Lecture - TRS

8/12/2019 Lecture - TRS

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Tropical Revolving Storms

Hurricanes

CyclonesTyphoons


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Introduction

Of all the dangers that Seafarers mayencounter Tropical Revolving Storms arethe most severe.

The extremes of weather are:

Strong winds

High seas

Storm surges

Torrential rain


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Formation

Tropical storms [wind speeds between33kts and 63kts] or TRS [wind speeds of64kts +] form within seven regions around

the world called 'basins'. Formation is normally within a specific

seasonearly Summer to late Autumn for

that hemisphere. The energy powering these storms comesfrom the heat stored in the oceans.


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The 7 Tropical Basins

Western North Atlantic; Eastern North Pacific;

Western North Pacific; Western South Pacific; North Indian Ocean (Bay of Bengal);

Western South Indian Ocean; Eastern South Indian Ocean.


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Saffir-Simpson Scale Category 1winds 64-82 kt

No real damage to buildings. Some damage to poorly constructed signs. Some coastalflooding and minor pier damage.- Examples: Allison 1995 & Nuri 2008

Category 2winds 83-95 ktSome damage to building roofs, doors and windows. Flooding damages piers and smallcraft in unprotected moorings may break their moorings. Some trees blown down.

- Examples: Bonnie 1998, Georges 1998 Category 3winds 96-113 kt

Some structural damage to small residences and utility buildings. Large trees blowndown. Poorly built signs destroyed. Flooding near the coast destroys smaller structureswith larger structures damaged by floating debris. Terrain may be flooded well inland.

- Examples: Keith 2000, Fran 1996, Category 4winds 114-135 kt

More extensive curtain wall failures with some complete roof structure failure on smallresidences. Major erosion of beach areas. Terrain may be floodedwell inland.

- Examples: Hugo 1989 and Dennis 1995 Category 5winds 135 kt +Complete roof failure on many residences and industrial buildings. Some completebuilding failures with small utility buildings blown over or away. Flooding causes majordamage to lower floors of all structures near the shoreline. Massive evacuation ofresidential areas may be required.

- Examples: Andrew 1992, Wilma 1995

Source: www.nhc.noaa.gov/aboutsshs.shtml
http://eobglossary.gsfc.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=15022http://www.nhc.noaa.gov/pdf/TCR-AL042005_Dennis.pdfhttp://www.nhc.noaa.gov/pdf/TCR-AL042005_Dennis.pdfhttp://www.nhc.noaa.gov/pdf/TCR-AL252005_Wilma.pdfhttp://www.nhc.noaa.gov/aboutsshs.shtmlhttp://www.nhc.noaa.gov/aboutsshs.shtmlhttp://www.nhc.noaa.gov/pdf/TCR-AL252005_Wilma.pdfhttp://www.nhc.noaa.gov/pdf/TCR-AL042005_Dennis.pdfhttp://eobglossary.gsfc.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=15022


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Karl

Jeanne

Lisa

Ivan


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Storm Names

Each season Tropical Depressions which reach the levelof 39mph / 33knots are given names

Since 1953, Atlantic tropical storms have been named

from lists maintained and updated by the WorldMeteorological Organization.

The original name lists featured only women's names. In1979, men's names were introduced and they alternatewith the women's names.

Six lists are used in rotation. Thus, the 2007 list will beused again in 2013.

List of North Atlantic Names
http://severe.worldweather.wmo.int/http://severe.worldweather.wmo.int/http://www.nhc.noaa.gov/aboutnames.shtmlhttp://www.nhc.noaa.gov/aboutnames.shtmlhttp://severe.worldweather.wmo.int/http://severe.worldweather.wmo.int/


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Storm Name Retirement

The only time that there is a change is if astorm is so deadly or costly that the futureuse of its name on a different storm would

be considered inappropriate for obviousreasons of sensitivity.

Not all of the most deadly or costly stormsare the strongestTS Allison in 2001caused $5,000,000,000 damage.


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1 Andrew 1992 5 US$26,500,000,000

2 Charley 2004 4 15,000,000,000

3 Ivan 2004 3 14,200,000,000

4 Frances 2004 2 8,900,000,000

5 Hugo 1989 4 7,000,000,0006 Jeanne 2004 3 6,900,000,000

7 Allison 2001 TS 5,000,000,000

8 Floyd 1999 2 4,500,000,000

9 Isabel 2003 2 3,370,000,000

10 Fran 1996 3 3,200,000,000

Some of the costliest tropical cyclones


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2005 Hurricanes Katrina (August) was an extraordinarily powerful and

deadly hurricane that inflicted large loss of life. It wasthe costliest and one of the five deadliest hurricanes toever strike the United States.

Rita (September) was an intense Category 5 hurricaneover the central Gulf of Mexico and had the fourth-

lowest central pressure (895mb) on record in the Atlanticbasin.

Stan (October) was associated with disastrous inlandflooding across portions of Central America and Mexico,and some estimates of the death toll are as high as

2000. Wilma (October) formed and became an extremely

intense hurricane over the north western Caribbean Sea.It had the all-time lowest central pressure (882mb) foran Atlantic basin hurricane.

5 Hurricanes from 2005 have been retired


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Development1

A pre-existing area of low pressure such as aTropical Disturbancein the North Atlantic. Warm tropical ocean water where the sea

surface temperature is at least 27C and

considerable depth of water. For formation the ITCZ must be at least 5of

latitude. There must be an absence of wind shear in the

upper troposphere, to enable strong verticalcloud development.

