ATL: DORIAN - Post-Tropical - Discussion

[gatorcane]

Latest IR rainbow image from floater showing an impressive looking invest with some deep convection blowing up right around the LLC (circular red blob near center of image):

[Gustywind]

Ozonepete, what are your best thoughts concerning the possible path?
Do you think that the EC have to worry about 98L at long term on not, or this thing should not pose any threat for the islands?

Thanks. for your daily input

[Utah]

New to board, and while I love following and trying to decipher the information - I am really interested and would love to understand more. I live in south Florida - moved here right after Wilma. Anyone interested in trying to help me understand the maps, terminology and whether to be concerned.
Sorry to break in on the discussion, just asking.
Kim

[SouthDadeFish]

Meriland, if we use the SHIPS model as guidance for the environment surrounding Invest 98L, there a few features that may deter development at different times in the future. Wind shear is expected to be light to moderate over the next 60 hours then increase above 20 knots beyond 72 hours. This may prevent intensification in the medium to long term, but it is low enough to allow genesis. Next, if we take a look at Sea Surface Temps (SST's) the SHIPS is showing SSTs becoming quite marginal (<26C) in 36-72 hours from now. This may hinder the development of deep convection, but if a circulation develops by then, I doubt it is enough alone to kill off the storm. Finally, if we take a look at moisture (using mid-level humidity as a guide) we can see the environment steadily becomes more dry as 98L moves WNW. From 72-120 hours 700-500mb RH's are <60%, which is somewhat dry... (To put that in perspective the current 700-500mb RH was analyzed to be 73%).

To sum things up, the current environment is favorable enough for genesis in my opinion. However, in about 2-3 days the environment will become less favorable and I think it is possible that if a tropical cyclone does develop, it may weaken and possibly dissipate. That being said, it may never even develop, or not dissipate in 3-5 days if it does develop. At this time it does appear that whatever does develop may stay north of the islands, but it is far too early to be sure of that. Some of the GFS ensemble members did bring a storm through the northern islands. Residents in this area should definitely keep an eye on 98L, but don't worry too much about it at this time. We have a few days to watch it.

[NDG]

I know how reliable GFS/EURO is with the general track and intensity of disturbances, but how reliable are they at forecasting dry air/ shear/ etc this far out?

IMO, they handle moisture content better in the atmosphere but shear is not handled very well. I lately like to stay in the 48-72 hr range when it comes to shear.

So what is working against this storm in the long run? And are these pretty definite circumstances ?

I think both dry air and shear. Like I have been saying the last couple of days the more northerly track it takes over the next 24-96 hrs the harder conditions it will encounter but if it stays on a more southerly latitude the better conditions it will have, IMO.

[baytownwx]

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=europe&sat=wm7&prod=vor&zoom=&time=

Vorticity wise, it looks to be slighty more south.

[gatorcane]

Here is the experimental global FIM model 18Z run track for 98L:

[stormhunter7]

think will know more in about 3 days.. it appears that an ULL will try to push/pull 98L more pole ward in the coming days. Its going to be west of 98L, ahead of it as it crosses the Atlantic. Will see, but I do think this 98L is now a TD, IMO.

[ozonepete]

I know how reliable GFS/EURO is with the general track and intensity of disturbances, but how reliable are they at forecasting dry air/ shear/ etc this far out?

IMO, they handle moisture content better in the atmosphere but shear is not handled very well. I lately like to stay in the 48-72 hr range when it comes to shear.

models are notoriously HORRIBLE for predicting dry air in the tropics. Have not looked in recent years, but before, RH values tended to have a high bias

I know what you mean, but I've been watching pretty closely in recent years and they have definitely improved. Probably a key reason is that we have better microwave satellite detection of moisture now so the models get better input. I would still say they are not great, but definitely much better than they used to be. Now shear forecasts are still often horrible, lol.

[RL3AO]

HWRF peaks as a 50kt storm tomorrow and then loses in in a few days.

[gatorcane]

New to board, and while I love following and trying to decipher the information - I am really interested and would love to understand more. I live in south Florida - moved here right after Wilma. Anyone interested in trying to help me understand the maps, terminology and whether to be concerned.
Sorry to break in on the discussion, just asking.
Kim

Hi Kim, you are in the right place for learning all about the tropics and staying up-to-date on the current activity out there.

We have amateur weather enthusiasts and professional meteorologists (the usernames in blue) that do a great job explaining the maps and terminology.

If you have a question about something, feel free to ask and you will get an answer. Welcome!

[ozonepete]

Ozonepete, what are your best thoughts concerning the possible path?
Do you think that the EC have to worry about 98L at long term on not, or this thing should not pose any threat for the islands?

