HURRICANE HUGO

Name ______________________________ ID# ______________________________

Objective:

Study the development of Hurricane Hugo through time by analysis of Hugo's location, wind speed, and atmospheric pressure at twelve-hour intervals from September 11-22, 1989. One excellent reason for detailed study of the time history of a hurricane such as Hugo, is to provide information that can be used to predict the behavior, motion, intensity, and characteristics of future hurricanes. This predictive information may then be used to reduce the hazard of hurricane damage from a storm as it develops in the Atlantic and travels across the ocean toward North America. Studies of many hurricanes like Hugo provide us with reasonably reliable forecast statistics for Atlantic hurricanes.

This assignment illustrates the detailed study of Atlantic hurricane development for a particularly significant hurricane, Hugo, which caused substantial damage in Puerto Rico and the South Carolina area. The assignment also provides practice with data plotting (maps and graphs) and analysis.

Procedure:

1. Using the attached table of Hurricane Hugo's location (in latitude and longitude), maximum sustained wind speed (in knots; 1 knot = 1.15 miles/hour = 1.85 km/hr), and minimum atmospheric pressure (in millibars or hPa), and the attached map of the north Atlantic Ocean, plot the location of Hurricane Hugo at twelve-hour intervals (locations are given at 1000 and 2200 hours for each date) from September 11 to 22. Using the dashed latitude and longitude lines on the north Atlantic Ocean map, for each location in the table (for example, for 2200 hours on September 11, the location is 12.8°N latitude and 30.5°W longitude), put a dot on the map at that location. For the locations at 2200 hours of each day, write the date (11, 12, etc.) next to the dot. As an example and to get you started, the first three data points are already plotted on the map for you. Note that you need to interpolate (estimate) the locations between the dashed latitude and longitude grid lines. Connect the dots with lines to show the track of the hurricane over time.

2. On the attached graph, plot the wind speed and atmospheric pressure data as a function of time. Use dots (·) for the wind speed data and open circles (o) for the pressure data. Connect the points with smooth lines to show the wind speed and pressure variation with time for Hurricane Hugo.

Questions:

1. Examine the track of Hurricane Hugo on the north Atlantic Ocean map. What is the approximate direction that Hugo traveled during the following periods (circle the correct direction)?

Time Period Direction of travel of Hugo

September 11-15 N NE E SE S SW W NW

September 17-21 N NE E SE S SW W NW

2. Using the track of Hugo plotted on the north Atlantic Ocean map and the kilometer scale provided on the map, what is the approximate speed that the hurricane was moving across the Atlantic during the time period of September 11-15 (4 days or 96 hours)?

__________ km/hr

Note that the hurricane's motion across the ocean slows down somewhat from September 16-19, and then speeds up again after September 19.

3. Examine the two copies of satellite photos (1701 hours, Sept. 20, 1989 and 2031 hours, September 21, 1989) of Hurricane Hugo. Place an asterisk (*) on your north Atlantic Ocean map along the track of Hugo at location (and therefore time) of Hugo corresponding to these two times. Using the satellite photo for 2031 Sept. 21, note the approximate length of coastline (from central Florida to Cape Hatteras, North Carolina) that was being affected by the hurricane. This distance provides an approximate measure of the width of a typical intense hurricane. Using the kilometer scale and your north Atlantic Ocean map, what is the approximate width (diameter) of Hugo as measured between these two points on the coastline (central Florida to Cape Hatteras)? (Measure on the north Atlantic Ocean map, not the satellite photo because the photo is not at the same scale as the map.)

__________ km

4. Examine the graph showing wind speed and pressure versus time for Hurricane Hugo. In general, the variations of wind speed and pressure for Hugo from September 11-22 can be described by (multiple choice, circle the correct response):

a. The two curves (time series of wind speed and pressure) appear to be un-related to each other.

b. The two curves are nearly inversely correlated, when the pressure decreases the wind speed increases and when the pressure increases, the wind speed decreases.

c. The two curves are nearly correlated implying that high pressure produced high wind speed.

5. During what time period does the hurricane intensify, attaining the lowest pressures and highest wind speeds (multiple choice, circle the correct response)?

a. September 11-14 c. September 19-20

b. September 15-18 d. September 22-23

6. Where is Hugo during this time of greatest intensity and how fast is it moving (multiple choice, circle the correct answer)?

a. In the central Atlantic, moving across the ocean with a speed of about 40 km/hr.

b. Just off the coast of South Carolina, moving across the ocean with a speed of about 20 km/hr.

c. In the eastern Caribbean (near the Greater Antilles and Puerto Rico), moving across the ocean with a speed of about 20 km/hr.

7. Hugo builds slowly from September 11-15 (winds increasing and pressure decreasing), but weakens rapidly after September 21. This rapid weakening is most likely caused by (multiple choice, circle the correct response):

a. The "age" of the hurricane; most tropical storms and hurricanes cannot sustain high winds for more than a few days.

b. The change of direction to the northwest after September 17.

c. The fact that the hurricane encounters land after September 21, thus removing the significant energy source of warm ocean waters and producing increased "friction" on air movements (wind) because of the rougher land surface.

8. At the most intense periods of the hurricane (September 16-18 and September 21), Hugo was what "category" storm on the Saffir-Simpson scale (see Table 14.2 in text) as indicated by wind speed (multiple choice, circle the correct response):

a. Category 1 d. Category 4

b. Category 2 e. Category 5

c. Category 3

Note the graphs of the storm surge (labeled maximum storm tide) along the South Carolina coastline. What category does the observed maximum storm surge height (about 30 km north of Charleston, South Carolina) indicate for Hugo?

1 2 3 4 5