Saison des ouragans

[saky92]

L'action a repris du coté de L'Atlantique. Il semble y avoir un bon potentiel dans le système no.1 qui arrive de L'Afrique. S'il atteint le stade, ça va être à surveiller, vu ça superficie.

 

TI-BOB

[RichardL]

Bertha est rétrograder tempete tropicale

[iceberg]

Cristobal le prochain systeme tropical dans 3 jours.

 

Water temps steering air currents will allow this low to develop to a tropical storm.

This one bears watching. Its now over the South-Central Atlantic.

Modifié le 14 juillet 2008 par iceberg

[meteomarc]

Cristobal le prochain systeme tropical dans 3 jours.

 

Water temps steering air currents will allow this low to develop to a tropical storm.

This one bears watching. Its now over the South-Central Atlantic.

Surement même que nous aurons Cristobal avant 3 jours. La dépression tropicale 94L montre des signes de dévellopement et a déjà de la bonne convection. De plus, le fait qu'elle se soit détachée de l'ITCZ(inter tropical convergence zone) montre en quelque sorte qu'elle a une bonne circulation. Je ne serais pas supris si 94L serait fait dépression tropicale d'ici 5h AM lundi et qu'elle soit nommée Cristobal avant même que Mardi arrive.

[iceberg]

Hurricane season getting longer..

 

Hurricane seasons have been getting longer over the past century and the big storms are coming earlier, LiveScience has learned. The trend has been particularly noticeable since 1995, some climate scientists say.

 

Further, the area of warm water able to support hurricanes is growing larger over time. The Atlantic Ocean is becoming more hurricane friendly, scientists say, and the shift is likely due to global warming.

 

"There has been an increase in the seasonal length over the last century," Jay Gulledge, a senior scientist with the Pew Center on Global Climate Change, told LiveScience. "It's pretty striking."

 

A study Gulledge co-authored with other climate scientists found a five-day increase in season length per decade since 1915.

 

Hurricane season officially starts June 1, but the first named storm of the 2008 season, Tropical Storm Albert, formed on May 31. The first hurricane of the season, Hurricane Bertha, formed on July 1, reaching hurricane strength on July 7, relatively early in the season for a major storm.

 

In the last decade, more strong storms have been forming earlier in the season, said hurricane researcher Greg Holland of the National Center for Atmospheric Research in Boulder, Colo.

 

While this trend hasn't been formally linked to global warming because climate models can't reproduce individual storms, Holland thinks it's likely that the warming caused by manmade greenhouse gases is a major factor in the seasonal shift based on observations of changes in recent decades and the predictions models are making for the changing conditions in the Atlantic basin.

 

The length of the hurricane season is "one of the potentially big signals" that could change in response to global warming, Holland said.

 

Defining the season

 

The definition of the hurricane season depends on who you ask: For hurricane forecasters and coastal residents living in an area prone to hurricane landfalls, the standard dates are June 1 to Nov. 30. The National Hurricane Center uses these dates because historically most storms occur within that span of six months and because having a definitive time frame helps to heighten the public's awareness of the dangers of hurricanes.

 

But for researchers looking at how hurricane activity has changed over time, those dates don't really matter - meteorologists look at the dates of the first and last named storms in a given year, which allow them to evaluate the actual length of each hurricane season.

 

Since 1995, hurricane seasons have been increasing in length based on the latter definition, Holland said, with stronger storms that typically wouldn't be seen until mid-August showing up in July (Bertha, which became a Category 3 storm in the Atlantic last week, is one example).

 

Expanding warm pool

 

Like a hurricane's intensity, the length of the hurricane season is affected by the temperature of the ocean that fuels the storms. The warmer the water, the more energy a storm has to draw from.

 

Hurricanes and tropical storms have been forming earlier in the season recently because "we now get warmer sea surface temperatures earlier in the year," Holland explained. "The whole season has extended out."

