Hurricane Preperadeness...

Thursday, May 26, 2011

It is that time of year again. This week May 22-28 has been officially recognized as Hurricane Preparedness Week.We are less than a week away from the start of the 2011 Atlantic Hurricane Season. The season officially starts on Wednesday, June 1 and concludes on Wednesday November 30. The purpose of this blog post is to provide you with pertinent information you need to be prepared should a storm target SW Louisiana during the upcoming season. I will break it up into parts to make it easier for you to read. The first parts that I will post this morning will include common terms we associate with tropical cyclones, some do's and dont's from before, during, and after a storm. I will also go ahead and list the cycle of names for the 2011 season, and conclude with my personal thoughts on the upcoming season. Many people are on edge, and understandably so, with the storms of recent years still heavy on our minds, and all of the violent tornadoes that been occurring in recent days and weeks. I will try to calm your fears just a bit in that regard in a few moments. Without further delay, let's get started...be sure to scroll down for the whole post. Additional information will be posted tonight.

It is essential to have a better understanding of not only hurricanes, but all tropical systems in general. One way to become more knowledgeable of these meteorological entities is to understand and know the meaning of certain terms we use over the course of the season.

As you know, tropical systems are divided into 3 stages for naming purposes: tropical depression, tropical storm, and hurricane. However, it can be taken further as all of these tropical systems begin from what is known as a tropical wave or tropical disturbance. Let's define each one.

Tropical Disturbance- An area of disorganized low pressure that develops in the Atlantic Basin, that is, the Gulf of Mexico, Caribbean Sea, and Atlantic Ocean. It generally evolves from a persistent area of thunderstorms, and lowering pressures over the Atlantic Basin.

Tropical Depression- An organized low pressure system with organized clouds and thunderstorms. It has sustained surface winds of 38 mph or less.

Tropical Storm- An organized low pressure system with organized clouds and intense rainfall. It has sustained surface winds of 39-73 mph.

Hurricane- The most intense of the tropical cyclones. It produced very heavy rainfall, and sustained surface winds must be at least 74 mph.

Hurricane intensity is measured using the Saffir-Simpson scale. It is broken down into 5 categories.

Category 1  74-95 mph. Minimal damage will result such as downed trees and power lines. Damage to poorly constructed mobile homes is possible. Minor roof damage possible to some well-built homes. Some signs could be damaged. Injury or death to people and animals can occur if debris falls on or hits them. Example of a category 1 storm (Dolly in 2008- South Texas).


Category 2- 96-110 mph. Extensive damage will occur. Examples of this include: Older mobile homes can be completely destroyed by the high winds and flying debris. The risk of death or injury to humans and animals increases. High rise buildings sway, and face the risk of having windows blown out.  Example of a category 2 storm (Hurricane Frances in 2004- East Central FL Coast).

Category 3 111-130 mph. Severe damage will occur. Major tree and power line damage occurs often producing prolonged power outages for over a week. Major communications can be cut off for more than a week. Almost all older mobile homes will be completely destroyed. Poorly constructed frame homes can face serious damage. Major roof damage will occur. Signs, fences, and canopies destroyed. Example of a category 3 (Hurricane Rita September 24, 2005- SW Louisiana/SE Texas). Hurricanes of category 3 intensity and above are considered major hurricanes.

Category 4 131-155 mph. Devastating damage. A very high risk of death to humans and animals due to falling and flying debris. Major structural damage to well built homes and offices. Certain demolition of mobile homes and trailers. Power failures will last for weeks due to numerous amount of falling trees and power lines. All major services will be unavailable for quite some time after the storm. Example of a category 4 storm (Hurricane Charley- August 2004- West Central Florida).

Category 5 156 mph or greater. Catastrophic damage. A very high risk to almost near certain death for humans and animals due to falling and flying debris. Major damage to well built structures. Nearly all signs, canopies, and fences will be destroyed. Nearly all trees and power lines will be snapped, uprooted, or downed. Expect utilities and services to be absent for weeks possibly months. Many areas will be uninhabitable, and human suffering will be immense. An example of a category 5 storm (Hurricane Andrew- August 1992, and Hurricane Camille- August 1969 Mississippi).

Other terms of note include:

Storm surge- A rapid rise in ocean height as a hurricane moves inland. More people are killed by the storm surge element than the wind element. The storm surge is extremely destructive to anything and everything in its path, especially if it comes in with a significant speed. You should remember that water is extremely heavy, and a cubic yard of water weighs about 1,700 pounds. The larger the storm, the higher the surge will be. The shape of the continental shelf across the coastal waters is also a contributing factor.


When a tropical system is threatening a portion of coastline, and conditions are imminent within a couple of days certain advisories are issued by the National Hurricane Center.

Tropical Storm Watch- Alert issued when tropical storm conditions are expected within 48 hours for a specific area of the coast.

Tropical Storm Warning- Alert issued when tropical storm conditions are expected within 36 hours for a specific area of the coast.

Hurricane Watch- Alert issued when hurricane conditions are expected for a specific portion of the coastline. It is issued within 48 hours of the anticipated onset of tropical storm force, because the stronger winds will make preparations more difficult to complete.

Hurricane Warning- Alert issued when hurricane conditions are expected for a specific portion of the coastline with 36 hours of the anticipated onset of tropical storm force winds. This is because preparations become more difficult to complete once the winds increase.

Tornadoes are also very common during tropical systems, mainly to the right (East) of the center of circulation.

Tornado- A small-scale, violently rotating column of air extending from the cyclonic motion.

These are the common terms used during the course of a tropical season.

__________________________________________________________________________________


The next section will actually cover something that took affect last year in 2010, but I want to familiarize you with it. The NHC (National Hurricane Center) made several changes to how they issue forecasts. Since, last year was a relatively quiet year as far as storm activity reaching the Gulf, you may not have even realized there were some changes, so I felt it was important to repeat this section from last year.

First, Watches and warnings for tropical storms and hurricanes along threatened coastal areas will be issued 12 hours earlier than in previous years. Tropical storm watches will be issued when tropical storm conditions are possible along the coast within 48 hours. Tropical storm warnings will be issued when those conditions are expected within 36 hours. Similar increases in lead-time will apply to hurricane watches and warnings.

Secondly, The format of the Tropical Cyclone Public Advisory is changing. The most significant changes are:

The Public Advisory will be organized into sections. Within these sections, keywords will be used to assist the human eye and computer software to find specific information more readily.

The summary section of the advisory will move to the top of the product, immediately following the headline. The summary section will contain more information than it did previously.

Watch and warning information will be organized differently and be presented in list or bullet form.

Thirdly, A summary section, identical to the one found in the Public Advisory, will be added to the Tropical Cyclone Update whenever storm information (e.g., position, intensity, movement, pressure, etc.) changes from the previous Advisory.

Fourth, The genesis forecasts for the risk of tropical cyclone development will be provided to nearest 10 percent, in both the text and graphical Tropical Weather Outlooks. In previous years, only risk categories (low/medium/high) were given.

Fifth, The National Weather Service and its National Hurricane Center will begin using the generic term "post-tropical" to refer to any system that no longer possesses sufficient tropical characteristics to be considered a tropical cyclone. Post-tropical cyclones can continue to carry heavy rains and strong winds. Some post-tropical cyclones will go on to become fully extratropical, that is, derive their energy from the temperature contrast between warm and cold air masses. Another type of post-tropical cyclone is the "remnant low", a weak system with limited thunderstorm activity and winds of less than tropical storm strength.

Next, The Saffir-Simpson Hurricane Wind Scale will become operational. The scale keeps the same wind speed ranges as the original Saffir-Simpson Scale for each of the five hurricane categories, but no longer ties specific storm surge and flooding effects to each category.

Lastly, The size of the tropical cyclone forecast cone will be adjusted. The cone represents the probable track of the center of a tropical cyclone, and is formed by enclosing the area swept out by a set of imaginary circles placed along the forecast track (at 12, 24, 36 hours, etc.). The size of each circle is set so that two-thirds of historical official forecast errors over a 5-year sample fall within the circle. The circle radii defining the cones in 2010 for the Atlantic and eastern North Pacific basins are given in the table below.

For more information log onto www.nhc.noaa.gov....The National Hurricane Center.

___________________________________________________________________________________

Finally, to close things out this morning. Here is the list of names for the 2011 Atlantic Hurricane Season. It should be noted, that names are only used once a tropical cyclone reaches tropical storm intensity and above. When a tropical cyclone is in tropical depression stage, it is only given a number. As usual, the list of names alternates boy/girl or girl/boy depending on what year it is. This year first up is Arlene, followed by Bret, and so forth. Remember, too, that the names are recycled every 6 years. For example, Arlene & the rest of the following names will show up again in 2017. There is an exception to that rule, and when you see this year's list you will see a perfect illustration of that. If a storm is influential, and not necessarily at or above major hurricane status, the name will be retired. Such retired names include Rita, Katrina, Ike, Gustav, Audrey, Andrew, Lili, Ivan, Frances, Charley, Wilma, Betsy, & Camille just to name a few. This year's list features many of the same names from 2005, but notice the replacements for Katrina, Rita, Dennis, Stan, & Wilma. The 2011 list of names is as follows:


Arlene
Bret
Cindy
Don
Emily
Franklin
Gert
Harvey
Irene
Jose
Katia
Lee
Maria
Nate
Ophelia
Philippe
Rina
Sean
Tammy
Vince
Whitney

There are no storm names for the letter Q, U, X, Y, & Z.


Check back for part 2 tonight which will feature what to do before, during, and after the storm, as well as hurricane climatology and history for SW Louisiana, and also include the science behind hurricanes, that is, the forecasting aspect. Iwill also include some predictions for the upcoming season. Even though I don't put numbers on it like some experts do, I will give my thoughts on the upcoming season. If you have any questions or comments please feel free to leave them right here, or you can e-mail me.  Be sure to scroll down for the latest forecast as well.

Have a great Thursday & be sure to check back later tonight.
God bless!
-DM