ATL: INVEST 95L - Discussion

[ouragans]

Still 50/70. Mention for the LA added

1. Central Tropical Atlantic (AL95):
Shower activity associated with a small area of low pressure located
roughly midway between the Cabo Verde Islands and the Lesser
Antilles is showing signs of organization. Although environmental
conditions are only marginally conducive, slow development is
expected and this system will likely become a tropical depression by
early next week while it moves westward across the tropical
Atlantic. Interests in the Lesser Antilles should monitor the
progress of this system.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...70 percent.

[REDHurricane]

I believe that the culprit of greatest influence is a massive easterly surge approaching from the east and northeast.

Yep, looks like it

[Sciencerocks]

[cycloneye]

8 AM TWO:

Central Tropical Atlantic (AL95):
Shower activity associated with a small area of low pressure located
roughly midway between the Cabo Verde Islands and the Lesser
Antilles continues to show signs of organization. Although
environmental conditions are only marginally conducive, some
additional gradual development is anticipated and this system will
likely become a tropical depression by early next week while it
moves westward across the tropical Atlantic. Interests in the
Lesser Antilles should monitor the progress of this system.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...70 percent.

[wxman57]

Doesn't look impressive at all this morning. Weak swirl east of limited convection. Model support is dwindling. Looking more like it won't make it to TD.

[cycloneye]

Is doing the small dip that the models have. From 12.4N at 06Z to 12.1N at 12z.

AL, 95, 2023072212, , BEST, 0, 121N, 417W, 25, 1012, LO

https://ftp.nhc.noaa.gov/atcf/btk/bal952023.dat

[underthwx]

Doesn't look impressive at all this morning. Weak swirl east of limited convection. Model support is dwindling. Looking more like it won't make it to TD.

Sure looks tiny out there over the ocean...is the system being inhibited by dust from the Sahara?

[REDHurricane]

Doesn't look impressive at all this morning. Weak swirl east of limited convection. Model support is dwindling. Looking more like it won't make it to TD.

Sure looks tiny out there over the ocean...is the system being inhibited by dust from the Sahara?

Guessing it's likely some combination of the Saharan air layer and stronger than expected easterly wind shear

[wxman57]

Doesn't look impressive at all this morning. Weak swirl east of limited convection. Model support is dwindling. Looking more like it won't make it to TD.

Sure looks tiny out there over the ocean...is the system being inhibited by dust from the Sahara?

The dry air isn't helping. Can't rule out a very small TS but that's looking less likely this morning.

[abajan]

Doesn't look impressive at all this morning. Weak swirl east of limited convection. Model support is dwindling. Looking more like it won't make it to TD.

Sure looks tiny out there over the ocean...is the system being inhibited by dust from the Sahara?

The dry air isn't helping. Can't rule out a very small TS but that's looking less likely this morning.

Looks like Mr. Weatherman (Meteorologist Brian Shields) is pretty much on the same wavelength as you. Great minds...



Link: https://youtu.be/3gh2WTdiN4Q

[USTropics]

Limited convection is a direct result of the background environment. We can see on the GFS 700-300mb RH analysis the obstacles 95L has to overcome. This causes multiple issues in the convective processes as (1) the system has to expend convective resources to battle against this background environment, (2) it limits convective expansion of the system (via degraded uplift in absent of a moist environment), and (3) it restricts inflow and outflow channels to the north and northwest:


Looking at the GFS sounding for 95L, while there isn't excessive shear, there is a change in steering regime starting at the mid-levels which is likely causing the displacement:


One other thing to note, as far as the SW dip, notice the orientation of the ridging here at the lower-levels (roughly highlighted in blue) and where the strongest steering influences are currently being felt with a weak/disorganized system. Don is making its second traverse over the top of an expanding subtropical high pressure area (track highlighted in pink), and this will again influence the orientation of the ridge:


The models haven't exactly handled the strength of Don particularly well, and you can see even at 24 hours Don has just enough of an influence on the SW periphery of the ridge to force 95L to dip southwest (where a center relocation would also be more expected given convective parameters):


With that said, the environment up until the Caribbean is marginally conducive for development. Once the system enters the eastern Caribbean, and with Don now out of the picture, high pressure begins to dominate the subtropical Atlantic:


This causes increased easterly flow in the Caribbean:


One last side note, there have been mentions on Twitter that this shear is related to El Nino; we would expect westerly wind shear (not easterly) if this was a result of El Nino (which typically occurs when the subtropical jet becomes amplified, which we haven't seen). This is your typical Caribbean/increased trades shear during July/early August.