Thanks. for your daily input

Hi Gusty. I would say the EC definitely is in the possible path around day 5 or 6, though it's way too early to tell. The Bermuda-Azores high has been quite strong this season and it's really digging in right now so there's nothing to take this north even after it nears you. You are on the southern end of the current model track consensus but I would suspect that the consensus track will waver north and south over the next couple of days so that you might at times be right in the middle of the forecast path. I would watch this one really closely, just because it seems to be developing so early, but I am also doubtful this will be really strong even if it does hit you. Just too early to tell. But I'd be watching this really carefully and hold off on plans for this weekend for a while if I lived there, especially in the more northern islands.

[Aric Dunn]

:uarrow: Even on the track you posted it would spend a day at most over marginal SSTs (darker green). The lighter green area, if that panned out, is more than enough for a TS to maintain. It just doesn't seem to be a significant factor.

Very true, I have seen tropical systems survive 25 deg C waters but as we know a bigger obstacle could be the more stable air further away from the itcz.

Yeah, mainly the dreaded dust. Right now you can see the SAL dust cluster is west and north of it but moving ahead of it at the same forward speed as this disturbance. If this system maintains its current speed or slows down at all it may never ingest much of it, similar to what happened with Chantal. Mid-level moisture is good right now (pretty obvious with all of that convection) but that can change as well. I would really want to wait for tonight's 00Z runs but especially tomorrow morning's runs to see what the models do with it (and its future environment) after they initialize it better.

yeah right now everything is miving in tandom and unlikely to ingest the dry air to the west until maybe a sw shear picks up. though even then its in a classic pouch and should be fine on the dry air.. the ssts are plenty warm as most of those maps are ambigious . also do to rotational affects.its likely to take a wsw motion for the next 24 to 36 while it tries to develop. by which time it will have pasted any very slightly cooler ssts

[Gustywind]

Ozonepete, what are your best thoughts concerning the possible path?
Do you think that the EC have to worry about 98L at long term on not, or this thing should not pose any threat for the islands?

Thanks. for your daily input

Hi Gusty. I would say the EC definitely is in the possible path around day 5 or 6, though it's way too early to tell. The Bermuda-Azores high has been quite strong this season and it's really digging in right now so there's nothing to take this north even after it nears you. You are on the southern end of the current model track consensus but I would suspect that the consensus track will waver north and south over the next couple of days so that you might at times be right in the middle of the forecast path. I would watch this one really closely, just because it seems to be developing so early, but I am also doubtful this will be really strong even if it does hit you. Just too early to tell. But I'd be watching this really carefully and hold off on plans for this weekend for a while if I lived there, especially in the more northern islands.

Interresting analysis as usual . I will keep an eye on 98L as the others carib islanders. Let's continue to follow the situation. Thanks for your precious updates, we appreciate us in th islands.

[hurricaneCW]

These waves sure are potent so early in the season, a few weeks early actually. Makes you wonder what will happen in 2-3 weeks when we really see an uptick in Cape Verde waves/storms.

I wouldn't be surprised if Dorian developed from this, but given conditions are marginal, it probably would end up Chantal-esque moving forward.

[Incoming!]

Ozonepete, what are your best thoughts concerning the possible path?
Do you think that the EC have to worry about 98L at long term on not, or this thing should not pose any threat for the islands?

Thanks. for your daily input

Hi Gusty. I would say the EC definitely is in the possible path around day 5 or 6, though it's way too early to tell. The Bermuda-Azores high has been quite strong this season and it's really digging in right now so there's nothing to take this north even after it nears you. You are on the southern end of the current model track consensus but I would suspect that the consensus track will waver north and south over the next couple of days so that you might at times be right in the middle of the forecast path. I would watch this one really closely, just because it seems to be developing so early, but I am also doubtful this will be really strong even if it does hit you. Just too early to tell. But I'd be watching this really carefully and hold off on plans for this weekend for a while if I lived there, especially in the more northern islands.

That we are! The GFS painted a bullseye on me on Saturday. That got my attention

[ROCK]

18Z NAVGEM...loses it after a few days...

https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical

[ozonepete]

Hi Gusty. I would say the EC definitely is in the possible path around day 5 or 6, though it's way too early to tell. The Bermuda-Azores high has been quite strong this season and it's really digging in right now so there's nothing to take this north even after it nears you. You are on the southern end of the current model track consensus but I would suspect that the consensus track will waver north and south over the next couple of days so that you might at times be right in the middle of the forecast path. I would watch this one really closely, just because it seems to be developing so early, but I am also doubtful this will be really strong even if it does hit you. Just too early to tell. But I'd be watching this really carefully and hold off on plans for this weekend for a while if I lived there, especially in the more northern islands.

That we are! The GFS painted a bullseye on me on Saturday. That got my attention

It should. Plenty of time to watch it at least. Best of luck to all of you down there. And you are always welcome Gusty.

[Hurricaneman]

The 0zGFS is farther south after 4 days so it might have a chance to avoid the cooler water and develop and may end up in the caribbean

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

[meriland23]

The 0zGFS is farther south after 4 days so it might have a chance to avoid the cooler water and develop and may end up in the caribbean

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

Strange that the GFS predicted a stronger TS but northerly track at 18z and now it is more south (near warmer waters) but a lot weaker than 18z.