{
 "generated_utc": "2026-08-26T05:27:32Z",
 "gfs_cycle_utc": "2026-08-26T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 497.5,
  "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_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260826_00Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 94257
 },
 "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": 1.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 03:15:00",
    "lat": -74.54139,
    "lon": -51.31238,
    "alt_m": 11884.8
   },
   "member_spread_deg": {
    "lat": 22.21,
    "lon": 317.6
   },
   "member_spread_now_deg": {
    "lat": 0.29,
    "lon": 1.44
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 18:24:19",
   "seed_lat": 37.58333,
   "seed_lon": -26.25,
   "seed_alt_m": 14390.0,
   "seed_age_h": 10.93,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 49.4271,
    "lon": -148.0914,
    "alt_m": 14432.6
   },
   "member_spread_deg": {
    "lat": 10.01,
    "lon": 335.5
   },
   "member_spread_now_deg": {
    "lat": 2.69,
    "lon": 2.45
   },
   "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": 7.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 25.7725,
    "lon": -36.07472,
    "alt_m": 13142.3
   },
   "member_spread_deg": {
    "lat": 17.48,
    "lon": 42.97
   },
   "member_spread_now_deg": {
    "lat": 0.74,
    "lon": 0.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 03:31:00",
   "seed_lat": 58.66667,
   "seed_lon": -175.625,
   "seed_alt_m": 12540.0,
   "seed_age_h": 1.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 03:00:00",
    "lat": 57.18656,
    "lon": 41.23494,
    "alt_m": 12330.9
   },
   "member_spread_deg": {
    "lat": 18.28,
    "lon": 116.62
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 2.36
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 22:02:00",
   "seed_lat": 47.875,
   "seed_lon": -117.41667,
   "seed_alt_m": 13320.0,
   "seed_age_h": 7.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 47.186,
    "lon": 58.21455,
    "alt_m": 13137.5
   },
   "member_spread_deg": {
    "lat": 17.97,
    "lon": 84.92
   },
   "member_spread_now_deg": {
    "lat": 0.53,
    "lon": 2.87
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 17:03:00",
   "seed_lat": 82.20833,
   "seed_lon": -72.08333,
   "seed_alt_m": 11970.0,
   "seed_age_h": 12.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 72.70177,
    "lon": 79.98638,
    "alt_m": 11971.8
   },
   "member_spread_deg": {
    "lat": 25.48,
    "lon": 271.63
   },
   "member_spread_now_deg": {
    "lat": 1.59,
    "lon": 11.38
   },
   "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": 39.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 51.1127,
    "lon": 158.60847,
    "alt_m": 12668.8
   },
   "member_spread_deg": {
    "lat": 31.87,
    "lon": 320.31
   },
   "member_spread_now_deg": {
    "lat": 16.09,
    "lon": 30.63
   },
   "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": 248.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 20.75112,
    "lon": -25.82605,
    "alt_m": 13388.5
   },
   "member_spread_deg": {
    "lat": 44.22,
    "lon": 284.99
   },
   "member_spread_now_deg": {
    "lat": 40.97,
    "lon": 143.84
   },
   "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": 22.77,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 54.6924,
    "lon": -68.66964,
    "alt_m": 13243.1
   },
   "member_spread_deg": {
    "lat": 18.77,
    "lon": 230.16
   },
   "member_spread_now_deg": {
    "lat": 4.6,
    "lon": 39.81
   },
   "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": 329.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 61.17087,
    "lon": 171.97284,
    "alt_m": 12258.7
   },
   "member_spread_deg": {
    "lat": 18.48,
    "lon": 321.24
   },
   "member_spread_now_deg": {
    "lat": 41.59,
    "lon": 274.43
   },
   "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": 14.02,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 39.58552,
    "lon": -179.56662,
    "alt_m": 12760.2
   },
   "member_spread_deg": {
    "lat": 26.97,
    "lon": 351.91
   },
   "member_spread_now_deg": {
