Seasonal Climate Forecast
MAURITIUS METEOROLOGICAL SERVICES
Summer 2017-2018 Outlook for the
Republic of Mauritius
This report gives an indication of the expected evolution of the 2017-2018 South West Indian Ocean (SWIO) summer particularly, the likely cyclone activity, summer rainfall and temperature in Mauritius, Rodrigues, St Brandon and Agalega. The official cyclone season for the Republic of Mauritius is from 01 November to 15 May of the following year.
The contents of this Outlook are meant to be used as general guidelines for planning purposes by stakeholders in various sectors.
2.0 General Background
Correlations between sea surface temperature and summer rainfall over Mauritius, Rodrigues, St Brandon and Agalega have been fairly well established. Persistence and the behaviour of meteorological and oceanic parameters in analogue years have been utilised to generate the most likely scenario for the 2017-2018 Southwest Indian Ocean summer. Global, Regional and Local Predictors are analysed during the process of preparation of this outlook.
3.0 Extreme Weather Events
Regional and global observations over the past two decades as well as scientific reports indicate that the frequency of extreme weather events has increased in the Southwest Indian Ocean Islands.
It is very likely that extreme weather events in the form of heavy and/or torrential rainfall leading to flash floods, violent thunderstorms as well as electric storms, heat wave with above normal temperatures lingering for days and explosive intensification of cyclones may occur during the forthcoming summer 2017-2018. Tropical cyclones evolving in the vicinity of the Mascarenes Islands may generate high waves and heavy swells that are most likely to reach the shores of the Islands of the Republic of Mauritius
After careful analysis of the behaviour of all indicators and taking into consideration analogue patterns, it is concluded that:
1. During most part of this summer, the average temperature for Mauritius and Rodrigues is likely to be slightly above normal. On certain days in Mauritius, temperatures will exceed the monthly average by more than two degrees Celsius in various locations. Maximum temperatures may reach 35 degrees Celsius at Port Louis and in some coastal areas during afternoons of peak summer months (January to March). At Rodrigues, maximum temperatures are likely to reach 32 degrees Celsius along coastal areas on certain occasions.
Temperatures at both St Brandon and Agalega will be near normal with maximum reaching 31 and 32 degrees Celsius, respectively.
Successive days with above normal temperatures, high humidity and light wind may cause torrid conditions resulting in severe discomfort. Such conditions are more likely to occur from January to March 2018.
2. The onset of summer rainfall is likely to be slightly delayed and is expected to occur during the second fortnight of December in both Mauritius and Rodrigues. Cumulative summer rainfall over Mauritius is expected to be near normal with a mean of about 1350 mm. However, the mean rainfall over Rodrigues will be slightly below normal with a mean of around 550 mm.
At Agalega and St Brandon cumulative summer rainfall will be near normal with about 1200mm and 700 mm, respectively.
4. Atmospheric conditions from January to March 2018 is likely to be conducive for the occurrence of extreme weather events such as torrential rains, flash floods, heat wave and violent thunderstorms.
5. It is likely that there will be 6 to 8 named storms over the South West Indian Ocean basin during the forthcoming summer, that is, from 01 November 2017 to 15 May 2018. Most of the storms for this season are likely to form to the west of Diego Garcia and the first storm is likely to be named by the end of December 2017.
1. All named storms that will develop in the Southwest Indian Ocean will NOT necessarily be a direct threat to the islands of the Republic of Mauritius.
2. All storms/cyclones will have a unique name in the southern Indian Ocean. For example, a storm/cyclone originating from the Australian region and entering the Area of Responsibility of Mauritius will retain its original name and vice versa.
This report may be updated upon the availability of fresh information.
12 January 2018