[gatorcane]

Limited convection is a direct result of the background environment. We can see on the GFS 700-300mb RH analysis the obstacles 95L has to overcome. This causes multiple issues in the convective processes as (1) the system has to expend convective resources to battle against this background environment, (2) it limits convective expansion of the system (via degraded uplift in absent of a moist environment), and (3) it restricts inflow and outflow channels to the north and northwest:
https://i.imgur.com/VhKLfez.png

Looking at the GFS sounding for 95L, while there isn't excessive shear, there is a change in steering regime starting at the mid-levels which is likely causing the displacement:
https://i.imgur.com/ZAa65e2.png

One other thing to note, as far as the SW dip, notice the orientation of the ridging here at the lower-levels (roughly highlighted in blue) and where the strongest steering influences are currently being felt with a weak/disorganized system. Don is making its second traverse over the top of an expanding subtropical high pressure area (track highlighted in pink), and this will again influence the orientation of the ridge:
https://i.imgur.com/g1UX0Hs.png

The models haven't exactly handled the strength of Don particularly well, and you can see even at 24 hours Don has just enough of an influence on the SW periphery of the ridge to force 95L to dip southwest (where a center relocation would also be more expected given convective parameters):
https://i.imgur.com/DBqB7py.png

With that said, the environment up until the Caribbean is marginally conducive for development. Once the system enters the eastern Caribbean, and with Don now out of the picture, high pressure begins to dominate the subtropical Atlantic:
https://i.imgur.com/7JueMxz.png

This causes increased easterly flow in the Caribbean:
https://i.imgur.com/mDmfnXe.png

One last side note, there have been mentions on Twitter that this shear is related to El Nino; we would expect westerly wind shear (not easterly) if this was a result of El Nino (which typically occurs when the subtropical jet becomes amplified, which we haven't seen). This is your typical Caribbean/increased trades shear during July/early August.

Thanks I really enjoy your posts and detailed analysis.

95l is really struggling this morning as posters have noted. It is not just dry air but some shear as well:

[Teban54]

Limited convection is a direct result of the background environment. We can see on the GFS 700-300mb RH analysis the obstacles 95L has to overcome. This causes multiple issues in the convective processes as (1) the system has to expend convective resources to battle against this background environment, (2) it limits convective expansion of the system (via degraded uplift in absent of a moist environment), and (3) it restricts inflow and outflow channels to the north and northwest:
https://i.imgur.com/VhKLfez.png

Looking at the GFS sounding for 95L, while there isn't excessive shear, there is a change in steering regime starting at the mid-levels which is likely causing the displacement:
https://i.imgur.com/ZAa65e2.png

One other thing to note, as far as the SW dip, notice the orientation of the ridging here at the lower-levels (roughly highlighted in blue) and where the strongest steering influences are currently being felt with a weak/disorganized system. Don is making its second traverse over the top of an expanding subtropical high pressure area (track highlighted in pink), and this will again influence the orientation of the ridge:
https://i.imgur.com/g1UX0Hs.png

The models haven't exactly handled the strength of Don particularly well, and you can see even at 24 hours Don has just enough of an influence on the SW periphery of the ridge to force 95L to dip southwest (where a center relocation would also be more expected given convective parameters):
https://i.imgur.com/DBqB7py.png

With that said, the environment up until the Caribbean is marginally conducive for development. Once the system enters the eastern Caribbean, and with Don now out of the picture, high pressure begins to dominate the subtropical Atlantic:
https://i.imgur.com/7JueMxz.png

This causes increased easterly flow in the Caribbean:
https://i.imgur.com/mDmfnXe.png

One last side note, there have been mentions on Twitter that this shear is related to El Nino; we would expect westerly wind shear (not easterly) if this was a result of El Nino (which typically occurs when the subtropical jet becomes amplified, which we haven't seen). This is your typical Caribbean/increased trades shear during July/early August.

Thanks I really enjoy your posts and detailed analysis.

95l is really struggling this morning as posters have noted. It is not just dry air but some shear as well:

https://i.postimg.cc/dVXX1b5V/goes16-vis-swir-95-L-202307221145.gif

Looks like the LLC is being pulled towards the convection.

[Sciencerocks]

[underthwx]

Sure looks tiny out there over the ocean...is the system being inhibited by dust from the Sahara?

The dry air isn't helping. Can't rule out a very small TS but that's looking less likely this morning.

Looks like Mr. Weatherman (Meteorologist Brian Shields) is pretty much on the same wavelength as you. Great minds...

https://youtu.be/3gh2WTdiN4Q

I haven't read about 95L, my apologies if my question had an obvious answer already posted here Abajan

[abajan]

The dry air isn't helping. Can't rule out a very small TS but that's looking less likely this morning.

Looks like Mr. Weatherman (Meteorologist Brian Shields) is pretty much on the same wavelength as you. Great minds...

https://youtu.be/3gh2WTdiN4Q

I haven't read about 95L, my apologies if my question had an obvious answer already posted here Abajan

No need to apologize, as my comment wasn't really referring to what you posted but to wxman57's (not that I had intentionally ignored what you stated).

[Teban54]

 https://twitter.com/OSUWXGUY/status/1682685629333643265

[Blown Away]

If model support continues to drop, thinking NHC going to lower odds soon.

[abajan]

Link: https://youtu.be/3jUVNIkTjg4

[cycloneye]

If model support continues to drop, thinking NHC going to lower odds soon.

Bingo.

Central Tropical Atlantic (AL95):
Shower activity associated with a small area of low pressure located
roughly midway between the Cabo Verde Islands and the Lesser
Antilles has become a little less organized since yesterday.
Environmental conditions are forecast to remain marginally conducive
for some gradual development, and this system could become a
tropical depression early next week while it moves westward across
the tropical Atlantic. Interests in the Lesser Antilles should
monitor the progress of this system.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...60 percent.