Le système d’alerte cyclonique amendé

4. Les services météorologiques de Maurice doivent –
(a) (i) En cas de dépression tropicale, une tempête tropicale modérée, une tempête tropicale sévère, un tropical
Le cyclone, un cyclone tropical intense ou un cyclone tropical très intense est susceptible d’affecter l’île de Maurice ou Rodrigues, le numéro A –
(A) Avertissement de cyclone de Classe I au moins 36 heures, ni plus de 48 heures, avant la survenue de rafales de 120 kilomètres par heure;
(B) Avertissement de cyclone de Classe II de manière à permettre, en ce qui concerne la lumière du jour, 12 heures de jour avant la survenue de rafales de 120 kilomètres par heure;
(C) Avertissement de cyclone de Classe III de manière à permettre, en ce qui concerne, 6 heures de lumière avant la survenue de rafales de 120 kilomètres par heure;
(D) Avertissement de cyclone de Classe IV Lorsque des rafales de 120 kilomètres par heure sont enregistrés à certains endroits et devraient se poursuivre;

(ii) Suivant la question d’une classe III d’alerte cyclone ou d’une classe IV de cyclone et d’observations ultérieures indiquant que le risque de rafales cycloniques de 120 kilomètres par heure a diminué et que le cyclone s’éloigne, émet un bulletin de sécurité aux fins de –
(A) Levage de la classe III d’alerte cyclone ou d’avertissement de cyclone, selon le cas; et
(B) informer le public de l’existence de toutes les conditions météorologiques sévères associées au cyclone et au autre risque environnemental, selon la nature et l’étendue des dommages se sont produits pendant le passage du cyclone;

(iii) Suite à la question d’un cyclone AVERTISSEMENT Classe I, d’une classe II d’alerte cyclone ou d’un bulletin de sécurité, selon le cas, émettre un bulletin de terminaison après consultation et suivre les conseils du Comité national de crise selon lesquelles les risques extérieurs ont considérablement diminué;

4. The Mauritius Meteorological Services shall –
(a) (i) in the event that a tropical depression, a moderate tropical storm, a severe tropical storm, a tropical
cyclone, an intense tropical cyclone or a very intense tropical cyclone is likely to affect the Island of Mauritius or Rodrigues, issue a –
(A) cyclone warning class I not less than 36 hours, nor more than 48 hours, before the occurrence of gusts of 120 kilometres per hour;
(B) cyclone warning class II so as to allow, as far as practicable, 12 hours of daylight before the occurrence of gusts of 120 kilometres per hour;
(C) cyclone warning class III so as to allow, as far as practicable, 6 hours of daylight before the occurrence of gusts of 120 kilometres per hour;
(D) cyclone warning class IV when gusts of 120 kilometres per hour are recorded in some places and are expected to continue;

(ii) following the issue of a cyclone warning class III or a cyclone warning class IV and subsequent observations indicating that the risk of cyclonic gusts of 120 kilometres per hour has abated and the cyclone is moving away, issue a safety bulletin for the purpose of –
(A) lifting the cyclone warning class III or cyclone warning class IV, as the case may be; and
(B) informing the public of the existence of any severe weather conditions associated with the cyclone and other environment risk, depending on the nature and extent of the damage occurred during the passage of the cyclone;

(iii) following the issue of a cyclone warning class I, a cyclone warning class II or a safety bulletin, as the case may be, issue a termination bulletin after consultation with, and following advice from, the National Crisis Committee to the effect that outdoor risks have considerably decreased;

Low pressure area: Region of the atmosphere in which the pressures are lower than those of the surrounding region at the same level and where the cloud masses do not appear to be organized.

Extra-tropical disturbance: Synoptic scale low pressure area outside of the tropics or former tropical disturbance having lost its tropical characteristics.

Sub-tropical disturbance: Synoptic scale low pressure area having during its life, characteristics which could belong to both tropical and extra-tropical depressions. In the South West Indian Ocean, the genesis of such system is regularly observed over the South of Mozambique Channel.

Zone of disturbed weather: Non-frontal synoptic scale low pressure area originating in the tropics or sub-tropics with enhanced convection and light surface winds.

Tropical wave: Trough or cyclonic curvature maximum in the trade wind easterlies or equatorial westerlies. The wave may reach maximum amplitude in the lower middle troposphere, or may be the reflexion of an upper-troposphere cold low or equatorial extension of a mid-latitude trough.

