Hurricane Isaac was a strong tropical cyclone that affected

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

in early October 2006. Isaac was the tenth and final

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

and fifth hurricane of the

2006 Atlantic hurricane season The 2006 Atlantic hurricane season was the least active since 1997 as well as the first season since 2001 in which no hurricanes made landfall in the United States, and was the first since 1994 in which no tropical cyclones formed during Octobe ...

. Isaac originated in a

tropical wave A tropical wave (also called easterly wave, tropical easterly wave, and African easterly wave), in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which ...

that entered the Atlantic Ocean on September 18. An associated area of disturbed weather eventually organized sufficiently to be declared a tropical depression on September 27, while located southeast of Bermuda. The depression was upgraded to a tropical storm just 12 hours later, though unfavorable atmospheric conditions, including high

wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal ...

and cool water temperatures, initially inhibited further intensification. Isaac ultimately peaked as a Category 1 hurricane on the Saffir-Simpson Hurricane Scale, and brushed Newfoundland as a tropical storm. Effects from the storm were minimal and limited to gusty winds, rough surf, and sporadic rainfall.

Meteorological history

emerged from the western coast of Africa and entered the Atlantic Ocean on September 18, 2006. On September 23, an associated area of disturbed weather began to exhibit indications of organization; in response, Dvorak classifications were initiated. Influenced by moderate to strong

, the system moved west-northwestward for several days. Once environmental conditions became more favorable for tropical cyclone development, the storm had sufficiently organized to be designated a tropical depression on September 27. At this time, the depression was located about southeast of

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. Despite being upgraded, deep

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...

had not wrapped around the entire center of circulation. Although the depression was approaching tropical storm status by later on September 27, wind shear continued to affect the cyclone. On September 28—about 12 hours after the storm's formation—it became the tenth tropical storm of the

, and received the name Isaac. Initially, the storm was tracking towards the northwest, between another low pressure system to its west and a low- to mid-level

ridge A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...

to its east. Throughout the day, thunderstorm activity remained unstable, possibly as a result of cooler waters churned up by previous storms. In addition, mid- to upper-level dry air had become entrained into the circulation, and the storm contained some subtropical characteristics with a

baroclinic In fluid dynamics, the baroclinity (often called baroclinicity) of a stratified fluid is a measure of how misaligned the gradient of pressure is from the gradient of density in a fluid. In meteorology a baroclinic flow is one in which the densi ...

-type cloud pattern. By early September 29, Isaac had slowed and turned towards the west. Convection began to intensify and consolidate later that day;

outflow Outflow may refer to: *Capital outflow, the capital leaving a particular economy *Bipolar outflow, in astronomy, two continuous flows of gas from the poles of a star *Outflow (hydrology), the discharge of a lake or other reservoir system * Outflow ...

had also improved, and became more symmetric in nature. Moving into warmer waters, Isaac continued to strengthen, and attained hurricane status on September 30. However, this period of intensification was short-lived, and the cyclone reached its peak intensity with winds of 85 mph (140 km/h) at around 0000 UTC on October 1. Around that time, a ragged

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

feature appeared on satellite imagery. "A fairly well-defined hurricane", Isaac began to recurve around the periphery of a subtropical ridge while accelerating in forward speed. While tracking towards the north-northeast, the storm began to gradually weaken as a result of increasing southwesterly wind shear and colder

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...

s. At about 1200 UTC on September 2, Isaac was downgraded to a tropical storm. The storm passed about to the southeast of the

Avalon Peninsula The Avalon Peninsula (french: Péninsule d'Avalon) is a large peninsula that makes up the southeast portion of the island of Newfoundland. It is in size. The peninsula is home to 270,348 people, about 52% of Newfoundland's population, according ...

on October 2, spawning tropical storm-force winds on land. After passing

Isaac transitioned into an

extratropical storm Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of ...

, and subsequently merged with a larger storm on October 3.

Preparations and impact

tropical storm watch Tropical cyclone warnings and watches are alerts issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local popul ...

was issued in response to Isaac on October 1 for the Avalon Peninsula. The watch was upgraded to a tropical storm warning the next day, while a separate watch was posted for the Burin and Bonavista peninsulas, though it was quickly discontinued. By 2100 UTC on October 2, all

tropical cyclone watches and warnings Tropical cyclone warnings and watches are alerts issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local popul ...

were lifted. Heavy rainfall and gusty winds were expected, prompting the issuance of rainfall warnings for parts of southeastern Newfoundland, while wind and gale advisories were declared offshore. On October 2, the ''Elektra'' (call sign SIWB) reported winds of while located about to the east of the storm's center. Two other ships, several buoys, and several oil platforms also recorded tropical storm-force winds. Waves offshore reached in height. Impacts on land were generally insignificant; no damages or fatalities were reported. However, parts of the Avalon Peninsula experienced tropical storm conditions. At

Cape Race Cape Race is a point of land located at the southeastern tip of the Avalon Peninsula on the island of Newfoundland, in Newfoundland and Labrador, Canada. Its name is thought to come from the original Portuguese name for this cape, "Raso", mea ...

, sustained winds peaked at , with gusts of up to . The most intense winds remained offshore. Due to the storm's rapid passage, rainfall was primarily light and amounted to less than .

References

External links

* The NHC'
archive on Hurricane Isaac
* The CHC'

{{DEFAULTSORT:Isaac (2006) 2006 Atlantic hurricane season Hurricanes in Canada Category 1 Atlantic hurricanes

Isaac Isaac; grc, Ἰσαάκ, Isaák; ar, إسحٰق/إسحاق, Isḥāq; am, ይስሐቅ is one of the three patriarchs of the Israelites and an important figure in the Abrahamic religions, including Judaism, Christianity, and Islam. He was the ...

Meteorological history

Preparations and impact

See also

References

External links