Case Study - Hurricane Irene August 2011

Tropical storm Irene developed over the Caribbean Sea on the 22^nd of August, gaining momentum it progressed northwards, strengthening to a Category 1 hurricane and swept across the US eastern seaboard. Hurricane Irene made landfall at north Carolina on the 27^th of August, with winds of 85 mph (140 km/h). It then moved rapidly northwards, as its energy dissipated the winds weakened to 75 mph (120 km/h) by the 28^th of August. By the time it reached New York it had been down graded by meteorologists to a tropical storm and had a less destructive impact.
 

As you can see from the timeline presented below, hurricane Irene has been the most severe cyclone of the hurricane season so far this year. At it’s strongest Irene became a Category 3 hurricane.



Thermal Image of Hurricane Irene.
 (Note how the eye of the storm is much cooler
where air subsides).

Consequences

• Severe flooding.
• Claimed 38 lives in 11 states.
• Estimated to have caused £6 billion ($10 billion) in damages.
• Prior warnings were declared to enable people to evacuate areas at high risk.
• 5 million homes and businesses experienced power cuts as utilities infrastructure were damaged.
• Homes were destroyed by the winds and fallen trees.
• Many trees were uprooted.

Highways reduced to rubble in Rodanthe, North Carolina.

Homes submerged under flood water at Pompo Lakes, New Jersey.

Classroom Activity

Categorise a range of storms and tropical cyclones to understand the scale of such events. Hand out a table containing the Saffir-Simpson Hurricane Scale categories used by meteorologists in the Atlantic Ocean and northern Pacific Ocean region, together with a selection of factual cards detailing past storms and tropical cyclones (including famous ones such as Hurricane Katrina which pupils may have some prior knowledge of).

Aim: To decide which category past tropical weather events fall under.

Note: To avoid confusion each the maximum strength for each storm will be presented as opposed to a sequence of wind strengths and characteristics that change through the life of a storm.

Saffir-Simpson Resource Sheet: