ATL: LAURA - Models

[lsuhurricane]

The CMC is like Molly Hatchet and is flirting with disaster on the Northern coasts of the Greater Antilles. One thing to note on the CMC though is how stout the ridge is.

Interesting little ridge centered in GA on that run. Likely landfall in LA/TX with that type of pressure to it’s north.

[USTropics]

The GFS is having a difficult time processing how this coalesces at the low-levels, and to be fair it's difficult to predict. There are currently 3 areas of low-level vort maximums in analysis (each one circled below), all embedded in the monsoonal trough/ITCZ (wind flow roughly highlighted in red).



For some clues on what is going to occur in the near-term future (~24 hours), we can take a look at higher levels in the atmosphere. Going up one level to near the mid-levels, you can see the western low-level vort maximum has no real discernible mid-level vorticity signature:


Given the "flattened" look in the first image (low-levels), we can distinguish this area is likely to dissipate tonight/be absorbed by 98L. That leaves the middle vort maximum (98L) and the eastern flank. We can start to see this far eastern vorticity maximum at the mid-levels is a bit more pronounced. What is likely to occur tonight and over the next day (this is a bit of a slow process), is this eastern vort maximum (purple) will begin to rotate towards the WNW and then W. 98L (red) will get pivoted around a new center point of rotation, and get pulled a bit back towards the E and then N.


You can see this evolution take place in the high-res ECMWF output (sorry for the crappy angle, this is the only free option able to post here):


This is all going to take a bit of time to process, which is why model runs currently should be taken with a grain of salt. Pay attention to what the ensembles do for now, there's likely to be some shifting in the coming days until an eventual center takes place.

[SouthFLTropics]

CMC 210 hours...Houston, you have a problem.


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[WeatherEmperor]

Here is the 0z UKMET. Can anyone plot all the points?


NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 84 HOURS
FORECAST POSITION AT T+ 84 : 19.0N 57.4W

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 21.08.2020 19.0N 57.4W WEAK
00UTC 22.08.2020 20.1N 60.3W WEAK LITTLE CHANGE
12UTC 22.08.2020 20.7N 63.5W WEAK LITTLE CHANGE
00UTC 23.08.2020 21.5N 66.6W WEAK LITTLE CHANGE
12UTC 23.08.2020 22.4N 70.1W WEAK LITTLE CHANGE
00UTC 24.08.2020 23.5N 73.5W MODERATE INTENSIFYING SLIGHTLY


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[blp]

Excellent analysis. Euro has the right idea here. Thanks

The GFS is having a difficult time processing how this coalesces at the low-levels, and to be fair it's difficult to predict. There are currently 3 areas of low-level vort maximums in analysis (each one circled below), all embedded in the monsoonal trough/ITCZ (wind flow roughly highlighted in red).

https://i.imgur.com/UxYV3RM.png

For some clues on what is going to occur in the near-term future (~24 hours), we can take a look at higher levels in the atmosphere. Going up one level to near the mid-levels, you can see the western low-level vort maximum has no real discernible mid-level vorticity signature:
https://i.imgur.com/9oQd2Cs.gif

Given the "flattened" look in the first image (low-levels), we can distinguish this area is likely to dissipate tonight/be absorbed by 98L. That leaves the middle vort maximum (98L) and the eastern flank. We can start to see this far eastern vorticity maximum at the mid-levels is a bit more pronounced. What is likely to occur tonight and over the next day (this is a bit of a slow process), is this eastern vort maximum (purple) will begin to rotate towards the WNW and then W. 98L (red) will get pivoted around a new center point of rotation, and get pulled a bit back towards the E and then N.
https://i.imgur.com/faOqt84.png

You can see this evolution take place in the high-res ECMWF output (sorry for the crappy angle, this is the only free option able to post here):
https://i.ibb.co/Lvkf0Lq/Webp-net-gifmaker-5.gif

This is all going to take a bit of time to process, which is why model runs currently should be taken with a grain of salt. Pay attention to what the ensembles do for now, there's likely to be some shifting in the coming days until an eventual center takes place.

