ATL: IRMA - Post-Tropical - Discussion

[FLpanhandle91]

Looking slightly better on IR on the most recent GOES16 frames.

[Blizzard96x]

NHC keeps it a Cat 5 160mph storm but has raised it to 930mb for the 2am advisory

[znel52]

NHC keeps it a Cat 5 160mph storm but has raised it to 930mb for the 2am advisory

Wow. Figured they would have dropped the winds a little.

[sbcc]

I'm wondering just how much damage Cuba could do to Irma before it gets away from it. If you guys remember Ike from 2008 it never fully recovered after passing through Cuba on its way to Texas. It's possible Irma doesn't fully recover either.

I believe what was particularly damaging to Ike is that it traveled almost the entire length of Cuba, right down the middle, for about two days--Irma will very likely remain away from the mountainous area.

I remember Ike's traverse of Cuba as well. In case anyone forgot, this is what the "weakened" Ike did to the barrier islands in Texas. This was estimated at 12 feet of surge and Cat 2.

[Aric Dunn]

if it keeps on this heading it will slowly gain distance from the coast as cuba begins to bend west shortly sooooo if the core can hold to gether it will have nothig to stop it..

[PTPatrick]

New Euro runs it all the way to the tip of Cuba(or the part where it starts to curve down) just about at 24 hrs...a whole day basically half on land

Edit: maybe I misrepresent it...it doesn't go to the tip... Think it's in the cone. But it exits the coast further west than it did previously. So gfs shifts east, Euro west

[Sciencerocks]

NHC keeps it a Cat 5 160mph storm but has raised it to 930mb for the 2am advisory

Still cat5


050730 2219N 07750W 6972 02646 9486 +134 +134 170097 102 139 060 03
050800 2219N 07752W 6965 02621 9444 +138 +138 170085 094 135 024 00

[znel52]

New Euro runs it all the way to the tip of Cuba(or the part where it starts to curve down) just about at 24 hrs...a whole day basically half on land

That would put it on the western edge of the current cone wouldn't it?

EDIT-Nevermind just saw the run. Pretty much on track.

[craptacular]

Looks like AF308 is climbing and on the way home ... just as AF 307 and NOAA9 are taking off. Good night, and stay safe down there!

Edited to say AF307 instead of 309 ... 307 and NOAA9 are going to Irma. AF309 is coming home from Jose. Skies are full of hurricane hunters!

[PTPatrick]

New Euro runs it all the way to the tip of Cuba(or the part where it starts to curve down) just about at 24 hrs...a whole day basically half on land

That would put it on the western edge of the current cone wouldn't it?

No still in the cone. I clarified. It moved the exit from Cuba further up the coast tho for sure

[znel52]

New Euro runs it all the way to the tip of Cuba(or the part where it starts to curve down) just about at 24 hrs...a whole day basically half on land

That would put it on the western edge of the current cone wouldn't it?

No still in the cone. I clarified. It moved the exit from Cuba further up the coast tho for sure

Yeah I just saw the run appears to be on track pretty much.

[PTPatrick]

So between 24 and 48 hrs new Euro jumps across key west toward sanibel island. God, 48 more hours til landfall. Of note, it deepens it over the straight as well and maintains a strong storm. 927 at landfall. This would certainly not be good for the sw coast.

[ronyan]

Most probably know this but the recon data lat/long are given as deg and minutes not decimal degrees for the last two digits. So minutes/60 gives decimal degrees. I made that mistake earlier.

[Petrichor]

It appears Irma is bouncing off the coast.

[url]https://i.imgur.com/5DZ5qol.gif[url]

nice shot thanks now what nw turn trying to come in play

Someone else mentioned it earlier, but the "bounce" looks to me to be a great example of a trochoidal wobble. It isn't necessarily so much a change in the long-term track as it is a sign of some instability in the structure of the cyclone. Now, we can easily see that the instability is caused by interaction with land, so it is and it isn't a 'bounce' off the coastline, sort of, LOL! The exact moment of reversal of the direction of wobble might not be causeed by the coastline of the landform, but the overall wobble is a result of instability induced by the landform!

You can see a couple of good trochoidal wobbles in the animated gif of Typhoon Usagi(2013) at this discover magazine article:

http://blogs.discovermagazine.com/imageo/2013/09/23/typhoon-action-in-the-pacific/#more-5036

Also, a brief three-liner at wikipedia:

https://en.wikipedia.org/wiki/Tropical_cyclone_track_forecasting

"Trochoidal motions"

"Small wobbles in a tropical cyclone's track can occur when the convection is distributed unevenly within its circulation. This can be due to changes in vertical wind shear or inner core structure. Because of this effect, forecasters use a longer term (6 to 24 hours) motion to help forecast tropical cyclones, which acts to smooth out such wobbles."

And if you really want to geek out this paper has some excellent diagrams and plenty of math:

https://www.semanticscholar.org/paper/The-Wavenumber-One-Instability-and-Trochoidal-Moti-NOLAN-MONTGOMERY/5b2dc77132ed9fef0c6b8f2ba731f915553b4c20

"The Wavenumber-One Instability and Trochoidal Motion of Hurricane-like Vortices"

"The instability is associated with a displacement of the vortex center (as defined by either minimum pressure or streamfunction) that rotates around the vortex core, and thus offers a physical mechanism for the persistent, small-amplitude trochoidal wobble often observed in hurricane tracks."

And, finally, I'm not a real expert, and the interaction with Cuba may indeed have more complex effects on the track than a mere wobble, but I'll leave that for the experts at the NHC. So far, their track forecasts have been very good!

[Aric Dunn]

Euro may be a little to progressive on the 275 to 280 motion at that speed... but we will see soon.. it also has it over land for a pretty long time.. that is the big player right now..

[znel52]

https://uploads.disquscdn.com/images/be ... b83f96.png

Horrible run for Tampa latest Euro

[ALhurricane]

Given satellite trends, Euro is going to be a little too far west I think.

[Aric Dunn]

Given satellite trends, Euro is going to be a little too far west I think.

agreed. its too fast first of all.

[sponger]

Has Tampa's luck finally run out?

[Aric Dunn]

the core is barely starting to show up on long range miami and key west radar. if convection was deeper we would probably be able to see it better.