ATL: GERT - Post-Tropical - Discussion

[gatorcane]

Last visible loop before sun goes down with popcorn convection starting:

[Steve]

Smells like 2013 all over again.

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

I think you may have drawn this comparison 2013 times already. It would still almost assuredly be wrong on the 2014th. Haha. I just don't see it.

[TheStormExpert]

Anticyclone building overhead, wind-shear should be low until it approaches the NE Caribbean, SAL starting to clear out some, and 850mb vorticity building about 9N, 36W which is too far south of the thunderstorm activity. Add in the unfavorable Atlantic background forcing and you likely have little to no chance of this amounting to much anytime soon.

[TheStormExpert]

Smells like 2013 all over again.

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

I think you may have drawn this comparison 2013 times already. It would still almost assuredly be wrong on the 2014th. Haha. I just don't see it.

Did you read the comments below the tweet?

[stormreader]

Last visible loop before sun goes down with popcorn convection starting:

And on the infrared. And as many have noted, it does look better. I mean it might surprise overnight. Possible that by tomorrow we have a different outlook on this feature.

[AubreyStorm]

‪ECMWF ensembles more aggressive with #Invest99L ‬
Here we go!

[txwatcher91]

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.

Looking through the CIMSS data, the wave axis has been trending closer to a neutral tilt and the vorticity as well. I think that’s why we are finally seeing some convection starting to build. A long ways to go though, we will see what happens tonight.

[Steve]

Yeah I did. But I never said I ever thought 99L would do anything for a while anyway, so that's not really a surprise to me. The outlier ideas came from the GFS and even more so the CMC with the recurve between the US and Bermuda. I distinctly recall discussing the GFS output on this system with Frank2, where I said the GFS would likely keep tending west like it does earlier in the year. And I said today that I didn't expect anything until 75W if ever. So again, I'm not disagreeing with Michael. I'm just amused by how badly you seem to want 2017 to Parallel 2013. I still think 2004 and maybe in some ways 95 and maybe even a hint of 88 all end up better analogs from recent years. One or possibly both of us will be dead wrong.

[gatorcane]

18Z Guidance:

[Kingarabian]

‪ECMWF ensembles more aggressive with #Invest99L ‬
Here we go!

[img]https://pbs.twimg.com/media/DGfqZMiWsAEO1CZ.jpg:large[img]

Less than 5% support for a TS for 99L throughout 240 hours per the 12z EPS.

[Hammy]

Smells like 2013 all over again.

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

I think you may have drawn this comparison 2013 times already. It would still almost assuredly be wrong on the 2014th. Haha. I just don't see it.

Did you read the comments below the tweet?

All it means is that others have a similarly wrong idea.

[Emmett_Brown]

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

This is an interesting solution. I wonder what causes the more northerly component of motion in the near term. Perhaps interacting with an upper low creates the northward component. The 12Z GFS has a stout ridge off of the US E coast at after 150 hours. Assuming this formed, it could continue W long enough to threaten land.

[abajan]

Just an observation. Seems to me that something is trying to organize around 12n 37w ...

Convection is increasing at those coordinates. Should be an interesting night.

[StormTracker]

Just give 99L some time. Remember, patience is a virtue! I think we're all going to look back on this discussion and feel some kind of way when this system does whatever it does...ST

[cycloneye]

Looking better.Let's see if DMAX helps it more.

[Hammy]

Just give 99L some time. Remember, patience is a virtue! I think we're all going to look back on this discussion and feel some kind of way when this system does whatever it does...ST

I'm still thinking this will at least spin up into a depression but not sure when--the models have certainly backed off on development, but at the same time the organization isn't decreasing any.

[floridasun78]

i think we need see how wave do next few days i think this one we need watch

[cycloneye]

8 PM TWO 30%-50%

Shower activity associated with an elongated area of low pressure
located about 1000 miles west-southwest of the Cabo Verde Islands
has become a little better organized during the past 24 hours.
Some additional slow development is possible during the next two to
three days before the system encounters less favorable
environmental conditions during the middle part of next week. This
system is expected to move generally west-northwestward across the
tropical Atlantic Ocean at about 15 mph.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...50 percent.

[AtlanticWind]

Kinda funny, the models now have backed off development significantly and
and the system is finally looking like it is forming.Has some convection and
is becoming more circular. Also spin is definitely evident tonight.

[tarheelprogrammer]

Actually, there is more vorticity with 99L than 90L currently. It has been consolidating all day long just like 90L.