2023 tropical cyclone season · Southern Hemisphere
Cyclone Ilsa Ilsa · SH182023
Cyclone Ilsa was tracked in the Southern Hemisphere from 2023-04-05 to 2023-04-15 (10 days), peaking at 135 kt (H4) with a minimum pressure of 924 hPa. 92 archived forecasts from ECMWF, ECMWF ENS, GFS, GEFS are verified against its best track; at 48 hours the closest was GEFS, 97 km off on average.
- ATCF ID
- SH182023
- Basin
- Southern Hemisphere
- Tracked
- 2023-04-05 → 2023-04-15 (10 days)
- Peak wind
- 135 kt · 69 m/s · H4
- Minimum pressure
- 924 hPa
- Archived forecasts
- 92
- Sources
- ECMWF · ECMWF ENS · GFS · GEFS
Forecast track error (km)
| Source | 24 h | 48 h | 72 h | 120 h |
|---|---|---|---|---|
| ECMWF | 71 (23) | 107 (19) | 114 (15) | 243 (3) |
| ECMWF ENS | 79 (23) | 115 (19) | 132 (15) | 165 (7) |
| GFS | 86 (22) | 117 (19) | 130 (15) | 597 (7) |
| GEFS | 74 (22) | 97 (19) | 131 (15) | 424 (7) |
Mean great-circle distance to the best track at each lead time, counted while the system was a tropical or subtropical cyclone; the number of cases is in brackets.
Best track
Six-hourly positions of the US best track (JTWC / NHC, one-minute winds); grades on the Saffir–Simpson scale.
| Time (UTC) | Position | Wind (kt) | Pressure (hPa) | Grade |
|---|---|---|---|---|
| 2023-04-05 12Z | 7.1°S 135.4°E | 15 | 1006 | TD |
| 2023-04-05 18Z | 7.4°S 134.1°E | 15 | 1005 | TD |
| 2023-04-06 00Z | 7.5°S 132.9°E | 15 | 1004 | TD |
| 2023-04-06 06Z | 8.1°S 132.4°E | 20 | 1003 | TD |
| 2023-04-06 12Z | 8.7°S 131.8°E | 20 | 1001 | TD |
| 2023-04-06 18Z | 8.9°S 131.3°E | 30 | 996 | TD |
| 2023-04-07 00Z | 8.9°S 130.7°E | 30 | 996 | TD |
| 2023-04-07 06Z | 9.0°S 130.6°E | 30 | 995 | TD |
| 2023-04-07 12Z | 9.1°S 130.5°E | 35 | 993 | TS |
| 2023-04-07 18Z | 9.4°S 130.3°E | 35 | 991 | TS |
| 2023-04-08 00Z | 9.7°S 130.0°E | 30 | 993 | TD |
| 2023-04-08 06Z | 10.1°S 129.7°E | 30 | 993 | TD |
| 2023-04-08 12Z | 10.7°S 129.3°E | 30 | 993 | TD |
| 2023-04-08 18Z | 11.1°S 128.5°E | 35 | 991 | TS |
| 2023-04-09 00Z | 11.7°S 127.3°E | 45 | 992 | TS |
| 2023-04-09 06Z | 12.2°S 126.4°E | 45 | 992 | TS |
| 2023-04-09 12Z | 12.5°S 125.5°E | 45 | 992 | TS |
| 2023-04-09 18Z | 12.5°S 124.8°E | 45 | 991 | TS |
| 2023-04-10 00Z | 12.5°S 124.2°E | 40 | 994 | TS |
| 2023-04-10 06Z | 12.8°S 123.6°E | 40 | 994 | TS |
| 2023-04-10 12Z | 13.1°S 123.2°E | 40 | 995 | TS |
| 2023-04-10 18Z | 13.5°S 122.3°E | 40 | 996 | TS |
| 2023-04-11 00Z | 13.9°S 121.3°E | 45 | 994 | TS |
| 2023-04-11 06Z | 13.9°S 121.3°E | 55 | 990 | TS |
| 2023-04-11 12Z | 15.1°S 120.5°E | 70 | 981 | H1 |
| 2023-04-11 18Z | 15.4°S 120.2°E | 70 | 979 | H1 |
| 2023-04-12 00Z | 15.6°S 119.9°E | 70 | 980 | H1 |
| 2023-04-12 06Z | 15.8°S 119.8°E | 75 | 975 | H1 |
| 2023-04-12 12Z | 16.0°S 119.7°E | 85 | 969 | H2 |
| 2023-04-12 18Z | 17.1°S 119.1°E | 100 | 957 | H3 |
| 2023-04-13 00Z | 17.8°S 118.9°E | 110 | 949 | H3 |
| 2023-04-13 06Z | 18.8°S 118.7°E | 125 | 935 | H4 |
| 2023-04-13 12Z | 19.6°S 119.1°E | 135 | 924 | H4 |
| 2023-04-13 18Z | 20.5°S 119.9°E | 100 | 956 | H3 |
| 2023-04-14 00Z | 21.4°S 121.3°E | 75 | 975 | H1 |
| 2023-04-14 06Z | 22.0°S 123.4°E | 65 | 982 | H1 |
| 2023-04-14 12Z | 22.2°S 125.4°E | 45 | 994 | TS |
| 2023-04-14 18Z | 22.7°S 128.3°E | 35 | 1001 | TS |
| 2023-04-15 00Z | 23.0°S 130.5°E | 30 | 1000 | TD |
| 2023-04-15 06Z | 22.9°S 132.9°E | 25 | 1005 | TD |