ATL: IRMA - Post-Tropical - Discussion

[Kazmit]

Irma's quite an unpredictable storm. Constantly flunctuating in intensity with so many EWRCs, and now moving west.

[knotimpaired]

Over the past 4-6 hours, it looks like there has been a temporary break from the earlier WSW motion, and Irma has been on a more W course. I'm intrigued to see how long this W motion lasts before a turn back to the WSW again. This could have big impacts on how close Irma gets to the Leeward islands/Puerto Rico.

I am on Vieques and while we are pretty much done with our prep (we have too many hurricanes under our belt not to) many, many people are not prepping which concerns me. They look at the SFWMD spag models ans see no threat.

What is your gut feeling for PR, Vieques and the Virgin Islands?

[cycloneye]

@anumetservice
Good news! For the last few hrs #Irma has been moving west instead of west-southwest, based on satellite images.

 https://twitter.com/anumetservice/status/904385669811851268

[Aric Dunn]

Looking at the sat loops from various scales and the steering and current ridging. the "wobble" is likely finishing up as the cloud pattern prior to the wobble west indicated that motion the present shift in the overall cloud pattern seems to indicate ths is about to start tumbling back WSW to sw again. Being that the ridge is still building in this type of motion is expected.

[AxaltaRacing24]

Looking at the sat loops from various scales and the steering and current ridging. the "wobble" is likely finishing up as the cloud pattern prior to the wobble north indicated that motion the present shift in the overall cloud pattern seems to indicate ths is about to start tumbling back WSW to sw again. Being that the ridge is still building in this type of motion is expected.

I'm worried that this only delays the SW motion and it'll continue for longer than expected.

[gatorcane]

Looks to be turning back WSW:

http://rammb.cira.colostate.edu/ramsdis ... display=12

[psyclone]

It's such a tightly knotted vortex that a 25 mile wobble could mean the difference between a moderate to high end TS vs close to major hurricane conditions for the islands. Some of those places will have no choice but to prep for a high impact event even if that is the less likely scenario...since by the time you'll know for sure whether or not a given location gets the high end event the weather will already be bad. Hopefully a less close shave will eliminate this concern and allow a little more breathing room..the current west wobble is a start.

[Gustywind]

Looking at the sat loops from various scales and the steering and current ridging. the "wobble" is likely finishing up as the cloud pattern prior to the wobble west indicated that motion the present shift in the overall cloud pattern seems to indicate ths is about to start tumbling back WSW to sw again. Being that the ridge is still building in this type of motion is expected.

ohoh... so you think that the ridge should really begin to force Irma to be in track on the wsw motion and could continue more longer than what the NHC have expected?

[AutoPenalti]

Looks to be turning back WSW:

http://rammb.cira.colostate.edu/ramsdis ... display=12

Yup, looks like it.

[AxaltaRacing24]

Looks to be turning back WSW:

http://rammb.cira.colostate.edu/ramsdis ... display=12

Yep. This storm will stair step SW over time but will wobble a bit around the ridge. It's not going to be flawless motion but it'll generally go WSW.

[ConvergenceZone]

While this temporary direction switch doesn't effect USA mainland impacts in the longterm, at least maybe it will increase the odds of it clearing the islands

[Gustywind]

Looking at the sat loops from various scales and the steering and current ridging. the "wobble" is likely finishing up as the cloud pattern prior to the wobble west indicated that motion the present shift in the overall cloud pattern seems to indicate ths is about to start tumbling back WSW to sw again. Being that the ridge is still building in this type of motion is expected.

Aric this wsw motion should stall till monday or tuesday or not? That should be a nightmare for most of the Leewards if Tuesday Irma continues this wsw motion... before the presumed west then wnw movement and plus an intensification as a Cat 4 (NHC forecast for Tuesday ).
Hope no!
Please Aric keeps un informed with your best thoughts because of the next 24h could be problematic for numerous Leewards islands and especially the Northern Leewards, Anguilla , Barbuda and PR the BVI...

[Aric Dunn]

again one thing to note... the system in the BOC is becoming better organized this morning and is something not directly related to IRMA. But the models that on the west side of the guidence and some earlier run the EURO that had it in the gulf had a stronger BOC system. possible reason is the synopic setup as the trough approaches is more condusive over the BOC like with less troughing and more ridging thus reducung shear over the BOC. so keep and eye on how that systems plays out.

[Gustywind]

Aric is that a very strong ridge that could really steer Irma on a more wsw course than predicted? Thanks!

[SouthDadeFish]

Over the past 4-6 hours, it looks like there has been a temporary break from the earlier WSW motion, and Irma has been on a more W course. I'm intrigued to see how long this W motion lasts before a turn back to the WSW again. This could have big impacts on how close Irma gets to the Leeward islands/Puerto Rico.

I am on Vieques and while we are pretty much done with our prep (we have too many hurricanes under our belt not to) many, many people are not prepping which concerns me. They look at the SFWMD spag models ans see no threat.

What is your gut feeling for PR, Vieques and the Virgin Islands?

It's still very possible for these areas to receive direct impacts from Irma. They are within the NHC's cone of uncertainty and some ensemble members bring Irma very close. I believe there is still too much uncertainty at this time to give you precise prediction unfortunately. Remain vigilant.

[Jimsot]

Would that bring it closer to Anguilla as well?

yes farther south means farther west.

each forecast is bringing it closer to Anguilla and St Maarten!

Yes it has. "How Close Can It get":

Saturday 11:00AM NHC Forecast Co-ordinates: 138.0 miles
Saturday 5:00PM NHC Forecast Co-ordinates: 97.1 miles
Saturday 11:00PM NHC Forecast Co-ordinates: 69.1 miles
Sunday 5:00AM NHC Forecast Co-ordinates: 38.6 miles
Sunday 11:00AM NHC Forecast C-ordinates: 33.5 miles Now a wobble might put the core right over you.

[Aric Dunn]

IRMA"s motion is like a rolling tire going down a hill hitting small objects and bouncing up and over them but over all its still going down..

[tiger_deF]

I can't understand why all these models immediately strengthen Irma there minute they start running. Itma is choking on dry air, and is entirely surrounded. The CDO is tiny because dry air is stripping the banding, and I doubt that this is even a category 3 at all. I haven't seen a single post in the past 2 pages about Irma, just meaningless cone speculation and model speculation.

[Siker]

I can't understand why all these models immediately strengthen Irma there minute they start running. Itma is choking on dry air, and is entirely surrounded. The CDO is tiny because dry air is stripping the banding, and I doubt that this is even a category 3 at all. I haven't seen a single post in the past 2 pages about Irma, just meaningless cone speculation and model speculation.

This again? The past two pages are full of posts concerning Irma's present movement because that is of great importance to those in the islands. That's about Irma currently, what are you looking for?

[Aric Dunn]

I can't understand why all these models immediately strengthen Irma there minute they start running. Itma is choking on dry air, and is entirely surrounded. The CDO is tiny because dry air is stripping the banding, and I doubt that this is even a category 3 at all. I haven't seen a single post in the past 2 pages about Irma, just meaningless cone speculation and model speculation.

unfortunately, we have no data from microwave to see if it is another ERC or not. the dry air is there but there is still a lot of convective bands out ahead of it so its all too bad. it could be stunting its intensification but we wont know till this afternoon when recon gets there.