AWIO20 FMEE 021201
TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

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

DATE: 2026/04/02 A 1200 UTC

PART 1: WARNING SUMMARY



Bulletins WTIO20 and WTIO30 004/13 issued at 06 UTC sur la Tempete Tropicale Moderee INDUSA. Next bulletins issued at 12 UTC.

PART 2 : TROPICAL WEATHER DISCUSSION:

A short and poorly-defined Monsoon Trough (MT) branch remains in place from 50oE to 65oE, between 6oS and 10oS, between a weak low-pressure area near the Seychelles and system number 13 south of the Chagos Islands, which reached tropical storm stage this Thursday morning and has been named INDUSA. Convective activity is weak to moderate over the western part of this MT and locally moderate to strong further east and near INDUSA. Local severe thunderstorm activity is also present between the north of Madagascar and the west of the Mascarene archipelago.

Despite a low-frequency context causing easterly anomalies near the equator, the MT pattern and INDUSA's cyclogenesis have been favored by the westerly wind surge in the lee of a moist MJO, associated with a Kelvin wave and the passage of an Equatorial Rossby wave. 
The MT pattern over the central part of the basin should vanish over the coming weekend as the Rossby wave moves away and the trade wind flow weakens under the influence of INDUSA, which should prevent tropical storm development for the next 5 days. 
A near-equatorial trough (NET) pattern should then start forming again over the eastern part of the basin during next week (in the lee of the MJO + new incoming Rossby wave), although remaining quite unefficient in the short run.

Moderate Tropical Storm INDUSA : 
Information at 09 UTC : 
Estimated position : 12.3 S / 73.4 E
Movement : South-South-West, 05 kt
Maximum wind speed (averaged over 10 minutes) : 45 kt
Estimated central pressure : 990 hPa
For further information, please refer to bulletins WTIO20 and WTIO30 issued at 06 UTC and following.

Apart from INDUSA, development of a tropical storm is not expected over the next 5 days.

10-day outlook:
Convergence and vorticity within the NET/MT over the east of our basin and in the Australian region should increase from the weekend of 11-12 April and the following week due to the improving equatorial wave background. Numerical models suggest the formation of a low-pressure area in the Australian region, which could then possibly develop into a tropical storm. If such a cyclogenesis occurs, its location remains uncertain, somewhere between the Australian region and the far east of our basin.

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.