June 1, 2012 officially kicks off the 2012 Atlantic hurricane season, even though we have already had an early start to the season with two named storms. When we talk about hurricanes in the United States, a few come to mind: Camille (1969), Hugo (1989), Andrew (1992), Charley (2004), Ivan (2004), Katrina (2005), Wilma (2005), and Ike (2008). Hurricanes can bring many types of destructive elements including storm surge, strong winds, flooding, and tornadoes. These large, powerful cyclones are created to simply distribute energy from the warm, ocean waters and transport that heat to the poles. In a way, they form as part of the Earth’s air conditioning unit to balance itself. May 27 through June 2 is NOAA’s Hurricane Preparedness Week. Here is a guide that summarizes things you can do to get ready for that potential big storm if it hits along the coast. You can find the same information, which can also be found in Spanish, by clicking on NOAA’s Hurricane Preparedness Guide.
What are hurricanes/typhoons?
Ever heard the phrase hurricanes, typhoons, or tropical cyclones? These names are all the same thing: They are storms that develop typically during the summer and early fall months around the world when sea surface temperatures are 80° Fahrenheit or roughly 27° Celsius. Unlike typical mid-latitude cyclones, these storms feed on these warm ocean temperatures and develop a warm core along the center of the storm. Once the system develops and organizes, it produces more thunderstorms along the center of the storm. As pressure lowers, the system becomes stronger and produces stronger winds. By the time the storm has 74 miles per hour, the system is considered a hurricane. In the Western Pacific, residents call these storms typhoons. In Australia, these systems are commonly referenced as tropical cyclones. In the United States and eastern Pacific, they are commonly referenced as hurricanes. These storms typically need warm ocean waters and little amounts of wind shear to develop. How do you define and visualize wind shear? Have you ever blown out a candle for your birthday? When you blow on the flame, the flame blows out. The air that you blew out can be considered wind shear, or vertical winds that can disrupt the organization of a tropical cyclone, or in our example, the flame on the candle. In summary, strong vertical wind shear is not good for a tropical cyclone.
There are five stages of a tropical cyclone as they form:
1)Tropical disturbance: A cluster of disorganized storms that are clustered in a region of possible development. These storms shows a decline in barometric pressure and can typically begin to spin up an area of low pressure.
2) Tropical depression: Once a disturbance sustains enough organization and thunderstorm activity, they are typically classified as depressions. These systems have wind speeds less than 39 mph and typically have barometric pressures around 1010-1000 millibars.
3) Tropical storm: Once a tropical depression has sustain winds over 39 mph, the system is then upgraded as a tropical storm. By the time they reach this status, the storms are given a name. Although depressions and storms are typically thought to be weak in compared to hurricanes, they can still cause plenty of problems. If they decide to hit land and stall over an area, flooding can be a major and destructive force that can create millions in damage. Just because they do not provide “strong” winds does not mean they can be destructive. Also, 40-50 mph winds can still cause damage. People typically underestimate the strength of a 50-60 mph wind gust. They can bring trees and powerlines down. Barometric pressure for these systems are typically around 1000 mb – 990 mb (rough estimate). Larger systems can have lower pressures, but sometimes, it takes more time for the winds to catch up with the pressure reading. Prime example: Hurricane Irene from 2011.
4) Hurricane/typhoon: Once a system reaches a sustained wind of 74 mph or greater, the system is upgraded into a hurricane. Hurricanes/typhoons develop an eye, which develops in the center of the storm. The center of the eye typically provide clear conditions and practically indicate that the storm is only halfway over. Hurricanes are rated through the Safer Simpson Scale based on wind speeds. The scale goes from 1-5, with Category 5 storms becoming very rare. Hurricanes are violent storms that can produce storm surge, flooding, and isolated tornadoes. Barometric pressures are typically below 990 mb or lower.
