Major Hurricane Helene

[stormtracker]

1 hour ago, WxWatcher007 said:

Thanks for reminding people, and not that anything I say matters, but for folks reading—this could be a high impact event, and we have not just posters but probably a lot of lurkers that will be reading this.

Not that anyone should be making decisions based on what’s said here lol (always follow official sources, etc) but for people posting I just ask that we set aside any wish casting, down playing, or non-contextualized posts (for example, posting an image of a hurricane model without analysis) as this comes together. Obviously stuff happens but let’s try to stay on track. 

There’s an opportunity to learn a lot here the next few days about tropical genesis, the development of inner core structures, and how TCs interact with troughing/deep layer shear, and that discussion gets lost in poor posts. 

tl;dr I sound like a prude lol but let’s be responsible and thoughtful in our posts as people will likely be seriously impacted by this one.

Well said.  I'm telling the mods to start clamping down in here pretty soon.   Good luck everybody.

[Windspeed]

Hurricane John's presence near the coast of Mexico and on the western periphery of the CAG has most likely contributed to pending TCG of 97L occurring further east away from Nicaragua/Honduras and tracking through the Yucatán channel. The models picked up on this yesterday, resolving further east solutions. PTC09 might even clip western Cuba now, though it should be noted that there will still be a day or two of NW to NNW motion as 500 mb heights pivot east of Florida. Had John not existed, the cutoff over the Yucatán would most likely have retrograded west faster without upper mass being evacuated off of John; as such, steering would have been more dictated by the surface-to-mid level flow around the gyre to keep 97L's broad vorticity over land longer and more in line with the initial weaker solutions late last week and over the weekend. As always, it's why we have to consider modeling can change quite abruptly even within a few days due to downstream changes/evolutions in steering influences and features.

[BoulderWX]

Good write up from Cantore

[hawkeye_wx]

The three recon passes found extrap pressure of 1008, 1006, and 1005 mb, so it's slowly dropping as the circulation develops.

[MANDA]

3 minutes ago, Windspeed said:

Hurricane John's presence near the coast of Mexico and on the western periphery of the CAG has most likely contributed to TCG of 97L occurring further east away from Nicaragua/Honduras and tracking through the Yucatán channel. The models picked up on this yesterday, resolving further east solutions. PTC09 might even clip western Cuba now, though it should be noted that there will see be a day or two of NW to NNW motion as 500 mb heights pivot east of Florida. Had John not existed, the cutoff over the Yucatán would most likely have retrograded west faster without upper mass being evacuated off of John; as such, steering being more dictated by the surface-to-mid level flow around the gyre to keeping 97L's broad vorticity over land longer and more in line with the initial weaker solutions late last week and over the weekend. As always, it's why we always have to consider modeling can change quite abruptly even within a few days due to downstream changes/evolutions in steering influences and features.

That ULL also helped to classically ventilate "John" allowing it to strengthen.  Likely a major at landfall over the next 6 hours or so.

The same ULL is currently generating shear over at least the western semicircle of TC9.  It is going to have to get out of the way before PTC9 can start to crank.

[StantonParkHoya]

18z GFS weaker and sw of 12z

[purduewx80]

Should have a good view from the Cayman Islands radar the next day or so, and then Cuba's after that.

https://www.weather.gov.ky/radar

[Wannabehippie]

33 minutes ago, Windspeed said:

Hurricane John's presence near the coast of Mexico and on the western periphery of the CAG has most likely contributed to pending TCG of 97L occurring further east away from Nicaragua/Honduras and tracking through the Yucatán channel. The models picked up on this yesterday, resolving further east solutions. PTC09 might even clip western Cuba now, though it should be noted that there will still be a day or two of NW to NNW motion as 500 mb heights pivot east of Florida. Had John not existed, the cutoff over the Yucatán would most likely have retrograded west faster without upper mass being evacuated off of John; as such, steering would have been more dictated by the surface-to-mid level flow around the gyre to keep 97L's broad vorticity over land longer and more in line with the initial weaker solutions late last week and over the weekend. As always, it's why we have to consider modeling can change quite abruptly even within a few days due to downstream changes/evolutions in steering influences and features.

I was just about to ask about the effects of Hurricane John, especially since it is predicted to become a cat 3 hurricane before landfall.

[Radtechwxman]

I'm not trusting any model intensity until we have a developed LLC and this system starts organizing. Models are struggling with intensity because the system hasn't got established yet so they're essentially grasping at straws that don't exist. 

[SnowGoose69]

Just now, Radtechwxman said:

I'm not trusting any model intensity until we have a developed LLC and this system starts organizing. Models are struggling with intensity because the system has got established yet so they're essentially grasping at straws that don't exist. 

The track on the hurricane models too IMO is not likely after landfall.  I think the NNE or NE movement after landfall is more likely, especially if this is a 3 or 4.  A hurricane that strong more often can be somewhat deflected by a feature such as the low over the WRN gulf states vs absorbed in.    

[Radtechwxman]

2 minutes ago, SnowGoose69 said:

The track on the hurricane models too IMO is not likely after landfall.  I think the NNE or NE movement after landfall is more likely, especially if this is a 3 or 4.  A hurricane that strong more often can be somewhat deflected by a feature such as the low over the WRN gulf states vs absorbed in.    

Yeah I'm really curious if we will see that cutoff and Helene Fujiwara with each other or if Helene will just deflect ne with little to no interaction. 

[TPAwx]

HAFS-B at 39 is slightly NW of 12z and 37mb weaker.  Lunchtime run was clearly out to lunch.

[Hotair]

Putting aside exact track and strength considerations, it is alarming that many forecast models are suggesting 10+ feet of storm surge possible just North of Tampa 

Coastal risk live link

[SnowGoose69]

A cool 100mb difference from the 12Z HAFS-B lol

[hawkeye_wx]

All of the hurricane models are much weaker at 18z because it takes a lot longer to organize.  The HAFS-B is 90 mb weaker at 12z Thursday (888 mb to 978).

The southerly shear in the nw Caribbean isn't going to help it organize.

[TPAwx]

HMON and HAFS-A also markedly weaker.

[SnowGoose69]

All of them seem closer to the Yucatan too.  A further NW track is not good overall as it might enable it to both stay over the Gulf longer and also hit the area of warmer waters 

[Amped]

10 minutes ago, TPAwx said:

HAFS-B at 39 is slightly NW of 12z and 37mb weaker.  Lunchtime run was clearly out to lunch.

 A lot of uncertainty here, the ceiling is high here, but so is the potential for organizational issue.

Also I'm not buying the tracks that go inland over the Yucatan yet.

[Random Chaos]

Until a well defined center of circulation forms (generally when it becomes a Tropical Storm) we won’t get accurate models. The variation in the HAFS-B from 12z to 18z is exactly what to expect until then.

[Radtechwxman]

50 minutes ago, hawkeye_wx said:

All of the hurricane models are much weaker at 18z because it takes a lot longer to organize.  The HAFS-B is 90 mb weaker at 12z Thursday (888 mb to 978).

The southerly shear in the nw Caribbean isn't going to help it organize.

888mb was just unrealistic. All the hurricane models were way overdone imo. Probably a more realistic portrayal. But like I said before, can't really trust any intensity guidance right now. Need our system to really develop first. 

[Boston Bulldog]

Giving any serious consideration to Hurricane models before a center of circulation has formed is totally foolish. HAFS at 12z had this thing already vertically stacked by this time

[Radtechwxman]

Real good spin within that area of convection south of Cuba. Curious if that's only a mid level circulation or if we ate getting a low level circulation developing within that area as well. 

[WxWatcher007]

12 minutes ago, Radtechwxman said:

Real good spin within that area of convection south of Cuba. Curious if that's only a mid level circulation or if we ate getting a low level circulation developing within that area as well. 

It may be trying to get to the surface but I think it’s going to be hard to get a read without recon, and it may take a while given the southwesterly shear. 

Cayman Islands radar could be helpful tonight as the process takes its first shot at it. 

https://www.weather.gov.ky/radar

[NavarreDon]

https://x.com/tropicaltidbits/status/1838341891659829451?s=46&t=0ZvB_AF2VfA6c0SDxf53yA


.

[qg_omega]

This thread is out of control with buns

[MattPetrulli]

https://x.com/MarkMeyerWx/status/1838381014676091068

[shaggy]

25 minutes ago, Radtechwxman said:

Real good spin within that area of convection south of Cuba. Curious if that's only a mid level circulation or if we ate getting a low level circulation developing within that area as well. 

Sure seems that's the best area of vorticity. It's young and still susceptible to center reformation. If this forms further east towards the cayman Islands we could see some model changes

[StantonParkHoya]

0z hurricane models really tight from Apalachicola to Atlanta

[Radtechwxman]

11 minutes ago, shaggy said:

Sure seems that's the best area of vorticity. It's young and still susceptible to center reformation. If this forms further east towards the cayman Islands we could see some model changes

My thoughts as well. Obviously a lot can change with motion as the mid/low level centers organize and try to align but right now this would be more east and is moving pretty nnw

[CheeselandSkies]

9 minutes ago, StantonParkHoya said:

0z hurricane models really tight from Apalachicola to Atlanta

Eh? Those aren't even out yet on Tidbits.