{
 "generated_utc": "2026-08-16T05:26:46Z",
 "gfs_cycle_utc": "2026-08-16T00:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 451.5,
  "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_20260816_00Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260816_00Z.geojson.gz"
 },
 "counts": {
  "flights": 24,
  "members": 9,
  "rows": 90315
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 12:53:40",
   "seed_lat": -59.83333,
   "seed_lon": 15.66668,
   "seed_alt_m": 12570.0,
   "seed_age_h": 16.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": -56.27935,
    "lon": 73.3852,
    "alt_m": 12461.5
   },
   "member_spread_deg": {
    "lat": 19.61,
    "lon": 217.35
   },
   "member_spread_now_deg": {
    "lat": 10.99,
    "lon": 31.49
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 03:03:18",
   "seed_lat": 53.89583,
   "seed_lon": 87.79167,
   "seed_alt_m": 12740.0,
   "seed_age_h": 2.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 02:30:00",
    "lat": 79.2716,
    "lon": -116.62472,
    "alt_m": 12323.0
   },
   "member_spread_deg": {
    "lat": 53.21,
    "lon": 348.46
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 1.26
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 23:28:18",
   "seed_lat": 48.02083,
   "seed_lon": 165.79167,
   "seed_alt_m": 14140.0,
   "seed_age_h": 5.86,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 44.03313,
    "lon": -76.5217,
    "alt_m": 14054.9
   },
   "member_spread_deg": {
    "lat": 24.02,
    "lon": 111.4
   },
   "member_spread_now_deg": {
    "lat": 0.57,
    "lon": 1.63
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 14:29:00",
   "seed_lat": 43.54167,
   "seed_lon": 22.45833,
   "seed_alt_m": 12750.0,
   "seed_age_h": 14.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 40.63004,
    "lon": -144.2058,
    "alt_m": 12968.6
   },
   "member_spread_deg": {
    "lat": 14.7,
    "lon": 331.45
   },
   "member_spread_now_deg": {
    "lat": 5.32,
    "lon": 3.88
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 149.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 6.84052,
    "lon": -86.37716,
    "alt_m": 14072.2
   },
   "member_spread_deg": {
    "lat": 39.96,
    "lon": 141.56
   },
   "member_spread_now_deg": {
    "lat": 33.99,
    "lon": 74.38
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-29",
   "flight_id": "DG2GG-29_2026-07-28",
   "payload_type": "WSPR",
   "seed_time": "2026-08-04 04:57:00",
   "seed_lat": 46.91667,
   "seed_lon": 165.25,
   "seed_alt_m": 13380.0,
   "seed_age_h": 288.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 48.92761,
    "lon": 61.83649,
    "alt_m": 13150.6
   },
   "member_spread_deg": {
    "lat": 94.39,
    "lon": 297.06
   },
   "member_spread_now_deg": {
    "lat": 73.97,
    "lon": 206.19
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 01:11:00",
   "seed_lat": 41.16667,
   "seed_lon": -123.08333,
   "seed_alt_m": 13380.0,
   "seed_age_h": 4.15,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 00:45:00",
    "lat": 49.33252,
    "lon": 82.86158,
    "alt_m": 12964.9
   },
   "member_spread_deg": {
    "lat": 14.87,
    "lon": 86.91
   },
   "member_spread_now_deg": {
    "lat": 0.9,
    "lon": 0.85
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 14:52:00",
   "seed_lat": 42.02083,
   "seed_lon": 16.04167,
   "seed_alt_m": 13300.0,
   "seed_age_h": 14.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 54.29943,
    "lon": -149.33585,
    "alt_m": 13239.8
   },
   "member_spread_deg": {
    "lat": 8.19,
    "lon": 21.0
   },
   "member_spread_now_deg": {
    "lat": 2.98,
    "lon": 0.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 23:03:00",
   "seed_lat": 85.5,
   "seed_lon": 140.70833,
   "seed_alt_m": 11810.0,
   "seed_age_h": 6.28,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 65.99265,
    "lon": 175.54908,
    "alt_m": 11877.8
   },
   "member_spread_deg": {
    "lat": 22.6,
    "lon": 352.03
   },
   "member_spread_now_deg": {
    "lat": 1.87,
    "lon": 352.81
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 23:18:00",
   "seed_lat": 61.66667,
   "seed_lon": -98.625,
   "seed_alt_m": 12590.0,
   "seed_age_h": 6.03,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 48.20943,
    "lon": -14.11727,
    "alt_m": 12693.6
   },
   "member_spread_deg": {
    "lat": 20.95,
    "lon": 88.15
   },
   "member_spread_now_deg": {
    "lat": 0.84,
    "lon": 0.68
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "GSN-TS",
   "flight_id": "GSN-TS_2026-08-15",
   "payload_type": "OTHER",
   "seed_time": "2026-08-16 01:30:23",
   "seed_lat": 53.81866,
   "seed_lon": 16.61656,
   "seed_alt_m": 9972.0,
   "seed_age_h": 3.83,
   "float_reliable": false,
   "dead_reckoned": false,
   "levels_spanned": 4,
   "nominal_end": {
    "valid_time": "2026-08-23 01:00:00",
    "lat": 39.73586,
    "lon": 162.19473,
    "alt_m": 9952.4
   },
   "member_spread_deg": {
    "lat": 23.98,
    "lon": 322.43
   },
   "member_spread_now_deg": {
    "lat": 0.19,
    "lon": 1.57
   },
   "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": 8.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 28.67317,
    "lon": -53.93896,
    "alt_m": 13435.7
   },
   "member_spread_deg": {
    "lat": 35.16,
    "lon": 48.17
   },
   "member_spread_now_deg": {
    "lat": 1.26,
    "lon": 3.83
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:57:03",
   "seed_lat": 60.95833,
   "seed_lon": 74.25,
   "seed_alt_m": 13350.0,
   "seed_age_h": 0.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 05:00:00",
    "lat": 61.75983,
    "lon": 133.20683,
    "alt_m": 13129.6
   },
   "member_spread_deg": {
    "lat": 20.23,
    "lon": 77.59
   },
   "member_spread_now_deg": {
    "lat": 0.06,
    "lon": 0.14
   },
   "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": 89.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 58.79212,
    "lon": 143.26653,
    "alt_m": 12589.5
   },
   "member_spread_deg": {
    "lat": 8.17,
    "lon": 312.16
   },
   "member_spread_now_deg": {
    "lat": 27.21,
    "lon": 119.84
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 15:50:00",
   "seed_lat": 36.875,
   "seed_lon": 24.08333,
   "seed_alt_m": 12710.0,
   "seed_age_h": 13.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 38.0822,
    "lon": -136.18474,
    "alt_m": 13008.1
   },
   "member_spread_deg": {
    "lat": 25.72,
    "lon": 357.66
   },
   "member_spread_now_deg": {
    "lat": 2.82,
    "lon": 3.92
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:26:00",
   "seed_lat": 63.3125,
   "seed_lon": -42.875,
   "seed_alt_m": 12260.0,
   "seed_age_h": 8.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 68.49134,
    "lon": 3.11985,
    "alt_m": 12083.1
   },
   "member_spread_deg": {
    "lat": 35.15,
    "lon": 282.84
   },
   "member_spread_now_deg": {
    "lat": 0.66,
    "lon": 2.89
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 56.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": 29.01361,
    "lon": -37.09119,
    "alt_m": 11243.8
   },
   "member_spread_deg": {
    "lat": 26.93,
    "lon": 190.59
   },
   "member_spread_now_deg": {
    "lat": 12.7,
    "lon": 27.45
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:55:45",
   "seed_lat": 71.54161,
   "seed_lon": 114.37502,
   "seed_alt_m": 13120.0,
   "seed_age_h": 0.4,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 05:00:00",
    "lat": 86.63477,
    "lon": -166.52427,
    "alt_m": 12771.8
   },
   "member_spread_deg": {
    "lat": 25.24,
    "lon": 82.54
   },
   "member_spread_now_deg": {
    "lat": 0.22,
    "lon": 0.08
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:51:00",
   "seed_lat": 15.27083,
   "seed_lon": 146.875,
   "seed_alt_m": 16730.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 04:15:00",
    "lat": 12.45603,
    "lon": 17.21469,
    "alt_m": 16601.7
   },
   "member_spread_deg": {
    "lat": 43.87,
    "lon": 95.46
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.19
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP6MPL-9",
   "flight_id": "SP6MPL-9_2026-08-02",
   "payload_type": "APRS",
   "seed_time": "2026-08-04 04:05:45",
   "seed_lat": 45.52942,
   "seed_lon": 75.286,
   "seed_alt_m": 12836.0,
   "seed_age_h": 289.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 23:30:00",
    "lat": 32.68758,
    "lon": -142.15125,
    "alt_m": 13324.3
   },
   "member_spread_deg": {
    "lat": 43.39,
    "lon": 344.82
   },
   "member_spread_now_deg": {
    "lat": 30.92,
    "lon": 251.48
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:21:00",
   "seed_lat": 45.83333,
   "seed_lon": 164.16667,
   "seed_alt_m": 13390.0,
   "seed_age_h": 0.98,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 03:45:00",
    "lat": 43.04865,
    "lon": -29.70591,
    "alt_m": 13563.2
   },
   "member_spread_deg": {
    "lat": 34.26,
    "lon": 115.78
   },
   "member_spread_now_deg": {
    "lat": 0.17,
    "lon": 0.42
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 04:20:23",
   "seed_lat": 50.79161,
   "seed_lon": 177.66669,
   "seed_alt_m": 13240.0,
   "seed_age_h": 0.99,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-23 03:45:00",
    "lat": 54.4933,
    "lon": -81.54268,
    "alt_m": 12895.4
   },
   "member_spread_deg": {
    "lat": 25.7,
    "lon": 63.17
   },
   "member_spread_now_deg": {
    "lat": 0.8,
    "lon": 0.51
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-16 01:39:00",
   "seed_lat": -27.66667,
   "seed_lon": -155.41667,
   "seed_alt_m": 12330.0,
   "seed_age_h": 3.68,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-23 01:15:00",
    "lat": -25.90917,
    "lon": 50.35992,
    "alt_m": 12433.7
   },
   "member_spread_deg": {
    "lat": 24.25,
    "lon": 137.0
   },
   "member_spread_now_deg": {
    "lat": 0.56,
    "lon": 1.7
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "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": 94.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 23:45:00",
    "lat": -24.62538,
    "lon": 8.87979,
    "alt_m": 15689.7
   },
   "member_spread_deg": {
    "lat": 27.02,
    "lon": 200.15
   },
   "member_spread_now_deg": {
    "lat": 12.31,
    "lon": 338.42
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}