How a hurricane forms
http://mywebpages.comcast.net/herbwx/hurrican.htmlhttp://news.bbc.co.uk/1/shared/spl/hi/world/03/hurricane_guide/html/default.stmhttp://news.bbc.co.uk/1/shared/spl/hi/world/03/hurricane_guide/html/default.stmhttp://mywebpages.comcast.net/herbwx/hurrican.html


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Development2

During the development of a TRS immenseamounts of heat are transported from seathrough clouds into the atmosphere and thenceto higher latitudes.

Once a tropical depression has formed aircontaining water vapour is drawn into the base. The moisture laden air ascends in the centre of

the cloud and cools as it rises. Water vapourcondenses to form the clouds and heat is

released which causes the air to rise faster. This process causes the wind speed to increase

and the escalation of the storm.


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Development TD TS

Weak low

Outflow aloft greater than Inflow

Warm sea surface

In flow

Moisture

evaporates

from sea

surface

Water droplets

condense in the

clouds Latent heatreleased into the

clouds

Air rises up

in the TD

Air rises

faster


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Development3

Eventually the spinning motion causes thecentre of the cloud mass to descend

toward the surface. Much in the same wayas emptying a wash basin creates avortex.


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Development TS TRS

CPV decreasing

Outflow aloft

Warm sea surface

In flow

Eye descends

Outflow aloft

In flow


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Development4

The vortexultimately becomes the eye ofthe storm, with cloud spiralling outward.

When the eye reaches the surface thestorm is classed as a full TRS (Hurricane,Typhoon, Cyclone)


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Development TS TRS

Outflow aloft

Anvil

Anvil

Cu

Cb

Cu Cu

Cb

Eye

Wall

Bar of

Storm

Hot

towers

Highest

Temperature

Warm Core

Subsidence

AdiabaticWarming

No

Cloud

Outflow aloft

200 100 0 100 200


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Twin Storms

In early May 2002 there was a strong westerly wind burstalong the equator in the western Indian Ocean.

This spawned twin cyclones in the northern and southern

hemispheres (TC 01A in the north and TC Kesiny in the

south).This area of strong westerlies and convective activity

propagated eastwards and proceeded to spawn a second set

of twin vortices in the eastern Indian Ocean a few days later

(TC Cyclone 02B in the north and TC Errol in the south).

The meteorological activity continued eastwards into the

Pacific Ocean and was responsible for the formation of Super

Tyhoon Hagibis in the NW Pacific and possibly Hurricane

Alma in the NE Pacific in the following two weeks.


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Movement1Initially the Tropical Depression moves in a westerlydirection[4, 9, 12] carried on the general windmovement of the Trade winds.It must be remembered that these storms are veryintense areas of low pressure and although the windflows into them, their intensity is not reduced.Historical data shows us that they follow 2 possibletracks. If they are blocked by an area of High pressure,they: continue to move west until encountering land[Emily 2005]; turn and move towards the pole[Fabian 2003];

Alternatively the Meteorological forecaster may try todetermine which way the storm will go based on thecurrent synoptic situation.


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Movement2

With all of the technology available toforecasters it is still very difficult to sayexactly where a storm is going to go

Erratic Just plain nasty

Track of Hurricane Katrina

Hurricane Gamede 2006


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Decay

As the storms are powered by the heat ofthe ocean, they will decay when deprivedof the energy source.

This occurs when they move: To cooler water;

Over the land;

To an area of strong wind shear and theclouds are ripped apart.


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Hurricane Gilbert

BBC documentary on Hurricaneforecasting

Happened to coincide with the arrival ofa Category 5 TRS

Old but relevant


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Make sure you understand:

The requirements for the formation of aTRS

How a storm develops Storm classification and symbology Influences on a storms movement

How a storm decays


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Katrina (2005)


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Fabian(2003)


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Emily (2005)


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Erratic

MovementKate (2003)

Nicholas

(2003)


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Heat Transfer


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Links

Animation "How a hurricane forms" NOAA Archive 2005

Retired Hurricane Names 1954-2005
http://news.bbc.co.uk/1/hi/world/americas/3565052.stmhttp://www.nhc.noaa.gov/archive/2005/http://www.nhc.noaa.gov/retirednames.shtmlhttp://www.nhc.noaa.gov/retirednames.shtmlhttp://www.nhc.noaa.gov/retirednames.shtmlhttp://www.nhc.noaa.gov/retirednames.shtmlhttp://www.nhc.noaa.gov/archive/2005/http://news.bbc.co.uk/1/hi/world/americas/3565052.stm


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Tropical Basins

F i f N h A l i


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Formation of a North AtlanticHurricane


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2005

2007


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Recent Retired Storms

1995LuisMarilyn

OpalRoxanne

1996CesarFran

Hortense

1997

1998Georges

Mitch

1999FloydLenny

2000Keith

2001Allison

IrisMichelle

2002Isidore

Lili

2003Fabian

IsabelJuan

2004Charley

FrancesIvanJeanne

2005Dennis

KatrinaRitaStanWilma


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ITCZ in January


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ITCZ in July


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Tropical Cyclone Gamede


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Tropical Cyclone Gamede

Tropical Cyclone Gamede on February 27,

2007 at 10am local time, as it brought

world-record rains to La Reunion Island in

the Indian Ocean. At the time, Gamede

was a Category 2 storm with top winds of

100 mph.

Image credit: NASA Earth Observatory.
http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14145http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=14145http://en.wikipedia.org/wiki/Image:Sidr_14_nov_2007_0445Z.jpg


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Sidr

Very SevereCyclonic Storm

Wind speeds>120knots

CPV

944 hPa
http://en.wikipedia.org/wiki/Image:Sidr_14_nov_2007_0445Z.jpghttp://en.wikipedia.org/wiki/Image:Sidr_14_nov_2007_0445Z.jpghttp://en.wikipedia.org/wiki/Image:Sidr_14_nov_2007_0445Z.jpg

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