_m": 12480.0,
   "seed_age_h": 11.36,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:30:00",
    "lat": -85.37885,
    "lon": 162.79422,
    "alt_m": 12203.5
   },
   "member_spread_deg": {
    "lat": 28.61,
    "lon": 349.71
   },
   "member_spread_now_deg": {
    "lat": 5.59,
    "lon": 2.3
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 17:02:18",
   "seed_lat": 38.85417,
   "seed_lon": -27.08333,
   "seed_alt_m": 14310.0,
   "seed_age_h": 0.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:00:00",
    "lat": 52.1494,
    "lon": -153.28935,
    "alt_m": 14191.8
   },
   "member_spread_deg": {
    "lat": 8.13,
    "lon": 330.59
   },
   "member_spread_now_deg": {
    "lat": 0.31,
    "lon": 0.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:34:00",
   "seed_lat": 35.8125,
   "seed_lon": -85.875,
   "seed_alt_m": 13050.0,
   "seed_age_h": 0.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 16:00:00",
    "lat": 27.38903,
    "lon": -46.47045,
    "alt_m": 13182.2
   },
   "member_spread_deg": {
    "lat": 16.02,
    "lon": 34.76
   },
   "member_spread_now_deg": {
    "lat": 0.15,
    "lon": 0.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 07:46:00",
   "seed_lat": 54.16667,
   "seed_lon": 152.66667,
   "seed_alt_m": 12360.0,
   "seed_age_h": 9.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 80.01384,
    "lon": 172.3909,
    "alt_m": 11851.1
   },
   "member_spread_deg": {
    "lat": 30.95,
    "lon": 270.24
   },
   "member_spread_now_deg": {
    "lat": 2.7,
    "lon": 6.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 01:42:00",
   "seed_lat": 36.39583,
   "seed_lon": -131.75,
   "seed_alt_m": 13340.0,
   "seed_age_h": 15.63,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 31.77251,
    "lon": -36.71859,
    "alt_m": 13382.2
   },
   "member_spread_deg": {
    "lat": 30.25,
    "lon": 79.54
   },
   "member_spread_now_deg": {
    "lat": 3.07,
    "lon": 2.61
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:03:00",
   "seed_lat": 82.08333,
   "seed_lon": -74.08333,
   "seed_alt_m": 11940.0,
   "seed_age_h": 1.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 15:30:00",
    "lat": 71.35725,
    "lon": 84.71838,
    "alt_m": 11887.8
   },
   "member_spread_deg": {
    "lat": 17.83,
    "lon": 40.24
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 0.55
   },
   "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": 27.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 51.0855,
    "lon": 152.16598,
    "alt_m": 12782.8
   },
   "member_spread_deg": {
    "lat": 18.37,
    "lon": 311.76
   },
   "member_spread_now_deg": {
    "lat": 14.46,
    "lon": 19.49
   },
   "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": 236.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 9.68937,
    "lon": -47.14911,
    "alt_m": 13391.9
   },
   "member_spread_deg": {
    "lat": 31.61,
    "lon": 208.51
   },
   "member_spread_now_deg": {
    "lat": 40.01,
    "lon": 127.81
   },
   "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": 10.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:30:00",
    "lat": 58.43993,
    "lon": -62.86987,
    "alt_m": 13370.9
   },
   "member_spread_deg": {
    "lat": 31.7,
    "lon": 244.56
   },
   "member_spread_now_deg": {
    "lat": 5.02,
    "lon": 13.4
   },
   "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": 317.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 68.53792,
    "lon": 167.21663,
    "alt_m": 12413.9
   },
   "member_spread_deg": {
    "lat": 43.85,
    "lon": 301.8
   },
   "member_spread_now_deg": {
    "lat": 29.22,
    "lon": 287.28
   },
   "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": 2.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 14:45:00",
    "lat": 32.89782,
    "lon": 175.7853,
    "alt_m": 12774.9
   },
   "member_spread_deg": {
    "lat": 14.34,
    "lon": 354.55
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "lon": 0.41
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 04:10:00",
