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Cyclone Yasi


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I'm making a new thread about this, as this is potentially an historic cyclone. The situation:

A very large cyclone is organizing in the South Pacific and it's on a beeline for the populated Queensland coast of Australia.

The striking thing is the almost-alarming agreement between the JTWC, the BoM, and the models, Re: the landfall point and intensity.

  • The JTWC brings it to the coast S of Cairns a few hours before 00Z 03 Feb. The 00Z 02 Feb fix (the final before landfall) shows 115 kt (1-min)-- a Cat 4 on our scale. The trend suggests it will continue to strengthen up to landfall.
  • The BoM has it coming ashore at 18Z 02 Feb in almost the exact same place-- around the town of Ingham-- with winds of 105 kt (10-min), which converts to ~120 kt (1-min). (This point is not shown on the forecast map below-- only in the Technical Bulletin.)

So the JTWC and BoM are in agreement: a Cat 4 (USA) coming ashore halfway between Cairns and Townsville. Wow.

By the way, a Cyclone Watch is already up for a large section of the Queensland coast.

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Calling the coast around Cairns "populated" might be accurate in a Australia-normative sense, but by US standards, this might as well be the Everglades or the S. Texas coast north of Brownsville.

Since the context of the discussion is Australia's cyclone country, it is therefore accurate. As mentioned previously on this forum, Australia's cyclone country-- spanning the entire N coast of the continent over three territories-- is mostly completely empty. Queensland S of Port Douglas is consistently dotted with towns, and two decent-size cities-- Cairns (pop. 164K) and Townsville (pop. 181K)-- are directly threatened. This region is actually way more populated than S TX (between Brownsville and Corpus) and SW FL (below Naples), where there really is almost nothing. (I've chased in both those areas.)

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Atmospheric conditions are superb for continued strengthening, but SSTs are just ok, with a cold eddy close to the projected track, but greater OHC and SSTs closer to the coast. I still think a LF close to 110kt (1-min) between Innisfail and Townsville, with the greater winds/damage in the latter.

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Atmospheric conditions are superb for continued strengthening, but SSTs are just ok, with a cold eddy close to the projected track, but greater OHC and SSTs closer to the coast. I still think a LF close to 110kt (1-min) between Innisfail and Townsville, with the greater winds/damage in the latter.

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Yeah, those SSTs are kind of blah. The JTWC shows slight weakening-- from 125 kt to 120 kt-- just before landfall, although perhaps that's due to the anticipated disruption of the inflow as the cyclone nears this rather mountainous part of Queensland. (Remember how Karl really got disrupted by such terrain as it neared Veracruz?)

Re: the winds, I agree, and I expect the windfield is going to be highly asymmetric, given that the cyclone will really be trucking when it comes ashore. Areas to the left (S) of the center are going to get really raked. I was talking with alby_14 on Skype today, and we noted that this was the first time either of us could remember seeing the BoM's windfield forecasts showing such a pronounced asymmetry. Usually they're these perfect circles.

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I have a friend who has recently moved to Townsville for studying abroad... so this storm has certainly peaked my interest for him!

Anyway, structurally I'm not very impressed, with a poorly defined eyewall (if you can even call it that) on microwave. We are certainly seeing some dry air being advected into the core of the circulation. Both AMSRE and CIMSS TPC MMIC show a pretty substantial area of dry air along the western flank of the circulation, and until that dry air is mixed out, we will see little if any development. I'm rather surprised given the current presentation that the cyclone is already classified as a Cat 2 (SS scale), with both the BoM and JWTC forecasting development into a Cat 3 (SS scale) cyclone within 12 hours. I think a more conservative approach should be taken intensity wise until the dry air mixes out (which will likely take at least 12 -24 hours). Still though, this is a rather large cyclone, so storm surge could be major, similar to how Ike 2004 was for the Texas coastline, despite not being more intense than a Cat 2.

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I'm surprised at all the hatin' on Yasi's structure. Reminder: it's not a major hurricane yet; the structure is still dynamic and evolving. I think it looks quite healthy.

it has risen by .3 T numbers in 24 hours...meh

and you know how pumped i was yesterday about it. this one is definitely having a hard time organizing its eyewall, and phil did a pretty good job of telling us why. also, i think it's easy to get mislead by the nice IR and WV presentations. if push came to shove i'd mark it 80kts.

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I'm surprised at all the hatin' on Yasi's structure. Reminder: it's not a major hurricane yet; the structure is still dynamic and evolving. I think it looks quite healthy.

