{
 "generated_utc": "2026-08-27T11:27:32Z",
 "gfs_cycle_utc": "2026-08-27T06:00:00Z",
 "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_20260827_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260827_06Z.geojson.gz"
 },
 "counts": {
  "flights": 20,
  "members": 9,
  "rows": 80586
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 23:18:40",
   "seed_lat": -70.79167,
   "seed_lon": -148.58332,
   "seed_alt_m": 12300.0,
   "seed_age_h": 12.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": -77.70047,
    "lon": -93.72691,
    "alt_m": 12118.0
   },
   "member_spread_deg": {
    "lat": 3.88,
    "lon": 38.25
   },
   "member_spread_now_deg": {
    "lat": 3.33,
    "lon": 4.85
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 11:01:18",
   "seed_lat": 44.14583,
   "seed_lon": 17.33333,
   "seed_alt_m": 14200.0,
   "seed_age_h": 0.31,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:00:00",
    "lat": 32.9447,
    "lon": -131.85911,
    "alt_m": 14513.0
   },
   "member_spread_deg": {
    "lat": 31.96,
    "lon": 337.3
   },
   "member_spread_now_deg": {
    "lat": 0.32,
    "lon": 0.35
   },
   "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": 37.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 20.74456,
    "lon": -107.1881,
    "alt_m": 13148.9
   },
   "member_spread_deg": {
    "lat": 18.29,
    "lon": 92.78
   },
   "member_spread_now_deg": {
    "lat": 4.25,
    "lon": 4.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:06:00",
   "seed_lat": 59.25,
   "seed_lon": -136.5,
   "seed_alt_m": 12380.0,
   "seed_age_h": 9.23,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 62.56704,
    "lon": -147.37041,
    "alt_m": 11961.4
   },
   "member_spread_deg": {
    "lat": 22.58,
    "lon": 325.3
   },
   "member_spread_now_deg": {
    "lat": 6.7,
    "lon": 8.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 21:52:00",
   "seed_lat": 43.79167,
   "seed_lon": -94.20833,
   "seed_alt_m": 13200.0,
   "seed_age_h": 13.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 50.2592,
    "lon": 108.98772,
    "alt_m": 13098.8
   },
   "member_spread_deg": {
    "lat": 24.35,
    "lon": 149.64
   },
   "member_spread_now_deg": {
    "lat": 0.85,
    "lon": 5.1
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:38:00",
   "seed_lat": 83.20833,
   "seed_lon": -24.91667,
   "seed_alt_m": 11920.0,
   "seed_age_h": 21.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 62.38497,
    "lon": 124.62211,
    "alt_m": 12498.1
   },
   "member_spread_deg": {
    "lat": 23.37,
    "lon": 263.96
   },
   "member_spread_now_deg": {
    "lat": 4.14,
    "lon": 16.63
   },
   "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": 69.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 54.78105,
    "lon": 131.70252,
    "alt_m": 12707.8
   },
   "member_spread_deg": {
    "lat": 23.5,
    "lon": 262.82
   },
   "member_spread_now_deg": {
    "lat": 21.74,
    "lon": 89.92
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "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": 278.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 25.13847,
    "lon": 8.20385,
    "alt_m": 13218.5
   },
   "member_spread_deg": {
    "lat": 38.34,
    "lon": 206.07
   },
   "member_spread_now_deg": {
    "lat": 49.44,
    "lon": 189.15
   },
   "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": 52.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 60.46138,
    "lon": -0.72012,
    "alt_m": 13089.2
   },
   "member_spread_deg": {
    "lat": 19.42,
    "lon": 189.86
   },
   "member_spread_now_deg": {
    "lat": 29.92,
    "lon": 39.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 10:14:00",
   "seed_lat": 32.52083,
   "seed_lon": 22.875,
   "seed_alt_m": 12740.0,
   "seed_age_h": 1.1,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 09:45:00",
    "lat": 54.94545,
    "lon": -161.52644,
    "alt_m": 12748.8
