{
 "generated_utc": "2026-08-28T17:26:59Z",
 "gfs_cycle_utc": "2026-08-28T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 471.0,
  "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_20260828_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260828_12Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 75393
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:13:40",
   "seed_lat": -64.54167,
   "seed_lon": -17.12499,
   "seed_alt_m": 11900.0,
   "seed_age_h": 1.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 16:15:00",
    "lat": -79.03895,
    "lon": -52.62609,
    "alt_m": 12180.3
   },
   "member_spread_deg": {
    "lat": 34.65,
    "lon": 216.18
   },
   "member_spread_now_deg": {
    "lat": 0.11,
    "lon": 0.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-27 14:01:48",
   "seed_lat": 43.125,
   "seed_lon": 21.54167,
   "seed_alt_m": 14180.0,
   "seed_age_h": 27.3,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 48.73588,
    "lon": -87.61828,
    "alt_m": 14316.6
   },
   "member_spread_deg": {
    "lat": 32.23,
    "lon": 353.23
   },
   "member_spread_now_deg": {
    "lat": 7.44,
    "lon": 18.02
   },
   "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": 67.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 21.47602,
    "lon": -85.99551,
    "alt_m": 13109.5
   },
   "member_spread_deg": {
    "lat": 17.86,
    "lon": 51.07
   },
   "member_spread_now_deg": {
    "lat": 8.95,
    "lon": 8.72
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 14:46:00",
   "seed_lat": 77.0625,
   "seed_lon": -80.75,
   "seed_alt_m": 12260.0,
   "seed_age_h": 2.57,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 14:15:00",
    "lat": 50.90993,
    "lon": -110.82096,
    "alt_m": 12332.9
   },
   "member_spread_deg": {
    "lat": 30.15,
    "lon": 306.45
   },
   "member_spread_now_deg": {
    "lat": 1.19,
    "lon": 4.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 16:17:00",
   "seed_lat": 46.47917,
   "seed_lon": -48.08333,
   "seed_alt_m": 13320.0,
   "seed_age_h": 1.05,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 16:15:00",
    "lat": 48.99366,
    "lon": 126.4476,
    "alt_m": 13297.9
   },
   "member_spread_deg": {
    "lat": 18.8,
    "lon": 94.79
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 11:53:00",
   "seed_lat": 76.5,
   "seed_lon": 46.625,
   "seed_alt_m": 11980.0,
   "seed_age_h": 5.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 79.98418,
    "lon": 177.65326,
    "alt_m": 12252.4
   },
   "member_spread_deg": {
    "lat": 37.82,
    "lon": 113.18
   },
   "member_spread_now_deg": {
    "lat": 1.27,
    "lon": 1.14
   },
   "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": 99.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": 45.17592,
    "lon": 151.54926,
    "alt_m": 12656.7
   },
   "member_spread_deg": {
    "lat": 32.15,
    "lon": 325.54
   },
   "member_spread_now_deg": {
    "lat": 16.28,
    "lon": 84.76
   },
   "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": 308.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": 43.93629,
    "lon": 42.5435,
    "alt_m": 12959.4
   },
   "member_spread_deg": {
    "lat": 50.37,
    "lon": 282.35
   },
   "member_spread_now_deg": {
    "lat": 41.59,
    "lon": 238.84
   },
   "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": 82.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 59.454,
    "lon": 26.83161,
    "alt_m": 12991.4
   },
   "member_spread_deg": {
    "lat": 25.61,
    "lon": 184.96
   },
   "member_spread_now_deg": {
    "lat": 43.29,
    "lon": 61.83
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 14:29:00",
   "seed_lat": 28.5625,
   "seed_lon": 33.41667,
   "seed_alt_m": 12740.0,
   "seed_age_h": 2.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 14:00:00",
    "lat": 23.87734,
    "lon": 178.49435,
    "alt_m": 12952.4
   },
   "member_spread_deg": {
    "lat": 38.1,
    "lon": 354.75
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.2
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 04:25:00",
   "seed_lat": 27.08333,
   "seed_lon": -164.41667,
   "seed_alt_m": 12960.0,
   "seed_age_h": 12.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 26.21616,
    "lon": -26.92919,
    "alt_m": 12977.4
   },
   "member_spread_deg": {
    "lat": 27.29,
    "lon": 53.22
   },
   "member_spread_now_deg": {
    "lat": 4.52,
    "lon": 3.97
   },
   "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": 114.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 52.14801,
    "lon": 154.76468,
    "alt_m": 12248.5
   },
   "member_spread_deg": {
    "lat": 31.56,
    "lon": 178.15
   },
   "member_spread_now_deg": {
    "lat": 19.1,
    "lon": 228.55
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 04:55:45",
   "seed_lat": 73.18745,
   "seed_lon": 179.45835,
   "seed_alt_m": 12780.0,
   "seed_age_h": 12.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": 54.78645,
    "lon": 19.08233,
    "alt_m": 12934.1
   },
   "member_spread_deg": {
    "lat": 26.97,
    "lon": 205.88
   },
   "member_spread_now_deg": {
    "lat": 2.57,
    "lon": 3.33
   },
   "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": 49.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": 49.1481,
    "lon": -148.99134,
    "alt_m": 13414.0
   },
   "member_spread_deg": {
    "lat": 22.66,
    "lon": 82.03
   },
   "member_spread_now_deg": {
    "lat": 2.95,
    "lon": 18.64
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 15:08:00",
   "seed_lat": 33.45833,
   "seed_lon": 22.66667,
   "seed_alt_m": 16470.0,
   "seed_age_h": 2.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 14:45:00",
    "lat": 35.90516,
    "lon": 141.88658,
    "alt_m": 16568.4
   },
   "member_spread_deg": {
    "lat": 31.94,
    "lon": 300.34
   },
   "member_spread_now_deg": {
    "lat": 0.83,
    "lon": 1.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 11:11:00",
   "seed_lat": 50.85417,
   "seed_lon": 82.5,
   "seed_alt_m": 13030.0,
   "seed_age_h": 6.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": 44.45301,
    "lon": -87.83719,
    "alt_m": 13532.8
   },
   "member_spread_deg": {
    "lat": 21.65,
    "lon": 78.14
   },
   "member_spread_now_deg": {
    "lat": 1.11,
    "lon": 1.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 11:20:23",
   "seed_lat": 45.58328,
   "seed_lon": 27.04169,
   "seed_alt_m": 13540.0,
   "seed_age_h": 5.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": 66.68836,
    "lon": -145.02028,
    "alt_m": 13215.7
   },
   "member_spread_deg": {
    "lat": 30.99,
    "lon": 288.97
   },
   "member_spread_now_deg": {
    "lat": 4.36,
    "lon": 1.65
   },
   "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": 260.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-04 11:30:00",
    "lat": -22.53301,
    "lon": 178.49931,
    "alt_m": 12359.7
   },
   "member_spread_deg": {
    "lat": 11.34,
    "lon": 343.79
   },
   "member_spread_now_deg": {
    "lat": 20.28,
    "lon": 125.84
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-28 01:21:00",
   "seed_lat": -25.875,
   "seed_lon": -135.66667,
   "seed_alt_m": 15340.0,
   "seed_age_h": 15.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-04 11:45:00",
    "lat": -5.6491,
    "lon": -56.76702,
    "alt_m": 15624.4
   },
   "member_spread_deg": {
    "lat": 40.19,
    "lon": 188.77
   },
   "member_spread_now_deg": {
    "lat": 2.47,
    "lon": 18.96
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}