Monday, August 13, 2007

TD 4 Forms, Saffir-Simpson Scale

The system that was the subject of the last blog post has taken its first step to becoming a major player in the weather during the next 7-14 days. The system has become a tropical depression, the weakest classified tropical system. Winds are currently sustained at 35 mph. As you can see below, the system is still a very long ways from land. Based on historical data of storms that form in that area, the projected path looks fairly consistent. However, those projections can change in a hurry, so don't put too much stock in them until the system evolves more.

So of course, the next questions are: How strong will this become and where will it head? Neither of those questions can be answered for sure yet; its still a very young system, being upgraded just today. However, I do think there is a good bet it will become a hurricane, possibly a "major" one. Some of the "experts" from have been saying Florida looks like a prime target. But in reality, its impossible to tell with any degree of certainty.

Wait a second...a "major" hurricane? What does that mean? Since hurricane season is heating up, its a good time to review the "Saffir-Simpson Scale," which is used to measure hurricanes based on wind speeds. There are 5 categories of hurricanes, 1 being the weakest, 5 the most powerful and rarest. Anything with a category 3 or higher is considered a "major" hurricane. Here is the complete scale, just focusing on categories and wind speeds:

  • Category 1: Winds between 74-95 mph
  • Category 2: Winds between 96-100 mph
  • Category 3*: Winds between 111-130 mph
  • Category 4*: Winds between 131-155
  • Category 5*: Winds over 156 mph
*Denotes a major hurricane

Now, these winds are sustained winds. Sustained winds are a 1-minute average. Individual gusts within the hurricane can far exceed the sustained wind speeds.

Keep checking back for updates on TD-4, which will like be named either "Dean" or "Erin" depending on another area of disturbed weather in the Western Gulf of Mexico.

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