ATL: IGOR - Ex Hurricane - Discussion

[Battlebrick]

I know folks laughed earlier, but SHIPS agrees that Igor has become marginally annular:

## ANNULAR HURRICANE INDEX (AHI) AL112010 IGOR 09/13/10 00 UTC ##
## PASSED SCREENING STEP, MIGHT BE ANNULAR, CALCULATE AHI FROM DISCRIMINANT ANALYSIS ##
## AHI= 1 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
## ANNULAR INDEX RAN NORMALLY

All i can say is..

what.

Was not expecting that.

[Windtalker1]

maybe this will help on what annular means ETC.

http://www.mmm.ucar.edu/wrf/users/works ... ns/9-1.pdf

[sponger]

I must admit it is looking more annular with every pass. Almost no spiral bands and a doughnt core.

Although a reading of 1 isn't so great. I give him a 15 at least. (Based on no scientific reasoning what so ever!

[brunota2003]

The contracting of the eye indicates an EWRC but I was contradicting that fact with the one that he has a nice ring of red around the center. I know it has yet to begin an EWRC but I'm pretty sure he's not that far off from reaching his peak or at least the strengthening phase.

The contracting of the eye just means that he is still strengthening. It allows the wind field to tighten up and drops the pressures as well.

[sponger]

The contracting of the eye indicates an EWRC but I was contradicting that fact with the one that he has a nice ring of red around the center. I know it has yet to begin an EWRC but I'm pretty sure he's not that far off from reaching his peak or at least the strengthening phase.

The contracting of the eye just means that he is still strengthening. It allows the wind field to tighten up and drops the pressures as well.

What we wouldn't give for some recon! It would be nice if we could on chip in for a flight! My paypal account is ready!

[Dean4Storms]

Igor appears to be losing a little latitude!

[Macrocane]

If I'm not wrong, Igos would be the first annular hurricane in the basin since Frances, right?

[hurricaneCW]

Although the little sw wobble doesn't necessarily mean anything, the fact that it's not gaining any latitude yet and the wobbles could be indicative of a slightly stronger subtropical ridge. How that would play out in the long term is very uncertain. I doubt it will even matter but who knows.

[sponger]

Solid south wobble the last 2 hours! Is that the high pressing down or the stronger storm feeling a different steering level? Or neither?

[Ivanhater]

[sponger]

Wow! Nice look Ivan!

[Florida1118]

The eye looks better now. I give him a 9.9/10 for looks.

[Cyclenall]

If I'm not wrong, Igos would be the first annular hurricane in the basin since Frances, right?

That's incorrect, Hurricane Epsilon of 2005 was likely a CAT1 annular hurricane. I also believe there could have been annular characteristics in Hurricane Gordon of 2006 at one point but a meteorologist on here didn't agree.

[wxmann_91]

I must admit it is looking more annular with every pass. Almost no spiral bands and a doughnt core.

Although a reading of 1 isn't so great. I give him a 15 at least. (Based on no scientific reasoning what so ever!

It's not annular... there have been plenty of small convective blowups on the periphery of the CDO (not characteristics of stable annular storms) and microwave images show numerous rainbands surrounding the eyewall.

The eye does appear to be contracting on satellite, but there is a nice ring of red around the eye. An EWRC will probably begin overnight and end sometime later tomorrow.

Since there's absolutely no evidence I can see of a second eyewall forming I take that your statement is just a guess.

I can't judge whether he was guessing or not, but there is actually evidence for the start of an ERC tonight. First, microwave images show that outer rainbands are consolidating, which is a necessary precursor to an ERC. Second, in past intense hurricanes, I have observed ERC's to begin ~24 hours after the beginning of a RIC, often in the diurnal maximum subsequent to the one when the initial RIC occurred. Third, the eye is contracting and the cloud tops are cooling, which often signals the peak prior to the onset of an ERC.

Inductively I will argue that an ERC is likely to begin tonight, perhaps within the next 12 hr. Not guaranteed, of course - after all, Igor was a little closer to annular earlier today, so it might be a little more stable internally than most storms.

[wxman57]

Doesn't appear annular to me. Still a good deal of banding north and south.

[wxmann_91]

Solid south wobble the last 2 hours! Is that the high pressing down or the stronger storm feeling a different steering level? Or neither?

Neither. Trochoidal wobble - more likely due to inner-core dynamics than synoptic forces.

I'll admit though, people in the northern Lesser Antilles who are watching the satellite must be sweating right now...

[SouthFLTropics]

All I can say is WOW...What a BEAST!!!

SFT

[Cyclenall]

I'll admit though, people in the northern Lesser Antilles who are watching the satellite must be sweating right now...

I think people in Bermuda are sweating bullets currently, I would be.

[cycloneye]

I'll admit though, people in the northern Lesser Antilles who are watching the satellite must be sweating right now...

You bet that is right by me and the friends in the NE Caribbean.

[Ptarmigan]

Igor has to be the most impressive hurricane of the season so far.