ATL: LEE - Post-Tropical - Discussion

[SouthFLTropics]

A monster in the making...

Last visible satellite images for the day...

[kevin]

The new forecast is adjusted higher than the last advisory,
near the model consensus, but there's a notable contingent of
guidance higher than this forecast. There is increasing confidence
on Lee becoming a very powerful hurricane by this weekend.

You know it's a big one when they say this after posting a 125 kt forecast.

[eastcoastFL]

This thing looks great already. It has potential to be a monster, I really hope that ridge is as forecasted when it gets near the islands next week.

[CrazyC83]

The new forecast is adjusted higher than the last advisory,
near the model consensus, but there's a notable contingent of
guidance higher than this forecast. There is increasing confidence
on Lee becoming a very powerful hurricane by this weekend.

You know it's a bit one when they say this after posting a 125 kt forecast.

I think we're going to see within a day or so an explicit forecast of a category 5 peak intensity.

[USTropics]

He says, long way to go.

https://twitter.com/webberweather/status/1699135527776313535

Does that suggest a more gradual intensification, rather than a rapid one?

He's referring to long-term upper-level steering parameters, and possible risks to the eastern coasts of the United States/Canadian maritime. We can see here at the end of the ECWMF operational run, there is a rather significant ridge that is preventing the storm from completing a recurve:


This is due to downstream amplification, and it makes a full recurve uncertain at this point (but still the most likely outcome). The 12z ECMWF ensemble members had roughly 10 (~20%) with rather erratic movement or a NW motion for an extended period of time:


As far as intensity, the environment (particularly beginning in 48 hours) is nearly ideal, something we haven't seen since Dorian/Laura. There are 3 significant upper-level outlets and a sprawling anticyclone beginning to build overhead. A prolonged period of rapid intensification should be expected thereafter as it continues to move westward:

[underthwx]

He says, long way to go.

https://twitter.com/webberweather/status/1699135527776313535

Does that suggest a more gradual intensification, rather than a rapid one?

He's referring to long-term upper-level steering parameters, and possible risks to the eastern coasts of the United States/Canadian maritime. We can see here at the end of the ECWMF operational run, there is a rather significant ridge that is preventing the storm from completing a recurve:
https://i.imgur.com/CJvycH6.png

This is due to downstream amplification, and it makes a full recurve uncertain at this point (but still the most likely outcome). The 12z ECMWF ensemble members had roughly 10 (~20%) with rather erratic movement or a NW motion for an extended period of time:
https://i.imgur.com/WnEjqtU.png

As far as intensity, the environment (particularly beginning in 48 hours) is nearly ideal, something we haven't seen since Dorian/Laura. There are 3 significant upper-level outlets and a sprawling anticyclone beginning to build overhead. A prolonged period of rapid intensification should be expected thereafter as it continues to move westward:
https://i.imgur.com/z02IVLW.png

Thankyou for your excellent reply!....

[SouthDadeFish]

For a tropical cyclone to reach category-5 intensity in the Atlantic, you need a very rare combination of ingredients: Very warm waters (and over a deep enough layer), low shear, a sufficiently moist air mass, as well as a vortex structure that is not overly broad. And you need all of these conditions.

Having said that, I would be surprised if this storm does not eventually attain category-5 intensity at some point in its life time. I'm really hoping the models are right that the core of the storm misses the Antilles, because this will be one very powerful TC.

[underthwx]

A monster in the making...

Last visible satellite images for the day...

https://i.imgur.com/OLuov2w.gif

Could Lee become a Hurricane by morning?...

[CryHavoc]

A monster in the making...

Last visible satellite images for the day...

https://i.imgur.com/OLuov2w.gif

Could Lee become a Hurricane by morning?...

Absolutely no disrespect to how amazing our hurricane models and the Meteorologists who interpret the data are, but if there's one thing that seems to be lagging it's how quickly we expect these storms to intensify. Not sure if that's due to the naturally conservative bias that most offices who forecast for tropical cyclones exhibit (looking at you, Japan) or if our models find it difficulty to keep up with how rapidly OHC is increasing due to global warming, but I could absolutely see this taking off before the weekend. Lots of time and warm water between now and Friday.

[aspen]

He says, long way to go.

https://twitter.com/webberweather/status/1699135527776313535

Does that suggest a more gradual intensification, rather than a rapid one?

He's referring to long-term upper-level steering parameters, and possible risks to the eastern coasts of the United States/Canadian maritime. We can see here at the end of the ECWMF operational run, there is a rather significant ridge that is preventing the storm from completing a recurve:
https://i.imgur.com/CJvycH6.png

This is due to downstream amplification, and it makes a full recurve uncertain at this point (but still the most likely outcome). The 12z ECMWF ensemble members had roughly 10 (~20%) with rather erratic movement or a NW motion for an extended period of time:
https://i.imgur.com/WnEjqtU.png

As far as intensity, the environment (particularly beginning in 48 hours) is nearly ideal, something we haven't seen since Dorian/Laura. There are 3 significant upper-level outlets and a sprawling anticyclone beginning to build overhead. A prolonged period of rapid intensification should be expected thereafter as it continues to move westward:
https://i.imgur.com/z02IVLW.png

50+ ACE here we come. I think there’s a decent chance we get a sub-915mb storm out of this.

[zal0phus]

If Lee reaches some record-breaking intensity but steers clear of land, could it still be retired? It would seem a little inappropriate for a potentially sub-910 storm's name to be reused in later years regardless of what it does

[Hypercane_Kyle]

Already organizing rapidly.

[USTropics]

A monster in the making...

Last visible satellite images for the day...

https://i.imgur.com/OLuov2w.gif

Could Lee become a Hurricane by morning?...

It's not out of the realm of possibility, it's hard to model or forecast the inner mechanisms of a still developing system. Currently there are defined banding features seen in the last visible imagery of the day, which precludes the beginning formations of the inner core of a still immature cyclone:


We'll need to see the development of a CDO and if there is a pulse down period. Typically these systems have a pulse up, where convection begins to deepen, the vorticity becomes reinforced, and there is an expansion of the wind field. However it can be a give and take, and if the surrounding background environment isn't sufficiently moist, there could be a pause on development for a brief period of time while the background environment "catches up". On the 12z GFS, there is some lurking dry air that could be entrained during this pulse up phase, and it could cause a temporary disruption of formation in the overnight hours. The system could also develop an inner core quicker and defend against these dry slot intrusions, it's a watch and see event:

[CryHavoc]

If Lee reaches some record-breaking intensity but steers clear of land, could it still be retired? It would seem a little inappropriate for a potentially sub-910 storm's name to be reused in later years regardless of what it does

Possibly, but if there are no catastrophic impacts it will likely be reused. Hurricane Lorenzo hit cat 5 status in 2019 and was not retired.

Given the number of island chains in the Atlantic, it wouldn't take much to have disastrous impacts if Lee were to theoretically go to 175mph+. Even a brush against an island at that strength would bring devastating storm surges to any land nearby, which is why a lot of Cat 5 storms that don't make direct impacts are still retired.

[WalterWhite]

If Lee reaches some record-breaking intensity but steers clear of land, could it still be retired? It would seem a little inappropriate for a potentially sub-910 storm's name to be reused in later years regardless of what it does

Tip was not retired despite being the most intense (by minimum central pressure) tropical cyclone on record. Lee would have to cause major damage in order to be retired.

[zzzh]

Clear eye structure on microwave.

[CryHavoc]

[BobHarlem]

Clear eye structure on microwave.

[eastcoastFL]

[eastcoastFL]

Clear eye structure on microwave.

https://i.imgur.com/HNu3M4L.gif

I’m not seeing it.