Cyclone: prévisions saisonnières

Seasonal Climate Forecast

Summer 2014-2015 Outlook for Mauritius and Rodrigues

Introduction

This report gives an indication of the expected evolution of the 2014-2015 South West Indian Ocean (SWIO) summer - namely, the likely cyclone activity, summer rains, temperatures, thunderstorm activities and other extreme events in Mauritius and Rodrigues. The official cyclone season for the Republic of Mauritius is from 01 November to 15 May of the following year.

The contents of this seasonal outlook are general guidelines for planning purposes to key stakeholders in various sectors.  

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 during southern hemisphere summer. Global, regional and local predictors are analysed during the process of preparation of this outlook.

Extreme Weather and Climate Events

Past regional and international observations and scientific reports indicate that the frequency of extreme events continues to increase over the Republic of Mauritius.

It is practically certain that similar events in the form of heavy and/or torrential rainfall leading to flash floods, violent thunderstorm or electric storm accompanied by mini tornadoes and hail storm, micro-bursts, high waves in the form of swells or freak waves, heat wave with high temperatures lingering for days and explosive growth of cyclonic activities will persistently occur during the forthcoming summer 2014-2015.

Conclusions

The analyses of the indicators and consideration of the analogue patterns points to the following conclusions:

1) Summer 2014-2015 is likely to be warmer than usual. On certain days, it is likely that temperatures will exceed the monthly average by more than two degrees Celsius. Maximum temperatures on some very hot days during peak summer may reach near 37 degrees Celsius at Port Louis and along the northern and western coastal areas.

At Rodrigues, maximum temperatures are likely to reach 33 degrees Celsius along coastal areas on certain occasions.

Persistent high temperatures are likely to cause heat waves and provoke torrid climatic conditions on certain occasions.

2) The onset of summer rains will be timely. Cumulative summer rainfall is expected to be slightly above normal with an average of about 1450 mm over Mauritius and around 700 mm over Rodrigues. On some occasion, the rainfalls are likely to be heavy and of short duration, causing accumulation of water and flooding.

   

3) During summer 2014-2015, the central equatorial region in the neighbourhood of Diego Garcia and the eastern equatorial region are more conducive to tropical storm formation. The number of named storms expected to evolve in the whole of the South West Indian Ocean basin during the 2014-2015 summer is likely to be between 10 – 12.

4) It is very likely that between  December 2014 and March 2015 atmospheric conditions will become conducive to the occurrence of extreme weather events such as torrential rains, flash flood, heat wave, violent thunderstorm accompanied by mini tornadoes and hail storm, micro-bursts and high waves in the form of swells or freak waves.

Note:

 1. All named storms that will develop in the South Indian Ocean will NOT necessarily be a direct threat to the islands of the Republic of Mauritius.

2. All cyclones/storms will have a unique name in the southern Indian Ocean (A cyclone/storm 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. 

10 October 2014

Meteorological Services

Vacoas.