   },
   "member_spread_deg": {
    "lat": 44.88,
    "lon": 354.58
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 0.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 04:25:00",
   "seed_lat": 28.08333,
   "seed_lon": -169.5,
   "seed_alt_m": 12940.0,
   "seed_age_h": 6.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 24.69767,
    "lon": -49.86308,
    "alt_m": 13045.7
   },
   "member_spread_deg": {
    "lat": 27.39,
    "lon": 60.93
   },
   "member_spread_now_deg": {
    "lat": 1.28,
    "lon": 2.48
   },
   "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": 84.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 60.35574,
    "lon": 148.28571,
    "alt_m": 12352.0
   },
   "member_spread_deg": {
    "lat": 21.34,
    "lon": 185.29
   },
   "member_spread_now_deg": {
    "lat": 20.57,
    "lon": 347.58
   },
   "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": 326.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 25.80769,
    "lon": -1.2331,
    "alt_m": 11157.1
   },
   "member_spread_deg": {
    "lat": 35.16,
    "lon": 342.87
   },
   "member_spread_now_deg": {
    "lat": 42.23,
    "lon": 317.77
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 03:00:45",
   "seed_lat": 77.66661,
   "seed_lon": 155.16669,
   "seed_alt_m": 12690.0,
   "seed_age_h": 8.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 61.21734,
    "lon": -29.10504,
    "alt_m": 12863.7
   },
   "member_spread_deg": {
    "lat": 19.43,
    "lon": 141.82
   },
   "member_spread_now_deg": {
    "lat": 2.31,
    "lon": 5.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 15:51:36",
   "seed_lat": 41.62025,
   "seed_lon": 25.112,
   "seed_alt_m": 13223.0,
   "seed_age_h": 19.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:45:00",
    "lat": 43.74594,
    "lon": -151.22956,
    "alt_m": 13515.0
   },
   "member_spread_deg": {
    "lat": 21.85,
    "lon": 67.55
   },
   "member_spread_now_deg": {
    "lat": 2.5,
    "lon": 4.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 10:31:00",
   "seed_lat": 36.77083,
   "seed_lon": 6.58333,
   "seed_alt_m": 16470.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 10:00:00",
    "lat": 39.37126,
    "lon": 172.07026,
    "alt_m": 16253.8
   },
   "member_spread_deg": {
    "lat": 21.87,
    "lon": 344.48
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 14:31:00",
   "seed_lat": 46.83333,
   "seed_lon": 23.125,
   "seed_alt_m": 13050.0,
   "seed_age_h": 20.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": 34.19899,
    "lon": -123.73775,
    "alt_m": 13368.8
   },
   "member_spread_deg": {
    "lat": 27.03,
    "lon": 83.29
   },
   "member_spread_now_deg": {
    "lat": 3.24,
    "lon": 5.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 10:55:23",
   "seed_lat": 54.27078,
   "seed_lon": 13.62502,
   "seed_alt_m": 13480.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 11:00:00",
    "lat": 51.2454,
    "lon": -173.60798,
    "alt_m": 13284.9
   },
   "member_spread_deg": {
    "lat": 27.58,
    "lon": 354.19
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.05
   },
   "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": 230.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": -29.93473,
    "lon": 92.20691,
    "alt_m": 12117.2
   },
   "member_spread_deg": {
    "lat": 17.28,
    "lon": 340.58
   },
   "member_spread_now_deg": {
    "lat": 18.56,
    "lon": 130.72
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 02:56:00",
   "seed_lat": -23.45833,
   "seed_lon": -160.20833,
   "seed_alt_m": 15500.0,
   "seed_age_h": 8.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-03 05:30:00",
    "lat": -14.63567,
    "lon": -52.39294,
    "alt_m": 15804.6
   },
   "member_spread_deg": {
    "lat": 43.87,
    "lon": 147.59
   },
   "member_spread_now_deg": {
    "lat": 1.38,
    "lon": 8.73
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}