AWIO20 FMEE 281110
TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

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

DATE: 2026/03/28 A 1200 UTC

PART 1: WARNING SUMMARY

NIL.

PART 2 : TROPICAL WEATHER DISCUSSION:

The basin is characterized by a hybrid configuration, with a small monsoon trough (MT) stretching between 50o and 60oE along 09oS, and a near-equatorial trough (NET) extending east of 70oE between 07o and 10oS. Convective activity is moderate north of the NET and in the northern part of the Mozambique Channel.

The low-frequency easterly anomaly observed in recent days is being counteracted by a westerly anomaly associated with an Equatorial Rossby Wave (ER) crossing the basin, thereby making conditions less unfavorable for cyclogenesis. The emergence of a TM or a strengthening of the TPE east of 70oE. In addition, a wet MJO signal also moves over the basin and crosses the ER in the central or eastern part of our basin, thereby reinforcing the signal generated by the waves.

Over the central part of the basin : 

Early next week, as the MT build between 70 and 80E, a low-pressure system could form in this area. This system could initially encounter favorable conditions, with good low-level convergence on both the equatorial and polar sides, as well as relatively weak upper-level wind shear.
Ensemble models and AI forecasts suggest the formation of a moderate tropical storm, with a low risk on Wednesday and a moderate risk on Thursday. Deterministic models predict the development of a tropical storm, but not for at least five days.

The likelihood of the formation of a moderate tropical storm becomes low from Wednesday 1st of April, then moderate from Thursday 2nd of April, south of Diego-Garcia.



10-day outlook:
Nothing to report.

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.