ATL: ISAIAS - Post-Tropical - Discussion

[MetroMike]

I'm getting bad vibes from this one, which is always the case when there is this much model support this far in advance. Not to mention it looks like it will take a classic Cape Verde hurricane track.

Yes you should, with trends like this Bermuda always seems to get hit as small as it is.

[Evil Jeremy]

That 30% jump in the 48 hour range is throwing me off.

The wording of the TWO didn't change substantially between 2pm and 8pm. Just a rearrangement of the same general terms. And it doesn't appear there were any significant meteorological developments today with 92L itself, or significant changes in the short term modeling.

Absent other rationale, I think the NHC thinks this could spin up sneaky quick.

[johngaltfla]

https://i.imgur.com/EtHrORH.jpg

Luis, we have to watch this one

I'm hoping for a recurve for all my friends in the islands. This stupid virus has delayed our travel down there now and I pray for all of you that it and all other storms are minor or fish this year. We really need some peace and quiet for everyone from San Juan to St. Lucia. Godspeed to all of you.

[aspen]

That 30% jump in the 48 hour range is throwing me off.

The wording of the TWO didn't change substantially between 2pm and 8pm. Just a rearrangement of the same general terms. And it doesn't appear there were any significant meteorological developments today with 92L itself, or significant changes in the short term modeling.

Absent other rationale, I think the NHC thinks this could spin up sneaky quick.

I think they bumped it up to 50% in 48 hours due to some of the models, especially the GFS, showing a weak TC developing in as little as two days. Most models have been gradually getting more aggressive with 92L.

[gatorcane]

As expected the SAL is doing a pretty good number on it. The low-level stretched vorticity is not under the deep convection, in fact the low-level vorticity is void of convection, you can see a good area of broad cyclonic turning tilted SW to NE around the vicinity of 12N, 32W.

Let’s not forget the ECMWF keeps this pretty weak the entire run really and especially the next 4-5 days. There will be SAL this wave will need to contend with in its journey west. But conditions do appear very favorable if it makes it into the SW Atlantic north of the islands and favorable enough on its approach to the islands where we can see some steady organization.

[gatorcane]

Dry air image as the SAL and dry stable air keeps a check on 92l for the time being. If we are lucky it will squash this completely or degrade the structure of the wave to only allow some weak development. Sometimes the models do get it wrong on these waves and yes even the if there is consensus on development.

[cycloneye]

00z Best Track: Low latitude.

AL, 92, 2020072600, , BEST, 0, 107N, 320W, 20, 1010, DB

[AutoPenalti]

Dry air image as the SAL and dry stable air keeps a check on 92l for the time being. If we are lucky it will squash this completely or degrade the structure of the wave to only allow some weak development. Sometimes the models do get it wrong on these waves and yes even the if there is consensus on development.

https://i.postimg.cc/PxQ974Py/g16split.jpg

That would be a huge bust from models if it does that especially in 2020.

[TheStormExpert]

Dry air image as the SAL and dry stable air keeps a check on 92l for the time being. If we are lucky it will squash this completely or degrade the structure of the wave to only allow some weak development. Sometimes the models do get it wrong on these waves and yes even the if there is consensus on development.

https://i.postimg.cc/PxQ974Py/g16split.jpg

That would be a huge bust from models if it does that especially in 2020.

Well it’s not like the models haven’t busted numerous times in the East Pacific within the last few months.

[TheStormExpert]

 https://twitter.com/andyhazelton/status/1287185013725974531

[aspen]

Dry air image as the SAL and dry stable air keeps a check on 92l for the time being. If we are lucky it will squash this completely or degrade the structure of the wave to only allow some weak development. Sometimes the models do get it wrong on these waves and yes even the if there is consensus on development.

https://i.postimg.cc/PxQ974Py/g16split.jpg

That would be a huge bust from models if it does that especially in 2020.

Well it’s not like the models haven’t busted numerous times in the East Pacific within the last few months.

I find it very hard to believe that the models would bust with 92L, since all of the globals agree on development and the Atlantic has been pumping out systems even without much model support.

[TheStormExpert]

That would be a huge bust from models if it does that especially in 2020.

Well it’s not like the models haven’t busted numerous times in the East Pacific within the last few months.

I find it very hard to believe that the models would bust with 92L, since all of the globals agree on development and the Atlantic has been pumping out systems even without much model support.

Oh I’m not saying it will bust, I’m just stating that the models have severely busted several times in the East Pacific within the last few months.

I definitely think development of 92L is 99.9% bound to happen.

[chaser1]

Best track has it near 10.7N. At last visible satellite it appeared that a new center was trying to form around 9.5N. Development will most likely occur where conditions are most ripe. 92L and Gonzalo both tapped into a very strong & moist southerly flow to their east. No SAL intrusion from the equator. The SAL intrusion to it's north will inhibit the already large circulation from wrapping up rapidly however it's pulsating convection should adequately allow pressure falls to start occurring in the next day or two. By the way, NHC's 50/80 makes total sense when you listen to the TWO..... "and a tropical depression could develop early next week". Well, tomorrow is Sunday and is the beginning of the new week. "Early" has to mean Monday or Tuesday, right? Anything less then 50% would be a direct contradiction to their own wording.

[Hurricane Mike]

Best track has it near 10.7N. At last visible satellite it appeared that a new center was trying to form around 9.5N. Development will most likely occur where conditions are most ripe. 92L and Gonzalo both tapped into a very strong & moist southerly flow to their east. No SAL intrusion from the equator. The SAL intrusion to it's north will inhibit the already large circulation from wrapping up rapidly however it's pulsating convection should adequately allow pressure falls to start occurring in the next day or two. By the way, NHC's 50/80 makes total sense when you listen to the TWO..... "and a tropical depression could develop early next week". Well, tomorrow is Sunday and is the beginning of the new week. "Early" has to mean Monday or Tuesday, right? Anything less then 50% would be a direct contradiction to their own wording.

That's the way I interpreted it, too. It is now Sunday, therefore it is not "early next week".

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Jul 26 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane
Hanna, located inland over south Texas.

A broad area of low pressure associated with a tropical wave located
about 1000 miles west-southwest of the Cabo Verde Islands is
producing a large area of cloudiness and disorganized showers and
thunderstorms. Environmental conditions appear conducive for
development, and a tropical depression is likely to form early this
week while the wave moves westward at around 15 mph across the
tropical Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...90 percent.

$$
Forecaster Latto

[CrazyC83]

One thing is for sure...we'll likely be dealing with this system for quite some time. The dreaded "I" storm...even if it is late July/early August.

[Chris90]

It has rotation, but it's really broad, and the heaviest convection seems decently far removed currently. I still think this is going to be a decent hurricane in the future, but I'm leaning more towards the 90% for 5 days with regards to initial classification. I think it's going to take more than 48 hours for this to put together a classifiable LLC.

[Shell Mound]

At this point, I am rather suspicious of the southward, weaker shift in the 00Z ECMWF-/EPS-based guidance. Both the ECMWF and its ensembles have, for the most part, been too conservative with the pace of development in the Atlantic this season, while overestimating the tempo of genesis and intensification in the C/EPAC. Like the G(E)FS, the EC/EPS performed poorly with both Gonzalo and Hanna, to not mention Douglas. In terms of intensity, the UKMET and its ensembles seem to have a better handle on 92L than either the G(E)FS or the EC/EPS. Therefore, I would expect a stronger system in the short term.

Furthermore, the past six runs of the EPS mean have been trending toward a stronger +NAO by day five, along with a slower, less progressive NWHEM pattern. If this continues, it would likely portend stronger ridging over or near the Southeastern U.S., along with a northward shift in the trough over the Northeastern CONUS, and instead favour “ridge bridging” over a cutoff low retrograding near the southern Plains. This kind of pattern, if current trends were to be sustained, would favour a track over or near the Leeward Islands/PR and then a significant threat to the southern Bahamas and South/Central Florida.

Therefore, at this point time, significant land interaction with Hispaniola is far from a given. 92L may track closer to PR instead of the DR.

I would not be surprised to see westward shifts beyond day five over the next several days, especially as 92L gradually organises and develops a LLC.

Ironically, just like Irma (2017), 92L/prospective “Isaias” will be interacting with a retreating TUTT during the next three to five days.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sun Jul 26 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical
Storm Hanna, located inland near the border of Texas and Mexico.

1. A broad area of low pressure associated with a tropical wave is
located about 1000 miles west-southwest of the Cabo Verde Islands.
This system is producing a wide area of disorganized showers and
thunderstorms as it moves westward around 20 mph across the
tropical Atlantic. Environmental conditions are forecast to be
conducive for development and a tropical depressions is likely to
form within the next few days as the system nears the Lesser
Antilles. Interests in the Lesser Antilles should monitor the
progress of this system.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...90 percent.

Forecaster Zelinsky

[SFLcane]

At this point, I am rather suspicious of the southward, weaker shift in the 00Z ECMWF-/EPS-based guidance. Both the ECMWF and its ensembles have, for the most part, been too conservative with the pace of development in the Atlantic this season, while overestimating the tempo of genesis and intensification in the C/EPAC. Like the G(E)FS, the EC/EPS performed poorly with both Gonzalo and Hanna, to not mention Douglas. In terms of intensity, the UKMET and its ensembles seem to have a better handle on 92L than either the G(E)FS or the EC/EPS. Therefore, I would expect a stronger system in the short term.

Furthermore, the past six runs of the EPS mean have been trending toward a stronger +NAO by day five, along with a slower, less progressive NWHEM pattern. If this continues, it would likely portend stronger ridging over or near the Southeastern U.S., along with a northward shift in the trough over the Northeastern CONUS, and instead favour “ridge bridging” over a cutoff low retrograding near the southern Plains. This kind of pattern, if current trends were to be sustained, would favour a track over or near the Leeward Islands/PR and then a significant threat to the southern Bahamas and South/Central Florida.

Therefore, at this point time, significant land interaction with Hispaniola is far from a given. 92L may track closer to PR instead of the DR.

I would not be surprised to see westward shifts beyond day five over the next several days, especially as 92L gradually organises and develops a LLC.

Ironically, just like Irma (2017), 92L/prospective “Isaias” will be interacting with a retreating TUTT during the next three to five days.

Though I tend to agree with this..it isn't reflected in the tracks we're seeing though yet. The nao is not what's going on here It's the cut-off trough over the eastern US.