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Hurricanes
Dr. R. B. Schultz &
Mr. Schaeffer =)
Hurricane Damage
• The vast majority of hurricane deaths and
damage are caused by relatively
infrequent, yet powerful storms.
• The costliest natural disaster in U.S.
history, with damages in excess of
____billion, was Hurricane Andrew in 1992.
Until 2005… Hurricane Katrina is estimated at
causing $47 billion!!
Oooohh!!! Wait… In 2012, Hurricane Sandy
came in at a whopping $60 Billion!!
Why the dramatic increases??
•
•
•
•
•
Increased __________________.
New Orleans “_______ ____ _______”
Better evaluation of lost income
Sandy and the East Coast!
______________?? Not sure on this
one, but it makes sense?
Hurricane Formation
• Most hurricanes form between the latitudes of 5°
and 20° over all tropical oceans except the South
Atlantic and eastern South Pacific.
• The North Pacific has the greatest number of
storms, averaging 20 per year.
• In the western Pacific, hurricanes are called
____________, and in the Indian Ocean, they are
referred to as _________. In the Atlantic, they’re
called ________________.
Hurricane Occurrences and Geographic Distribution
Hurricane Generation
• A steep pressure _____________ generates
the rapid, inward spiraling winds of a
hurricane.
• As the warm, moist air approaches the core
of the storm, it turns upward and ascends in a
ring of cumulonimbus towers and forms a
doughnut-shaped wall called the ____ ____.
• At the very center of the storm, called the
_____, the air gradually descends,
precipitation ceases, and winds subside.
Why clockwise?!?
Wha…
•_________________
AND flow from high to
low!! (away from high)
Why up?
•Warm air “______”
•Moisture is _________
so clouds “pull” air up,
too.
Why counterclockwise?
•_________________
AND flow toward eye
(into low pressure)
In much the same way an
ice skater spins more
quickly as her arms are
tucked close into her body,
a hurricane also spins at a
faster pace near the
center than near the outer
edge.
Hurricane Generation (cont.)
• A hurricane is a heat engine fueled by the
________ _______liberated when huge
quantities of water vapor condense.
• They develop most often in late summer
when ocean waters have reached
temperatures of 27°C (80°F) or higher and
are thus able to provide the necessary heat
and moisture to the air.
DOUBLE LOW EQUALS MORE WINDS!
This warm water vapor
condenses and ______!
BUT…
LOW
It’s heat warms the air up
here!! This drops the
pressure again…
Evaporation of warm water
and heating of air causes an
updraft, which…
LOW
______________________
WARM OCEAN/WARM AIR
Stages of Development
• The initial stage of a tropical storm's life cycle,
called a _____________ _____________, is a
disorganized array of clouds that exhibits a weak
pressure gradient and little or no rotation.
• Tropical disturbances that produce many of the
strongest hurricanes that enter the western North
Atlantic and threaten North America often begin as
large undulations or ripples in the trade winds
known as easterly waves.
Stages of Development (cont.)
• Each year, only a few tropical disturbances
develop into full-fledged hurricanes that require
minimum wind speeds of 119 kilometers per
hour (______ mph).
• When a cyclone's strongest winds do not
exceed 61 kilometers per hour, it is called a
________________.
• When winds are between 61 and 119
kilometers per hour, the cyclone is termed a
__________________.
Hurricane Diminishment
• Hurricanes diminish in intensity
whenever they:
• (1) move over ocean waters that cannot
supply __________, ________ _____,
• (2) move _________ __________, or
• (3) reach a location where there is massive
high level _______ __________.
The _______________ Scale
• Although damage caused by a
hurricane depends on several factors,
including the size and population
density of the area affected and the
near-shore bottom configuration, the
most significant factor is the strength of
the storm itself.
The Saffir Simpson Scale
•The Saffir-Simpson scale ranks the relative intensities
of hurricanes.
•The Saffir-Simpson Hurricane Scale is a 1-5 rating
based on the hurricane's present intensity.
•This is used to give an estimate of the potential
property damage and flooding expected along the coast
from a hurricane landfall.
•Wind speed is the determining factor in the scale, as
storm surge values are highly dependent on the slope
of the continental shelf in the landfall region.
•Note that all winds are using the U.S. 1-minute
average.
•Category One Hurricane:
•Winds ________ mph (64-82 kt or 119-153 km/hr). Storm
surge generally 4-5 ft above normal. No real damage to
building structures. Damage primarily to unanchored mobile
homes, shrubbery, and trees. Some damage to poorly
constructed signs. Also, some coastal road flooding and
minor pier damage.
•Category Two Hurricane:
•Winds ________ mph (83-95 kt or 154-177 km/hr). Storm surge
generally 6-8 feet above normal. Some roofing material, door, and
window damage of buildings. Considerable damage to shrubbery
and trees with some trees blown down. Considerable damage to
mobile homes, poorly constructed signs, and piers. Coastal and
low-lying escape routes flood 2-4 hours before arrival of the
hurricane center. Small craft in unprotected anchorages break
moorings.
•Category Three Hurricane:
•Winds _________ mph (96-113 kt or 178-209 km/hr). Storm surge
generally 9-12 ft above normal. Some structural damage to small residences
and utility buildings with a minor amount of curtain wall failures. Damage to
shrubbery and trees with foliage blown off trees and large trees blown down.
Mobile homes and poorly constructed signs are destroyed. Low-lying
escape routes are cut by rising water 3-5 hours before arrival of the center
of the hurricane. Flooding near the coast destroys smaller structures with
larger structures damaged by battering from floating debris. Terrain
continuously lower than 5 ft above mean sea level may be flooded inland 8
miles (13 km) or more. Evacuation of low-lying residences with several
blocks of the shoreline may be required.
•Category Four Hurricane:
•Winds _________ mph (114-135 kt or 210-249 km/hr). Storm surge
generally 13-18 ft above normal. More extensive curtain wall failures with
some complete roof structure failures on small residences. Shrubs, trees,
and all signs are blown down. Complete destruction of mobile homes.
Extensive damage to doors and windows. Low-lying escape routes may be
cut by rising water 3-5 hours before arrival of the center of the hurricane.
Major damage to lower floors of structures near the shore. Terrain lower
than 10 ft above sea level may be flooded requiring massive evacuation of
residential areas as far inland as 6 miles (10 km).
•Category Five Hurricane:
•Winds greater than __________(135 kt or 249 km/hr). Storm surge
generally greater than 18 ft above normal. Complete roof failure on
many residences and industrial buildings. Some complete building
failures with small utility buildings blown over or away. All shrubs, trees,
and signs blown down. Complete destruction of mobile homes. Severe
and extensive window and door damage. Low-lying escape routes are
cut by rising water 3-5 hours before arrival of the center of the
hurricane. Major damage to lower floors of all structures located less
than 15 ft above sea level and within 500 yards of the shoreline.
Massive evacuation of residential areas on low ground within 5-10
miles (8-16 km) of the shoreline may be required. Hurricane Mitch of
1998 was a Category Five hurricane at peak intensity over the western
Caribbean. Hurricane Gilbert of 1988 was a Category Five hurricane at
peak intensity and is one of the strongest Atlantic tropical cyclones of
record.
Surprisingly…
Katrina was a level 5 but weakened to a 4 just
before landfall and
Sandy was actually a post-hurricane
________!
Damage Classes
• Damage caused by hurricanes can be divided
into three classes:
• (1) _______ _______, which is most intense on the
right side of the eye where winds are blowing toward
the shore, occurs when a dome of water 65 to 80
kilometers (40 to 50 miles) wide sweeps across the
coast near the point where the eye makes landfall,
• (2) _______ _________, and
• (3) ___________ ______________ ___________,
which is caused by torrential rains that accompany
most hurricanes.
Storm Surge
Before a
hurricane
…
After a
hurricane.
Warning Systems
• North Atlantic hurricanes develop in the trade
winds, which generally move these storms from
_____ to ______at about 25 kilometers (15 miles)
per hour.
• Today, because of early warning systems that help
detect and track hurricanes, the number of deaths
associated with these violent storms have been
greatly reduced.
• Because the tropical and subtropical regions that
spawn hurricanes consist of enormous areas of
open oceans, meteorological data from these vast
regions are provided primarily by satellites.
Information and Watches
• Other important sources of hurricane information
are:
• aircraft reconnaissance,
• radar, and
• remote, floating instruments called data buoys.
• Using data from the observational tools,
meteorologists can issue an announcement, called
a hurricane _________, aimed at specific coastal
areas threatened by a hurricane, generally within
___ hours.
Hurricane Warnings
• By contrast, a hurricane ___________
is issued when sustained winds of 119
kilometers per hour (74 mph) or higher
are expected within a specified coastal
area in ____ hours or less.
• Two important factors in the watch-and
warning decision process are:
• (1) adequate lead time and
• (2) attempting to keep overwarning at a
minimum.
Katrina = 1833
Sandy = 285
Key Terminology
Typhoon
Eye Wall
Tropical Disturbance
Tropical Depression
Saffir-Simpson Scale
Inland freshwater flooding
Hurricane Warning
Cyclone
Eye
Easterly Wave
Tropical Storm
Storm Surge
Hurricane Watch