{
 "generated_utc": "2026-08-26T17:27:26Z",
 "gfs_cycle_utc": "2026-08-26T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 470.5,
  "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_20260826_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260826_12Z.geojson.gz"
 },
 "counts": {
  "flights": 20,
  "members": 9,
  "rows": 77634
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 03:43:40",
   "seed_lat": -56.58333,
   "seed_lon": -169.29165,
   "seed_alt_m": 11840.0,
   "seed_age_h": 13.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": -86.04975,
    "lon": -174.52617,
    "alt_m": 12171.8
   },
   "member_spread_deg": {
    "lat": 28.28,
    "lon": 329.67
   },
   "member_spread_now_deg": {
    "lat": 4.46,
    "lon": 13.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:43:18",
   "seed_lat": 35.89583,
   "seed_lon": -6.625,
   "seed_alt_m": 14390.0,
   "seed_age_h": 0.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 16:45:00",
    "lat": 54.39894,
    "lon": -147.03175,
    "alt_m": 14104.2
   },
   "member_spread_deg": {
    "lat": 17.3,
    "lon": 316.37
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.33
   },
   "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": 19.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:30:00",
    "lat": 14.67014,
    "lon": -62.89007,
    "alt_m": 13136.2
   },
   "member_spread_deg": {
    "lat": 25.24,
    "lon": 47.81
   },
   "member_spread_now_deg": {
    "lat": 2.11,
    "lon": 0.5
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 04:21:00",
   "seed_lat": 58.66667,
   "seed_lon": -173.79167,
   "seed_alt_m": 12540.0,
   "seed_age_h": 12.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 69.80558,
    "lon": 11.7451,
    "alt_m": 12220.0
   },
   "member_spread_deg": {
    "lat": 29.38,
    "lon": 104.97
   },
   "member_spread_now_deg": {
    "lat": 1.1,
    "lon": 11.56
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:12:00",
   "seed_lat": 46.02083,
   "seed_lon": -99.29167,
   "seed_alt_m": 13220.0,
   "seed_age_h": 1.13,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 15:45:00",
    "lat": 44.61633,
    "lon": 59.69127,
    "alt_m": 13133.0
   },
   "member_spread_deg": {
    "lat": 24.89,
    "lon": 134.86
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.45
   },
   "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": 3.7,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 13:15:00",
    "lat": 77.6003,
    "lon": 137.95161,
    "alt_m": 12412.4
   },
   "member_spread_deg": {
    "lat": 26.19,
    "lon": 104.14
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 7.0
   },
   "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": 51.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 65.91873,
    "lon": 161.51018,
    "alt_m": 12426.0
   },
   "member_spread_deg": {
    "lat": 32.97,
    "lon": 305.13
   },
   "member_spread_now_deg": {
    "lat": 19.38,
    "lon": 47.17
   },
   "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": 260.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 29.35122,
    "lon": -5.49102,
    "alt_m": 13193.7
   },
   "member_spread_deg": {
    "lat": 47.41,
    "lon": 269.78
   },
   "member_spread_now_deg": {
    "lat": 45.61,
    "lon": 165.78
   },
   "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": 34.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:30:00",
    "lat": 56.11742,
    "lon": -27.69393,
    "alt_m": 13032.2
   },
   "member_spread_deg": {
    "lat": 25.52,
    "lon": 353.46
   },
   "member_spread_now_deg": {
    "lat": 10.88,
    "lon": 41.32
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 13:24:00",
   "seed_lat": 39.64583,
   "seed_lon": 8.25,
   "seed_alt_m": 12840.0,
   "seed_age_h": 3.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 13:00:00",
    "lat": 34.05834,
    "lon": 173.34188,
    "alt_m": 12897.4
   },
   "member_spread_deg": {
    "lat": 15.89,
    "lon": 341.14
   },
   "member_spread_now_deg": {
    "lat": 0.85,
    "lon": 0.8
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 05:10:00",
   "seed_lat": 31.60417,
   "seed_lon": -169.625,
   "seed_alt_m": 12980.0,
   "seed_age_h": 12.17,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 43.68848,
    "lon": -36.46208,
    "alt_m": 13040.8
   },
   "member_spread_deg": {
    "lat": 18.76,
    "lon": 64.13
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 1.08
   },
   "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": 66.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 11:30:00",
    "lat": 73.40438,
    "lon": 124.60558,
    "alt_m": 12611.0
   },
   "member_spread_deg": {
    "lat": 19.55,
    "lon": 149.36
   },
   "member_spread_now_deg": {
    "lat": 12.53,
    "lon": 231.38
   },
   "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": 308.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 30.91998,
    "lon": -15.88691,
    "alt_m": 11238.2
   },
   "member_spread_deg": {
    "lat": 48.45,
    "lon": 343.77
   },
   "member_spread_now_deg": {
    "lat": 50.92,
    "lon": 217.75
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 07:50:45",
   "seed_lat": 81.70828,
   "seed_lon": 127.58335,
   "seed_alt_m": 12600.0,
   "seed_age_h": 9.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:45:00",
    "lat": 64.41942,
    "lon": -33.01198,
    "alt_m": 12735.2
   },
   "member_spread_deg": {
    "lat": 18.83,
    "lon": 339.99
   },
   "member_spread_now_deg": {
    "lat": 1.06,
    "lon": 12.01
   },
   "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": 1.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 15:15:00",
    "lat": 44.35349,
    "lon": -106.16402,
    "alt_m": 13182.8
   },
   "member_spread_deg": {
    "lat": 7.78,
    "lon": 34.15
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.29
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 16:11:00",
   "seed_lat": 29.6875,
   "seed_lon": -2.45833,
   "seed_alt_m": 16600.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 15:45:00",
    "lat": 42.6372,
    "lon": 115.03926,
    "alt_m": 16204.1
   },
   "member_spread_deg": {
    "lat": 17.07,
    "lon": 316.0
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.46
   },
   "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": 2.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 14:00:00",
    "lat": 35.27085,
    "lon": -132.21835,
    "alt_m": 13366.5
   },
   "member_spread_deg": {
    "lat": 28.01,
    "lon": 323.02
   },
   "member_spread_now_deg": {
    "lat": 1.02,
    "lon": 1.71
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 15:25:23",
   "seed_lat": 50.93745,
   "seed_lon": 2.25002,
   "seed_alt_m": 13420.0,
   "seed_age_h": 1.91,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 15:00:00",
    "lat": 45.20182,
    "lon": 124.11591,
    "alt_m": 13583.6
   },
   "member_spread_deg": {
    "lat": 23.97,
    "lon": 335.8
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 1.19
   },
   "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": 212.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 11:30:00",
    "lat": -26.18993,
    "lon": 60.6142,
    "alt_m": 12385.9
   },
   "member_spread_deg": {
    "lat": 17.69,
    "lon": 291.82
   },
   "member_spread_now_deg": {
    "lat": 23.46,
    "lon": 355.38
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 03:56:00",
   "seed_lat": -26.41667,
   "seed_lon": 175.5,
   "seed_alt_m": 15480.0,
   "seed_age_h": 13.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:30:00",
    "lat": -9.12565,
    "lon": -65.84191,
    "alt_m": 15770.2
   },
   "member_spread_deg": {
    "lat": 36.43,
    "lon": 95.54
   },
   "member_spread_now_deg": {
    "lat": 3.73,
    "lon": 9.14
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}