Tropical Wave About to Emerge from Africa (Is Invest 93L)

[ElectricStorm]

1. A strong tropical wave is expected to emerge off of the western
coast of Africa in a few days. Additional development of this
system is possible thereafter, and a tropical depression could form
by early next week as it moves west-northwestward over the far
eastern Atlantic near the Cabo Verde Islands.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

This one might be one of those that gets tagged as an invest either right after it exits Africa or while it's still over land. Capo Verde may take some impacts from this so it will need to be watched as soon as it leaves the coast.

[cycloneye]

Is not going west to the Caribbean but instead, is going to curve to the NW and north.

[SconnieCane]

Strange that the orientation of the orange shading (I realize it's not a track forecast, but still the implication is there) suggests an immediate NW heading and quick recurvature, but the text says west-northwest.

[IcyTundra]

This should become Nicholas. I'm not expecting much out of this, but it could bring impacts to the Cabo Verde islands.

[Hurricaneman]

Intensity or development not withstanding does this loop back to Africa like the Euro or end up near Florida like the GFS, we’ll see in a few days

[Spacecoast]

[LarryWx]

Is not going west to the Caribbean but instead, is going to curve to the NW and north.

Actually, although a quick recurve is favored as of now, it is still far from set in stone imo. This is that same AEW emerging 9/10-11 that has been on the models and discussed since the 8/31 12Z EPS (8 days ago). Soon after this, the op Euro had it immediately once it was in range (on 0Z 9/2 run). Since that run, the Euro has had a TS+ on about every run. Once it came into range of the UKMET, it has had a TC every time, including several runs with a H. Since then, the rest of the models have picked up on it and had it on every run.

There continues to be a split: the Euro, UKMET, ICON, and CMC have on just about every run been having it recurve enough early on to make to get it far north enough to make it a non-threat other than possibly to the CV Islands. In many cases, it later just dissipates.

But interestingly, similar to the latest JMA and NAVGEM, the GFS has always had it remain a weak surface low moving WSW in the E Atlantic and then W at a much lower latitude all of the way to at least 60W. Many of these runs actually went over the L.A.’s, then into the NE Caribbean ~9/18, and then NW from there to as far as the FL Straits/S FL on a few runs a few days ago and all staying weak. The 12Z 9/5 GFS run was the first one showing this AEW doing this and every run has been similar (14 runs in a row).

So, it is mainly the GFS that tells me to not bet the farm on this quick recurve yet. In addition, the Euro and EPS mean have been gradually trending SW overall. A few EPS members on many runs have not been recurving, including on the brand new 18z. If it comes off Africa further south than the Euro followed by a WSW move and especially if it stays weak, it very likely won’t recurve early and will thus have a decent chance to get pretty far west.

[ouragans]

2. A strong tropical wave is expected to emerge off of the west coast
of Africa Saturday. Environmental conditions are forecast to be
conducive for development thereafter, and a tropical depression
could form late this weekend or early next week as it moves
west-northwestward over the far eastern Atlantic near the Cabo Verde
Islands.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...medium...60 percent.

[Nimbus]

GFS global run has a monster storm threatening east coast of Florida in two weeks so hopefully the ridge doesn't build back in behind this one?

[SconnieCane]

Up to code red (70%) on the five-day outlook and no invest yet? Do they have to wait for "splashdown"?

[cycloneye]

Looks like we will have the invest soon. This is the first step.

GENESIS033, AL, L, , , , , 76, 2021, DB, O, 2021091000, 9999999999, , 033, , , , GENESIS, , AL762021

https://ftp.nhc.noaa.gov/atcf/index/AL_storms.txt.nhc

[cycloneye]

Is a big wave.

[ouragans]

Up to code red (70%) on the five-day outlook and no invest yet? Do they have to wait for "splashdown"?

It was the same for Larry

[SconnieCane]

Wow. Looks like it spans over 10 degrees of latitude with the potential for competing north and south "lobes." Could be one of those 2020-style waves that's too beefy for its own good and takes forever to organize. That could mean it gets further west before developing, though.

[floridasun78]

could take same track as larry

[ouragans]

2. A strong tropical wave is expected to emerge off of the west coast
of Africa by tonight. Environmental conditions are forecast to be
conducive for gradual development thereafter, and a tropical
depression is likely to form late this weekend or early next week as
the system moves west-northwestward over the far eastern Atlantic
near the Cabo Verde Islands. Interests in the Cabo Verde Islands
should monitor the progress of this system.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...70 percent.

[tomatkins]

Is a big wave.

https://i.imgur.com/ItE4bfE.gif

I feel like forecasting for these big waves ends up being tricky because its not clear where exactly the center will consolidate and what kind of environment the consolidation will have left.

[LarryWx]

Is a big wave.

https://i.imgur.com/ItE4bfE.gif

I feel like forecasting for these big waves ends up being tricky because its not clear where exactly the center will consolidate and what kind of environment the consolidation will have left.

That’s probably why the GFS and Euro have been so different. Also, usually the large ones are slow to develop, meaning all of those old Euro runs and UKMET runs developing it quickly and strongly would be wrong.

Interestingly, the 6Z Euro was about its weakest run yet along with a slightly more SW track, suggesting it is moving toward the GFS idea of it staying weak and not recurving so sharply. Remember when the Euro was coming off Africa way up at 20N? Also, the GFS has in recent runs been trending toward a slightly higher latitude track and a little earlier recurvature of a still weak but perhaps slightly stronger low than the numerous runs bringing it across very weak to the Lesser Antilles near or south of 15N before moving WNW. So, the Euro and GFS are finally starting to come together as each moves closer to the other’s solution. The consensus now seems to be for a mainly weak low that recurves east of the Lesser Antilles and never threatens land after the CVs with it not being strong near the CVs. But all of that still remains to be seen, of course.

[LarryWx]

There is now a tight ball of convection with probably a LLC of sorts just offshore near 14N, 18W moving seemingly WSW per the visible loops. Let’s see whether or not this area ends up being the focus of this large AEW and, if so, whether or not it develops further.

Edit: The Euro suite doesn’t develop this and instead delays development til late tonight in the same area moving WNW. Perhaps this is why there has been such disagreement between the Euro and GFS.

[Teban54]

Getting that look: