{
 "generated_utc": "2026-08-15T23:26:39Z",
 "gfs_cycle_utc": "2026-08-15T18:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 445.5,
  "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_20260815_18Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260815_18Z.geojson.gz"
 },
 "counts": {
  "flights": 22,
  "members": 9,
  "rows": 83412
 },
 "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": 10.44,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": -48.82196,
    "lon": 44.57094,
    "alt_m": 12509.3
   },
   "member_spread_deg": {
    "lat": 32.99,
    "lon": 133.41
   },
   "member_spread_now_deg": {
    "lat": 5.68,
    "lon": 23.15
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 13:36:48",
   "seed_lat": 54.8125,
   "seed_lon": 77.125,
   "seed_alt_m": 12860.0,
   "seed_age_h": 9.72,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 80.02527,
    "lon": -129.80377,
    "alt_m": 12443.3
   },
   "member_spread_deg": {
    "lat": 50.8,
    "lon": 357.14
   },
   "member_spread_now_deg": {
    "lat": 0.34,
    "lon": 0.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 22:58:19",
   "seed_lat": 48.16667,
   "seed_lon": 165.625,
   "seed_alt_m": 14140.0,
   "seed_age_h": 0.36,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 23:00:00",
    "lat": 50.83012,
    "lon": -66.58425,
    "alt_m": 13765.1
   },
   "member_spread_deg": {
    "lat": 27.33,
    "lon": 139.48
   },
   "member_spread_now_deg": {
    "lat": 0.02,
    "lon": 0.16
   },
   "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": 8.85,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 42.19592,
    "lon": -143.03555,
    "alt_m": 12685.2
   },
   "member_spread_deg": {
    "lat": 17.79,
    "lon": 14.41
   },
   "member_spread_now_deg": {
    "lat": 3.21,
    "lon": 3.13
   },
   "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": 143.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 17.12193,
    "lon": -90.23794,
    "alt_m": 14047.0
   },
   "member_spread_deg": {
    "lat": 34.77,
    "lon": 144.16
   },
   "member_spread_now_deg": {
    "lat": 33.54,
    "lon": 69.89
   },
   "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": 282.38,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 34.99405,
    "lon": 64.43851,
    "alt_m": 13318.6
   },
   "member_spread_deg": {
    "lat": 74.08,
    "lon": 318.93
   },
   "member_spread_now_deg": {
    "lat": 74.71,
    "lon": 209.48
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 22:41:00",
   "seed_lat": 39.97917,
   "seed_lon": -124.16667,
   "seed_alt_m": 12860.0,
   "seed_age_h": 0.65,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 22:15:00",
    "lat": 50.40689,
    "lon": 81.12575,
    "alt_m": 12517.4
   },
   "member_spread_deg": {
    "lat": 25.91,
    "lon": 79.22
   },
   "member_spread_now_deg": {
    "lat": 0.1,
    "lon": 0.05
   },
   "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": 8.47,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 53.16509,
    "lon": -178.93075,
    "alt_m": 13249.2
   },
   "member_spread_deg": {
    "lat": 8.25,
    "lon": 355.14
   },
   "member_spread_now_deg": {
    "lat": 1.51,
    "lon": 0.48
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 10:43:00",
   "seed_lat": 81.70833,
   "seed_lon": 99.16667,
   "seed_alt_m": 11900.0,
   "seed_age_h": 12.62,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 64.50386,
    "lon": 163.61172,
    "alt_m": 12030.6
   },
   "member_spread_deg": {
    "lat": 21.12,
    "lon": 343.15
   },
   "member_spread_now_deg": {
    "lat": 4.24,
    "lon": 344.03
   },
   "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 22:33:00",
   "seed_lat": 61.72917,
   "seed_lon": -99.29167,
   "seed_alt_m": 12620.0,
   "seed_age_h": 0.78,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 22:00:00",
    "lat": 82.67828,
    "lon": 58.61841,
    "alt_m": 12703.0
   },
   "member_spread_deg": {
    "lat": 33.05,
    "lon": 67.33
   },
   "member_spread_now_deg": {
    "lat": 0.09,
    "lon": 0.09
   },
   "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": 2.49,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 20:15:00",
    "lat": 27.97631,
    "lon": -45.15658,
    "alt_m": 13405.9
