{
 "generated_utc": "2026-08-26T11:27:44Z",
 "gfs_cycle_utc": "2026-08-26T06:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 498.0,
  "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_20260826_06Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260826_06Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 85734
 },
 "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": 7.61,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": -77.13563,
    "lon": 100.16298,
    "alt_m": 12440.0
   },
   "member_spread_deg": {
    "lat": 18.77,
    "lon": 293.2
   },
   "member_spread_now_deg": {
    "lat": 2.31,
    "lon": 7.0
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 10:53:18",
   "seed_lat": 33.16667,
   "seed_lon": -12.875,
   "seed_alt_m": 14360.0,
   "seed_age_h": 0.45,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:00:00",
    "lat": 43.39943,
    "lon": -131.63952,
    "alt_m": 14232.3
   },
   "member_spread_deg": {
    "lat": 19.49,
    "lon": 309.44
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.26
   },
   "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": 13.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": 15.92857,
    "lon": -67.17542,
    "alt_m": 13113.5
   },
   "member_spread_deg": {
    "lat": 9.59,
    "lon": 30.75
   },
   "member_spread_now_deg": {
    "lat": 1.61,
    "lon": 0.77
   },
   "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": 6.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 58.38066,
    "lon": 8.20763,
    "alt_m": 11991.7
   },
   "member_spread_deg": {
    "lat": 23.23,
    "lon": 99.63
   },
   "member_spread_now_deg": {
    "lat": 0.37,
    "lon": 7.67
   },
   "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": 13.3,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": 54.53689,
    "lon": 59.48648,
    "alt_m": 12953.2
   },
   "member_spread_deg": {
    "lat": 21.69,
    "lon": 44.52
   },
   "member_spread_now_deg": {
    "lat": 2.31,
    "lon": 5.49
   },
   "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": 18.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": 82.11619,
    "lon": 126.92976,
    "alt_m": 12451.6
   },
   "member_spread_deg": {
    "lat": 30.06,
    "lon": 315.96
   },
   "member_spread_now_deg": {
    "lat": 1.75,
    "lon": 21.97
   },
   "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": 45.12,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 48.89267,
    "lon": 127.1156,
    "alt_m": 12647.1
   },
   "member_spread_deg": {
    "lat": 31.04,
    "lon": 303.78
   },
   "member_spread_now_deg": {
    "lat": 17.63,
    "lon": 38.15
   },
   "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": 254.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 26.94216,
    "lon": -10.11182,
    "alt_m": 13191.5
   },
   "member_spread_deg": {
    "lat": 48.32,
    "lon": 272.14
   },
   "member_spread_now_deg": {
    "lat": 43.88,
    "lon": 154.48
   },
   "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": 28.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": 45.31607,
    "lon": -49.31829,
    "alt_m": 13279.0
   },
   "member_spread_deg": {
    "lat": 33.95,
    "lon": 217.88
   },
   "member_spread_now_deg": {
    "lat": 5.19,
    "lon": 42.08
   },
   "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": 335.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 60.25105,
    "lon": 148.72474,
    "alt_m": 12661.7
   },
   "member_spread_deg": {
    "lat": 26.75,
    "lon": 264.22
   },
   "member_spread_now_deg": {
    "lat": 46.79,
    "lon": 271.58
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 09:09:00",
   "seed_lat": 37.85417,
   "seed_lon": 1.95833,
   "seed_alt_m": 12730.0,
   "seed_age_h": 2.18,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 08:45:00",
    "lat": 46.46461,
    "lon": -141.13913,
    "alt_m": 12752.2
   },
   "member_spread_deg": {
    "lat": 26.48,
    "lon": 347.42
   },
   "member_spread_now_deg": {
    "lat": 0.21,
    "lon": 0.4
   },
   "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": 6.17,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 37.74315,
    "lon": -85.29537,
    "alt_m": 13044.4
   },
   "member_spread_deg": {
    "lat": 21.0,
    "lon": 49.86
   },
   "member_spread_now_deg": {
    "lat": 0.27,
    "lon": 0.66
   },
   "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": 60.32,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": 76.60913,
    "lon": 134.19976,
    "alt_m": 12542.1
   },
   "member_spread_deg": {
    "lat": 30.91,
    "lon": 194.0
   },
   "member_spread_now_deg": {
    "lat": 9.11,
    "lon": 233.48
   },
   "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": 302.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 05:45:00",
    "lat": 26.00173,
    "lon": -12.77509,
    "alt_m": 11162.6
   },
   "member_spread_deg": {
    "lat": 38.21,
    "lon": 340.09
   },
   "member_spread_now_deg": {
    "lat": 47.5,
    "lon": 205.52
   },
   "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": 3.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 07:15:00",
    "lat": 61.7705,
    "lon": -33.22798,
    "alt_m": 12811.9
   },
   "member_spread_deg": {
    "lat": 24.09,
    "lon": 250.39
   },
   "member_spread_now_deg": {
    "lat": 0.3,
    "lon": 6.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KJ4AWK-1",
   "flight_id": "KJ4AWK-1_2026-08-22",
   "payload_type": "APRS",
   "seed_time": "2026-08-26 11:04:06",
   "seed_lat": 41.981,
   "seed_lon": 22.64416,
   "seed_alt_m": 13262.0,
   "seed_age_h": 0.27,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:00:00",
    "lat": 36.17658,
    "lon": -131.75892,
    "alt_m": 13227.5
   },
   "member_spread_deg": {
    "lat": 11.79,
    "lon": 11.27
   },
   "member_spread_now_deg": {
    "lat": 0.04,
    "lon": 0.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 10:41:00",
   "seed_lat": 28.75,
   "seed_lon": -4.58333,
   "seed_alt_m": 16640.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 10:15:00",
    "lat": 50.97744,
    "lon": 122.28474,
    "alt_m": 15756.9
   },
   "member_spread_deg": {
    "lat": 14.33,
    "lon": 318.63
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.33
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 09:56:00",
   "seed_lat": 47.54167,
   "seed_lon": 16.91667,
   "seed_alt_m": 13310.0,
   "seed_age_h": 1.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 09:30:00",
    "lat": 43.0303,
    "lon": -118.65631,
    "alt_m": 13296.7
   },
   "member_spread_deg": {
    "lat": 18.84,
    "lon": 65.41
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.25
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-26 10:55:23",
   "seed_lat": 48.81245,
   "seed_lon": -0.58331,
   "seed_alt_m": 13420.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 11:00:00",
    "lat": 45.64784,
    "lon": 120.09638,
    "alt_m": 13588.7
   },
   "member_spread_deg": {
    "lat": 7.6,
    "lon": 301.23
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.17
   },
   "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": 206.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": -20.24807,
    "lon": 21.65942,
    "alt_m": 12430.4
   },
   "member_spread_deg": {
    "lat": 28.48,
    "lon": 298.76
   },
   "member_spread_now_deg": {
    "lat": 21.28,
    "lon": 350.76
   },
   "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": 7.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-02 05:30:00",
    "lat": -10.99122,
    "lon": -82.45185,
    "alt_m": 15796.4
   },
   "member_spread_deg": {
    "lat": 31.6,
    "lon": 103.44
   },
   "member_spread_now_deg": {
    "lat": 2.71,
    "lon": 359.33
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}