Chapter 30 – Storms and Weather Forecasts

Name: Period: Date:

INVESTIGATION: HURRICANE WEATHER

Hurricane Alicia passed over the town of Alvin, Texas, in August 1983. Alvin is 48 km inland from the Gulf of Mexico. Weather conditions recorded in Alvin as the hurricane passed are shown in the Hurricane Data Chart. By graphing the weather data, you will be able to draw conclusions about the characteristics of a hurricane.

Date / Hour / Temp / Wind Speed / Wind Direction / Air Pressure / Inches of Rainfall
AUG
17 / MDT / 81 / 12 / NE / 1013 / 0.0
0300 / 80 / 16 / NE / 1012 / 0.0
0600 / 80 / 22 / NE / 1011 / 0.12
0900 / 79 / 29 / NE / 1013 / 0.04
1200 / 78 / 35 / NE / 1012 / 0.03
1500 / 78 / 35 / NE / 1009 / 0.09
1800 / 80 / 38 / NE / 1006 / 0.18
2100 / 80 / 48 / NE / 1005 / 0.12
AUG 18 / MDT / 77 / 67 / NE / 1001 / 0.90
0300 / 77 / 53 / SW / 987 / 2.83
0600 / 77 / 53 / SE / 967 / 2.68
0900 / 78 / 37 / S / 993 / 0.67
1200 / 82 / 35 / SW / 1005 / 0.10
1500 / 83 / 22 / SW / 1007 / 0.0
1800 / 84 / 16 / S / 1008 / 0.0
2100 / 83 / 18 / S / 1010 / 0.0
AUG 19 / MDT / 82 / 18 / SE / 1012 / 0.01013

HURRICANE DATA CHART

PROCEDURE

1. Use the graph to plot all of the weather information on the Hurricane Data Chart. Note the scales for the weather characteristics are on the right and left vertical axes and the time scale is on the top horizontal axis.

2. With a colored pencil, plot the temperature (along the top left vertical axis) versus the hour. Connect the points with a ruler and label the line “temperature”.

3. With a second colored pencil, plot the wind speed (along the lower left vertical axis) versus the hour. Connect the points and label the line “wind speed”.

4. In addition to the wind speeds recorded in the chart, two higher-speed wind gusts were also recorded. The first was 82 mph at 2340 hours on August 17th, and the second was 102 mph at 0049 on August 18th. With the second colored pencil, plot the first gust and connect its point with a dashed line to the wind speed points for 2100 and MDT. Do the same for the second gust, connecting its point to the points for MDT 0300.

5. With a third colored pencil, plot the air pressure (along the top right vertical axis) versus the hour. Connect the points and label the line “air pressure”.

6. With a fourth colored pencil, plot the rainfall (along the lower right vertical axis) versus the hour. Connect the points and label the line “rainfall”.

7. Write the abbreviated wind direction for each three-hour period along the bottom line of the graph.

CONCLUSION QUESTIONS

1. What does the graph show about the relationship between air pressure and wind speed?

2. The storm center in the eye wall of the hurricane is where the weather conditions are the most extreme. Referring to your graph, choose a period of six hours during which you think the storm center passed over Alvin. Explain why you chose that period.

3. What happened to the wind direction as the storm center passed over Alvin?

4. What relationship exists between the amount of rainfall and the storm center?

5. What relationship exists between the air pressure and amount of rainfall?

6. How much rain fell in total?

7. Did the hurricane have a significant effect on the temperature of the area?

8. You may have noticed that the wind speeds are well below the 74 mph threshold for a storm to be considered a hurricane. Was Hurricane Alicia still a “hurricane” when it passed over Alvin? If not, then what was it? What caused its winds to diminish?