Yea looks can certainly be deceiving, especially in regards to IR. It has a nice presentation, but microwave really tells the story. I still think this has a shot to get to major hurricane status, its just likely going to be delayed until closer to landfall. However, if that dry air on the western flank doesn't modify in time, it could end up being its achilles heel.

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Yea looks can certainly be deceiving, especially in regards to IR. It has a nice presentation, but microwave really tells the story. I still think this has a shot to get to major hurricane status, its just likely going to be delayed until closer to landfall. However, if that dry air on the western flank doesn't modify in time, it could end up being its achilles heel.

Yes, after years or tracking and chasing hurricanes, I think I understand the value of MW imagery for evaluating structure :D-- and to me, the MW doesn't look half bad for a developing Cat 2. It's really subjective, isn't it? I mean, I can think it looks nice and you can think it doesn't-- it's cool for us to have different reactions to it.

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Well, the BoM ain't agreein' with you guys. The brand-new forecast package has upped it to 85 kt (10-min), and remarks:

Centre embedded within White to give DT 5.0. MET 5.0 with PAT 5.0. FT based on DT. Improved organisation with rapid development during last 6 to 12 hours. Expect system to continue intensifying within favourable environment of low shear and good upper outflow.

The new forecast track brings the center ashore just a hair S of Cairns in under 48 hrs with winds of 105 kt (10-min)-- a very intense storm.

So y'all can just hush up. B)

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Well, the BoM ain't agreein' with you guys. The brand-new forecast package has upped it to 85 kt (10-min), and remarks:

Centre embedded within White to give DT 5.0. MET 5.0 with PAT 5.0. FT based on DT. Improved organisation with rapid development during last 6 to 12 hours. Expect system to continue intensifying within favourable environment of low shear and good upper outflow.

The new forecast track brings the center ashore just a hair S of Cairns in under 48 hrs with winds of 105 kt (10-min)-- a very intense storm.

So y'all can just hush up. B)

I agree that there's a lot of potential... ridge has been progged stronger each run, hence the farther north track...this also means warmer SSTs and a little less dry air. 110kt (1-min) now looks a bit conservative, IMO.

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I agree that there's a lot of potential... ridge has been progged stronger each run, hence the farther north track...this also means warmer SSTs and a little less dry air. 110kt (1-min) now looks a bit conservative, IMO.

Ah, OK-- makes sense. It's like when one of our Caribbean Cruisers stays W rather than bending poleward. Always a good sign if you want a big landfall.

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That's as pretty of a curved band as I've seen. T5.0 for a curved band is rare, but cool, imo.

And not sure what y'all are seeing about mixing dry air out. It doesn't really have to mix anything, just have the convection pinch off the last quadrant of the developing eyewall. It's not typical eyewall organization in the Atlantic, but this is pretty normal for a large, monsoon system.

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Ah, OK-- makes sense. It's like when one of our Caribbean Cruisers stays W rather than bending poleward. Always a good sign if you want a big landfall.

Yep, some continental dry air is possible close to LF, but trough related dry air (which most of the time is the problem because it goes hand by hand with shear) won't be a problem. With all the convection going on that little moat of dry air will get dealt with pretty quickly.

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That's as pretty of a curved band as I've seen. T5.0 for a curved band is rare, but cool, imo.

And not sure what y'all are seeing about mixing dry air out. It doesn't really have to mix anything, just have the convection pinch off the last quadrant of the developing eyewall. It's not typical eyewall organization in the Atlantic, but this is pretty normal for a large, monsoon system.

Thanks for this! I was beginning to think I was going crazy because I thought it looked healthy. :lol:

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Since the context of the discussion is Australia's cyclone country, it is therefore accurate. As mentioned previously on this forum, Australia's cyclone country-- spanning the entire N coast of the continent over three territories-- is mostly completely empty. Queensland S of Port Douglas is consistently dotted with towns, and two decent-size cities-- Cairns (pop. 164K) and Townsville (pop. 181K)-- are directly threatened. This region is actually way more populated than S TX (between Brownsville and Corpus) and SW FL (below Naples), where there really is almost nothing. (I've chased in both those areas.)

Hi Josh

Woke up this morning and wow things have changed a bit......well as warned I could be in for a direct hit but I'll wait and see if she changes again.....I may wake up tomorrow morning and she could be going to Cooktown. Even if she does I think I'll still feel the effects......

You guys had me confused as in Australia most locals call Townsville "Brownsville" - because it's usually a fairly dry area.....

hhhmmm lets see what happens next.

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