Sub-Tropical, Tropical, Extra-Tropical=Extra Confusing...

I know it can be a little confusing trying to keep up with all of these terms we sometimes so loosely throw around.  Believe me, it is just as frustrating either not having enough time to explain it or trying cram it in to our allotted weather time.  I guess that is what the ole weather blog is for huh? 

Well, here we go.  Here is your brief lesson on everything tropical.  Let's start with the tropical stuff.  A  tropical disturbance forms over waters greater than 80 degrees.  This disturbance is an organized cluster of storms usually 100 to 300 miles in diameter and sustains itself for greater than 24 hours.  The disturbance begins to spin and then begins to strengthen slightly.  If the winds get to 30 mph, it is deemed a tropical depression.  If it continues to strengthen to winds greater than 38 mph, it becomes a tropical storm.  The defining features are the fact it developed in the tropics, it has a warm core and uses latent energy, or energy from the warm evaporating water from the tropics to characterize it as a tropical entity. 

Let's move to the other side of things with the extratropical.  These storms are areas of low pressure, which mean they spin counter-clockwise, like their tropical cousins.  However, they use the potential energy provided by the clashing of cold and warm air masses to sustain themselves.  They have a colder core as opposed to its surrounding environment.  As tropical storms move northward, they can become extratropical. 

Now on to the hybrid or the mix of both the extratropical and tropical which is the sub-tropical.  Easy enough right?  Well, it is not an exact science and there is a little subjectivity to the matter so not everyone will agree on what is what in this matter.  Bottom line, they form away from the tropics and exert both types of characteristics of the aforementioned.  Depending on which type is dominant, depends on whether or not the storm gets a name.  Our friend off the Carolina coast still shows more signs of an extratropical cyclone so it still has no name.  Another note is that subtropical storms can have hurricane force winds within them but they will not be considered a hurricane unless it attains complete tropical characteristics which can take up to 3 days so rapid intensification is usually not expected as is the case for our latest system. 

Hope that helps clear the waters.  If you have any questions, fire away, that's what this blog is for. 

Rob Hatchell | Chief Meteorologist | rhatchell@wmbfnews.com

Comments

[Sandy Keller]

We moved to North Myrtle Beach from the metro Washington, D.C. area about five years ago. Prior to that we had a second home and vacationed here for years.

I first want to say I love your station because it is the only one that is "real time" for this area.

Today I went into your Blog and was delighted to see you have blogged on subjects that I have also blogged about. I even put a menu bottom on my web site called, "Myrtle Beach Secret" where I wrote about this area actually having four seasons even though it is semi-tropical. Unless people have visited the Grand Strand every month of the year they do not know the secret.