Hurricanes

Group Members
Muhammad Nauman Zia
Muhammad Ali Raza
Zia Ur Rehman

Contents
 Introduction
 History of Hurricanes
 Season of Hurricanes
 Formation
 Structure of Hurricanes
 Movement of Hurricanes
 Hurricane Tracking
 Hurricane Forecasting
 The Difference between Hurricanes, Typhoons, and Cyclones
Watches and Warnings
 Areas at Risk
 Storm Surge
 Damage Potential

Introduction
The word Hurricane comes from the Spanish word “Hurácan”
A hurricane is a huge storm! It can be up to 600 miles across
and have strong winds spiraling inward and upward at speeds
of 75 to 200 mph.
Hurricanes gather heat and energy through contact with warm
ocean waters.
Hurricanes rotate in a counter-clockwise direction around an
"eye" in the Northern Hemisphere and clockwise direction in
the Southern Hemisphere.
When they come onto land, the heavy rain, strong winds and
large waves can damage buildings, trees and cars.

History of Hurricanes
Galveston Hurricane 1900:
 On September 8, 1900, a Category 4 hurricane ripped through
Galveston, Texas, killing an estimated 6,000 to 8,000 people.
 At the time of the 1900 hurricane, Galveston was filled with vacationers.
 Sophisticated weather forecasting technology didn’t exist at the time, but
the U.S. Weather Bureau issued warnings telling people to move to
higher ground. However, these advisories were ignored by many
vacationers and residents alike.
 A 15-foot storm surge flooded the city, which was then situated at less
than 9 feet above sea level, and numerous homes and buildings were
destroyed.
 The hurricane remains the worst weather-related disaster in U.S. history
in terms of loss of life.
 It had estimated winds of 145 miles per hour (233 km/h) at landfall.

Hurricane Katrina 2005:
 Early in the morning on August 29, 2005, Hurricane Katrina
struck the Gulf Coast of the United States.
When the storm made landfall, it had a Category 3 rating on the
Saffir-Simpson Hurricane Scale–it brought sustained winds of
100–140 miles per hour–and stretched some 400 miles across.
The storm itself did a great deal of damage, but its aftermath was
catastrophic.
Hundreds of thousands of people in Louisiana, Mississippi and
Alabama were displaced from their homes, and experts estimate
that Katrina caused more than $100 billion in damage.
An estimated 1,836 people died in the hurricane.

Hurricane Isabel 2003:
On September 18, 2003, Hurricane Isabel made landfall as a
Category 2 hurricane between Cape Lookout and Ocracoke
Island in North Carolina with winds of 105 mph.
The storm tracked northwest through North Carolina,
Virginia, West Virginia, and into Pennsylvania, causing over
$5 billion in damage.
The storm became extra tropical over Pennsylvania and
tracked into Canada.

Hurricane Ike 2008:
On September 13, 2008, Hurricane Ike made landfall in
Texas at the north end of Galveston Island, sending a 10- to
15-foot storm surge into Galveston and parts of the western
end of Galveston Bay, and up to a 20-foot surge over the
Bolivar Peninsula and parts of Chambers County, Texas.
Virtually every structure on parts of the Bolivar Peninsula
was wiped away. Broken glass littered streets in downtown
Houston.
Ike was responsible for $29.5 billion in damage, making it
the second-costliest U.S. hurricane on record, second only to
Katrina at the time.

Season of Hurricanes
Hurricane season is a set of days corresponding to the
likelihood of the development of a tropical depression, tropical
storm, or hurricane.
The hurricane season officially runs from June 1st through
November 30th.
The peak season for Maine begins the last week in August and
runs through the end of September.
North Atlantic Ocean:
 Hurricane season: June 1 - November 30
 The most active period runs from about mid August through the latter
part of October.

Eastern North Pacific Ocean:
 Hurricane season: May 15 - November 30
This is the second most active region for tropical cyclones in the
world.
Northwest Pacific Ocean:
Typhoon season: All year.
This is the most active basin in the world. Most typhoons form
between Julys through November.
Bay of Bengal / Arabian Sea:
 Severe Cyclonic storm season: April 1 - December 30
This basin has a double maximum because of the monsoon trough
moving through at two different times of the year.

Southwest Pacific Ocean:
 Severe Tropical Cyclone Season: October 15 - May 1.
These tropical cyclones may affect eastern Australia.
Southeast Indian Ocean:
 Severe Tropical Cyclone Season: October 15 - May.
This basin has a double maximum in mid January, and mid
February through early March.
Southwest Indian Ocean:
Tropical Cyclone Season: October 15 - May 15.
These tropical cyclones may affect Madagascar and
southeastern Africa.

Formation
Hurricanes typically begin as a cluster of clouds and
thunderstorms.
These clusters of storms usually move from east to west driven
by the trade winds.
The birth of a hurricane requires at least three conditions.
First, the ocean waters must be warm enough at the surface to
put enough heat and moisture into the overlying atmosphere to
provide the potential fuel for the thermodynamic engine that a
hurricane becomes.

Formation
Second, atmospheric moisture from sea water
evaporation must combine with that heat and energy
to form the powerful engine needed to propel a
hurricane.
Third, a wind pattern must be near the ocean surface
to spirals air inward.
Bands of thunderstorms form, allowing the air to
warm further and rise higher into the atmosphere.
If the winds at these higher levels are relatively light,
this structure can remain intact and grow stronger: the
beginnings of a hurricane!

Structure of Hurricanes
A mature hurricane is nearly circular in shape.
The winds of a hurricane are very light in the center of the storm
(blue circle in the image below) but increase rapidly to a maximum
10-50 km (6-31 miles) from the center (red) and then fall off slowly
toward the outer extent of the storm (yellow).

Three main features make up a hurricane:
Eye:
The eye is the "hole" at the center of the storm.
Winds are light in this area.
Skies are partly cloudy, and sometimes even clear.
Eye wall:
The eye wall is a ring of thunderstorms.
These storms swirl around the eye.
The wall is where winds are strongest and rain is heaviest.

Rain bands:
Bands of clouds and rain go far out from a
hurricane's eye wall.
 These bands stretch for hundreds of miles.
They contain thunderstorms and sometimes
tornadoes.

Movement of Hurricanes
The typical hurricane moves at an average speed of around 12
mph.
Its movement is affected by several factors including the upper
level winds called “steering currents”, and by other areas of
high and low pressure.
The movement of a hurricane from one location to another is
known as hurricane propagation.
The hurricane propagates in the direction of this wind field,
which also factors into the system’s propagation speed.

Hurricane Tracking
Tropical cyclones usually form far at sea and spend much of their
existence over remote oceanic areas, detection and monitoring of
these storms have traditionally posed serious problems to the
forecaster.
The advent of geostationary weather satellites has largely solved the
detection problem and has improved the monitoring problem.
However, the satellites are remote sensors and it is not unusual for
position estimates to have errors of tens of miles or for wind speed
estimates to be in error by tens of knots.
Although advancements have been made using microwave imagery,
it is still not possible to determine surface wind field distributions or
detailed structural characteristics of tropical cyclones from present
satellites.

Hurricane Tracking
Hurricane Hunters:
The brave "hurricane hunters" work for the National Oceanic and
Atmospheric Administration (NOAA).
Each mission lasts about ten hours, with the crews passing four to six
times through the storm.
The planes carry radar, sophisticated computers, and weather
instruments that determine characteristics such as temperature, air
pressure, wind speed, and wind direction inside the hurricane.
The crews also release instruments that measure temperature, air
pressure, and wind at different levels as the devices drop through the
hurricane toward the ocean.
By mission's end, NOAA can warn everyone in the hurricane's path.

Hurricane Tracking
Satellites:
The first satellite sent up by the United States to monitor
weather conditions was TIROS in 1960.
 Though its capabilities were primitive compared to today's
satellite technology, TIROS it opened the door for
meteorologists to understand a great deal more about
tropical cyclones.
Satellite images are very important to forecasters because by
putting several hours of satellite pictures into motion, they
can gather information on the track and development of the
tropical cyclone.

Hurricane Tracking
Doppler Radar:
New Doppler radar can detect rain associated with tropical
cyclones.
It typically covers rain within a 200 to 250 mile distance
from the radar location and provides estimates of rainfall
amounts and depicts hurricane's rain bands, its eye and its
eye wall.
The newest generation of Doppler radar provides forecasters
with improved data on the movement of tropical cyclones,
tornado activity that can accompany a tropical cyclone, and
estimates of wind speed within a tropical cyclone.

Hurricane Forecasting
The responsibility of predicting these tracks falls on the
National Hurricane Center (NHC) in Coral Gables, Florida
(near Miami).
One of the most useful tools forecasters have at their disposal
is the use of computers.
There are several computer models that are created.
Some models are statistical while others are dynamic.
Statistical models use the climatologically data of past
hurricane movement to predict movement of the current storm.
Dynamic models use equations to simulate atmospheric
conditions at different levels of the atmosphere to predict a
storms future movement.

The Difference between
Hurricanes, Typhoons, and
Cyclones
Aside from slightly different wind speeds, there is no difference
between a hurricane, a typhoon, and a cyclone.
They are all different names for the same kind of intense low
pressure system.
Most people are familiar with two different types of weather
systems:
 Low pressure systems, also called "cyclones," spin counter-clockwise in
the northern hemisphere
 High pressure systems, also called "anticyclones," spin clockwise in the
northern hemisphere.
All low pressure systems are cyclones.
There are two different kinds of cyclones that affect the United
States most often: tropical cyclones and extra tropical cyclones

Cyclones
Tropical Cyclones:
A tropical cyclone is a warm-core system that has a warm, humid,
tropical air mass throughout the entire storm.
Tropical cyclones derive their energy from the intense
thunderstorm activity that forms around the eye of the storm.
Tropical cyclones most often take on the appearance of a tight,
spiraling mass of clouds...or a big white bagel.
Tropical cyclones has no fronts.
 Strongest winds are near the Earth's surface.

Cyclones
Extra tropical Cyclones:
 From fall through the winter and well into spring, extra tropical storms
dominate the weather across much of the United States and other parts
of the globe outside the tropics.
 "Extra tropical" means the storms originate outside the tropics.
 These storms move generally west to east across the oceans and
continents.
 The extra tropical storm's center is an area of low atmospheric pressure
with winds going counterclockwise in the Northern Hemisphere,
clockwise south of the equator.
 The winds pulls cold air toward the equator from the polar regions and
bring warm air toward the poles.
 The clash of warm and cold air leads to the widespread precipitation the
storms bring.
 Strongest winds in the upper atmosphere.

Watches and Warnings
The National Weather Service is responsible for collecting data,
creating forecasts, and disseminating warnings to the public.
When a watch or a warning is issued, preparations should
begin for the predicted weather event.

Watches are issued by the NOAA's SPC, and warnings are
issued by local offices of the National Weather Service (NWS).
Severe Thunderstorm Watch & Warning:
A severe thunderstorm watch is issued whenever there is the
possibility of a severe thunderstorm within a specified area.
 A severe thunderstorm is defined as one with tornadoes
and/or funnel clouds, hail of ¾ inch in diameter, and/or
winds in excess of 58 mph.

Tornado Watch& Warning:
A tornado watch is issued whenever the conditions are favorable
for tornado development.
A Tornado warning is issued when a tornado has been spotted and
is issued for a specific area.
Tropical Storm Watch & Watch:
A Tropical Storm Watch is issued for coastal areas when
there is the threat of tropical storm conditions within 36
hours.
A Tropical Storm Warning is issued when tropical storm
conditions, including sustained winds of 39 to 73 mph are
expected within 36 hours or less.

Hurricane Watch & Warning:
A Hurricane Watch is issued when hurricane conditions pose
threat to a specified coastal area within 36 hours.
A Hurricane Warning is issued when sustained winds of
74mph or higher are expected in a specified coastal area
within 24 hours or less.

Areas at Risk
COASTAL AREAS:
All coastal areas of Maine are subject to hurricanes or
tropical storms.
The coastal areas are subject to a higher risk than inland
areas due to storm surge, storm tide, higher winds, and
heavy rains.
In addition, coastal areas have a greater need for evacuations
than do inland areas.

Areas at Risk
INLAND AREAS:
 Inland areas of Maine are also at risk of hurricanes and tropical
storms.
 The risk is higher for southern Maine than it is for northern parts.
This is due to the fact that hurricane winds have usually been
reduced substantially by the time the storm reaches northern
Maine.
However, the risk is still high for all inland areas for flooding.
 Especially for towns located along rivers and streams such as the
Androscoggin and Little Androscoggin Rivers.

Storm Surge
A storm surge is a change in sea level that is caused by a storm.
They can lead to extensive flooding and are dangerous for
people living in many coastal areas.
For example, when Hurricane Katrina approached the US coast
in 2005, it generated a storm surge of more than 8 meters in
some areas.
This led to widespread flooding, including almost all of the city
of New Orleans where the sea defenses couldn't cope with the
water level.
More than 1800 people were killed across the US by Hurricane
Katrina, many of them by the storm surge flooding.
The main cause of a storm surge is high winds pushing the sea
water towards the coast, causing it to pile up there

Damage Potential
Saffir—Simpson Damage Potential Scale:
 In 1972, Robert Simpson, former Director of the National
Hurricane Center had difficulty describing to emergency
management and disaster officials what to expect for damage
from approaching hurricanes.
 The determination was made that a scale was needed to give
disaster officials an idea of what to expect.
 Herbert Saffir, a consulting engineer who was known as the
“father of the Miami building code” was enlisted to work with
Simpson on this project.
Together they created the Saffir-Simpson Damage Potential Scale
that is used today.
The scale was introduced in public advisories in 1975, and is
described below:

Damage Potential
Category 1 (74-95 MPH)
Damage is done primarily to shrubbery, trees, foliage, and
unanchored mobile homes.
No real damage to other structures, though there may be
some damage to poorly constructed signs.
A storm surge of 4 to 5 feet above normal is to be expected.
Low-lying coastal roads will become inundated, and there
would be minor pier damage.

Damage Potential
Category 2 ( 96-110 MPH ):
 Considerable damage to shrubbery, tree foliage, and vegetation can be
expected, and some trees may be blown down.
 Major damage is possible to exposed mobile homes, and extensive damage
to poorly constructed signs.
 There may also be some damage to the roofing materials, doors, and/or
windows of buildings.
 A storm surge of 6 to 8 feet above normal can be expected. Low-lying escape
routes to inland areas can be cut off by rising water from 2 to 4 hours in
advance of the storm center.
 Small craft will be torn from their moorings in exposed anchorage.
 Evacuation of some shoreline residences and low-lying island areas will be
required.

Damage Potential
Category 3 (111-130 MPH ):
Foliage will be torn from trees and some large trees will be blown
down.
Practically all poorly constructed signs will be blown down.
There will be some damage to roofing, doors, and windows.
There may also be structural small residences and utility
buildings, with a minor amount of curtain-wall failures. Mobile
homes can be destroyed.
A storm surge of 9 to 12 feet above normal can be expected that
would cause serious flooding along the coast.
Many smaller structures along the coastline may be destroyed,
and larger structures may be damaged by battering waves and
floating debris.

Damage Potential
Low-lying escape routes to inland areas can be cut off by
rising water from 3 to 5 hours in advance of the storm
center.
Flat terrain 5 feet or less above sea level will be flooded
inland up to 8 miles or more.
Evacuation of low-lying area residences within several
blocks of the shoreline would possibly be required.

Damage Potential
Category 4 (131-155 MPH):
Shrubs, trees, and signs are blown down.
There will be extensive damage to roofing materials, doors, and
windows.
Complete failure of roofs on many small residences, and
complete destruction of mobile homes.
A storm surge of 13 to 18 feet above normal can be expected.
 Flat terrain 10 feet or less above sea level will be flooded as far as
6 miles.
Major damage will occur to lower floors of structures near the
shoreline due to flooding and battering of waves and floating
debris.

Damage Potential
Low-lying escape routes to inland areas can be cut off by
rising water from 3 to 5 hours in advance of the storm
center.
Major erosion of beaches can be expected, and massive
evacuation of all residences within 500 yards of the
shoreline will possible be required.
Evacuation of single story residences on low ground within
2 miles of shore will be required

Damage Potential
Category 5 (155 MPH):
Shrubs, trees, and signs will be blown down.
Considerable damage to roofs and very severe damage to
windows and doors can be expected.
Complete failure of roofs on many small residences and
industrial buildings.
Extensive shattering of glass in windows and doors, as
well as some complete building failures.
Small buildings are overturned or blown away. Complete
destruction of mobile homes.
A storm surge in excess of 18 feet above normal can be
expected.

Damage Potential
Major damage to the lower floors of all structures less than
15 feet above sea level and within 500 yards of shore.
Low-lying escape routes to inland areas are cut off by rising
water from 3 to 5 hours in advance of the storm center.
Massive evacuation of residential areas on low ground
within 5 to 10 miles of shore possibly required.

References
http://meted.ucar.edu/ of the University Corporation for Atmospheric Research (UCAR)
pursuant to a Cooperative Agreements with the National Oceanic and Atmospheric
Administration, U.S. Department of Commerce.
http://www.aoml.noaa.gov/hrd/tcfaq/A15.html
http://www.aoml.noaa.gov/hrd/tcfaq/A4.html
http://www.hurricanescience.org/science/science/hurricanestructure/
http://www.nc-climate.ncsu.edu/climate/hurricanes/structure.php
http://www.lakeeriewx.com/Meteo241/ResearchTopicFour/HurricaneStructure.html
http://www.hurricanescience.org/science/science/hurricanemovement/
http://www.ametsoc.org/policy/hurr2.html
http://thevane.gawker.com/what-is-the-difference-between-a-cyclone-typhoon-and-
1617803648
http://www.weather.com/encyclopedia/charts/tropical/saffirscale.html
http://www.weather.com/outlook/weather-news/hurricanes/articles/hurricane-tracking-
hurricanes_2010-05-24
Hurricanes & Tropical Storms Their Impact on Maine and Androscoggin County by
Wayne Cotterly
http://www.nhc.noaa.gov/outreach/history/

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