Understand all about this “exceptional bulge”

Tahiti, 12 July 2022 – Qualify “exceptional” By Météo France, the episode of severe bloating that should affect almost all of French Polynesia, except for the Marquesas, has not been known since 2005. Tuesday evening, south of the community archipelago, Tuamotu, Gambier and Austral. Put on red alert. Back “gradual” Back to normal from Thursday morning. Absolute caution until then.

It is a qualified meteorological phenomenon “exceptional” by Meteo France. A 6m south-southwest swell is expected to generate 8m breakers near the east coast through Thursday morning over nearly all of French Polynesia. On Tuesday afternoon, seven regions were placed on high alert: Windward and Leeward Islands, West and South Tuamotos, Gambier, Central Australas and Raba. Absolute vigilance and caution are necessary around the coast and marine activities are prohibited in these areas, except for ships over 24 meters in height depending on the strength of the swell.

To understand the origin of this phenomenon, Météo France explains that the bulge is caused by an extensive low pressure system located more than 2,000 km south of Rapa. Strong winds swirl around this depression. The so-called sea of ​​the windexplains Sebastien Hugoni from Météo France. “This energy will come out of this low pressure system and will ripple to form the swell. The bulge will spread this energy and release it at the level of the coasts with the breaking waves.” It appears that Météo France is particularly good at modeling and thus forecasting. To find out the height of the waves, the Jason satellite – which circles the Earth by the poles – makes it possible to determine the exact level of sea height twice a day, thanks to a very accurate altimeter on a strip of 100 km, somewhat close to Polynesia. The data has been integrated into Météo France’s prediction models and controlled by Jason’s new lanes. Recorded data for this particular event has not been recorded since the bulge ring of 2005, which particularly affected Polynesia.

Note in passing that the rain that hit the island of Tahiti on Tuesday was not at all related to the depression that led to this swell. “exceptional”. Another atmospheric phenomenon was related to moist trade winds currently passing over the Windward Islands but is expected to subside on Tuesday evening. Therefore, there is no a priori, any particular wind or rain forecast with this bloated phenomenon. Even if this other aspect of the weather is currently very secondary to forecasters. Météo France usually updates its vigil at 5 a.m. and 3 p.m. Except in exceptional cases. The reason for the publication of Vigilance at 12 noon on Tuesday.

  • Red vigil, koisaku?

Regarding state and country services – a computer crisis was installed moreover Monday evening at the High Commission – Météo France on Tuesday afternoon put seven regions of the southern archipelago of the company, Tuamotu, Gambiers and Australs on red alert. The development of the phenomenon will be gradual and is expected to peak in Tahiti and Moorea during the day on Wednesday. It should be feeling back to normal by Thursday morning. But be careful, as Météo France warned, it will ‘gradually diminishing’ The caution will remain in effect Thursday, July 14.

In the language of the forecaster, the . file “red alert” It is the maximum stage that can be reached and means that a Absolute vigilance is essential. This stage is reserved for “Dangerous weather phenomena of exceptional intensity”. The recommendations are to stay up to date with the developments of the weather and to strictly comply with the specific advice for each phenomenon on the Météo France website and the specific instructions issued by the High Commission and transmitted in the media.

  • General ban on water activities

This red and orange vigil carries restrictions that the country’s state services announced on Tuesday. The High Commission was particularly insistent on the consequences of the 2005 incident. “A similar phenomenon has caused a lot of damage, particularly physical damage through the influence of the coast, in several areas of Polynesia with airports particularly affected and damage to dwellings located on the coast.”, mentions the director of Tuamotu-Gambier, Frédéric Sutron. In Bora Bora in particular, seaside homes were affected and in Tuamotu several airports were frozen due to the flooding of the landing and take-off runways.

For regions in the red alert state, a Banning maritime traffic and recreational and professional marine activities for ships of less than 24 meters in length. It was taken by order. Ships providing service between Tahiti and Moorea can theoretically sail, but depending on the height of the swell and the technical capabilities of the ships. “The goal is to ensure the protection of people and property”, identifies Frédéric Sautron. The High Commission has set itself a 6-hour anticipation period between the launch of the vigil and the arrival of the first inflated trains in the areas concerned. It suffices to give yourself time to catch up, for example, of the five fishing boats that set sail on Tuesday morning at Topway despite the vigilance.

Therefore, the Al-Hosaria recommends the greatest vigilance for the exposed constructions, checking the moorings of the boats in the port and calls not to approach the coast by avoiding going and taking pictures of the phenomenon, for example. High waves will also be associated with high tides, and the lake itself also promises turbulence with large coastal waves and strong currents. More specifically, the country has announced the closure of access to the Toaroto and Vaiava beaches at PK18, Mahana Park, Rohotu, Taharuu and Tahiamanu in Moorea. Municipal protection plans have also been launched and it is likely that municipalities will take specific measures to restrict movement on the ground. In Teahupoo in particular, mutoi and gendarmes must monitor the site to prevent surfers from luring the devil onto the jaws of the peninsula. A ban is likely to be challenged, but it would nevertheless be a very bad idea. At least until Thursday.

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