Tropical disturbance: Generic term for a non-frontal synoptic scale low pressure area, originating over tropical or sub-tropical waters with organized convection and definite cyclonic surface wind circulation (average wind speed estimated to be not exceeding 27 knots (50 km/h, force 6 in

the Beaufort scale).

Tropical depression: Tropical disturbance in which the maximum of the average wind speed is estimated to be in the range 28 to 33 knots (51 to 62 km/h, force 7 in the Beaufort scale).

Moderate tropical storm: Tropical disturbance in which the maximum of the average wind speed is estimated to be in the range 34 to 47 knots (63 to 88 km/h, force 8 or 9 in the Beaufort scale).

Severe tropical storm: Tropical disturbance in which the maximum of the average wind speed is estimated to be in the range 48 to 63 knots (89 to 117 km/h, force 10 or 11 in the Beaufort scale).

Tropical cyclone: Tropical disturbance in which the maximum of the average wind speed is estimated to be in the range 64 to 89 knots (118 to 165 km/h, force 12 in the Beaufort scale).

Intense tropical cyclone: Tropical disturbance in which the maximum of the average wind speed is estimated to be in the range 90 to 115 knots (166 to 212 km/h).

Very intense tropical cyclone: Tropical disturbance in which the maximum of the average wind speed is estimated to exceed 115 knots (212 km/h).

Remnant low: A former tropical system that has weakened and is no longer associated with established and/or organized convection. Within the related low-pressure circulation the maximum estimated average wind does not exceed 27 knots (50 km/h, force 6 on the Beaufort scale).

Filling low: A former tropical system undergoing sustained weakening and whose related minimum pressure is raising.

Dissipating low: A former tropical system in the final decaying phase that is doomed to vanish rapidly.

Post-tropical depression: A former tropical system (tropical depression, tropical storm or tropical cyclone) in the extra-tropical transition phase, which no longer presents all the characteristics of a tropical system but has not yet completed its transition and cannot, therefore, be considered an extra-tropical depression and qualified as such.

This is usually a transient stage lasting in most cases less than 24 hours.

Centre of the tropical disturbance: Geometric centre of the cloud eye or, if not discernible, the wind/pressure centre.

Eye of the tropical disturbance: Relatively clear and calm area inside the circular wall of the convective clouds, the geometric centre of which is the centre of the tropical disturbance.

Direction of movement of the tropical disturbance: Direction towards which the tropical disturbance centre is moving.

Speed of movement of the tropical disturbance: Speed of movement of the centre of the tropical disturbance.

Gust: Instantaneous peak value of surface wind speed recorded or expected

Storm tide: Actual sea level as influenced by a weather disturbance. The storm tide consists of the normal astronomical tide and the storm surge.

Storm surge: Difference between the actual water level as influenced by a meteorological disturbance (i.e., the storm tide) and the level which would have been attained in the absence of the meteorological disturbance (i.e., astronomical tide). Storm surge results from the shoreward movement of water combined with the comparatively minor effects of low barometric pressure.

 

Mauritius is responsible for naming storms forming in the region lying between longitude 55ºE and 90ºE. Madagascar is responsible for the region west of longitude 55ºE and the Australian Bureau of Meteorology for the region east of 90ºE.

Whenever a cyclone moves from the Australian region of responsibility to that of Mauritius, it keeps its Australian name as per decision of the Tropical Cyclone Committee held in Nairobi in 2010.

	Names	Provided by
1	ALVARO	Mozambique (M)
2	BELAL	Mauritius (M)
3	CANDICE	France (F)
4	DJOUNGOU	Comoros (N)
5	ELEANOR	Zimbabwe (F)
6	FILIPO	Botswana (M)
7	GAMANE	Eswatini (F)
8	HIDAYA	Tanzania (F)
9	IALY	Madagascar (F)
10	JEREMY	Seychelles (M)
11	KANGA	South Africa (N)
12	LUDZI	Malawi (N)
13	MELINA	Tanzania (F)
14	NOAH	France (M)
15	ONIAS	Zimbabwe (M)
16	PELAGIE	Madagascar (F)
17	QUAMAR	Comoros (M)
18	RITA	Seychelles (F)
19	SOLANI	Eswatini (M)
20	TARIK	Mauritius (M)
21	URILIA	South Africa (N)
22	VUYANE	Lesotho (M)
23	WAGNER	Kenya (M)
24	XUSA	Malawi (N)
25	YARONA	Botswana (N)
26	ZACARIAS	Mozambique (M)