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Seasonal Climate Forecast

MAURITIUS METEOROLOGICAL SERVICES

Winter 2018- Seasonal Climate Outlook 

 

1.0 Introduction

 

The winter 2018 Seasonal Outlook prepared by the Mauritius Meteorological Services, gives an insight of the expected evolution of the climate during the winter months at Mauritius and Rodrigues. The contents of this outlook are meant to be used as general guidelines for planning purposes by stakeholders in various socio-economic sectors.  Wintry type weather starts around May and ends around October. However, May and October are usually known as transition months where both summer and winter type weather prevails. As such the analysis presented in this report is applicable mainly for the period June to September.

 

2.0 Background

 

Seasonal climate forecast provides information on how likely it is that the coming season will be wetter, drier, warmer or colder than normal. A seasonal climate forecast is not an attempt to forecast the detailed day-to-day evolution of weather.

 

Winter weather is often characterized by persistent trade winds emanating from anticyclones in the South Indian Ocean and temperatures are cooler.

 

The behaviour of various meteorological parameters in analogue years as well as El Nino Southern Oscillation (ENSO) and sea surface temperature in the Indian Ocean are analysed to generate objective scenarios for the winter months. Global, regional and local predictors as well as output from global producers of long range forecast are used during the preparation of this outlook.

 

3.0 MMS Outlook for winter 2018

 

Winter weather will gradually set in by the second week of May 2018. Based on statistical models and objective analysis of available meteorological parameters as well as probabilistic climate forecast from various climate models, the most likely outcome for winter 2018 is as follows:

 

(a) Rainfall

Cumulative rainfall over Mauritius is likely to be slightly above normal  with a mean of about 780 mm. Wetter conditions may prevail in May, July and August while June rainfall is expected to be close to the normal. Rainfall may be close to slightly below normal in September and October. The Central Plateau, the eastern and southern slopes are likely to be wetter than the other regions.

 

Near normal rainfall is expected at Rodrigues with a mean of about 370 mm over the island.

 

(b) Temperature

Day temperature is likely to be near normal, both at Mauritius and Rodrigues whereas night temperature is likely to be above normal. Thus, the mean temperature (average of maximum and minimum) for winter is expected to be slightly above normal over both islands.

 

However, there will be intra-seasonal variations when on a few occasions cold spells may set in for a few days, especially in the months of June to August. Further, during clear sky and light wind conditions, it is likely that minimum temperature may plummet to 12 degrees Celsius at Mauritius and around 14 degrees Celsius at Rodrigues during peak winter months.

 

Table 1 and Table 2 below show the forecast monthly average maximum and minimum temperatures in degrees Celsius for the different regions of Mauritius as well as for Rodrigues (Pointe Canon and Plaine Corail).

 

Table 1: Expected monthly average maximum and minimum temperatures over Mauritius.

 

Month

May

Jun

Jul

Aug

Sept

Oct

Region

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

EAST

28

22.5

26

21

25

20

25

20

26

20.5

27

21.5

WEST

28.5

21

27

19.5

26

19

26

19

27.5

19

27.5

19.5

NORTH

29.5

21.5

27.5

19.5

26.5

19

27

19.5

28

19.5

29

20.5

SOUTH

28

22.5

26.5

21.5

25.5

20.5

25.5

20.5

26.5

21

27.5

21.5

CENTRE

25.5

19.5

24

18

23

17

23

17

24

17.5

25

18.5

 

 

Table 2: Expected monthly average maximum and minimum temperatures over Rodrigues.

 

Month

May

Jun

Jul

Aug

Sept

Oct

Region

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Min

Pte-Canon

29

23

27

21.5

26

20

26

20

27

21

28

22

Plaine Corail

28.5

23

26.5

21

25.5

20

25.5

20

26.5

21

27.5

21.5

 

 

 

 

 

 

Other features of winter weather

 

i) Winter months in Mauritius and Rodrigues are windier than in summer. It is likely that the trade wind, mainly from the East South East, will blow at an average speed of 20 to 30 km/h.

 

Occasionally, during peak winter months, namely: July and August, the passage of strong anticyclones to the south of the Indian Ocean may strengthen the wind over the Mascarenes, resulting in wind gusts reaching 80-90 km/h in the exposed areas.

 

ii) On some occasions, the sea is likely to become very rough with heavy swells generated by the combined effect of deep travelling lows and strong anticyclones to the south of the Mascarenes. The breaking waves are likely to reach the southern and western shores of Mauritius and Rodrigues and cause temporary inundation of low lying areas.

 

iii) In line with the findings of IPCC fifth Assessment Report, extreme weather events including high intensity rainfall, large variation of temperature and windy conditions are very likely to occur occasionally over Mauritius and Rodrigues.

 

This report will be updated at the end of July 2018.

 

Meteorological Services

St Paul Road, Vacoas

 

03 May 2018