Archive for the ‘Occluded front’ Tag


Two independent left clicks should enlarge this image.
Two independent left clicks should enlarge this image.

The storm that is at the North Carolina-South Carolina border may look like a hurricane but it is not. The National Weather Service is calling it a non-tropical cyclone. A more common term for such cyclones is “extratropical cyclone.” “Extra” means “outside of.” This refers to their developing outside of the tropics. Hurricanes are tropical cyclones. Even though in the northern hemisphere they both rotate counterclockwise around a central region of low pressure, tropical cyclones have warm cores and are often referred to as “warm core lows.” Relatively cold air occupies part of most extratropical cyclones and this is most certainly the case with this one. The doublet image of the system that I have prepared which you see (above) shows a visible satellite view of the storm earlier today and compares it with a surface analysis.  The two do not represent exactly the same time but it’s close; 44 minutes separate them. So, it’s a near match.

For those of you who know your frontal symbols, notice that there are three different types of fronts, all three representing boundaries between relatively warm air and relatively cool air. An occluded front arcs out from the center of the storm and there is a warm front whose axis runs ENE-WSW, and a stationary front curving down to the south.

In spite of the fact that it is extratropical and therefore un-named, it has many of the characteristics of a tropical storm.  People located in the storm’s vicinity should be alert to the potential hazards. Also, there is a strong chance that it will interact with tropical storm Kyle in the interesting Fujiwhara effect.  If you are interested in that phenomenon, see the following link and also view the post that followed it (at the next higher post location on the page).  To do that you will need to scroll to the top of the page and click on the “blog” tab.  That will access you to all entries.

Tropical Wave AL 93 Might Dance Within a Few Days!