{
 "generated_utc": "2026-09-07T17:26:57Z",
 "gfs_cycle_utc": "2026-09-07T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 485.0,
  "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_20260907_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260907_12Z.geojson.gz"
 },
 "counts": {
  "flights": 19,
  "members": 9,
  "rows": 85482
 },
 "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": 241.11,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": -56.10203,
    "lon": -17.04508,
    "alt_m": 12064.4
   },
   "member_spread_deg": {
    "lat": 36.67,
    "lon": 248.59
   },
   "member_spread_now_deg": {
    "lat": 33.66,
    "lon": 146.66
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 16:15:18",
   "seed_lat": 32.64583,
   "seed_lon": -65.04167,
   "seed_alt_m": 14540.0,
   "seed_age_h": 1.08,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 15:45:00",
    "lat": 27.67669,
    "lon": -8.63896,
    "alt_m": 14471.0
   },
   "member_spread_deg": {
    "lat": 15.32,
    "lon": 38.04
   },
   "member_spread_now_deg": {
    "lat": 0.33,
    "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": 307.85,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": -1.37949,
    "lon": -30.15068,
    "alt_m": 13182.0
   },
   "member_spread_deg": {
    "lat": 39.9,
    "lon": 83.37
   },
   "member_spread_now_deg": {
    "lat": 12.55,
    "lon": 63.47
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 04:41:00",
   "seed_lat": 86.0,
   "seed_lon": 110.20833,
   "seed_alt_m": 11660.0,
   "seed_age_h": 60.65,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": 84.59311,
    "lon": -175.54839,
    "alt_m": 11655.8
   },
   "member_spread_deg": {
    "lat": 21.0,
    "lon": 353.85
   },
   "member_spread_now_deg": {
    "lat": 8.56,
    "lon": 43.84
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 01:52:00",
   "seed_lat": 41.85417,
   "seed_lon": -141.29167,
   "seed_alt_m": 13380.0,
   "seed_age_h": 15.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": 21.78358,
    "lon": -74.37118,
    "alt_m": 13599.0
   },
   "member_spread_deg": {
    "lat": 42.11,
    "lon": 130.3
   },
   "member_spread_now_deg": {
    "lat": 1.58,
    "lon": 3.58
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-32",
   "flight_id": "DG2GG-32_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 04:56:00",
   "seed_lat": 45.0,
   "seed_lon": 119.0,
   "seed_alt_m": 13370.0,
   "seed_age_h": 12.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 29.75174,
    "lon": 144.04733,
    "alt_m": 13975.4
   },
   "member_spread_deg": {
    "lat": 31.38,
    "lon": 276.07
   },
   "member_spread_now_deg": {
    "lat": 1.79,
    "lon": 4.28
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-31 09:53:00",
   "seed_lat": 62.54167,
   "seed_lon": 91.41667,
   "seed_alt_m": 11930.0,
   "seed_age_h": 175.45,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 61.00222,
    "lon": 161.71411,
    "alt_m": 11986.6
   },
   "member_spread_deg": {
    "lat": 41.16,
    "lon": 304.75
   },
   "member_spread_now_deg": {
    "lat": 18.51,
    "lon": 324.53
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DO3GU-47",
   "flight_id": "DO3GU-47_2026-09-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 06:11:23",
   "seed_lat": 45.72917,
   "seed_lon": 115.79167,
   "seed_alt_m": 13960.0,
   "seed_age_h": 11.14,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": 41.57024,
    "lon": -33.08864,
    "alt_m": 14007.0
   },
   "member_spread_deg": {
    "lat": 36.69,
    "lon": 190.74
   },
   "member_spread_now_deg": {
    "lat": 1.49,
    "lon": 7.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "I1RFQ",
   "flight_id": "I1RFQ_2026-09-06",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:25:00",
   "seed_lat": 38.8125,
   "seed_lon": 34.04167,
   "seed_alt_m": 12750.0,
   "seed_age_h": 3.92,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 13:00:00",
    "lat": 40.06355,
    "lon": -153.02312,
    "alt_m": 12715.9
   },
   "member_spread_deg": {
    "lat": 24.62,
    "lon": 120.85
   },
   "member_spread_now_deg": {
    "lat": 0.38,
    "lon": 0.34
