ATL: TEN - Models

[tarheelprogrammer]

Wow the Atlantic must be hostile, as evidence by the fact that this system, as well as 93L are weak even as they pass north of the islands. So much for great conditions. If only they were in the BOC or in the middle of the Atlantic. This could be the story all season. Models seem to be backing off developing this system.

[SouthFLTropics]

Trough swinging in...off to the northern Gulf Coast 92L will go.

[gatorcane]

Tightening consensus with a track just north of the islands but still lots of uncertainty with 92L:

[coreyl]

We've seen enough rain this summer here in south Mississippi and New Orleans area but obviously if in future models it starts to show strengthening that's a different story

[Steve]

Wow the Atlantic must be hostile, as evidence by the fact that this system, as well as 93L are weak even as they pass north of the islands. So much for great conditions. If only they were in the BOC or in the middle of the Atlantic. This could be the story all season. Models seem to be backing off developing this system.

It's the model thread. But has anyone said "Great Conditions" or is that just something you're saying we're not currently experiencing? If so, please direct me to that as I'd love to read whomever would post that the Atlantic's conditions are great just to see for myself. I really don't recall anyone saying that conditions were "great". I mean they are in some places I'm sure.
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I'm not sure about 91L/92L modeling. I kind of agree that 91L is a southern runner and 92L would come up farther north. It usually works that way. But 91l buried into Central America vs. Bay of Campeche could be the difference between a recurve/FL hit or Gulf storm with 92L. I don't have a good feel yet for how north 91L breaks.

[Bocadude85]

What the 12z Euro showed today may be a trend towards showing development in the vicinity of the Bahamas, the Euro showed the same thing with Gert before it jumped on the development bandwagon a few runs later.

[SouthFLTropics]

Tightening consensus with a track just north of the islands but still lots of uncertainty with 92L:

That's about as tight a cluster as you'll ever see at 144 hours. I think the track is pretty laid out unless something dramatic changes. What form it decides to take is the question.

[ronjon]

12z Euro at 240 hrs - into Cedar key as a depression.

https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=watl&pkg=uv850_vort&runtime=2017081612&fh=168&xpos=0&ypos=0

[gatorcane]

One thing to watch for is the possible recurve in the vicinity of Cuba/Florida/Eastern Gulf. The 12Z Euro is pretty close to the 00Z Euro out through about 168 hours but on the 12Z run it recurves the system rather abruptly north then NE in the SE GOM near the west coast of Florida.

There looks to be a potent Upper-Low that will move through the Great Lakes and SE Canada in about a week that greatly erodes the Bermuda High ridge over the Bahamas and Florida. It is still not out of the question that this could recurve before reaching Florida too if it develops but it could just as easily recurve after moving past Florida. As always it will come down to timing.

12Z ECMWF 144-240 hour animation:

[blp]

What the 12z Euro showed today may be a trend towards showing development in the vicinity of the Bahamas, the Euro showed the same thing with Gert before it jumped on the development bandwagon a few runs later.

Good point. The trend has been in the models to overdo the hostile conditions in that area in the mid range.

[tolakram]

Another run that shows the wave getting into the gulf and then some development. It's going to be an interesting week for sure. I do not believe conditions are so hostile that nothing develops between now and the wave entering the eastern gulf, and it's too far out to really predict conditions anyway.

[ronjon]

Another run that shows the wave getting into the gulf and then some development. It's going to be an interesting week for sure. I do not believe conditions are so hostile that nothing develops between now and the wave entering the eastern gulf, and it's too far out to really predict conditions anyway.

Really good point - you'd almost have to give climatology equal if not greater weight at this point after a weeks time on these model runs. The idea that we'd have some vorticity in the GOM in late August is concerning.

[OuterBanker]

Seems plausible. Also shows 93L as fish food just making it to 60 w before going ots. I would venture a guess that because 92 l is weaker around 60 w it doesn't pulled up in the weakness like 93 l.
Or, 93 l is at a higher latitude when it gets to 60 w. Really not sure which scenario it sees.

[Nimbus]

These computer models are limited by random changes to the atmosphere, they can only be deterministic to a certain degree.

With three tropical systems there is likely to be a lot more uncertainty in the forecast.
The upper air troughs and ridges respond to the heat energy driven vortexes in ways that can only partially be determined so errors compound quickly.

Models that have some value at 10 days under quiet tropical conditions are probably worthless with our current condition. The statistical advantage of forecasting at that range would be like trying to count into a six deck shoe.

[gatorcane]

12Z HWRF-P shows some organization when the run ends as it heads W to WNW towards Bahamas:

[gatorcane]

12Z GFS ensembles. Notice the hook north at the end. Of course a lot of GFS ensembles do not develop this and those that do are not particularly strong:

[Alyono]

12Z HWRF-P shows some organization when the run ends as it heads W to WNW towards Bahamas:

you CANNOT use the parent grid. Different physics. That is not a valid model

[blp]

12Z Ukmet. Big shift SW from 00z now over Cuba. It would be much stronger if not for land interaction. I think the ridge will keep this one from recurve.

[Emmett_Brown]

12Z HWRF-P shows some organization when the run ends as it heads W to WNW towards Bahamas:

you CANNOT use the parent grid. Different physics. That is not a valid model

Glad you brought this up... parent grid was confusing me. What is it for, and which one should we be using?

[Emmett_Brown]

These computer models are limited by random changes to the atmosphere, they can only be deterministic to a certain degree.

With three tropical systems there is likely to be a lot more uncertainty in the forecast.
The upper air troughs and ridges respond to the heat energy driven vortexes in ways that can only partially be determined so errors compound quickly.

Models that have some value at 10 days under quiet tropical conditions are probably worthless with our current condition. The statistical advantage of forecasting at that range would be like trying to count into a six deck shoe.

I'm not an expert in fluid dynamics (although I had to consider it when building my time machine). But I would tend to agree with you that if 3 TC's form in the same neighborhood, their paths would probably affect each other a bit and make track forecasts extra tricky and unpredictable.