   "seed_lat": 30.70833,
   "seed_lon": -167.58333,
   "seed_alt_m": 13010.0,
   "seed_age_h": 13.17,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 41.07597,
    "lon": -56.32268,
    "alt_m": 12919.8
   },
   "member_spread_deg": {
    "lat": 41.9,
    "lon": 70.36
   },
   "member_spread_now_deg": {
    "lat": 1.18,
    "lon": 5.24
   },
   "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": 42.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 11:30:00",
    "lat": 76.57182,
    "lon": 118.36162,
    "alt_m": 12285.0
   },
   "member_spread_deg": {
    "lat": 30.98,
    "lon": 199.07
   },
   "member_spread_now_deg": {
    "lat": 5.07,
    "lon": 223.92
   },
   "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": 284.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 25.75928,
    "lon": -18.5603,
    "alt_m": 11228.0
   },
   "member_spread_deg": {
    "lat": 37.9,
    "lon": 287.79
   },
   "member_spread_now_deg": {
    "lat": 36.0,
    "lon": 162.18
   },
   "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": 63.57,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": 62.99474,
    "lon": -40.78539,
    "alt_m": 12858.2
   },
   "member_spread_deg": {
    "lat": 20.79,
    "lon": 196.19
   },
   "member_spread_now_deg": {
    "lat": 9.87,
    "lon": 135.6
   },
   "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 17:05:34",
   "seed_lat": 43.58258,
   "seed_lon": 2.10166,
   "seed_alt_m": 13257.0,
   "seed_age_h": 0.24,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:00:00",
    "lat": 40.05405,
    "lon": -123.20389,
    "alt_m": 13125.0
   },
   "member_spread_deg": {
    "lat": 20.95,
    "lon": 46.12
   },
   "member_spread_now_deg": {
    "lat": 0.0,
    "lon": 0.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:38:30",
   "seed_lat": 22.91667,
   "seed_lon": -5.875,
   "seed_alt_m": 16640.0,
   "seed_age_h": 0.69,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 16:15:00",
    "lat": 40.61675,
    "lon": 61.90147,
    "alt_m": 16285.5
   },
   "member_spread_deg": {
    "lat": 14.4,
    "lon": 199.67
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.04
   },
   "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": 1.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 15:15:00",
    "lat": 43.18534,
    "lon": -126.86116,
    "alt_m": 13228.2
   },
   "member_spread_deg": {
    "lat": 22.98,
    "lon": 334.76
   },
   "member_spread_now_deg": {
    "lat": 0.62,
    "lon": 1.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:55:23",
   "seed_lat": 37.62495,
   "seed_lon": -16.04164,
   "seed_alt_m": 13540.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 17:00:00",
    "lat": 44.92781,
    "lon": 122.67552,
    "alt_m": 13527.9
   },
   "member_spread_deg": {
    "lat": 11.29,
    "lon": 300.79
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.15
   },
   "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": 188.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 11:30:00",
    "lat": -18.70432,
    "lon": 23.80393,
    "alt_m": 12571.7
   },
   "member_spread_deg": {
    "lat": 16.14,
    "lon": 137.64
   },
   "member_spread_now_deg": {
    "lat": 10.27,
    "lon": 349.53
   },
   "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": 322.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-01 11:45:00",
    "lat": -28.24168,
    "lon": 137.03149,
    "alt_m": 15997.3
   },
   "member_spread_deg": {
    "lat": 39.9,
    "lon": 233.94
   },
   "member_spread_now_deg": {
    "lat": 33.16,
    "lon": 265.16
   },
   "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 05:26:00",
   "seed_lat": -27.04167,
   "seed_lon": 152.16667,
   "seed_alt_m": 15550.0,
   "seed_age_h": 11.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 11:30:00",
    "lat": -28.68047,
    "lon": -21.23384,
    "alt_m": 15497.9
   },
   "member_spread_deg": {
    "lat": 51.03,
    "lon": 81.2
   },
   "member_spread_now_deg": {
    "lat": 0.71,
    "lon": 10.98
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}