INVEST 90L: Central Tropical Atlantic (50/70)

[MJO812]

[BarryStantonGBP]

14 minutes ago, MJO812 said:

Thread made

[GaWx]

Latest UKMET (0Z) still pretty weak and a little west of 12Z  though still not far W of Bermuda:

 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 102 HOURS
              FORECAST POSITION AT T+102 : 20.6N  64.4W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 23.08.2025  108  21.3N  65.7W     1010            28
    0000UTC 24.08.2025  120  22.9N  67.2W     1011            30
    1200UTC 24.08.2025  132  24.5N  68.2W     1011            35
    0000UTC 25.08.2025  144  26.9N  68.9W     1011            35
    1200UTC 25.08.2025  156  29.9N  68.4W     1012            35
    0000UTC 26.08.2025  168  33.3N  67.2W     1011            31

[MJO812]

Gfs is now offshore at 0z

[WxWatcher007]

Not quite sure what to make of the operational models backing off development when the ensembles still have a pretty robust signal for TC genesis. Erin's evolution will have a big impact on what happens with this one. 

[Wannabehippie]

 

Looks like there has been upwelling from Erin. How much will this impact this disturbance and the other one out in the Atlantic.

[eyewall]

2 hours ago, WxWatcher007 said:

Not quite sure what to make of the operational models backing off development when the ensembles still have a pretty robust signal for TC genesis. Erin's evolution will have a big impact on what happens with this one. 

There is a big Saharan air layer out there

[WxWatcher007]

7 minutes ago, eyewall said:

There is a big Saharan air layer out there

Posting for others to see. I know it’s there and that every system is different, but Erin was able to get past SAL and develop. Even this wave has convective activity.

But the 12z GEFS signal declined near the Antilles too. Maybe it doesn’t develop, or maybe it’s a late developer. I lean toward the latter at this point, with the SW Atlantic being more favorable perhaps.

[NorthHillsWx]

As others have said, I’m a little surprised that model support has waned on this system. It seemed to be in a moist pocket and shear seemed manageable. I do wonder if models are now catching onto the pronounced outflow from Erin as a source of shear that affects this system. It could be one that doesn’t get going until Erin moves away. Also, guidance has continued to trend more towards this system moving north through the same break Erin is traveling through. The chances of an east coast impact seem to be diminishing 

[BarryStantonGBP]

a quote

 

 

USTropics

Professional-Met

Posts: 2670

Joined: Sun Aug 12, 2007 3:45 am

Location: Florida State University

Re: Tropical Wave in the Central Atlantic (10/60)

•  

#239 by USTropics » Tue Aug 19, 2025 1:19 pm 

BobHarlem wrote:12z GFS you have to use the 850mb vorticity to see anything (it's late august right?), but you can tell the southern lobe eventually splits and it spits up into Erin's wake and the southern lobe into Gulf on the 12z. No development up to then anyway (unless that split fires up in the Gulf).

This is a solid assessment, at the end of the day this area just had too many competing vorticity maxima to consolidate. 50W longitude right now is kind of the magical line—if vorticity doesn't consolidate before then the low-level flow acceleration into the Caribbean really gets cranking and it's nearly impossible at that point (the Caribbean graveyard effect). A wave fracture is the most likely outcome now.

[Wannabehippie]

On 8/18/2025 at 3:06 PM, cptcatz said:

The convection blob still remains on the southwest side of this huge wave. I don't trust any model until this consolidates and as long as that convection blob remains to the southwest, I'd still lean towards a more south/west track...

That blob of convection was, and remains pretty far south. Almost at 5 degrees. The low coriolis effect will probably inhibit development. Add in the SAL, and I don't get how this is listed as an orange by the NHC.

[WxWatcher007]

The GFS never killed it, but some signs of life both on IR and in the ensembles again. 

[BarryStantonGBP]

AL, 90, 2025082112, , BEST, 0, 171N, 555W, 25, 1011, DB, 34, NEQ, 0, 0, 0, 0, 1014, 180, 60, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 019, SPAWNINVEST, al792025 to al992025, SPAWNINVEST, al792025 to al902025,

 

[GaWx]

 Now the hurricane models will run. This could possibly affect Bermuda directly but would there even be much to it?

[BarryStantonGBP]

8 minutes ago, GaWx said:

 Now the hurricane models will run. This could possibly affect Bermuda directly but would there even be much to it?

Is it gonna be a highly saturated/wet storm?

[WxWatcher007]

1 hour ago, BarryStantonGBP said:

AL, 90, 2025082112, , BEST, 0, 171N, 555W, 25, 1011, DB, 34, NEQ, 0, 0, 0, 0, 1014, 180, 60, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 019, SPAWNINVEST, al792025 to al992025, SPAWNINVEST, al792025 to al902025,

 

About time they tagged it. 

39 minutes ago, GaWx said:

 Now the hurricane models will run. This could possibly affect Bermuda directly but would there even be much to it?

I think the GFS has led the way here in not losing the signal for genesis like the Euro/EPS and other guidance. The wave while elongated still, is consolidating and importantly has become convectively active, though high shear is nearby. There may be a jet streak that enhances this once it is north of the Antilles. I was bullish on this wave before and was a little confused as to why the guidance signal dropped the way it did. We’ll see what happens.

[BarryStantonGBP]

1 hour ago, WxWatcher007 said:

About time they tagged it. 

I think the GFS has led the way here in not losing the signal for genesis like the Euro/EPS and other guidance. The wave while elongated still, is consolidating and importantly has become convectively active, though high shear is nearby. There may be a jet streak that enhances this once it is north of the Antilles. I was bullish on this wave before and was a little confused as to why the guidance signal dropped the way it did. We’ll see what happens.

Thoughts 

Near the Leeward Islands in the Tropical Atlantic (AL90):
An area of disorganized showers and thunderstorms associated with
a tropical wave is located a few hundred miles east of the Leeward
Islands. Environmental conditions appear conducive for further
development of this system, and a tropical depression is likely to
form this weekend while it moves near or to the north of the
northern Leeward Islands.
* Formation chance through 48 hours...medium..50 percent.
* Formation chance through 7 days...high...70 percent.