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 322.77,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 29.57554,
    "lon": 145.17362,
    "alt_m": 14240.7
   },
   "member_spread_deg": {
    "lat": 50.16,
    "lon": 291.28
   },
   "member_spread_now_deg": {
    "lat": 32.08,
    "lon": 220.05
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KC7RW-3",
   "flight_id": "KC7RW-3_2026-08-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-03 08:04:00",
   "seed_lat": 37.27083,
   "seed_lon": 133.375,
   "seed_alt_m": 12750.0,
   "seed_age_h": 105.27,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 29.08449,
    "lon": 157.24413,
    "alt_m": 12947.4
   },
   "member_spread_deg": {
    "lat": 11.58,
    "lon": 330.25
   },
   "member_spread_now_deg": {
    "lat": 27.46,
    "lon": 321.1
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 16:35:00",
   "seed_lat": 27.14583,
   "seed_lon": -1.125,
   "seed_alt_m": 12980.0,
   "seed_age_h": 0.75,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 16:00:00",
    "lat": 48.86548,
    "lon": -141.47514,
    "alt_m": 13038.7
   },
   "member_spread_deg": {
    "lat": 19.06,
    "lon": 325.31
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-09-06 22:56:00",
   "seed_lat": 62.79167,
   "seed_lon": -124.54167,
   "seed_alt_m": 12340.0,
   "seed_age_h": 18.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 50.42247,
    "lon": 23.81427,
    "alt_m": 12755.4
   },
   "member_spread_deg": {
    "lat": 26.93,
    "lon": 132.99
   },
   "member_spread_now_deg": {
    "lat": 2.1,
    "lon": 23.03
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-09-05 15:25:45",
   "seed_lat": 57.95828,
   "seed_lon": 16.20835,
   "seed_alt_m": 13120.0,
   "seed_age_h": 49.9,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:30:00",
    "lat": 73.88445,
    "lon": -82.37963,
    "alt_m": 12889.5
   },
   "member_spread_deg": {
    "lat": 22.13,
    "lon": 207.79
   },
   "member_spread_now_deg": {
    "lat": 7.98,
    "lon": 6.57
   },
   "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": 289.47,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": 27.10705,
    "lon": -3.64729,
    "alt_m": 13414.6
   },
   "member_spread_deg": {
    "lat": 51.4,
    "lon": 177.24
   },
   "member_spread_now_deg": {
    "lat": 18.03,
    "lon": 119.62
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 02:41:00",
   "seed_lat": 24.25,
   "seed_lon": -159.45833,
   "seed_alt_m": 16160.0,
   "seed_age_h": 14.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-09-14 11:45:00",
    "lat": 22.06845,
    "lon": -162.16073,
    "alt_m": 16357.2
   },
   "member_spread_deg": {
    "lat": 39.67,
    "lon": 346.11
   },
   "member_spread_now_deg": {
    "lat": 8.88,
    "lon": 11.04
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 16:11:00",
   "seed_lat": 48.91667,
   "seed_lon": -41.20833,
   "seed_alt_m": 13440.0,
   "seed_age_h": 1.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 15:45:00",
    "lat": 42.35174,
    "lon": 126.47725,
    "alt_m": 13285.3
   },
   "member_spread_deg": {
    "lat": 41.43,
    "lon": 152.92
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 1.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 16:55:23",
   "seed_lat": 40.99995,
   "seed_lon": -116.49998,
   "seed_alt_m": 13660.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 17:00:00",
    "lat": 49.50811,
    "lon": 50.09352,
    "alt_m": 13594.3
   },
   "member_spread_deg": {
    "lat": 25.25,
    "lon": 42.03
   },
   "member_spread_now_deg": {
    "lat": 0.13,
    "lon": 0.23
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6WBT-1",
   "flight_id": "ZS6WBT-1_2026-08-19",
   "payload_type": "WSPR",
   "seed_time": "2026-09-07 13:31:00",
   "seed_lat": -22.79167,
   "seed_lon": 25.625,
   "seed_alt_m": 15590.0,
   "seed_age_h": 3.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-09-14 13:00:00",
    "lat": -19.89255,
    "lon": 113.10236,
    "alt_m": 15748.5
   },
   "member_spread_deg": {
    "lat": 13.81,
    "lon": 294.98
   },
   "member_spread_now_deg": {
    "lat": 0.46,
    "lon": 1.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  }
 ]
}