Remember Frances and Jeanne?
By Joe Zelenak
Since the last update, things have really started to change in the tropics. During the months of June and July, most of the activity had been centered with systems forming close to home. In other words, the storms were born in close proximity to the coastline. Storms of this nature usually do not have enough time to get wound up because they are born so close to land.
In August, things begin to make a dramatic change. One look at a satellite loop of Africa will detail an ample supply of thunderstorms and waves moving across the continent toward the Atlantic. The parade is constant and the waves that have the most convection are the most likely candidates to be our next named system. Some will survive, and others might encounter things like vertical wind shear and/or dry air from Saharan Dust and will simply fizzle out like a dud firecracker. The ones that survive can often create a lot of anxiety, as we track them across the ocean.
Storms that form far out in the Atlantic are often referred to as "long-trackers" or "Cape Verde storms." These cyclones will often take a week or longer to make their track across the ocean. These are the most feared of all storms. Cape Verde storms have a nasty reputation of gaining strength rapidly and sometimes blossoming into Category 4 or 5 hurricanes. Fortunately, a certain percentage of these systems will re-curve out to sea before making landfall. Often times, that re-curve comes way too close for comfort. A good example was Hurricane Floyd, which created the largest evacuation in peacetime history.
Other times, we are not so lucky. Hurricanes tend to be steered by high pressure ridges, which are present every summer. As troughs move across the northern United States, a weakness will develop in the ridge that will allow the storm to re-curve to the north. If that weakness develops near your location, you are going to get a hurricane.
In addition, sometimes the leading edge of a ridge will drape right across the center of Florida. This was the case in 2004. Both Frances and Jeanne were steered into us by a high-pressure ridge that was draped across our region almost all summer. If this scenario develops, you become a central target for almost every bullet that is shot at you.
Another factor that can influence storms is whether we are under the influence of El Nino, a warming of the ocean off the coast of South America, or La Nina, a cooling of the waters - one or the other condition occurring every four to 12 years. Right now, we are in ENSO neutral, which means that neither is playing a part in our weather. This was also the case in 2004 when Florida was hit from almost every angle possible.
So far, we have been protected by both a ridge and by dry air, vertical shear and a high-pressure ridge. This ridge is helping to keep storms well to our south. This has been the case for Ernesto, Florence and Depression 7. I expect these conditions to change as the month progresses, and we must all be ready when it does. As I have said many times before, be sure you have a plan and a hurricane kit ready. Be prepared, and be safe.
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