[Steve]

CMC 210 hours...Houston, you have a problem.


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Cat 2ish there and wound up. Heads up the Piney Woods toward the eastern side of the Metroplex
https://www.tropicaltidbits.com/analysi ... 800&fh=210

[ConvergenceZone]

CMC 210 hours...Houston, you have a problem.

Yea huge shift west with CMC...A bit weaker though in the gulf though compared to the previous run. (980ish vrs 970ish)

[Shell Mound]

CMC 210 hours...Houston, you have a problem.

Yea huge shift west with CMC...A bit weaker though in the gulf though compared to the previous run. (980ish vrs 970ish)

CMC basically says Ike 2.0, with a track across Cuba and into the Gulf.

[lsuhurricane]

Last point on the UKMET is East of Bahamas. Would imagine a recurve on that spot

[SouthFLTropics]

00z GEFS-PARA Ensembles are showing an uptick in activity with 98L in the Northern Islands East of PR.


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[blp]

Use the GEFS at this point. GFS won't be useful until it consolidates.

[ConvergenceZone]

Last point on the UKMET is East of Bahamas. Would imagine a recurve on that spot

UKMET is almost always wrong, I usually just throw it out...

[Ubuntwo]

Last point on the UKMET is East of Bahamas. Would imagine a recurve on that spot

UKMET is almost always wrong, I usually just throw it out...

Huh? The UKM has the second highest track verification among global models. This run in particular is similar to the euro.

[CrazyC83]

CMC 210 hours...Houston, you have a problem.

Yea huge shift west with CMC...A bit weaker though in the gulf though compared to the previous run. (980ish vrs 970ish)

It has a low resolution though so it would be much stronger. Basically a carbon copy of Ike a couple weeks earlier in the season.

[lsuhurricane]

Use the GEFS at this point. GFS won't be useful until it consolidates.

Adding to this point, none of the stronger 0z GFS ensembles recurve before landfall. Either a spine attack up the peninsula or into the GOM. Perhaps validation of CMC ridge depiction?

[ConvergenceZone]

Last point on the UKMET is East of Bahamas. Would imagine a recurve on that spot

UKMET is almost always wrong, I usually just throw it out...

Huh? The UKM has the second highest track verification among global models. This run in particular is similar to the euro.

Regardless, both of them will probably shift left tomorrow. They are underestimating the strong ridge....

[AxaltaRacing24]

Use the GEFS at this point. GFS won't be useful until it consolidates.

Adding to this point, none of the stronger 0z GFS ensembles recurve before landfall. Either a spine attack up the peninsula or into the GOM. Perhaps validation of CMC ridge depiction?

honestly, nobody knows right now. we can guess, but nobody knows. this could end like irma, ike, or a simple fish storm.

[TheProfessor]

I wouldn't automatically assume that the Ukie and Euro are underestimating the ridge. These models tend to have a left bias and sometimes overdue ridging(especially the Ukie) so if you see them east of the other models, especially together, you usually pay attention to it. That's not to say that they're not both wrong, it's just that it's not normal for them to be on the eastern side of guidance early on. However, as we all know, this year is anything but normal.

[ConvergenceZone]

I wouldn't automatically assume that the Ukie and Euro are underestimating the ridge. These models tend to have a left bias and sometimes overdue ridging(especially the Ukie) so if you see them east of the other models, especially together, you usually pay attention to it. That's not to say that they're not both wrong, it's just that it's not normal for them to be on the eastern side of guidance early on. However, as we all know, this year is anything but normal.

IN MY OPINION, If this goes out to sea, then I think everything is going to go out to sea this year(which obviously is a good thing), especially since it's only August, because August is the best chance for storms NOT to recurve...... It's usually not until September when storms get carried out to sea regularly by troughs. August suppose to be the time for long-trackers. Troughs are only going to get more intense and more frequent as we head into September, so then we will just have to watch the Carib and Gulf of Mexico...
I've just seen too many Septembers where it's trough after trough after trough after trough

[ColdMiser123]

It would surprise me if this missed the US: