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The winds that change.

Published by Robert Buckley in Weather Emergencies · 19/8/2015 15:39:00
Tags: HurricaneWindwinddamage
Welcome to Disaster Control and Prevention's third installment in our Hurricane Preparedness Series. In this series you will learn the terminology used by the experts, the effects of different types of wind in the Hurricane setting and how to keep yourself and others as safe as possible should you find yourself exposed to them.

Heres a jump start on terminology:

1. Sustained Winds: It is the average speed of the wind from the eye to the outer band of the storm. This is the wind speed you can expect to experience through the duration of the Hurricane. For instance, a report on the Hurricane will typically read: "Hurricane Danny has SUSTAINED winds of 80mph with GUSTS to 95mph." From this, if you are caught in the storm, you can expect to be hit with AT LEAST winds of 80mph through the duration of the storm. You could be stuck in this for 12-18 hours. That is a long time to be battered by winds of 35mph, much less 80mph.

2. Maximum or 'Gusts to' Winds: To truly understand this term, we need a basic, working knowledge of just what is going on in this tempest. I know Hurricanes appear to be these large, meandering storms that lumber around and just crash into things. Trust me, that is not whats happening. Hurricanes are a very busy and broad area of organized thunderstorms in an extremely low pressure, compacted state. In much the same way a Tornado picks up debris and throws it at unsuspecting people and structures; Hurricanes collect thunderstorms, protect them, hide them, and then pitch them down onto the Earth at terrifying speeds with no concern for the lives in their path. The energy produced in these downdrafts can typically be measured by comparing them to 'atom/nuclear bombs' in fact, many Meteorologists often use that comparison. There can be hundreds of these supercell thunderstorms embedded in a Hurricane. This is where we see the 'Max or Gust' winds. Its estimated that Hurricane Ike (a Category 3 Storm) that hit Galveston Tx just a few years ago, did most of its damage by producing supercell thunderstorms which produced over fifty (50) Tornadoes and had wind gusts in excess of 180-200mph, even though the SUSTAINED winds were reported to only be 100-110mph. These embedded storms are usually the culprit in 'catastrophic damage' reports of Hurricanes.

Okay, so now that we've covered that keep in mind that you shouldn't be experiencing these things because you heeded the advice at the 72hr mark and you are 50+miles outside of the storm track (path) right? Well, we understand that things happen and there is a possibility you might have to contend with at least some part of this storm.

Below is a link from our partners at the National Oceanographic and Atmospheric Administration (NOAA) that very simply depicts the wind's effect as it relates to the Saffir-Simpson Wind Scale. This is the scale used to determine the 'category' in which a Hurricane is placed. Please click and observe the deteriorating conditions from a Category 1 to a Category 5.

Now, lets remember this is Savannah. I'll get the bad news out of the way. A substantial portion of Savannah homes are more than twenty years old, ok maybe fifty years old to be completely realistic. Even at Category 1, you are going to incur an impressive amount of damage for a couple of reasons:
First, the age of your home is a big factor. In the 70's and 80's there were few real studies pertaining to how structures fail in inclement weather such as Hurricanes. Even when there were really big breakthroughs in energy absorbing and protective construction techniques, often the practices were so expensive they priced homes out of the grasp of the average home buyer. Add to that, the vast amount of Victorian homes that have had very few improvements since, oh...the turn of the century (not this past one, the one before that), and you begin to visualize the enormity of destruction a Category 3 storm could inflict on our city.

Second, the kind of debris. We have some of the oldest oak trees in the nation. They look to be impressively stable and unshakable. Not so. Our oaks are incredibly heavy and their root systems tend to extend outward, not downward. Meaning, if you soak the surrounding ground of this enormous tree, the roots will come loose due to a phenomena called liquefaction. You might be familiar with this term in reference to earthquakes. Its very similar here on the east coast, only here it is actually liquid water shaking this tree loose. Add in an 80mph wind, and what you have is a 8-10 ton giant, smashing anything and everything in its reach. Pine trees, generally are much lighter, 2-5 tons. Your home may be able to support a 2 ton pine tree for a short time with some moderate roof damage. An eight ton Oak will lay waste to anything short of Ft. Pulaski. Next time you go to Kroger, count how many of these huge Oaks you see and note where they are. Many parts of Savannah have one in EVERY yard. Savannah will absorb a tremendous amount of damage in a Category 3 Hurricane. Remember, a Category 3 storm has winds of 111-129mph with nine feet of water running freely down every major street. Please don't be here when that happens. We recommend using the the shelters and resources available to you from great organizations like CEMA (Chatham Emergency Management Agency), the Red Cross, GEMA (Georgia Emergency Management Agency), friends and family out of the danger zone. You can ALWAYS come here to Disaster Control and Prevention for questions about any and all of these Agencies. In an emergency like a Hurricane, Tornado, Terrorist Event, Flood, we are always a call, email, or text away. We remain committed to the safety of our hometown and its people. 

Here are some links to give you a visualization of how wind effects structures:

Check back for Installment 4 and 5 where we will talk about pets, children, names and numbers and what to do once the storm has passed.

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