 

Peter Webster of Georgia Tech put a finer point on it. "There is some work that says that the length of the North Atlantic hurricane season has become longer as SSTs [sea surface temperatures] warm up more quickly early in the season," he said.

 

Tropical storms and hurricanes need water of at least 80 degrees Fahrenheit (26.5 degrees Celsius) to form. The area where water temperatures meet or exceed that mark is called the warm pool.

 

In recent years, the warm pool has expanded, creating a larger area over which hurricanes can develop and strengthen, Holland told LiveScience. It is now reaching all the way to the coast of Africa, allowing storms to form farther east, and so giving them more time to strengthen as they traverse the Atlantic.

 

Bertha, for example, formed farther east than any other July storm on record.

 

These storms that form so far over in the eastern Atlantic are called "Cape Verde-type" storms, after the chain of islands off the western coast of Africa. Cape Verde-type storms account for a major proportion of all major hurricanes (Category 3 and higher), Holland said.

 

These storms tend to take a straight westward path across the Atlantic, avoiding land and cooler waters, which can kill a storm. Hurricane Andrew, which devastated southern Florida in 1992, and 2007's Hurricane Dean, which wreaked havoc in the state of Yucatán in Mexico, were both Cape Verde-type storms, along with Bertha.

 

Holland thinks that the growth of the warm pool will be a factor in the length of future hurricane seasons by promoting these and other early-forming storms.

 

 

 

 

Other early storms, outliers to the standard June 1 to Nov. 30 season, such as this season's Tropical Storm Arthur or last year's Subtropical Storm Andrea (which formed on May 9), aren't all that unusual. Such early birds were seen even before global warming became an issue - the earliest-forming storm in recorded weather history was observed on March 7, 1908.

 

"There's always been the odd one out," Holland said, adding that we'll likely see more of these in a warming world.

 

"We have to expect that they'll be more outliers," he said, though he doubts that the official dates of hurricane season will change, since most will still lie within that window.

 

But these aren't the early-forming storms that Holland is worried about, because they tend to be weaker. It's the major storms, like the Cape Verde-type, that are forming in July and later that are the ones to watch out for, he said.

 

These shift to more major storms is also cause for concern because the Atlantic historically had fairly timid hurricane seasons compared to other storm-producing basins such as the Indian Ocean. Because the Atlantic basin wasn't optimized for hurricane formation already, "it didn't take much of a change to see a difference," Holland said.

 

One other way the Atlantic basin is becoming more hurricane-friendly, besides warmer oceans, is more favorable atmospheric conditions. Warming ocean temperatures also change atmospheric circulation patterns. Holland said some changes are already happening over the Atlantic and climate models predict that these changes will also tend to promote the development of storms off the coast of Africa.

 

"All of the stars are lining up," he said.

[Pooram]

http://i23.photobucket.com/albums/b362/kellyoo14/94L2.gif

 

Sans commentaire pour 94L - je n'ai pas beaucoup de temps pour analyser mais pour l'instant, je ne mise pas beaucoup pour ce tralala ...

[saky92]

Regarder moi cette belle ligne de dépression qui s'étend de L'Afrique au Pacifique. On devrait avoir une belle saison de tempête surtout du coté de L'Atlantique. Pour l'instant un ouragan, 3 tempêtes et presque une autre du coté de L'Afrique qui semble vouloir s'organiser.

 

TI-BOB

[saky92]

Voici une autre image du sud de la Floride.

 

TI-BOB

[Regg001]

Pas vraiment... Tant que la ligne (comme tu dis) demeure à cette latitude, ça ne fera rien de dangeureux sinon de grosses cellules orageuses et des tempêtes en mer. Pour que les ouragans se forment, il faut que le tout remonte un peu vers le nord pour atteindre minimalement les Caraibes.

 

Sinon tu n'auras que de grosses tempêtes en mer.

[iceberg]

Most powerful hurricanes

Modifié le 17 juillet 2008 par iceberg

[iceberg]

Cristobal will soon be named the next tropical storm as indicated in the last log.

3 days. Will this disturbance become Cristobal? We think so. The system may have a rough time revving up at first due to its proximity to South America, but once it reaches the central Caribbean it will be free to turn into a hurricane. Long range indicators suggest the storm will eventually track across the Yucatan and then head into Mexico without having any direct impact on the United States.

[Hurry]

Bonjour, voici un site sur les ouragans que j'affectionne tout particulièrement depuis plus de 10 ans et qui en plus des radars et tout le reste, il comporte des correspondants dans les Antilles qui décrivent ce qui se passe en temps réel lors de tempête chez eux. Un site anglais, mais que je trouve super. Je voulais le partager avec vous, amateurs d'ouragan comme moi

 

http://stormcarib.com/

 

http://stormcarib.com/nav/

[castor028]

http://www.nhc.noaa.gov/refresh/graphics_a...?large#contents

[saky92]

Non je ne pense pas, il va perdre de la force sur le bord des côtes. Donc pas lui le troisième. C'est mon idée.

 

TI-BOB

[castor028]

et voilà: http://www.nhc.noaa.gov/

[dom]

Cristobal est né! Il s'agit d'une tempête tropicale et étant donné sa latitude actuelle, il y a peu de chances que ce système devienne un ouragan. Cependant, les vacanciers de la construction le long de la côte est auront du temps médiocre... :P

 

Vers mardi, Cristobal devrait être encore une tempête tropicale et pourrait déverser ds quantités d'eau considérables sur les Maritimes...

Modifié le 20 juillet 2008 par dom

[Regg001]

Ah ouin....... Une tempête tropicale sur les côtes de la Nouvelle Écosse. mmmm Est-ce que ça se chasse ?

Modifié le 20 juillet 2008 par Regg001

[JF Massicotte]

Ah ouin....... Une tempête tropicale sur les côtes de la Nouvelle Écosse. mmmm Est-ce que ça se chasse ?

Oui...........

[Pierre]

Dolly est née cet après-midi....il y en a maintenant trois en même temps !

[dom]

Dolly est née cet après-midi....il y en a maintenant trois en même temps !

Bon, c'est sur que ce ne sont que des prédictions et du hasard, mais me semble que ça s'annonce actif pour cette année, non? Déjà 3 systèmes en tempêtes tropicales à cette date! Ouf!

 

Je suis aussi très surpris de voir une tempête tropicale remonter aussi haut avec autant de force! Elle est presque rendue en Islande!!! Est-ce que les eaux seraient plus chaudes qu'à l'habitude sur l'Atlantique Ouest?!?

 

Chose certaine, nous ne sommes qu'en juillet et le bal est parti, ce qui est relativement tôt. Reste à voir si la tendance se maintiendra, et si 2008 sera marquante...

[meteomarc]

Et on pourrait très bientôt parler de la cinquième tempête de la saison! Pour la première fois depuis que je suis les ouragans, le NHC mentionne une vague tropicale qui est toujours 200-300 km à l'intérieur des terres et lui donne de 20 à 50% de chance de se dévelloper dans les 48 prochaines heures!...Donc probablement dans les 35 premières heures au-dessus de l'eau! Et 3 des 4 modèles majeurs la dévellope. Ça reste à voir mais c'est impressionnant(laissez moi vous dire qu'elle paraît assez bien merci, des clouds tops d'ouragan!)

[shawn_strat]

Pour ceux/celles avec GRlevel, l'image radar de Brownsville, Texas est très interessant en ce moment. L'ouragan Dolly est à 25 km de la cote.

[Mathieu Lussier]

merci beaucoup

[Patrick28]

voila l'ouragan sur grlevel

[Jean]

Bonjour,

 

Des Webcams particulièrement intéressantes:

 

http://www.cctexas.com/webcam