No longer Annular

[Stormchaser16]

See? It was undergoing a transformation. This explains the ragged appearance of Isabel just a few hours ago. As i mentioned it was probably a precursor to a future event with the storm. And so it was. The event is that Isabel is losing its annular characteristics. Outflow bands are very evident on IR imagery now, and it no longer has a donut shape ring appearance. The environment does not support an annular storm anymore. The only last thing we have yet to see, is the eye of the storm shrink up.

[Stormchaser16]

Thoughts? Comments?

[Raebie]

I'm just not seein' it SC. Sorry. Enlighten me...

[Stormsfury]

Some transition is going on. Noticing some stronger SW'ly winds to the NW of Isabel now. The donut shape is less pronounced but the storm may not weaken just yet.

SF

[Derek Ortt]

This isnt weakening much, if at all.

Latest sat imagery indicates a slight decrease in cloud top temps.

What has happened is that the UL is briefly producing some westerly shear, which is affecting the western edge of the outflow.

However, the overall size of the storm is large. Also, rmember that hurricanes seldom, if ever, maintain this intensity for this length of time. Some weakening is climotologically expected, though not below cat 4 until this approaches the coast.

In short, dont expect this to re-enact Gloria and just be a garden variety cat 1 cane at the time of landfall

[Stormchaser16]

Alright no problem at all. Ive been talking this over with a few different people. An annular hurricane is a donut shaped storm.
http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

Take a look at that loop. In the beginning you see a donut shaped convective storm(not the appearances of the oranges in a circular fashion). Advance to the end of the loop now and examine the appearance of the hurricane. Note the two blue bands, one to the north and one to the south. Also very characteristic is the Convective cluster feeding the northern band. The oranges are no longer in a circular fashion. When these bands become visible on Ir imagery, it is said that the system is no longer an annular hurricane.

[Derek Ortt]

I dont care if it is annular or not. The bottom line is this has not yet shown signs of significant weakening.

Also, models are in good agreement about getting rid of this shear in about 12 hours, creating a favorable environment for about 24-36 hours, before the environment becomes slightly less favorable

[Air Force Met]

DId the same thing last 2 nights Derek. Eyewall cycles invovled as well...

[Stormchaser16]

Nope the storm is not weakening much if it all like Derek has stated. What is occcuring though is that the system cannot maintain an annular formation in the face of a shifting environment. The stronger SW winds off to the west could be the cause of the system losing its annular characteristics. If conditions approve, it may once again take that form however i do not expect that to occur. The transition on the loop that i have provided is a very beautiful and inspiring one as you see the strong bands emerge from the convective cluster!

[Stormchaser16]

Derek I am not saying that the system is weakening, I am just saying that it is losing its annular characteristics in the face of a changing environment.

[JetMaxx]

I agree with Derek....at landfall, I expect Isabel's effects to be similar in scope to the severe 1938 (115 kt/ 946 mb) and 1944 (115 kt/ 947 mb) East Coast hurricanes ...and possibly as intense as 1954's Hazel (120 kt/ 938 mb) and Hugo in 1989 (120 kt/ 934 mb)..