ATL: OSCAR - Remnants - Discussion

[Cachondo23]

CV season not over? 2024 continues however it likes…

[Travorum]

Curious how the NHC says possible short-lived system but the spaghetti models want to carry 94L close to the Lesser Antilles. The EURO also hints at development close to the Lesser Antilles too.

Probably because even if 94L becomes a TC right now, it's expected to dissipate in the Central Atlantic and only possibly reform further west as it gets closer to land. The NHC considers each "iteration" of a storm's life separately, even if there's a chance of reformation being anticipated the first time it dissipates.

For example, the following was said for remnants of Harvey in the Caribbean:

This is the last public advisory issued by the National Hurricane
Center on this system unless regeneration occurs or if tropical
cyclone watches or warnings are required for land areas.

Gert last year was one notable example of this, it was a 35kt tropical storm for all of a day before dissipating and then regenerating over a week later and getting up to 50kt.

[cycloneye]

2 PM:

Near the Cabo Verde Islands (AL94):
Showers and thunderstorms remain disorganized in association with
an area of low pressure passing through the western portions of the
Cabo Verde Islands. Earlier satellite data and recent surface
observations indicate that the system has winds up to about 40
mph, with higher gusts, but the circulation is elongated. Some
additional development is possible, and a short-lived tropical storm
could form while the system moves westward or west-northwestward at
10 to 15 mph away from the Cabo Verde Islands. On Saturday,
environmental conditions are forecast to become less conducive, and
further development appears unlikely after that time. Regardless of
development, winds to tropical storm force and areas of heavy rain
are likely to continue over portions of the Cabo Verde Islands
through tonight. For additional information on this system,
including gale warnings, please see High Seas Forecasts issued by
Meteo France.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...medium...50 percent.

[Sciencerocks]

[TomballEd]

Even as just an invest, a mid-October CV system is impressive.

The real risk from this is if it doesn't develop, Euro ensembles have this becoming something close to the Caribbean.

[AnnularCane]

I'm guessing redevelopment is in the somewhat distant future since the TWO doesn't mention it yet? (haven't been paying close attention, sorry)

[underthwx]

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

Looks fairly healthy on this satellite loop....I wonder will 94L offer some surprises?...

[zhukm29]

There's definitely an argument for TS here, especially with the ASCAT this morning and how much better it looks now:

[cycloneye]

8 PM:

Near the Cabo Verde Islands (AL94):
Showers and thunderstorms remain disorganized in association with an
area of low pressure just west of the Cabo Verde Islands. Some
development is possible tonight, and a short-lived tropical storm
could form while the system moves westward or west-northwestward at
10 to 15 mph away from the Cabo Verde Islands. On Saturday,
environmental conditions are forecast to become less conducive, and
further development appears unlikely after that time. Regardless of
development, gusty winds and areas of heavy rain are likely to
continue over portions of the Cabo Verde Islands through tonight.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

[abajan]

8 PM:

Near the Cabo Verde Islands (AL94):
Showers and thunderstorms remain disorganized in association with an
area of low pressure just west of the Cabo Verde Islands. Some
development is possible tonight, and a short-lived tropical storm
could form while the system moves westward or west-northwestward at
10 to 15 mph away from the Cabo Verde Islands. On Saturday,
environmental conditions are forecast to become less conducive, and
further development appears unlikely after that time. Regardless of
development, gusty winds and areas of heavy rain are likely to
continue over portions of the Cabo Verde Islands through tonight.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

Surprising. I expected the formation chances to be at least 60 percent.

[AnnularCane]

8 PM:

Near the Cabo Verde Islands (AL94):
Showers and thunderstorms remain disorganized in association with an
area of low pressure just west of the Cabo Verde Islands. Some
development is possible tonight, and a short-lived tropical storm
could form while the system moves westward or west-northwestward at
10 to 15 mph away from the Cabo Verde Islands. On Saturday,
environmental conditions are forecast to become less conducive, and
further development appears unlikely after that time. Regardless of
development, gusty winds and areas of heavy rain are likely to
continue over portions of the Cabo Verde Islands through tonight.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

Surprising. I expected the formation chances to be at least 60 percent.

I expected a rise in percentages too, especially since I could swear I glimpsed red on the map at the top of the page, but turns out the red is Leslie.

Oh well, I guess we keep an eye on it, although I do kind of wish the TWOs would talk about future prospects.

[USTropics]

There's an argument that could be made it was a cyclone earlier, but the center was clearly elongated (however, with reanalysis and the 40mph winds reported, perhaps a candidate for designation later). The NHC isn't doing a hindcast though, they're forecasting development, and looking at the future environment, the models paint a very bleak picture. In 12 hours, the environment really starts to dry out:


Here is a SAL analysis that shows this very dry mid-upper level atmosphere:


We can see on the ECMWF, 94L is going to have to plow through this dry air mass:


The HWRF essentially has this as a dry wave axis in 39 hours:


So for the next ~5 days, I would say chances of development are on the lower side. If 94L can make it to the Caribbean down the road though, a lack of moisture won't be an issue.

