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EX Credit PROJECT: Estimating Hurricane Strength using Storm Surge
In 1922, a strong hurricane made landfall along the southern coast of the US. During this time, there were
no satellites to monitor the motion of the storm, no weather radar to estimate wind speeds and rainfall, and
very few surface weather stations. Therefore, it is a challenge to now estimate the strengths of historical
storms when very limited data is available.
One set of data is available: the heights of the storm surges that the towns along the coast experienced.
Storm surge height is related to wind speed – the higher the wind speed a community experienced, the
higher the storm surge. We have storm surge data for four towns affected by the 1922 storm: Avalon, Pine
Crest, Otis and Port Smiley. We can use this data, along with our knowledge of how wind speeds vary in the
different hurricane categories, to make a reasonable estimate of the strength of the 1922 storm.
The centerline of the path of the 1922 storm is reasonably known – it passed between the towns of Pine
Crest and Otis (see Map 1). Wind speeds decrease as one moves away from the eye of the storm, with the
stronger hurricanes not only having the higher wind speeds, but higher winds extend further out from the
center.
In this project you will:
• Determine the distances each town is from the storm’s centerline
• Determine the expected wind speeds each town should have experienced for Category 2, 3, 4 and 5
hurricanes
• Estimate the wind speeds that each town actually experienced based on their storm surge heights
• Determine the likely hurricane category of the 1922 storm
Task 1: Measure the distances from the storm’s centerline
Map 1 on page 3 shows four coastal towns that were affected by the 1922 storm. Avalon and Pine
Crest were located to the left of the storm’s path, while Otis and Port Smiley were located to the
right of the storm’s path.
Using the map scale on Map 1, measure how far each of these four towns are from the centerline of
the storm (noted as 0 miles on the map). Note that the towns to the right will have positive distance
values, while the towns on the left have negative distance values. Your distances should be to the
nearest 10-mile interval (10, 20, 30, 40, etc.). Record these distances in the worksheet.
Task 2: Determine the expected wind speeds for a CATEGORY 2 hurricane
The four graphs on Page 4 show how the wind speeds for Category 2, Cat 3, Cat 4, and Cat 5
hurricanes are distributed from the center of the storm outward. The blue line represents the
expected wind speeds to the right of the storm’s path; the brown line represents the expected wind
speeds to the left of the storm’s path. The winds speeds get weaker the further from the eyewall of
each storm category.
Note that the blue wind speeds to the right of the storm’s path are higher. Because winds in a
tropical cyclone spiral in a counter-clockwise direction, the winds on the right side of the storm’s
path are blowing in the same direction as the storm is moving, making these winds stronger than on
the left side.
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Use the Cat 2 graph to determine the expected winds speeds at the distances the four towns are
from the center – the Task 1 distances. Record these in the appropriate spaces in the table.
Task 3: Determine the expected wind speeds for a CATEGORY 3 hurricane
Use the Cat 3 graph to determine the expected winds speeds at the distances the four towns are
from the center – the Task 1 distances. Record these in the appropriate spaces in the table.
Task 4: Determine the expected wind speeds for a CATEGORY 4 hurricane
Use the Cat 4 graph to determine the expected winds speeds at the distances the four towns are
from the center – the Task 1 distances. Record these in the appropriate spaces in the table.
Task 5: Determine the expected wind speeds for a CATEGORY 5 hurricane
Use the Cat 5 graph to determine the expected winds speeds at the distances the four towns are
from the center – the Task 1 distances. Record these in the appropriate spaces in the table.
Task 6: Determining wind speed using storm surge height
The storm surge heights measured in the four towns during the 1922 hurricane are listed below:
Avalon 3.5 ft
Pine Crest 9 ft
Otis 22 ft
Port Smiley 5 ft
Graph 1 on Page 3 relates wind speed to the expected storm surge. Using Graph 1, determine the
wind speeds that would be responsible for the storm surge heights measured in each town. Record
these in the worksheet.
Task 7: What is the most reasonable hurricane category for the 1922 hurricane?
Compare the estimated wind speeds that these four towns experienced from Task 6 to the wind
speeds that these towns should have experienced for the four categories from Task 2 through Task
5. Based on these comparisons, what is the most reasonable hurricane category for the 1922 storm?
Explain/defend your decision – convince me that your decision is the correct choice.
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Map 1
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EXTRA CREDIT WORKSHEET: Storm Surge, Wind Speed and Hurricane Category
Avalon Pine
Crest
Otis Port
Smiley
Task 1: Distances from storm centerline
Task 2: Cat 2 expected wind speeds for the task 1 distances
Task 3: Cat 3 expected wind speeds for the task 1 distances
Task 4: Cat 4 expected wind speeds for the task 1 distances
Task 5: Cat 5 expected wind speeds for the task 1 distances
Avalon Pine
Crest
Otis Port
Smiley
Storm surge measured in each town: 3.5 ft 9 ft 22 ft 5 ft
TASK 6: Wind speed based on storm surge (from graph 1)
TASK 7: What is the category of the 1922 hurricane? Circle your choice.
Cat 2 Cat 3 Cat 4 Cat 5
Explain/defend your choice – convince me that you picked the correct category.