ATL: GERT - Post-Tropical - Discussion

[TheStormExpert]

Video discussion by Tropical Tidbits Levi Cowan.

 https://twitter.com/tropicaltidbits/status/893895793819750401

[gatorcane]

North of Puerto Rico at 144 hours:

[BobHarlem]

The 12 z gfs and euro are a lot more aligned now than ever, although the euro is surprisingly slightly north and slower than the GFS. Land interaction with the Caribbean probably will be the qualifier if it really ever gets going or not.

[gatorcane]

168 hours:

[OuterBanker]

Just an observation. Seems to me that something is trying to organize around 12n 37w. Convection is on the increase and what appears to be banding on the outside perimeter.

Probably just seeing things. But if it does it the latitude will be further north than I assumed it would be. So far it has seemed to hang around 10n.

[Siker]

Change from previous Euro runs is that shear looks pretty darn favorable once this is in the vicinity of Hispaniola and Cuba and beyond into the Gulf. Dry air and land entanglement probably preventing development there this run.

[Steve]

I'd wait until 75W before writing it off. It it rides low, I could see something forming later on. Could be a sacrificial low for down the line just the same. But I think anything getting toward the big islands will have potential going forward. Not much model support other than the CMC for anything of note. And you better take that with a shaker of salt.

[RL3AO]

It looks better than yesterday. And by that, I mean it only looks like garbage compared to complete utter garbage yesterday.

[tiger_deF]

99L is actually beginning to fire convection at its 'center'. Still looks pretty bad, but unlike yesterday when it pretty much didn't exist the wave actually looks like a wave. vorticity is on the rise as well

[gatorcane]

It looks somewhat better today I agree. What we we need to watch out for is possible development downstream if it manages to avoid the Greater Antilles north or south. Any kind of low-level vort the models are showing moving into an area such as the Bahamas needs close monitor this time of year.

[Nimbus]

The large circulation pulled some dryer air in from the north and I don't think anyone has been expecting much till -45w where the moisture content is higher. The mid Atlantic TUTT may provide some lift and even an outflow channel before the islands. That probably was the bullish GFS and HWRF scenario a couple runs ago. Current thinking appears to be no closed circulation, no model support..

[bamajammer4eva]

Change from previous Euro runs is that shear looks pretty darn favorable once this is in the vicinity of Hispaniola and Cuba and beyond into the Gulf. Dry air and land entanglement probably preventing development there this run.

Looks like 99L's tour of all of the big islands of the Caribbean on both GFS and Euro could be why both models never develop it but now the Euro at least keeps the vort identifiable all the way into the Gulf. Probably something the NHC will keep an eye on and keep a mention in their outlooks for a while.

[Steve]

Agreed. There was an early shot for development, but I think that's passed for now. I'm watching it too but I doubt anything happens for at least 6 or so days.

[txwatcher91]

Vorticity is becoming a bit stronger and the axis is beginning to consolidate better now. It could begin organizing tonight if trends continue.

[abajan]

It looks better than yesterday. And by that, I mean it only looks like garbage compared to complete utter garbage yesterday.

You're right. That's what I observed earlier this afternoon before I commented that it seemed to be consolidating.

[AJC3]

Vorticity is becoming a bit stronger and the axis is beginning to consolidate better now. It could begin organizing tonight if trends continue.

Two things you would look for toward that end...

1) Obviously, consolidating of the vorticity, higher values. Thunderstorms along the central and southern flank of the wave axis would help increase convergence and thus vorticity.

2) Also, the wave axis trending toward more of a neutral tilt with time. From strictly a fluid mechanics standpoint, the environment needs to be favorable so that deformation stress can push the northern flank of the wave axis forward relative to the rest of the wave. In other words, the ambient easterly component to the wind flow needs to be stronger, the farther north along the wave axis you go, for the entire length of its axis. This would increase convergence as well.

So far, this hasn't occurred enough to allow the wave to organize. Also, it seems to me that the overall thermodynamic environment hasn't been all that great this far, as has been pointed out by others several times.

[AtlanticWind]

https://www.tropicaltidbits.com/analysi ... 0&ypos=179

HWRF in about 5 days, would make nervous if it looked like this in 5 days.

[gatorcane]

12Z UKMET with development again with west turn at the end:

[TheStormExpert]

Smells like 2013 all over again.

 https://twitter.com/pppapin/status/893915338567450624

[northjaxpro]

I agree that for the short term, we are probably not going to see development from this entity 99L.

HOWEVER, I would not yet put in a call to Bones, like someone referenced earlier on this thread of doing. I think what the EURO is showing of a decent semblance of vorticity moving west during the next several days needs to watched very closely. Conditions look to gradually get better with shear once the system traverses by 70 degrees Longitude.

Do not be lulled to sleep regarding 99L!! There is still a window possibly for this entity to get its act together next week!!