Thirteen tropical cyclones formed in the south-west Indian Ocean during the last rainy season and had some effect on southern Africa weather although only three made a landfall.

The cyclones were among the topics discussed at the 24th Southern African Climate Outlook Forum (SARCOF-24), the regular meeting of Southern African weather experts.

SADC Climate Services Centre expert Dr Arlindo Meque said tropical cyclone Ambali was the strongest last season with sustained wind speed of 220km/h and wind gusts up to 315km/h. This cyclone formed as a tropical depression in the southern Indian Ocean on 4 December last year and quickly strengthened into a tropical storm.

It was located west-southwest of Diego Garcia, an island north of Madagascar.

The 2019-2020 rainfall season, a moderate El Nino year, brought above normal rainfall in the north-eastern part of SADC with part of the south of the region experiencing below normal rainfall conditions.

“In terms of climate prediction, it was a half miss,” said a climate expert. “We had a challenge in detecting signals in some parts of the region.” Dr Meque also noted that the observed rainfall pattern was consistent with the consensus seasonal forecast issued last year in Angola despite that the forecast did not perform well in some places.

When tropical cyclones do make landfall, they usually bring cloudy weather, heavy rains and strong winds to the sections they hit. Cylones in the Indian Ocean, hurricanes in the Atlantic and typhoons in the Pacific are identical phenomena.

Most of Sadc, including Zimbabwe, is expected to receive normal to above normal rains in the coming season, while a belt across in the northern part of the region is likely to have normal to below normal in the first half of the season. This is almost the direct opposite of what happened last season. The La Niña expected this year accounts for the difference.

In El Nino years, the south and centre of the region tends to have lower rainfall and the north higher rainfall, with the position switched in La Nina years. But many other factors moderate or aggravate these trends.

More cyclones tend to be seen in Lan Nina years, but the worst to hit Zimbabwe in half a century, Cyclone Idai at the end of the 2018-19 season occurred in an El Nino year.

But the Sadc climate experts warned that member states should not be complacent as the region is likely to experience an average or above-average number of tropical cyclones this season.

“In La Nina years, it is possible that we are likely to see more tropical cyclones affecting the southern African region, especially across the eastern coastline,” said a climate expert. “The season will almost certainly be more active than the last and this means the Sadc region must activate its disaster preparedness plans because the likelihood of damage from a tropical cyclone is high this season.”

Tropical Cyclone Idai, the worst in more than 50 years, brought heavy rainfall and strong winds to Malawi, Mozambique and Zimbabwe between March 5 and 19, 2019, causing severe flooding which led to loss of lives, destruction of infrastructure, disruption of livelihoods and destruction of crops.

It is estimated that close to 780 000ha of croplands in the three countries were destroyed by the cyclone, with the majority of this area being in Mozambique.

Dams and wells were also damaged, and livestock were washed away. SADC launched a US$323 million appeal to support the disaster response and recovery efforts related to Tropical Cyclone Idai impacts.