AWIO20 FMEE 181116 TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

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

DATE: 2021/08/18 AT 1200 UTC

PART 1: WARNING SUMMARY: Nil.

PART 2 : TROPICAL WEATHER DISCUSSION: The deep convection in the near equatorial zone of the South Indian Ocean, is mainly present within two areas of low level vorticity evolving north of 10S and east of 50E. During the last 24 hours, no significant change was noted on the rainy organization of these two areas.

West of the Chagos archipelago: The area of low-level vorticity is now evolving between the Seychelles and Agalega without presenting a closed surface circulation according to the latest available observations. This system has no more potential to develop into a tropical storm since 48h. It will dissipate in the next few days over the northwestern part of the basin.

East of the Chagos archipelago : The thunderstorm activity remains disorganized within an area of relative low pressure that still has no surface circulation center. If the conditions are still neutral for a development tomorrow (moderate shear but weak low levels convergence), the environment should deteriorate in the mid levels from Friday with the increase of the mid shear associated with a fairly important intrusion of dry air from the west. In this pattern, the potential for development to the stage of a tropical storm is now considered negligible.

There is therefore no more risk of development of a tropical storm east of the Chagos during the next 5 days.

NOTA BENE: The likelihood is an estimate of the chance of the genesis of a moderate tropical storm over the basin and 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.