Tropical Wave over the SE Bahamas (Is INVEST 91L)

[cycloneye]

Is not common to see a Tropical Wave analized inside Africa.

[Hurricaneman]

The reason the Euro starts to develop this sooner is that unlike the GFS the Euro goes north of Hispaniola, Puerto Rico and Cuba so that will be the thing to watch for, and if this area strengthens quicker then th Euro track might be the most feasible as it most likely will be a little bit farther north compared to the GFS

[CyclonicFury]

Models currently don't do much with this, at least not in the short term, but this is likely a wave that might have to be watched when it gets farther west. Sometimes models do not pick up waves until they emerge into the Atlantic, so that's still a possibility with this one. NHC must be seeing something to think it warrants a TWO mention, though. It's the first time this year I have seen them mention a wave while it is still over Africa.

It will be interesting to see if this gets an invest designation after splashdown. I don't think this will be one of those waves that rapidly develops near Cabo Verde.

[floridasun78]

let see what do when hit water we seen a lot come apart when their move into ocean

[AutoPenalti]

Models currently don't do much with this, at least not in the short term, but this is likely a wave that might have to be watched when it gets farther west. Sometimes models do not pick up waves until they emerge into the Atlantic, so that's still a possibility with this one. NHC must be seeing something to think it warrants a TWO mention, though. It's the first time this year I have seen them mention a wave while it is still over Africa.

It will be interesting to see if this gets an invest designation after splashdown. I don't think this will be one of those waves that rapidly develops near Cabo Verde.

Well, I'm 100% positive that the folks at the NHC don't issue TWO's solely on models run, so they must be, like you said, looking at something that neither us or the models see at the moment.

[cycloneye]

@AndyHazelton
The wave moving off Africa tomorrow is firing convection (likely enhanced by the Guinea Highlands) and seems to have broad rotation. NHC has highlighted it for a 20% chance of development within 5 days, and the 10-day ECMWF maintains the signature to the Bahamas. Worth watching.

 https://twitter.com/AndyHazelton/status/1032442539876524032




@AndyHazelton
One positive for this wave is it is more of a "southern track" wave, and thus may have better moisture/SST around than other waves recently. The MDR is still rather stable, however, which may explain why global models are lackluster about the short term development.

 https://twitter.com/AndyHazelton/status/1032445588439289856

[smithtim]

Is not common to see a Tropical Wave analized inside Africa.

^ yep! And,
I think the words normal and common can just be pretty much thrown out now when talking about tropical cyclones ( or maybe weather in general ).

I've frequently monitored clouds patterns in western Africa and watched them quickly become invets, TS or whatever once hit water, but I don't ever recall NHC putting an invest like this? Regardless, this is very odd to see, and definitely worthy to monitor closely... welcome to 2018 cape verde???????

[AnnularCane]

Is not common to see a Tropical Wave analized inside Africa.

^ yep! And,
I think the words normal and common can just be pretty much thrown out now when talking about tropical cyclones ( or maybe weather in general ).

I've frequently monitored clouds patterns in western Africa and watched them quickly become invets, TS or whatever once hit water, but I don't ever recall NHC putting an invest like this? Regardless, this is very odd to see, and definitely worthy to monitor closely... welcome to 2018 cape verde???????

It doesn't happen often, but it's not the first time. I've seen yellow and even orange circles for waves still over Africa before.

[Hurricaneman]

Looks like the 0zGFS doesn’t do much with this after 96 hrs

[cycloneye]

00z ECMWF mantains integrity of wave on day 10 in Florida straits.

[cycloneye]

NWS San Juan discussion about effects of wave in Puerto Rico.

On Tuesday night surface flow turns more east northeast as a
tropical wave approaches the area with the best moisture since at
least last week. This will cause a considerable increase in shower
and thunderstorm activity Tuesday night through Thursday. The
tropical wave will have deep moisture even if the TUTT low, that
was just northwest of the area on Tuesday retreats to the
northwest and enlarges over the western Atlantic just north of 25
north, leaving less than optimal upper level dynamics to enhance
convection. Nevertheless, at this time the GFS has a lifted index
of minus 10 at 30/18Z. If this should hold, some thunderstorms
could yield small hail and gusty winds along with the usual urban
and small stream flooding in west northwest Puerto Rico.

[wxGuy]

GFS maintains and takes this one to Texas coast

[Dean4Storms]

NHC is paying more attention to this wave due to many factors, lower latitude, SST's in the MDR are now pretty much 27C+ and nearing their peak and SLP forecasts are showing lowering pressures in the MDR over the next few weeks.

[cycloneye]

Down to 10%.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Thu Aug 23 2018

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

A tropical wave is forecast to emerge off the west coast of Africa
early Friday and then move quickly westward at about 20 mph. No
development is expected during the next few days, but environmental
conditions could become a little more conducive for some development
of the wave early next week over the central tropical Atlantic
Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...10 percent.

$$
Forecaster Berg

[abajan]

They need something to update regularly or they'll get too bored just like the rest of us
...

The NHC is a professional organization. They don't operate like that. But I guess you were just saying it in jest.

[Dean4Storms]

Looking at the forecast pattern of a large ridge over the eastern CONUS the first week of Sept. I would suspect a western Gulf or LA to MX area would want to really keep an eye on this system. Noted many ECM ENS with a low in the Gulf come the 5th of Sept. with 9 of them with a Low in the central or northern Gulf with 3 Lows in the BOC.

[cycloneye]

Some rotation is seen in visible loop.

[cycloneye]

12z GFS has zero development but mantains wave all the way to just south of Corpus Christi,Texas.

[CyclonicFury]

This may be a case of a wave that struggles in the MDR but develops farther west. I think TC genesis is highly unlikely for the next 5-7 days but after that time it may need to be watched if it finds a more favorable environment farther west. This wave is likely to be nearly devoid of deep convection at times while it moves quickly through the MDR.

[TheStormExpert]

Sounds in ways similar to Harvey which managed though to briefly spin-up near the Lesser Antilles then degenerated until it reached the western Gulf.