{
 "generated_utc": "2026-08-16T23:27:02Z",
 "gfs_cycle_utc": "2026-08-16T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 469.5,
  "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_20260816_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260816_18Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 92916
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 11:53:40",
   "seed_lat": -55.79167,
   "seed_lon": 64.62501,
   "seed_alt_m": 12300.0,
   "seed_age_h": 11.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": -57.01709,
    "lon": 89.19583,
    "alt_m": 12353.5
   },
   "member_spread_deg": {
    "lat": 7.67,
    "lon": 18.99
   },
   "member_spread_now_deg": {
    "lat": 1.04,
    "lon": 4.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:45:17",
   "seed_lat": 51.875,
   "seed_lon": 105.33333,
   "seed_alt_m": 12610.0,
   "seed_age_h": 0.58,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 22:15:00",
    "lat": 83.90346,
    "lon": 82.09362,
    "alt_m": 12255.7
   },
   "member_spread_deg": {
    "lat": 53.02,
    "lon": 250.85
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:49:48",
   "seed_lat": 42.25,
   "seed_lon": 176.04167,
   "seed_alt_m": 14120.0,
   "seed_age_h": 0.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 22:15:00",
    "lat": 47.64461,
    "lon": -71.05493,
    "alt_m": 13904.0
   },
   "member_spread_deg": {
    "lat": 22.28,
    "lon": 94.37
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.09
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 10:09:00",
   "seed_lat": 43.29167,
   "seed_lon": 30.625,
   "seed_alt_m": 12660.0,
   "seed_age_h": 13.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 38.17461,
    "lon": -136.48902,
    "alt_m": 12985.8
   },
   "member_spread_deg": {
    "lat": 36.5,
    "lon": 306.93
   },
   "member_spread_now_deg": {
    "lat": 3.06,
    "lon": 7.88
   },
   "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": 167.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 7.44099,
    "lon": -73.23918,
    "alt_m": 14070.0
   },
   "member_spread_deg": {
    "lat": 54.68,
    "lon": 147.79
   },
   "member_spread_now_deg": {
    "lat": 33.45,
    "lon": 82.72
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 306.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 44.79544,
    "lon": 102.86632,
    "alt_m": 13401.0
   },
   "member_spread_deg": {
    "lat": 100.18,
    "lon": 349.58
   },
   "member_spread_now_deg": {
    "lat": 67.88,
    "lon": 208.72
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:11:00",
   "seed_lat": 49.25,
   "seed_lon": -109.0,
   "seed_alt_m": 12750.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 21:45:00",
    "lat": 53.98291,
    "lon": 105.612,
    "alt_m": 12591.3
   },
   "member_spread_deg": {
    "lat": 13.7,
    "lon": 116.3
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 12:32:00",
   "seed_lat": 40.41667,
   "seed_lon": 26.29167,
   "seed_alt_m": 13180.0,
   "seed_age_h": 10.8,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 51.50551,
    "lon": -148.78695,
    "alt_m": 13215.0
   },
   "member_spread_deg": {
    "lat": 32.27,
    "lon": 22.59
   },
   "member_spread_now_deg": {
    "lat": 1.76,
    "lon": 2.71
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:18:00",
   "seed_lat": 87.5,
   "seed_lon": -76.08333,
   "seed_alt_m": 11730.0,
   "seed_age_h": 1.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 21:45:00",
    "lat": 58.90444,
    "lon": 154.25571,
    "alt_m": 11920.4
   },
   "member_spread_deg": {
    "lat": 23.54,
    "lon": 331.55
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 3.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:08:00",
   "seed_lat": 59.16667,
   "seed_lon": -78.625,
   "seed_alt_m": 12500.0,
   "seed_age_h": 1.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 21:45:00",
    "lat": 67.71486,
    "lon": 55.02329,
    "alt_m": 12493.0
   },
   "member_spread_deg": {
    "lat": 31.29,
    "lon": 81.47
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "GSN-TS",
   "flight_id": "GSN-TS_2026-08-15",
   "payload_type": "OTHER",
   "seed_time": "2026-08-16 01:30:23",
   "seed_lat": 53.81866,
   "seed_lon": 16.61656,
   "seed_alt_m": 9972.0,
   "seed_age_h": 21.83,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 4,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 67.69267,
    "lon": -169.8538,
    "alt_m": 9816.1
   },
   "member_spread_deg": {
    "lat": 28.17,
    "lon": 343.75
   },
   "member_spread_now_deg": {
    "lat": 5.74,
    "lon": 6.41
   },
   "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": 26.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 25.01005,
    "lon": -93.53574,