   },
   "member_spread_deg": {
    "lat": 29.78,
    "lon": 43.05
   },
   "member_spread_now_deg": {
    "lat": 1.09,
    "lon": 1.13
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 14:57:04",
   "seed_lat": 59.41667,
   "seed_lon": 73.5,
   "seed_alt_m": 13410.0,
   "seed_age_h": 8.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 61.3257,
    "lon": 118.23464,
    "alt_m": 13146.1
   },
   "member_spread_deg": {
    "lat": 12.97,
    "lon": 67.27
   },
   "member_spread_now_deg": {
    "lat": 0.5,
    "lon": 1.19
   },
   "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": 83.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 53.85743,
    "lon": 139.26212,
    "alt_m": 12528.4
   },
   "member_spread_deg": {
    "lat": 12.93,
    "lon": 314.23
   },
   "member_spread_now_deg": {
    "lat": 28.73,
    "lon": 112.04
   },
   "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": 7.5,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 35.13487,
    "lon": -146.36006,
    "alt_m": 13050.9
   },
   "member_spread_deg": {
    "lat": 30.69,
    "lon": 343.94
   },
   "member_spread_now_deg": {
    "lat": 1.92,
    "lon": 1.33
   },
   "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": 2.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 20:00:00",
    "lat": 69.89846,
    "lon": 132.42094,
    "alt_m": 12027.0
   },
   "member_spread_deg": {
    "lat": 38.06,
    "lon": 307.74
   },
   "member_spread_now_deg": {
    "lat": 0.28,
    "lon": 0.73
   },
   "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": 50.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": 32.90228,
    "lon": -37.26784,
    "alt_m": 11236.0
   },
   "member_spread_deg": {
    "lat": 26.86,
    "lon": 144.3
   },
   "member_spread_now_deg": {
    "lat": 16.5,
    "lon": 23.21
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 10:30:45",
   "seed_lat": 75.41661,
   "seed_lon": 111.33335,
   "seed_alt_m": 13180.0,
   "seed_age_h": 12.82,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 84.46583,
    "lon": -148.66154,
    "alt_m": 12868.0
   },
   "member_spread_deg": {
    "lat": 53.28,
    "lon": 347.34
   },
   "member_spread_now_deg": {
    "lat": 6.5,
    "lon": 4.54
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 22:51:00",
   "seed_lat": 14.08333,
   "seed_lon": 150.16667,
   "seed_alt_m": 16640.0,
   "seed_age_h": 0.48,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 22:15:00",
    "lat": 11.19852,
    "lon": 20.28362,
    "alt_m": 16609.3
   },
   "member_spread_deg": {
    "lat": 40.61,
    "lon": 94.39
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.22
   },
   "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": 283.24,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 17:30:00",
    "lat": 27.70405,
    "lon": -172.86787,
    "alt_m": 13177.1
   },
   "member_spread_deg": {
    "lat": 57.42,
    "lon": 331.57
   },
   "member_spread_now_deg": {
    "lat": 30.07,
    "lon": 249.93
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 22:26:00",
   "seed_lat": 47.66667,
   "seed_lon": 161.41667,
   "seed_alt_m": 13390.0,
   "seed_age_h": 0.9,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-22 22:00:00",
    "lat": 45.91853,
    "lon": -47.8243,
    "alt_m": 13328.4
   },
   "member_spread_deg": {
    "lat": 25.23,
    "lon": 112.05
   },
   "member_spread_now_deg": {
    "lat": 0.12,
    "lon": 0.55
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 22:44:00",
   "seed_lat": -28.0,
   "seed_lon": -162.625,
   "seed_alt_m": 12380.0,
   "seed_age_h": 0.6,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-22 22:15:00",
    "lat": -21.22591,
    "lon": 34.94867,
    "alt_m": 12532.5
   },
   "member_spread_deg": {
    "lat": 12.58,
    "lon": 133.39
   },
   "member_spread_now_deg": {
    "lat": 0.07,
    "lon": 0.25
   },
   "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": 88.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-22 17:45:00",
    "lat": -25.92265,
    "lon": 20.11614,
    "alt_m": 15777.4
   },
   "member_spread_deg": {
    "lat": 14.07,
    "lon": 201.33
   },
   "member_spread_now_deg": {
    "lat": 10.33,
    "lon": 341.11
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}