Low Pressure in the Central Atlantic (Is Invest 91L)

[SFLcane]

Euro has this right.

[Hurricaneman]

This could be a problem down the road if it breaks the Monsoon Trough. (I'm saying "if" because it could get retrograded back into the larger system at the African Coast.)

Dry air (and/or SAL) is limited ahead of it.
https://s4.gifyu.com/images/g16split.jpg
https://s4.gifyu.com/images/g16split.jpg
Might be outflow already? (Look to the far right)
https://s4.gifyu.com/images/wg8wvir.gif
https://s4.gifyu.com/images/wg8wvir.gif
Impressive convection with a lot of lightning within it. (Is there a circulation with it as well?)
https://s4.gifyu.com/images/53431668.gif
https://s4.gifyu.com/images/53431668.gif

Upper divergence holy cow!

I was thinking of the same thing too, this could be a troublemaker down the road if it keeps going like this. And it's basically Midnight where this system is located! The strong convection appears to be nonstop in the past few hours.

More like the last 24 hrs which really is concerning and I believe the islands need to keep tabs on this for late next week

[IsabelaWeather]

When is DMIN? Is it right as the sun rises, or like 3 or 4 am?

[aspen]

I believe the SW lobe will win out, the NE lobe is fighting dry air a I do believe SAL will get that one while the vorticity with the SW one will increase with little to no dry air to inhibit it

The NE lobe still has the strongest 850mb vorticity signature, so the SW lobe will need to maintain its exceptional convection in order to win out. There’s also some dry air just north of this lobe that might try to sneak its way in. If this looks as good tomorrow morning as it does now, then we could have something brewing.

[skyline385]

Looking at all these weak & broad vorticity centers it is going to need a LOT of consolidating before it starts developing. One of those centers is actually the size of Florida

[Iceresistance]

Upper divergence holy cow!

I was thinking of the same thing too, this could be a troublemaker down the road if it keeps going like this. And it's basically Midnight where this system is located! The strong convection appears to be nonstop in the past few hours.

More like the last 24 hrs which really is concerning and I believe the islands need to keep tabs on this for late next week

Only if it maintains this kind of convection, which I do believe is possible since this area has been mostly untapped this year.

Also appears that the SW area is the dominating system, the NE part of the very broad disturbance is likely the sacrificial part to get the other convective area really going.

[weeniepatrol]

When is DMIN? Is it right as the sun rises, or like 3 or 4 am?

Right as the sun sets, after the heating of the day flattening the temperature gradient between surface and upper troposphere. Right as the sun rises is DMAX from radiational cooling restrengthening the temperature gradient. Remember that convection is a function of vertical temperature difference and it takes less energy to warm / cool the upper levels than surface due to less moisture content (water vapor has a higher heat capacity and there's less of it higher up) and overall less density (pressure is lower higher up)

[InfernoFlameCat]

When is DMIN? Is it right as the sun rises, or like 3 or 4 am?

DMIN is at sunset. DMAX is at sunrise.

[LarryWx]

I believe today's 12Z is the first UKMET run developing this in addition to it still having the other genesis it has had for a couple of days.

[skyline385]

DMAX should be at night as the upper troposphere cools from a lack of solar radiation and enhances the gradient between the warm waters and cooler atmosphere. During the day, the gradient decreases as the atmosphere heats up and this results in DMIN.

If we are talking about the time of day when DMIN is at it's absolute lowest then it should be during sunset as the temperature gradient is lowest then after the sustained heating during the day.

Here is one random article I found which explains it in more detail than what I said above

https://www.carstensweather.com/post/th ... convection

[Landy]

00z GFS may be correcting towards Euro's solution. 850mb vorticity similar with 18z Euro @ 00z Saturday.

[Iceresistance]

Outflow is almost 100% complete on the convective area!


https://s4.gifyu.com/images/wg8wvir-1.gif

Comparison from previous update

https://s4.gifyu.com/images/wg8wvir.gif

(Again, the bottom right corner is where it is)

[skyline385]

0Z ICON is very interesting to say the least

[USTropics]

0Z ICON is very interesting to say the least

https://i.imgur.com/kY3YF1V.png

No more "OMG ITS A DOUBLE FUJIWARA" memes

[skyline385]

Outflow is almost 100% complete on the convective area!

https://s4.gifyu.com/images/wg8wvir-1.gif
https://s4.gifyu.com/images/wg8wvir-1.gif

Comparison from previous update
https://s4.gifyu.com/images/wg8wvir.gif
https://s4.gifyu.com/images/wg8wvir.gif

(Again, the bottom right corner is where it is)

CIMSS has an East Atlantic option for wind analyses



Lots of upper divergence reflecting the large outflow

[Iceresistance]

Outflow is almost 100% complete on the convective area!

https://s4.gifyu.com/images/wg8wvir-1.gif
https://s4.gifyu.com/images/wg8wvir-1.gif

Comparison from previous update
https://s4.gifyu.com/images/wg8wvir.gif
https://s4.gifyu.com/images/wg8wvir.gif

(Again, the bottom right corner is where it is)

CIMSS has an East Atlantic option for wind analyses

https://i.imgur.com/u2J2wGE.png

Lots of upper divergence reflecting the large outflow

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

Yep, I'm watching it, this was unexpected in terms of location, I'm thinking that the NHC may have to have a secondary area of AOI because of that system

[Sciencerocks]

[USTropics]

Looking at all these weak & broad vorticity centers it is going to need a LOT of consolidating before it starts developing. One of those centers is actually the size of Florida

https://i.imgur.com/nkNj4wD.png

Most of the vorticity analyzed there is associated with the monsoon trough and not so much the wave axis. Below I've highlighted the wave axis in pink. Watch for the southern vorticity lobe associated with the monsoon trough here (red), it should pivot north along the wave axis later tonight/tomorrow and then amplify as it pivots towards the southwest further west near 40W:


18z ECMWF through 90 hours shows this evolution excellently:

[Landy]

00z GEM finally woke up and is developing this.

00z GFS seems to have corrected and is developing this as well.

[USTropics]

Hey look, when the GFS doesn't initialize the vorticity down by 9N it actually develops this: