Transition from Tropical to extratropical storm?

[stormyskies]

Hoi,

Just wondering what is involved in transitioning from tropical cyclone to extratropical (a regular atlantic low).

From what I understad, a tropical cylcone is established as a warm-core low with a core of high pressure at the centre and high up. Where as a cold core is a regular low here that has its lowest central pressure at its core.

So how does it transform itself?

The reason I ask is because I hear of ex hurricane this and ex tropical storm, with that remnants are able to make it here in Europe. They drop huge amounts of rain and pack quite a punch.

I can't seem to understand it. An explanation would be greatly appreciated! Thanks!

 

[maritimesbob]

I'm no expert on this, but here goes.

A tropical storm or hurricane has a warm core. As you know, tropical storms need a source of warm SST`s among other ingredients. Take away those warm SST`s and the tropical storm loses it`s main source of fuel. Eventually it transitions to to extra tropical.

Satellite imagery will normally show a large dry slot wrapping in, as opposed to the closed circulation in a tropical storm.

Also, the storm loses it`s compact circular shape becoming stretched out, sometimes developing the classic comma shape. The moisture/rain bearing clouds tend to move away from the center (usually to the northwest). Gradually a warm and cold front(s) will develop. Also with extra tropical storms, the highest winds tend to be at the upper levels while with a tropical storm the strongest will be at the surface and around the eyewall. That`s not to say extra-tropical storm are still not dangerous.

Once they get out over the north Atlantic, the pressure can sometimes bomb out bringing intense gales to northwestern Europe and your neck of the woods!

 

[oldseadog]

Not much more to add to that. They often tend to become a much larger entity, sometimes stretching out hundreds of miles and more.