    "alt_m": 13418.6
   },
   "member_spread_deg": {
    "lat": 42.76,
    "lon": 127.49
   },
   "member_spread_now_deg": {
    "lat": 2.91,
    "lon": 13.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 15:13:33",
   "seed_lat": 63.3125,
   "seed_lon": 70.5,
   "seed_alt_m": 13340.0,
   "seed_age_h": 8.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 63.14446,
    "lon": 114.75157,
    "alt_m": 13209.7
   },
   "member_spread_deg": {
    "lat": 13.35,
    "lon": 89.63
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 2.63
   },
   "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": 107.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 64.38773,
    "lon": 84.02545,
    "alt_m": 12472.0
   },
   "member_spread_deg": {
    "lat": 23.98,
    "lon": 238.22
   },
   "member_spread_now_deg": {
    "lat": 26.42,
    "lon": 257.97
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 13:50:00",
   "seed_lat": 47.77083,
   "seed_lon": 57.0,
   "seed_alt_m": 12500.0,
   "seed_age_h": 9.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 45.03703,
    "lon": -124.95698,
    "alt_m": 12860.9
   },
   "member_spread_deg": {
    "lat": 40.51,
    "lon": 351.25
   },
   "member_spread_now_deg": {
    "lat": 0.46,
    "lon": 4.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 19:31:00",
   "seed_lat": 70.25,
   "seed_lon": -41.83333,
   "seed_alt_m": 12260.0,
   "seed_age_h": 3.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 19:00:00",
    "lat": 81.86564,
    "lon": -175.95411,
    "alt_m": 11812.4
   },
   "member_spread_deg": {
    "lat": 34.99,
    "lon": 338.93
   },
   "member_spread_now_deg": {
    "lat": 0.82,
    "lon": 1.7
   },
   "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": 74.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": 41.84348,
    "lon": 79.04536,
    "alt_m": 11103.4
   },
   "member_spread_deg": {
    "lat": 22.68,
    "lon": 196.17
   },
   "member_spread_now_deg": {
    "lat": 32.04,
    "lon": 18.66
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 09:35:45",
   "seed_lat": 70.24995,
   "seed_lon": 114.29169,
   "seed_alt_m": 13120.0,
   "seed_age_h": 13.74,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 87.47628,
    "lon": -46.249,
    "alt_m": 12744.3
   },
   "member_spread_deg": {
    "lat": 26.27,
    "lon": 265.19
   },
   "member_spread_now_deg": {
    "lat": 6.52,
    "lon": 1.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 06:36:00",
   "seed_lat": 15.47917,
   "seed_lon": 145.875,
   "seed_alt_m": 16600.0,
   "seed_age_h": 16.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 8.98602,
    "lon": 23.36627,
    "alt_m": 16450.7
   },
   "member_spread_deg": {
    "lat": 39.4,
    "lon": 111.26
   },
   "member_spread_now_deg": {
    "lat": 3.72,
    "lon": 6.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 307.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 17:30:00",
    "lat": 46.74477,
    "lon": -123.62217,
    "alt_m": 12947.9
   },
   "member_spread_deg": {
    "lat": 57.99,
    "lon": 319.67
   },
   "member_spread_now_deg": {
    "lat": 31.5,
    "lon": 258.18
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:11:00",
   "seed_lat": 39.33333,
   "seed_lon": 173.04167,
   "seed_alt_m": 13420.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 21:45:00",
    "lat": 45.366,
    "lon": -31.79331,
    "alt_m": 13388.8
   },
   "member_spread_deg": {
    "lat": 29.58,
    "lon": 111.91
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 0.43
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:55:23",
   "seed_lat": 52.35411,
   "seed_lon": -160.49998,
   "seed_alt_m": 13330.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 23:00:00",
    "lat": 55.70835,
    "lon": -29.18225,
    "alt_m": 13295.7
   },
   "member_spread_deg": {
    "lat": 16.02,
    "lon": 51.57
   },
   "member_spread_now_deg": {
    "lat": 0.41,
    "lon": 0.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 22:44:00",
   "seed_lat": -25.77083,
   "seed_lon": -110.83333,
   "seed_alt_m": 12380.0,
   "seed_age_h": 0.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 22:15:00",
    "lat": -32.28428,
    "lon": 151.75391,
    "alt_m": 11850.7
   },
   "member_spread_deg": {
    "lat": 22.84,
    "lon": 125.71
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.31
   },
   "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": 112.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-23 17:45:00",
    "lat": -11.27452,
    "lon": -28.22515,
    "alt_m": 16044.8
   },
   "member_spread_deg": {
    "lat": 13.05,
    "lon": 177.26
   },
   "member_spread_now_deg": {
    "lat": 11.66,
    "lon": 331.35
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}