Jean-noel DEGRACE, Chef du Service régional MétéoFrance Martinique

HURRICANE SEASON 2011 in the FRENCH WEST INDIES

Nineteen tropical storms, including 7 hurricanes were identified during the 2011 hurricane season in the North Atlantic and Carribean basin but none hurricane has been a threat for the FWI.However, 4 tropical storms (Emily, Irene, Maria and Ophelia) needed a close monitoring, with regard to heavy rain and poor associated predictabilities. Some of them led to the activation of the vigilance system, mostly for heavy rain and consequences such as flash floods, mud and land slides that caused damage especially in Martinique. It has to be highlighted that the hurricane season arrived right after a very unusual and rainy first semester that broke several records with regard to rainfall accumulation and number of rainy days. As a consequence, the soil was well saturated and the level of the rivers was relatively high.

Tropical Storm EMILY

On the 30th of July, a very well organized tropical wave with a minimum located near 12,5N and 48,5W was a threat for our islands. Several models showed a potential for development, even if hurricane force winds were not expected, with tracks crossing the Lesser Antilles somewhere between St-Lucia and St-Barth/St Martin.

Tropical Storm EMILY… continued

Especially because it was a week-end and even if the system was not yet identified by RSMC Miami as a Tropical Depression, MeteoFrance started to issue vigilance bulletins on the 30th evening in order to ensure that everybody would have time to be prepared before the 1st of August. The threat was mostly due to heavy rainfalls and remember, the islands at this time were very vulnerable due to a very rainy first semester

Tropical Storm EMILY… continued

The center of the storm passed in the Dominica Chanel, a couple of miles north of Martinique, on the 1st of August in the afternoon. At this time, the tropical storm was somehow poorly organized and there was no wind in its southern half. Weather stations in Guadeloupe reported gusts between 70 and 100 km/h, 96km/h on La Desirade, 83km/h on Marie-Galante and 74km/h at the Raizet Airport.The main consequences came from the very intense rainfall that occurred at the rear of the system, in the southerly convergent and humid low level flux. Martinique experienced more than 150mm of rain on the 2nd of August, early morning, that produced a lot of floodings and landslides in the center of the island where half of the population is concentrated.

Tropical Storm EMILY… continued

Tropical Storm IRENE

Tropical storm IRENE was officially born roughly 250km east of Martinique on the 20th evening (23 Utc= 7pm local time !!! Grrrrrrrrrrrr !!! ) with max sustained winds of 85km/h (gusts up to 100km/h).

The two official forecasts ofIRENE on the 20th

evening/night (the first at 7pmwith a back-analysed positionat 18 Utc and the following at 11pm) showed tracks between Martinique and Guadeloupe during the second half of the night, with a slightintensification.

Tropical Storm IRENE… continued

The risk associated with the passage of IRENE close to the French islands had been well anticipated, even once again if the storm was not named yet. The yellow level for heavy rain had been issued since the 19th

evening and then upgraded to orangelevel for a somewhatweak tropical cycloneon the 20th noon, for Guadeloupe and St-Barth/St-Martin. Since Martinique wassupposed to be on thesouth part of the storm, the island was mostlyconcerned by a forecastof heavy rain.

Tropical Storm IRENE… continued

Since the center of IRENE passed north of Guadeloupe, the consequences were not as important as anticipated. The main rainy clusters have stayed on sea and the rainfall accumulation in 24 hours has been moderate with measures between 20-40mm for Martinique, 30-50mm locally 80mm for Guadeloupe and

67mm over St-Barth and 91 over St-Martin.As for the wind, gusts between 80 and 100km/h were recorded in the northern islands, especially inSt-Barth on the 21th around noon (local time). Mean waves between 3,5 and 4meters were recorded by the wave rider north east of Guadeloupe (la vigie) with peak waves up to 5,6m

Tropical Storm MARIA

MARIA was another weak system, not well organized which became very dissymmetric as it was approaching the Lesser Antilles. The system was sheared on its west side and the low level center was quite far away from the main activity.

Tropical Storm MARIA… continued

On the 8 and 9 of September, the official forecasts as well as most of the models outputs were suggesting a track crossing the Lesser Antilles, between Martinique and St-Martin. The center of the storm crossed the Antilles between Antigua and Barbuda but the main active part, associated with deep convection, always remained offshore.

Tropical Storm MARIA… continued

MeteoFrance started to issue vigilance bulletins for Maria on the evening of the 7th September, with a yellow level according to the lead time and the uncertainty associated with Maria. Then the level was upgraded to orange as Maria was approaching the center of the Lesser Antilles and was supposed to pass very close to Guadeloupe, but with a weak intensity

Tropical Storm MARIA… continued

Maria was very sheared and the main activity remained oversea. 24 hours rain accumulation has been light to moderate over land with values from 20 to 60mm in Martinique, Guadeloupe and St-Martin …but the radar show 24 hours accumulation above 200mm dozens of kilometres east or north of the islands !!!

Even if the center passed less than 40km far from Guadeloupe and St-Barth/St-Martin, the islands remained on the western and southern part of the storm that was relatively quite. A max sustained wind at 50km/h (with gusts around 80km/h) was recorded at the Raizet Airport in Guadeloupe, 80 km/h (MSW) and 100km/h (gusts) in La desirade. In St-Martin, the MSW was 50km/h with gusts up to 80km/h.The two waveriders, on the east coast of Guadeloupe and Martinique recordedmean waves between 3,5 and 4 meters with peak waves up to 6 meters.

Tropical Storm MARIA… continued

The lightning activity was very intense in the south-westerly flux, at the rear of the system and the islands experienced a lot of thunderstorms, especially during the night between the 10th and the 11th of September. One very intense lightning fall down on the main power plant in Martinique and caused a 12 hours long “black out” !!!

Tropical Storm OPHELIA

Ophelia was the last weak tropical storm that brought severe weather over the islands, even if the very poor organised center remained at least 200km far on the North-East of Guadeloupe.Ophelia arrived close to the northern Lesser Antilles, on the 25/09 morning as a weak tropical storm, with max sustained wind around 60 km/h. Then, since the conditions were not favourable, Ophelia weakened and was even unclassified on the 26/09.

Tropical Storm OPHELIA… continued

The disturbance remained in the same area during roughly 72 hours and generated a south-westerly flux, with an important activity with regard to thunderstorm and rainfall intensity, especially between Antigua and Martinique.

Tropical Storm OPHELIA… continued

On the 28th in the morning, one of the active clusters, pushed by the westerly flux, intensified on the west coast of Martinique and brought around 100mm of rainfall within 3 hours. Several flash floods occured and local flooding were observed in the communities of Carbet and Bellefontaine..

2011, a rainy year breaking records !!!

In addition to these 4 tropical storms, the French West Indies experienced many other severe weather events that caused flash floods, landslides and other consequences including loss of life in Guadeloupe . Finally, it appeared that 2011 broke the record in terms of yearly amount of rain in many places, included places where measures have been recorded for more than 60 years and as another consequence, the agriculture suffered a lot !

MERCI DE VOTRE ATTENTION( only 4 french words …that’s all I can afford ! )