Compare and contrast weather advisories such as “hurricane watch” and “hurricane warning.”
Give examples of actions to take to prepare for a hurricane.
Describe the conditions necessary for a hurricane to develop and how it dies out.
Like other Atlantic hurricanes, Andrew started as a low-pressure system in the tropics off the west coast of Africa. Warm water and moisture-laden air supplied the energy for it to strengthen into an ordinary and average tropical storm. Surface winds began to move the storm westward.
Although all tropical storms form and develop in this way, only a few intensify into hurricane. Most encounter upper air winds moving in the opposite direction as the surface winds. As a result, these storms weaken and soon die out. Tropical Storm Andrew, on the other hand, encountered upper air winds moving in the same direction as the surface winds. These reinforcing winds caused Andrew to quickly strengthen into an unusually powerful hurricane. Andrew proved to be one of the most intense Atlantic hurricanes of the 20th century.
History and Basics:
Weather satellites collect latitude and longitude coordinates to allow people to plot the paths of hurricanes and make predictions and advisories as to where they will make landfall. The National Hurricane Center tracks the hurricanes and issues their best estimate as to when and where a hurricane will hit and possible intensity levels.
A tropical depression is an organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 miles per hour.
A hurricane has a well-defined surface circulation with sustained winds of 74 mph or greater and are categorized by their winds speeds. Category 1 is the weakest and Category 5 is the strongest.
If a hurricane is predicted to make landfall within 24-36 hours, the area affected is put under a hurricane watch. If a hurricane is predicted to make landfall in less than 24 hours, that area is put under a hurricane warning.
The deadliest part of a hurricane is the storm surge - a wall of ocean water pushed by the winds of a hurricane. This storm surge can come ashore up to 12 hours prior to landfall and can raise the sea level up to 25 feet.
The calm “eye” of the hurricane can be up to 40 miles wide and often fools people into believing the storm is over resulting in injuries and fatalities. The eye wall winds around the eye have the most severe winds.
The death of a hurricane results from the loss of moisture and warm water. Upon landfall (or crossing an island), hurricanes begin to die out due to a lack of the moist, warm water which helps to intensify them. Higher latitude (cooler waters) can also cause a hurricane to dissipate.
Prior to 1953, hurricanes were named by where they hit or their coordinates. In 1953, hurricanes began having female names to help identify them in tropical waters, especially when there were multiple storms occurring simultaneously. It wasn’t until 1979 that the hurricanes began alternating between male and female names in alphabetical order in a six-year rotating list. These names are used repeatedly unless they are retired due to substantial damage or death.
Throughout Virginia’s history, over 69 eyes of cyclones have passed over the state and 11 have made landfall within 60 miles of Virginia’s coasts.
PROCEDURES: PLEASE READ AND FOLLOW THE INSTRUCTIONS CAREFULLY.
1. Using the Wind speeds on the Data Table and the Saffir/Simpson Scale below, determine the status of the storm either a Tropical Storm or a Hurricane + Category. Fill in this information in the last column of the Data Table. (Two examples are done for you.)
PART I: Tracking the Storm – Latitude and Longitude
2. Using the Hurricane Andrew Data Table, plot the track of Hurricane Andrew on the Map by marking a point at the correct latitude and longitude given.
3. Label each point you have plotted with the date and the time. Notice the times are on a 24-hour clock.
Example: the 1st lat/long point for August 21, 03:00 hrs, should be labeled “21/03.” August 21, 09:00 hrs = “21/09.”
4. Develop a colored coded key to represent the status of the storm. You will use five different colors. Create a key in the margin of the map. Example: Blue = Tropical Storm, Green = Category 1 Hurricane, and so on. Connect the lat/long points on your map with a colored pencil showing the storms track.
PART II: Graphing the Wind Speed & Graphing the Air Pressure
You will plot two different sets of data on the same graph!
5. Use a colored pencil or a marker to plot the data for Hurricane Andrew’s WIND SPEED vs. TIME on the Graph. Connect the points with a smooth curve.
6. Use a different colored pencil or marker to plot the data for the hurricane’s AIR PRESSURE vs. TIME on the same graph. (The scale for air pressure is on the other side across from wind speed.) Connect the points with a smooth curve.
Part III: Landfall Times
7. Look at the map where you plotted the track of the Hurricane. Circle the points where the Hurricane touches land.
Part IV: Answer the Analysis and Conclusion Questions