    "lat": 3.12,
    "lon": 3.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 04:25:00",
   "seed_lat": 31.70833,
   "seed_lon": -169.625,
   "seed_alt_m": 13000.0,
   "seed_age_h": 0.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 04:30:00",
    "lat": 31.50199,
    "lon": -65.54375,
    "alt_m": 13100.0
   },
   "member_spread_deg": {
    "lat": 29.96,
    "lon": 273.53
   },
   "member_spread_now_deg": {
    "lat": 0.08,
    "lon": 0.15
   },
   "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": 54.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 68.48651,
    "lon": 128.06481,
    "alt_m": 12531.9
   },
   "member_spread_deg": {
    "lat": 18.2,
    "lon": 193.66
   },
   "member_spread_now_deg": {
    "lat": 6.6,
    "lon": 234.12
   },
   "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": 296.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 23.77534,
    "lon": -10.82014,
    "alt_m": 11156.2
   },
   "member_spread_deg": {
    "lat": 37.99,
    "lon": 302.58
   },
   "member_spread_now_deg": {
    "lat": 43.46,
    "lon": 187.72
   },
   "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 04:30:45",
   "seed_lat": 82.18745,
   "seed_lon": 122.66669,
   "seed_alt_m": 12600.0,
   "seed_age_h": 0.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 04:30:00",
    "lat": 68.56818,
    "lon": -31.5189,
    "alt_m": 12872.9
   },
   "member_spread_deg": {
    "lat": 18.66,
    "lon": 176.73
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 2.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-25 17:24:41",
   "seed_lat": 43.69967,
   "seed_lon": 2.45866,
   "seed_alt_m": 13253.0,
   "seed_age_h": 11.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 43.22561,
    "lon": -118.18434,
    "alt_m": 13052.6
   },
   "member_spread_deg": {
    "lat": 18.51,
    "lon": 38.68
   },
   "member_spread_now_deg": {
    "lat": 1.21,
    "lon": 3.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 16:53:00",
   "seed_lat": 22.9375,
   "seed_lon": -5.91667,
   "seed_alt_m": 16640.0,
   "seed_age_h": 12.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": 43.71019,
    "lon": 110.4067,
    "alt_m": 16046.2
   },
   "member_spread_deg": {
    "lat": 17.96,
    "lon": 192.68
   },
   "member_spread_now_deg": {
    "lat": 2.55,
    "lon": 2.24
   },
   "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": 13.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 44.54716,
    "lon": -128.7349,
    "alt_m": 13211.5
   },
   "member_spread_deg": {
    "lat": 22.3,
    "lon": 332.69
   },
   "member_spread_now_deg": {
    "lat": 1.37,
    "lon": 11.36
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-25 17:15:23",
   "seed_lat": 37.66661,
   "seed_lon": -15.70831,
   "seed_alt_m": 13540.0,
   "seed_age_h": 12.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": 47.05896,
    "lon": 135.32859,
    "alt_m": 13521.2
   },
   "member_spread_deg": {
    "lat": 14.22,
    "lon": 315.0
   },
   "member_spread_now_deg": {
    "lat": 5.75,
    "lon": 3.85
   },
   "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": 200.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-01 23:30:00",
    "lat": -21.37633,
    "lon": 10.04913,
    "alt_m": 12500.0
   },
   "member_spread_deg": {
    "lat": 24.47,
    "lon": 318.42
   },
   "member_spread_now_deg": {
    "lat": 14.51,
    "lon": 343.12
   },
   "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": 334.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-01 23:45:00",
    "lat": -29.91812,
    "lon": 159.08166,
    "alt_m": 15830.4
   },
   "member_spread_deg": {
    "lat": 39.7,
    "lon": 236.75
   },
   "member_spread_now_deg": {
    "lat": 33.8,
    "lon": 276.97
   },
   "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": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 03:30:00",
    "lat": -14.38237,
    "lon": -81.89682,
    "alt_m": 15781.1
   },
   "member_spread_deg": {
    "lat": 30.31,
    "lon": 97.11
   },
   "member_spread_now_deg": {
    "lat": 0.54,
    "lon": 1.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}