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Weather hazards: a case study on Hurricane Katrina
Hurricane Katrina occurred in late august 2005 in the south eastern part of the USA.
Hurricane Katrina formed as a tropical depression over the south-eastern Bahamas in august 23
2005 due to the remains of a tropical depression and tropical wave. The tropical storm moved to
Florida and then became a hurricane but weakened over the land however this intensified when
Hurricane Katrina travelled over the Gulf of Mexico. The hurricane grew from being a category 3
hurricane to a category 5 hurricane when travelling over the gulf. Hurricane Katrina made its peak on
August 28th with sustained winds of
175mph and a central pressure of
902 mbar (unit of pressure).
Hurricane Katrina reached land again
on the 29th of august near Louisiana
and passed over New Orleans. At
this point, Katrina's sustained wind
speed was approximately 200
km/h. The storm passed directly
through New Orleans, destroying
many lighter buildings and causing
extensive damage to others.
Hurricane force winds were
recorded along a 200km stretch of
coastline, with scenes of similar
destruction and flooding in
Louisiana, Mississippi and Alabama.
The hurricane then passed into
Mississippi where it begins to lose strength and degrades to a tropical depression near Clarksville,
Tennessee and the remaining tropical storm moves rapidly to the northeast and affecting eastern
A hurricane is a large rotating storm centred on an area of very low pressure with winds
blowing at high speeds of 74miles plus. Hurricanes form between 5 and 30 latitude overseas with a
minimum temperature of 26°C. The whole hurricane may be up to 500miles wide and move forward
at speeds up to 20mph. The influential factors of a hurricane forming are:* a source of warm moist
air from tropical oceans with high surface temperatures.* sufficient spin or twist from the rotating
earth. Hurricanes start when strong clusters of thunderstorms drift over warm ocean waters. The
warm air from the storm and ocean surface begins to rise which creates low pressure at the surface.
Winds blowing in opposing directions cause the storm to start spinning. The rising warm air causes
pressure to decrease at higher altitudes. The air rises faster to fill the low pressure drawing more
warm air off the sea and sucking cooler drier air downwards. As the storm moves over the water it
picks up more warm air and as the wind speed begins to increase more air is sucked into the low
pressure circle. Hurricanes consist of an eye of calm winds, low pressure surrounded by a vortex of
high winds and heavy rainstorms. A scale to measure hurricanes is called the Saffir Simpson scale
and is used to categorise typhoons and cyclones also.
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Satellite images are important for forecasters as by putting several hours
of satellite pictures into motion, they gather information on the track and development of the hurricane.
The Doppler radar can detect rain associated with tropical hurricanes. It covers rain within a 200250
mile distance from the radar location and provides estimates of rainfall amounts and depicts hurricane
The economic effects of the storm were far reaching as since April 2006 Administration
had sought $105 billion for repairs and reconstruction in the region.…read more