AWIO20 FMEE 081150
TROPICAL CYCLONE CENTER / RSMC LA REUNION / METEO-FRANCE

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

DATE: 2026/05/08 A 1200 UTC

PART 1: WARNING SUMMARY

NIL.

PART 2 : TROPICAL WEATHER DISCUSSION:

The basin presents a Near-Equatorial Trough (NET) pattern extending between 55o and 83oE and between 3o and 8oS. Convective activity is weak along the northern edge of this NET and moderate to locally strong along its eastern edge, near a circulation located at 10.7oS and 81.54oE.

The westerly anomaly currently present over our basin is expected to strengthen as a powerful equatorial Rossby wave is expected to cross paths with an so much intense Kelvin wave, both coupled with a westerly surge behind the moist MJO moving through the eastern part of the basin. This strengthening of the westerly anomaly could improve the TPE and thus low-level convergence on the equatorial side, thereby promoting cyclogenesis.

Suspect area over the northeastern part of the basin :
Unfortunately, this morning's latest ASCAT and KUSCAT swaths passed too far from the system (designated 93S by the JTWC) to accurately locate its center or measure the intensity of the strongest winds. However, the GCOM-W microwave satellite measurement at 0751Z allowed us to locate the center at 10.7oS and 81.5oW. This center is situated on the northern edge of the system's convection, which is subject to nothern moderate deep-level wind shear (approximately 20 kt).  In the coming hours, wind shear and dry air intrusions are expected to prevent the system from developing, even though it has fairly favorable convergence in the lower layers. 
The deterministic and AI models, which in previous runs were forecasting a moderate tropical storm this weekend, have changed their scenario, and the latest runs no longer predict cyclogenesis. However, some members of the ensemble models (especially EPS) continue to forecast cyclogenesis starting on May 12, as environmental conditions improve.

The risk of a tropical storm forming in the northeastern part of the basin is considered very low starting today, and then low from Tuesday, May 12.



10-day outlook:
The westerly anomaly present in the wave context loses its canonical character. But with the decrease in wind shear over the next 6-7 days, a late and difficult cyclogenesis within the area mentioned above remains possible.

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.