ATL: EARL - Post-Tropical - Discussion

[cycloneye]

8 PM TWO:

1. Central Tropical Atlantic:
Shower and thunderstorm activity associated with an elongated area
of low pressure located several hundred miles east of the Lesser
Antilles has increased since yesterday. Although environmental
conditions are only marginally conducive, additional gradual
development of this system is expected and a tropical depression
is likely to form within the next few days. The disturbance is
forecast to move slowly toward the west and then west-northwest
at 5 to 10 mph, toward the adjacent waters of the northern Leeward
Islands. Additional information on this system can be found in High
Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...80 percent.

[Sciencerocks]

[tolakram]

Might have a race on our hands. I think the area in the central subtropical Atlantic will get named first.

[cycloneye]

Might have a race on our hands. I think the area in the central subtropical Atlantic will get named first.

The other thing is the race to get named before August is over.

[Teban54]

Might have a race on our hands. I think the area in the central subtropical Atlantic will get named first.

The other thing is the race to get named before August is over.

At this point I would rather have the historic rarity of a dead August followed by a very active September in NS counts, 1961-style.

[MJGarrison]

Might have a race on our hands. I think the area in the central subtropical Atlantic will get named first.

The other thing is the race to get named before August is over.

Only 24 hours left in this race. It just hit 0z Aug 31.


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[ScottNAtlanta]

It looks like it could be a depression now. Has some good outflow. The convection is weighted just a tad to the east of the center, but it has really tightened up.

[Hammy]

It looks like it could be a depression now. Has some good outflow. The convection is weighted just a tad to the east of the center, but it has really tightened up.

Probably need another ascat pass to confirm, it was pretty elongated earlier. But certainly getting there

[BobHarlem]

The convection blob from overnight collapsed this morning, it's back to not looking too hot with 3 convective areas, the one that was obvious last night was the northern area, which is where it'll likely refire later today. No named storms in August it is.

[Blown Away]

Latest.

[cycloneye]

Central Tropical Atlantic:
Shower and thunderstorm activity associated with an area of low
pressure located several hundred miles east of the Lesser Antilles
has changed little this morning. Although environmental conditions
are only marginally conducive, additional gradual development of
this system is expected and a tropical depression is likely to form
within the next couple of days. The disturbance is forecast to move
slowly toward the west-northwest, toward the adjacent waters of the
northern Leeward Islands. Additional information on this system can
be found in High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...80 percent.

[MarioProtVI]

Almost as soon as the old convection collapsed new convection is firing again closer to center. Might be close to becoming a TD but I think it will be named Earl since 93L might be Danielle first.

[USTropics]

The forecasted interaction with the upper-level low is beginning to show its teeth this morning. The system is resembling more of a wave axis at the lower levels, albeit with maxima vorticity still favored on the northern flank:





Moving further up in the atmosphere, the mid-upper levels remains severely disorganized due to the inhibiting shear from the ULL:


The environment out in front of this system remains rather hostile for the next few days, with extremely low RH values:


We can already see on visible satellite imagery the system is having a difficult time rotating convection upshear, which leaves the main low-level circulation on the leading edge of the convection. In order for true TCG, we need tilt reduction through a vortex merger process (i.e., a singular closed circulation from 950-500mb). With the mid-level circulation offset/weak, the flow configuration doesn't allow for optimal near-surface vortex stretching or deep updrafts. Surface entropy budget (both moist entropy and entropy from surface fluxes) play a part in this evolution, and you can read this article from Rios-Berrios et al. (https://agupubs.onlinelibrary.wiley.com ... 16JD025065) on more of the specifics of a developing tropical system in the face of vertical shear:


TL:DR: Before TCG can occur the wave axis will likely need to transition from it's positive tilt (a natural occurrence as the wave propagates westward in the region) as well as a reduction in upper-level shear.

[aspen]

On visible, it looks like the circulation is focusing more to the northern lobe. It’s still broad but isn’t as squished as it has been for the last few days, and convection is finally favoring one side over the other. Last night’s blowup was impressive, but it didn’t favor any part of the circulation.

[cycloneye]

ASCAT missed.

 https://twitter.com/TorenWX/status/1564999878568251397

[Iceresistance]

ASCAT missed.

https://twitter.com/TorenWX/status/1564999878568251397

Also missed 93L as well.

[Sciencerocks]

[BobHarlem]

Starting to recover some convection, but there's still a lot going against it (WV helps see it with the dry air and the upper level low)

[IsabelaWeather]

Starting to recover some convection, but there's still a lot going against it (WV helps see it)

https://i.imgur.com/YwLz2u1.gif

The dry air doesnt seem like a problem, the dry air has no way into the storm and its created a nice pocket of moist air.


Also looks like it's still moving due W to me.

[Fancy1001]

12 hours remaining, and this will be the first August in 25 years without a name storm and if I’m correct the first August on record with no name storms during a La Niña. Weird.