16/11/20161 Introduction Heavy rains hits Mahe Island during dry season.

16/11/20162 The season This is a relatively drier and cooler period when the wind flow over the Seychelles is dominated by the 'South-east Trades' which reaches its peak in the month of July/August. Precipitation during this period is normally light in nature and rather short- lived. Southeast Monsoon - May to October

16/11/20163 Easterly Wave which hit Seychelles on 10 th July On 10th July 2009 an active easterly wave influenced the region of Seychelles, particularly Mahe and some of its Inner islands, with bad weather. On 7th July 09 a low pressure system was depicted far to the east beyond 70 degrees longitude and monitored propagating westward in the form of a wave. In fact most statistical and numerical models, particularly RSMC-Pretoria, Arperge and FNMOC, were predicting that the system will hit Mahe in three days time and cause heavy rainfall of more than 50mm over a 24 hours period. Clouds associated with the low pressure were also depicted on the satellite imagery, however the movement of the wave was not well apparent on the MSL synoptic chart. In fact if it was not because of the models it would have been very difficult to capture the movement of the system based on local data and analysis. The National Meteorological Service (NMS) issued a press release of bad weather situation and also had TV coverage 12hours prior to the event. The aftermath caused a lot of damages in terms of flooding, landslide…etc,. July is normally the driest month of the year with average of 74mm of rainfall (based on long term mean), and total amount recorded over just the 24 hours period on the 10th July was 342mm.

16/11/20164 Satellite imagery and models (cont…)

16/11/20165 Satellite imagery and models (cont…)