First Visible Satellite Shot of Ivan's Eye this morning

[logybogy]

[Innotech]

it looks annular

[Dean4Storms]

Looks just like a Russian's eye after a Hangover!!

[Rob Beaux]

I keep seeing references to annular eyes. anyone want to explain what it is and how they effect the streght of the hurricane. And do you have an example of a hurricane that did this with pictures.

[Hyperstorm]

Pictures are better than words...Aren't they?



And no, it's not yet becoming one...

[tonyc]

Isabel

[Steve Cosby]

I keep seeing references to annular eyes. anyone want to explain what it is and how they effect the streght of the hurricane. And do you have an example of a hurricane that did this with pictures.

Also called "donut hurricanes", here's the approximate definition:

Intensity tendencies of annular hurricanes indicate that these storms maintain their intensities longer than the average hurricane, resulting in larger-than-average intensity forecast errors and thus a significant intensity forecasting challenge. In addition, these storms are found to exist in a specific set of environmental conditions, which are only found 3% and 0.8% of the time in the east Pacific and Atlantic tropical cyclone basins during 1989–99, respectively.

This is from a study at http://www.ssec.wisc.edu/~kossin/articles/annularhurr.pdf

Not only are eyewall replacement cycles tough to forecast, these bad boys are even harder.

[bahamaswx]

That's not a definition...just a characteristic.

[Steve Cosby]

That's not a definition...just a characteristic.

Sorry, too early in the morning.

these storms are distinctly more axisymmetric with circular eyes surrounded by a nearly uniform ring of deep convection and a curious lack of deep convective features outside this ring. Because of this symmetry, these storms have also been referred to as truck tires and doughnuts.

Same source.

[clueless newbie]

I keep seeing references to annular eyes. anyone want to explain what it is and how they effect the streght of the hurricane. And do you have an example of a hurricane that did this with pictures.

Annular hurricanes do not have spiral bands, just a disproportionately large eye and a solid donut of CDO.

The eye seems to maintain itself via several mesovortices, so there is usually no eye contraction and there are no eyewall replacement cycles, just a huge steady eye (see Isabel last year). Once the eye starts to contract, the hurricane is usually no more annular.

Annular hurricanes can support high wind speeds even with relatively warm tops of CDO, so their strength is (was?) often underestimated.

In the paper referenced in another post there are several pictures of annular hurricanes. Last year, Isabel and Kate were annular at some periods of their life, although the annular hurricanes are supposed to be rare. Nowadays, some people are screaming 'annular hurricane' whenever they see a big eye...

[Steve Cosby]

Nowadays, some people are screaming 'annular hurricane' whenever they see a big eye...

Yes - Ivan is not annular at this point.