Tropical Wave in the West-Central Caribbean (Is Invest 91L)

[cycloneye]

Up to 50%.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Sep 28 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A broad area of low pressure is expected to form over the western
Caribbean Sea in a few days. Environmental conditions are forecast
to be conducive for some development thereafter, and a tropical
depression could form late this week or this weekend while the
system moves slowly west-northwestward over the northwestern
Caribbean Sea.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

$$
Forecaster Blake

[WxEp]

Anyway, I think it was TheProfessor this morning who mentioned keeping a close eye on the thunderstorm complex SOUTH of Puerto Rico and if they collapse and the energy sticks close to the S coast down there then the GFS and crew may be on to something. If the storms persist and energy stays further N this could easily effect those solutions. Convection hasn't collapsed so we will have to watch this for sure to see if storms persist into the night. Could be the spark happening earlier than modeled. We'll see.

Looking at it on satellite, the energy seems to have migrated north throughout the day today. Recent trend seems to be for more energy S of PR and less energy near South America.

[toad strangler]

Quiet in this thread even after the GFS ran. Took a look and see why. Looks like it is actually a bit like the Euro driving this SW:

https://i.postimg.cc/446tpKhL/gfs-z850-vort-watl-fh0-168.gif

I'm not a big fan of the sit and spin for multiple days in a general area solutions. We'll see! I think the prudent thing to do here with this murky setup is be more skeptical than usual of solutions 96 hours plus out.

[SFLcane]

[toad strangler]

Anyway, I think it was TheProfessor this morning who mentioned keeping a close eye on the thunderstorm complex SOUTH of Puerto Rico and if they collapse and the energy sticks close to the S coast down there then the GFS and crew may be on to something. If the storms persist and energy stays further N this could easily effect those solutions. Convection hasn't collapsed so we will have to watch this for sure to see if storms persist into the night. Could be the spark happening earlier than modeled. We'll see.

Looking at it on satellite, the energy seems to have migrated north throughout the day today. Recent trend seems to be for more energy S of PR and less energy near South America.

Yes, the far N section of this wave axis has all the punch for now. Soooo, we track ....

[SFLcane]

18z Para rolling... interested to see if it sticks to developing the northern axis of the tropical wave.

Edit: continues to do develop northern part although weaker starting off.

[ronjon]

Nothing is set in stone. I don’t see how it goes SW when all I hear is troughs.

Quiet in this thread even after the GFS ran. Took a look and looks like it is actually a bit like the Euro driving this SW:

https://i.postimg.cc/151BQhDT/gfs-z850-vort-watl-fh114-168.gif

Actually a piece of energy shunts off to the NE over central Florida on Sunday from the cyclone near the Yuc. This tells me that the stall may not be set in stone with GFS and perhaps parallel has the right idea. We'll see.

[aspen]

18z parallel still has a further north track, although it’s weaker and less defined.

[SFLcane]

18z parallel still has a further north track, although it’s weaker and less defined.

Yeah it's gone Cat3-Cat2-Cat1-TS...

By tomorrow night might be a cumulus cloud.

[toad strangler]

18z parallel still has a further north track, although it’s weaker and less defined.

Yeah it's gone Cat3-Cat2-Cat1-TS...

By tomorrow night might be a cumulus cloud.

Intensity is the last thing to look at with these models this far out. #remember Hanna & Laura

[aspen]

18z parallel still has a further north track, although it’s weaker and less defined.

Yeah it's gone Cat3-Cat2-Cat1-TS...

By tomorrow night might be a cumulus cloud.

Intensity is the last thing to look at with these models.

I think the lowering intensity is due to the model being confused about the size of the wave, and which part will have the primary vorticity. It does have the northern part develop as before, but at 72 hours, the wave axis is ridiculously long — all the way from Panama to Jamaica — and prevents the system from quickly spinning up.

[Blown Away]

18z parallel still has a further north track, although it’s weaker and less defined.

It’s about the same as past few runs, not sure you can draw much conclusions when there is @5-10 mb swings at @150 hours... Continues to show a decent TS/Cat 1 into SW Fl...

[psyclone]

I'm leaning on the NHC for development odds rather than the manic model behavior. They're relentlessly increasing the odds. Now up to a coin toss. that's decent and trending up. Doesn't mean it will be significant. But considering the calendar and location...I'm definitely tuned in as anything can happen. we've had plenty of slow developing systems this year and systems that vastly exceeded initial expectations. this has been a year of close in sucker punches.

[GeneratorPower]

I'm leaning on the NHC for development odds rather than the manic model behavior. They're relentlessly increasing the odds. Now up to a coin toss. that's decent and trending up. Doesn't mean it will be significant. But considering the calendar and location...I'm definitely tuned in as anything can happen. we've had plenty of slow developing systems this year and systems that vastly exceeded initial expectations. this has been a year of close in sucker punches.

The odds are increasing because there’s a 5 day fuse on the forecast. Time is getting closer so odds have to match. You’ll see the 48 hour odds increase soon, too.

[chaser1]

This is purely conjecture but I'm assuming that the reason that the GFS-Para has backed off on intensity, is simply because it and other models are far better anticipating the near term post-front conditions that will be in place over Florida and the Gulf region. Suffice it to say, a quicker development and track toward Florida would suggest a weaker storm or minimal hurricane. On the other hand, the longer this system takes, the more time for cool dry conditions over Florida to be modified.

[Ubuntwo]

 https://twitter.com/burgwx/status/1310724962005770240

[TheStormExpert]

Yeah it's gone Cat3-Cat2-Cat1-TS...

By tomorrow night might be a cumulus cloud.

Intensity is the last thing to look at with these models.

I think the lowering intensity is due to the model being confused about the size of the wave, and which part will have the primary vorticity. It does have the northern part develop as before, but at 72 hours, the wave axis is ridiculously long — all the way from Panama to Jamaica — and prevents the system from quickly spinning up.

We have three distinct different areas coming into the general Western Caribbean area. All competing for which will be dominant. Wouldn't surprise me when all is said and done if nothing much comes from this than a large monsoon-like gyre sloppy mess!

[Hurricaneman]

Looks like some low to mid level low near 69W 15N

[SFLcane]

Evening view of tropical wave moving through the eastern Caribbean.

[Loveweather12]

How might that affect the track etc?

Evening view of tropical wave moving through the eastern Caribbean. Not much going on to it’s south.

https://i.imgur.com/ivOm7Ex.gif