Tropical Wave south of the Cabo Verde Islands (Is Invest 91L)

[aspen]

Once again, AIFS at 18z run develops it and it clips the northern Leewards.

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

I’m skeptical of this solution, as it should be prevented by soon-to-be Kirk. Either Kirk’s outflow shreds this disturbance (either as simply a wave or a developed TC), or it allows an opening for it to escape OTS, or both.

[cycloneye]

iCON has been very consistent developing it in a strong way. This is the 00z run.

[cycloneye]

Eastern Tropical Atlantic:
A tropical wave located a few hundred miles south-southeast of the
Cabo Verde Islands is producing limited shower and thunderstorm
activity. Upper-level winds are forecast to become more conducive
for gradual development of this system during the next few days, and
a tropical depression could form during the middle or latter part of
this week while it moves slowly westward or west-northwestward over
the eastern tropical Atlantic.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...medium...60 percent.

[cycloneye]

Wow, very strong 00z Euro run.

[cycloneye]

All the global models develop this wave but there are differences in terms of tracks from GFS with the most early recurving, to the others that recurve much more west.

[cycloneye]

We have a cherry now. 8 AM TWO:

Eastern Tropical Atlantic:
Showers and thunderstorms have increased in association with a
tropical wave located a few hundred miles south of the Cabo Verde
Islands. Upper-level winds are forecast to become more conducive
for gradual development, and a tropical depression is likely to form
in a few days while it moves slowly westward over the eastern
tropical Atlantic.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...high...80 percent.

[Hurricane2022]

Cherry cherry Leslie!

[aspen]

I still remain a little skeptical of a potential island threat despite most of the model consensus supporting it. Kirk is right there to open an easy escape path. Plus, we’ve seen before that models will often overhype a second MDR disturbance closely trailing an already-developing one that may impart outflow-induced shear. It doesn’t always happen (an extreme example is Irma and Jose), but it’s something to keep in mind.

[chaser1]

Put simply, I fully agree with Aspen regarding likely future track for this Easternmost MDR wave. In particular one key element will be "where" will it ultimately develop. The ICON seems to develop this storm a bit further south than other models which might imply enough lower latitude mid-level ridging between Kirk and itself. I just do not see nearly enough distance between the two systems that could result in anything less than a Northwest motion that would likely have it follow Kirk poleward. Time will tell of course but it's hard for me to buy into this system posing a potential threat to the Lesser Antilles.

[WeatherBoy2000]

Put simply, I fully agree with Aspen regarding likely future track for this Easternmost MDR wave. In particular one key element will be "where" will it ultimately develop. The ICON seems to develop this storm a bit further south than other models which might imply enough lower latitude mid-level ridging between Kirk and itself. I just do not see nearly enough distance between the two systems that could result in anything less than a Northwest motion that would likely have it follow Kirk poleward. Time will tell of course but it's hard for me to buy into this system posing a potential threat to the Lesser Antilles.

Eh it does happen occasionally where the second disturbance does go further west despite being in the wake of a major recurving storm, Fran 1996 and Earl 2010 are examples of this. This could be a Lessar Antilles threat if it develops later due to Kirk induced shear and thus doesn't feel the weakness until later down the line (if at all).

[xtyphooncyclonex]

Pretty big shift west from the GFS this run and going...

[Kazmit]

ICON has the Azores high sneaking in quickly after Kirk departs. Keeps it chugging west. Still, I'd be surprised if it became a threat to the islands. October is not an ideal time for persistent ridging.

[chaser1]

Put simply, I fully agree with Aspen regarding likely future track for this Easternmost MDR wave. In particular one key element will be "where" will it ultimately develop. The ICON seems to develop this storm a bit further south than other models which might imply enough lower latitude mid-level ridging between Kirk and itself. I just do not see nearly enough distance between the two systems that could result in anything less than a Northwest motion that would likely have it follow Kirk poleward. Time will tell of course but it's hard for me to buy into this system posing a potential threat to the Lesser Antilles.

Eh it does happen occasionally where the second disturbance does go further west despite being in the wake of a major recurving storm, Fran 1996 and Earl 2010 are examples of this. This could be a Lessar Antilles threat if it develops later due to Kirk induced shear and thus doesn't feel the weakness until later down the line (if at all).

It's certainly possible but I don't think the comparison is quite right. In 1996 Fran essentially followed the same track that Edouard took from near the African coast, to about 70W. I agree that 2010 might be a better example to your point given that Earl's track continued west to threaten Puerto Rico in spite of Danielle having recurved in the E. Atlantic. The biggest difference between this current event and those two years however is the calendar. Fran (1996) and Earl (2010) both formed in August when Atlantic ridging is at it Climatological peak. We're entering October when the tropical wave crawl typically begins. Aside from the typical transition for mid latitude ridging to break down in the face of increasing Westerlies and dropping troughs, the strength of low latitude Easterlies in the Atlantic MDR begins to wane thus the slower westward progression which typically occurs during October

[WeatherBoy2000]

Put simply, I fully agree with Aspen regarding likely future track for this Easternmost MDR wave. In particular one key element will be "where" will it ultimately develop. The ICON seems to develop this storm a bit further south than other models which might imply enough lower latitude mid-level ridging between Kirk and itself. I just do not see nearly enough distance between the two systems that could result in anything less than a Northwest motion that would likely have it follow Kirk poleward. Time will tell of course but it's hard for me to buy into this system posing a potential threat to the Lesser Antilles.

Eh it does happen occasionally where the second disturbance does go further west despite being in the wake of a major recurving storm, Fran 1996 and Earl 2010 are examples of this. This could be a Lessar Antilles threat if it develops later due to Kirk induced shear and thus doesn't feel the weakness until later down the line (if at all).

It's certainly possible but I don't think the comparison is quite right. In 1996 Fran essentially followed the same track that Edouard took from near the African coast, to about 70W. I agree that 2010 might be a better example to your point given that Earl's track continued west to threaten Puerto Rico in spite of Danielle having recurved in the E. Atlantic. The biggest difference between this current event and those two years however is the calendar. Fran (1996) and Earl (2010) both formed in August when Atlantic ridging is at it Climatological peak. We're entering October when the tropical wave crawl typically begins. Aside from the typical transition for mid latitude ridging to break down in the face of increasing Westerlies and dropping troughs, the strength of low latitude Easterlies in the Atlantic MDR begins to wane thus the slower westward progression which typically occurs during October

I agree that it's not particularly likely to be an Antilles/further west threat, but the potential is there unlike Kirk. The gfs is trending further west and the other operational models do show something that could potentially threaten the Antilles. At this stage it doesn't look to be as clean of a recurve. Although climatology suggests this should recurve easily before the Antilles, it is not like 2024 has been a very climatological season and these two systems certainly aren't in line with it.

[WaveBreaking]

So far, the best way that this wave could continue west and become a land threat is if it:

1. Doesn’t develop quickly enough to feel the mid-level weakness that will pull Kirk north
2. Gets close enough to Kirk where it gets sheared thus limiting development but not too close as it would get pulled in/absorbed
3. Manages to get stuck under a ridge that happens to form after Kirk’s exit

I could see events 1 and the first part of 2 happening, but after that it comes down to chance and where this wave’s center develops.

[CrazyC83]

So far, the best way that this wave could continue west and become a land threat is if it:

1. Doesn’t develop quickly enough to feel the mid-level weakness that will pull Kirk north
2. Gets close enough to Kirk where it gets sheared thus limiting development but not too close as it would get pulled in/absorbed
3. Manages to get stuck under a ridge that happens to form after Kirk’s exit

I could see events 1 and the first part of 2 happening, but after that it comes down to chance and where this wave’s center develops.

Another limiting factor could be upwelling, if Kirk rapidly intensifies and becomes a major hurricane well before the turn, this system could go into a cool wake.

[cycloneye]

So far, the best way that this wave could continue west and become a land threat is if it:

1. Doesn’t develop quickly enough to feel the mid-level weakness that will pull Kirk north
2. Gets close enough to Kirk where it gets sheared thus limiting development but not too close as it would get pulled in/absorbed
3. Manages to get stuck under a ridge that happens to form after Kirk’s exit

I could see events 1 and the first part of 2 happening, but after that it comes down to chance and where this wave’s center develops.

Another limiting factor could be upwelling, if Kirk rapidly intensifies and becomes a major hurricane well before the turn, this system could go into a cool wake.

Unless it stays south of the upwelled waters.

[cycloneye]

2 PM: I think invest 91L will come very soon.

Eastern Tropical Atlantic:
Showers and thunderstorms continue to increase in association with a
tropical wave located a few hundred miles south of the Cabo Verde
Islands. Upper-level winds appear conducive for further
development, and a tropical depression is very likely to form in a
few days while it moves slowly westward over the eastern tropical
Atlantic.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...90 percent.

[zzzh]

Note that

Upper-level winds appear conducive for further development

it's near the edge of the strong upper easterlies and the TUTT induced by Kirk's outflow.

[chaser1]

So far, the best way that this wave could continue west and become a land threat is if it:

1. Doesn’t develop quickly enough to feel the mid-level weakness that will pull Kirk north
2. Gets close enough to Kirk where it gets sheared thus limiting development but not too close as it would get pulled in/absorbed
3. Manages to get stuck under a ridge that happens to form after Kirk’s exit

I could see events 1 and the first part of 2 happening, but after that it comes down to chance and where this wave’s center develops.

Another limiting factor could be upwelling, if Kirk rapidly intensifies and becomes a major hurricane well before the turn, this system could go into a cool wake.

Unless it stays south of the upwelled waters.

That's what I was thinking too.
Most models develop this to sub 1000 mb pressures in 3-5 days and that would lead me to believe it'll more or less follow Kirk. Maybe GFS and other models will begin to back off of intensification long enough to get further west in the basin to pose a future risk.