[underthwx]

There's definitely an argument for TS here, especially with the ASCAT this morning and how much better it looks now:

https://i.ibb.co/KL9R0hb/goes16-ir-94-L-202410111905.gif

Agree.....looks very healthy....

[TomballEd]

The big blowup of storms was completely removed from an elongated low level swirl. It is embedded in dry air. Which is bad news, a struggling system has a much better chance of getting to the Caribbean than a well developed system near the CVs. Especially in October with shorter wave lengths in the jet. Even in August most CV storms recurve.

ECENS and GEFS have members that get this into the Caribbean. Because they keep it weak. Ensembles below are after whatever may or may not develop in a week has left the scene.

[Cachondo23]

There's an argument that could be made it was a cyclone earlier, but the center was clearly elongated (however, with reanalysis and the 40mph winds reported, perhaps a candidate for designation later). The NHC isn't doing a hindcast though, they're forecasting development, and looking at the future environment, the models paint a very bleak picture. In 12 hours, the environment really starts to dry out:
https://i.imgur.com/BA9GCYf.png

Here is a SAL analysis that shows this very dry mid-upper level atmosphere:
https://i.imgur.com/VHUEqh1.png

We can see on the ECMWF, 94L is going to have to plow through this dry air mass:
https://i.imgur.com/Iu9WL4r.png

The HWRF essentially has this as a dry wave axis in 39 hours:
https://i.imgur.com/6E7TNS8.png

So for the next ~5 days, I would say chances of development are on the lower side. If 94L can make it to the Caribbean down the road though, a lack of moisture won't be an issue.

We still have SAL in mid october…

[underthwx]

The big blowup of storms was completely removed from an elongated low level swirl. It is embedded in dry air. Which is bad news, a struggling system has a much better chance of getting to the Caribbean than a well developed system near the CVs. Especially in October with shorter wave lengths in the jet. Even in August most CV storms recurve.

ECENS and GEFS have members that get this into the Caribbean. Because they keep it weak. Ensembles below are after whatever may or may not develop in a week has left the scene.

https://imagizer.imageshack.com/img923/2481/1ePdLY.png

Should 94L make it to the Carribean....will the environment there be favorable for organization?..... I read the long term forecast discussion for San Juan PR....It mentions a wetter period in the long term for the region.

.LONG TERM...Monday through Thursday...

PREV DISCUSSION... /issued 527 AM AST Fri Oct 11 2024/

At the beginning of next week, a wet pattern is expected to
persist, accompanied by easterly winds. According to the latest
precipitable water (PWAT) models, values on Monday are projected
to range from 1.8 to 2 inches, which falls within the normal
range. At the upper levels, the axis of the TUTT low is
anticipated to be near our area, enhancing rainfall development
across the islands. Furthermore, the potential for thunderstorm
activity is likely to increase, as 500 mb temperatures are
expected to remain around -6 degrees Celsius. While winds may
increase slightly, helping to expedite the movement of showers,
some flooding in urban areas, on roads, and in small streams
cannot be ruled out, particularly during the afternoon hours.

Variable conditions are expected to continue through mid-week. On
Tuesday and Wednesday, mixed patches of moisture and dry pockets
will shift within the easterly wind flow, creating a more typical
weather pattern with morning showers across the eastern sectors of
Puerto Rico and local islands, and afternoon convection in the
interior and western regions. By Thursday, models indicate an
increase in moisture, further enhancing rainfall development
across the islands. Throughout this period, warm to hot conditions
are anticipated.

Will this environment support any type of development....Should 94L venture thar far?

[zhukm29]

Looks like ASCAT missed tonight, but here is an OSCAT-3 pass instead. I don't think NHC uses this product though, but it does give us a picture of the circulation, and the winds seem reasonable compared to the earlier ASCAT pass.

[Sciencerocks]

[cycloneye]

For the first time, NHC says it will move westward and development is not anticipated unril midweek.

Eastern Tropical Atlantic (AL94):
The circulation associated with an area of low pressure located a
couple of hundred miles west of the Cabo Verde Islands appears to
have become slightly better defined this morning. However, the
associated shower and thunderstorm activity is only marginally
well-organized, and environmental conditions are expected to become
less conducive for further development later today. A short-lived
tropical depression could still form at any time today while the
system moves generally westward. After that time, the system is
forecast to continue moving westward across the central tropical
Atlantic, but further development is not anticipated through at
least the middle of next week.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

[jlauderdal]

For the first time, NHC says it will move westward and development is not anticipated unril midweek.

Eastern Tropical Atlantic (AL94):
The circulation associated with an area of low pressure located a
couple of hundred miles west of the Cabo Verde Islands appears to
have become slightly better defined this morning. However, the
associated shower and thunderstorm activity is only marginally
well-organized, and environmental conditions are expected to become
less conducive for further development later today. A short-lived
tropical depression could still form at any time today while the
system moves generally westward. After that time, the system is
forecast to continue moving westward across the central tropical
Atlantic, but further development is not anticipated through at
least the middle of next week.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

https://i.imgur.com/6NhqUoL.png

Oct 12th should be a quiet time for PR, hope it stays away or remains weak.