AWIO20 FMEE 241034
TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

BULLETIN FOR CYCLONIC ACTIVITY AND SIGNIFICANT TROPICAL WEATHER
IN THE SOUTHWEST INDIAN OCEAN

DATE: 2026/02/24 A 1200 UTC

PART 1: WARNING SUMMARY



Bulletins WTIO20 and WTIO30 021/11 issued at 06 UTC sur le Cyclone Tropical Intense HORACIO. Next bulletins issued at 12 UTC.

PART 2 : TROPICAL WEATHER DISCUSSION:

The basin is in a hybrid pattern and is heavily influenced by the presence of the tropical cyclone HORACIO in the center of the basin. In the eastern part of the basin, east of 80E and around 10S, a Near-Equatorial Trough (NET) branch is forming. Convection is mainly present around HORACIO and the slowdown trade winds zone to the northwest of Diego-Garcia, moderate to strong. It is weaker around the Seychelles, off the Tanzanian coasts, and east of the NET branch.

During the first part of the week, a Kelvin wave will cross the basin from west to east and eventually intersect with the MJO's westerly thrust and a new Rossby wave at the eastern borders of our basin, generating vorticity outside the basin.
This weak Kelvin wave is also crossing a Rossby wave over the Seychelles today and tomorrow, which could also generate vorticity within an already existing convection system.

intense Tropical Cyclone HORACIO :
Information at 09 UTC : 
Estimated position :   23.1S / 64.3 E
Movement : S 11kt
Maximum wind speed (averaged over 10 minutes) : 90 kt
Estimated central pressure : 958 hPa
For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and following.

Overt the eastern borders of the basin:
An elongated low-pressure system is present at around 93oE/11oS on the eastern edge of the NET. Its polar convergence is good but weak on the equatorial side. While the ondulatory contribution would allow it to strengthen this equatorial convergence towards the middle of the week, its polar convergence will run out of steam on Thursday as a trough passes further south, destroying the anticyclone in the southeast of the basin.
None of the AI ensembles suggest cyclogenesis, and among the classic ensemble models, only a few members develop to the stage of a moderate tropical storm, all of them in the Australian zone. It cannot be ruled out that a storm could return to the area in the end of next week.

Apart from system HORACIO, development of a new tropical storm is not expected for the next 5 days.

To the northeast of Madagascar :
A convective zone is present northeast of Madagascar, near the Seychelles. Some members of the EPS ensemble model suggest a low risk of cyclogenesis between now and Friday. This scenario is not supported by the GEFS ensemblist and AI models. In addition, environmental conditions appear to be deteriorating in this area, with either deep wind shear increasing or a lack of convergence in the lower layers.

Apart from system HORACIO, development of a new tropical storm is not expected for the next 5 days.





NOTA BENE: The likelihood is an estimate of the chance of genesis of a moderate tropical storm over the basin within the next five days:

Very low: less than 10%      Moderate: 30% to 60%      Very high: over 90%
Low: 10% to 30%              High: 60% to 90%

The Southwestern Indian ocean basin extends from the Equator to 40S and from the african coastlines to 90E.