5) Major Hurricane/Super Typhoons: In the United States, storms that are Category 3 (sustained winds over 111 mph) or stronger are considered a major hurricane. In the western Pacific, storms that acquire approximately Category 4 strength (wind speeds over 130 mph) or stronger are called Super Typhoons. These terms can change pending on the regions you live in, but typically, these are some of the most violent storms on Earth. They can produce widespread wind and flooding damage and are very destructive.
Now that we understand these systems, let’s prepare and take precautions now instead of later!
Storm surge is an abnormal rise of water generated by a storm’s winds. Storm surge can reach heights well over 20 feet and can span hundreds of miles of coastline. In the northern hemisphere, the highest surge values typically occur in the right front quadrant of a hurricane coincident
with onshore flow; in the southern hemisphere, the left front quadrant. More intense and larger hurricanes produce higher surge. In addition, shallower offshore waters contribute to higher storm surge inundation. Storm surge is by far the greatest threat to life and property along the immediate coast, NOT winds.
Storm tide is the water level rise during a storm due to the combination of storm surge and the astronomical tide. For example, if a hurricane moves ashore at a high tide of 2 feet, a 15 foot surge would be added to the high tide, creating a storm tide of 17 feet. The combination of high winds and storm tide topped with battering waves can be deadly and cause tremendous property damage along an area of coastline hundreds of miles wide. The destructive power of storm surge and large battering waves can result in loss of life, buildings destroyed, beach and dune erosion and road and bridge damage along the coast. Storm surge can travel several miles inland. In estuaries and bayous, salt water intrusion endangers public health and the environment.
Winds and tornadoes:
Hurricane-force winds, 74 mph or more, can destroy buildings and mobile homes. Debris, such as signs, roofing material, siding and small items left outside become flying missiles during hurricanes. Winds can stay above hurricane strength well inland. In 2004, Hurricane Charley made landfall at Punta Gorda on the southwest Florida coast and produced major damage well inland across central Florida with gusts of more than 100 mph. Hurricanes and tropical storms can also produce tornadoes. These tornadoes most often occur in thunderstorms embedded in rain bands well away
from the center of the hurricane; however, they can also occur near the eyewall. Usually, tornadoes produced by tropical cyclones are relatively weak and short-lived, but they still pose a significant threat.
Tropical cyclones often produce widespread, torrential rains in excess of 6 inches, which may result in deadly and destructive floods. In fact, flooding is the major threat from tropical cyclones for people living inland. Flash flooding, defined as a rapid rise in water levels, can occur quickly due to intense rainfall. Longer term flooding on rivers and streams can persist for several days after the storm. Rainfall amounts are not directly related to the strength of tropical cyclones but rather to the speed and size of the storm, as well as the geography of the area. Slower moving and larger storms produce more rainfall. In addition, mountainous terrain enhances rainfall from a tropical cyclone. Storm surge and inland flooding are the most deadly part of hurricanes, NOT winds.
The strong winds of a tropical cyclone can cause dangerous waves that pose a significant hazard to mariners and coastal residents and visitors. When the waves break along the coast, they can produce deadly rip currents—even at large distances from the storm. Rip currents are channeled currents of water flowing away from shore, usually extending past the line of breaking waves, that can pull even the strongest swimmers away from shore. In 2008, despite the fact that Hurricane Bertha was more than a 1,000 miles offshore, the storm resulted in rip currents that killed three people along the New Jersey coast and required 1,500 lifeguard rescues in Ocean City, Maryland, over a 1 week period. In 2009, all six deaths in the United States directly attributable to tropical cyclones occurred as the result of drowning from large waves or strong rip currents.
If you live along the coastline, there is a threat to see hurricanes each and every year. If watches or warnings are issued, the best defense is to leave! Unlike tornadoes that can strike in a short amount of time, tropical systems are typically seen days in advance. National Hurricane Center does a great job in tracking where the storm will move. If a hurricane is within the cone of uncertainty in your area, you should leave! Simply the best defense!
Before the storm:
-Determine safe evacuation routes inland.
-Learn locations of official shelters.
-Check emergency equipment, such as flashlights, generators and battery-powered equipment such as cell phones and your NOAA Weather Radio All Hazards receiver.
-Buy food that will keep and store drinking water.
-Buy plywood or other material to protect your home if you don’t already have it.
-Trim trees and shrubbery so branches don’t fly into your home.
-Clear clogged rain gutters and downspouts.
-Decide where to move and secure your boat.
-Review your insurance policy.
-Find pet-friendly hotels on your evacuation route.
If you are in a tropical storm or hurricane watch, take these precautions. Remember, a watch means conditions are possible for a tropical storm or hurricane force winds to hit your area within 48 hours:
-Frequently listen to radio, TV or NOAA Weather Radio All Hazards for official bulletins of the storm’s progress.
-Fuel and service family vehicles.
-Inspect and secure mobile home tie downs.
-Ensure you have extra cash on hand.
-Prepare to cover all windows and doors with shutters or other shielding materials.
-Check batteries and stock up on canned food, first aid supplies, drinking water and medications.
-Bring in light-weight objects such as garbage cans, garden tools, toys and lawn furniture.
If a hurricane warning has been issued, it means hurricane force winds are likely within 36 hours and all precautions should be made immediately.
-Closely monitor radio, TV or NOAA Weather Radio All Hazards for official bulletins.
-Close storm shutters.
-Follow instructions issued by local officials. Leave immediately if ordered!
-Stay with friends or relatives at a low-rise inland hotel or at a designated public shelter outside the flood zone.
-DO NOT stay in a mobile or manufactured home.
-Notify neighbors and a family member outside of the warned area of your evacuation plans.
-Take pets with you if possible, but remember, most public shelters do not allow pets other than those used by people with disabilities. Identify pet-friendly hotels along your evacuation route.
If you decide to “weather out the storm”, then use these precautions:
-Turn refrigerator to maximum cold and keep it closed.
-Turn off utilities if told to do so by authorities.
-Turn off propane tanks.
-Unplug small appliances.
-Fill bathtub and large containers with water in case clean tap water is unavailable. Use water in bathtubs for cleaning and flushing only. Do NOT drink it.
-Stay away from windows and doors, even if they are covered. Take refuge in a small interior room, closet or hallway.
-Close all interior doors. Secure and brace external doors.
-If you are in a two-story house, go to an interior first floor room.
-If you are in a multi-story building and away from water, go to the 1st or 2nd floor and stay in the halls or other interior rooms away from windows.
-Lie on the floor under a table or other sturdy object ONLY if the winds become extremely violent.
You should always have an emergency supply kit with you in times of danger. Here is what the Red Cross, FEMA, and NOAA recommend:
-At least a 3-day supply of water (one gallon per person, per day)
-At least a 3-day supply of non-perishable food
-At least, one change of clothing and shoes per person
-One blanket or sleeping bag per person
-Battery-powered NWR and a portable radio
-Flashlight, extra batteries
An Emergency Supplies Kit Should Include:
-Extra set of car keys
-Credit card and cash
-Special items for infant, elderly or disabled family members
-Prescription and non-prescription medicines
If you take these procedures, you will be ready for a storm. Once again, the best defense to protecting you and your loved ones from a hurricane is by evacuating and moving inland!
Bottom line: Hurricane season is upon us and now is the time to be prepared! Have a plan for your and your family and find out where you should go or relocate if a hurricane strikes your area. The best line of defense is to leave your area, especially if you live along the coast and near the ocean. Flooding and storm surge are the biggest threats with hurricanes, not strong winds. It only takes one storm to make the season memorable, even if forecasts call for a below average or average year. We might only see eight storms, but if one produces damage like Andrew or Katrina, we will always remember. Have you ever been through a hurricane? Is there something that you did differently that you would like to share? EarthSky encourages you to comment below and share your experiences and let us know what you learned after experiencing Mother Nature’s worse storms. If we can all prepare now, we can avoid loss of life and injuries.