ATL: ISAIAS - Post-Tropical - Discussion

[Evan_Wilson]

Seeing a few minor bursts of convection in 92L this morning, if this thing can literally pull itself together it might have a chance.

[Aric Dunn]

There is some convection building over that llc about 11N some low level cloud line to the SE pulling in moisture through that boundary.

let see if this continues to increase.

[TheStormExpert]

I was looking at the dust forecast last week and wondering how in the world was 92L going to develop in the middle of the MDR with so much dust being forecasted to come out of Africa with it so I was skeptical about development or at surviving for too long with so much dry dusty air surrounding it and that's what the Euro finally started seeing.
The energy is strong so it may have to be watched when it gets to the western basin if the not the Lesser Antilles.

https://i.imgur.com/puLMCqV.jpg
https://i.imgur.com/Au0fEzA.gif

It seems like SAL this year just doesn’t want to let up. I know people will say it’s late-July but a decline should be expected by now if not very soon.

Is normal, back in 2017 late July through the third week of August the middle of the MDR was very dusty, the reason the Atlantic's MDR didn't really got going until late August.

https://i.imgur.com/BX9gk5N.png

Ok. It just seems like it’s been relentless over the past month or so. Not to mention there’s been a lot of mid-level dry air which I assume is due highly in part to the SAL?

[TheStormExpert]

We will see Mr. Ventrice...bust?

The convectively active phase of the Kelvin wave that spawned Hurricane #Douglas over the East Pacific is now passing the Atlantic basin. Watch for another Atlantic tropical cyclone to spawn over the Main Development Region today or tomorrow.

https://twitter.com/mjventrice/status/1 ... 71424?s=21

He hugs these Kelvin Waves to no end.

We might see a TD or a weak short-lived TS form from 92L but I’ve grown highly skeptical of anything significant forming from it despite the favorable Kelvin Wave.

[plasticup]

Amazing to see the forum turn so bearish on an objectively strong feature

[Evil Jeremy]

It does seem odd in hindsight that NHC hiked the 48 hour % so quickly... I remember Saturday it went from 10% at 8am to 50% at 8pm without the kind of increased organization that usually accompanies such jumps in such a short timespan. I don’t think 92L is much closer to development now than it was Saturday morning. Which is good news for those in the NE Caribbean. NHC kind of backed themselves into a corner with that 8pm TWO on Saturday.

[Evan_Wilson]

Amazing to see the forum turn so bearish on an objectively strong feature

Agreed, this is an incredible invest in which professionals are labeling as a 90% chance of development. The invest nor is this season dead.

[Ritzcraker]

We will see Mr. Ventrice...bust?

The convectively active phase of the Kelvin wave that spawned Hurricane #Douglas over the East Pacific is now passing the Atlantic basin. Watch for another Atlantic tropical cyclone to spawn over the Main Development Region today or tomorrow.

https://twitter.com/mjventrice/status/1 ... 71424?s=21

He hugs these Kelvin Waves to no end.

We might see a TD or a weak short-lived TS form from 92L but I’ve grown highly skeptical of anything significant forming from it despite the favorable Kelvin Wave.

I hope this ages well...

[NDG]

It seems like SAL this year just doesn’t want to let up. I know people will say it’s late-July but a decline should be expected by now if not very soon.

Is normal, back in 2017 late July through the third week of August the middle of the MDR was very dusty, the reason the Atlantic's MDR didn't really got going until late August.

https://i.imgur.com/BX9gk5N.png

Ok. It just seems like it’s been relentless over the past month or so. Not to mention there’s been a lot of mid-level dry air which I assume is due highly in part to the SAL?

Yes, it is due to the SAL outbreaks, for the most part.

[Aric Dunn]

Amazing to see the forum turn so bearish on an objectively strong feature

Agreed, this is an incredible invest in which professionals are labeling as a 90% chance of development. The invest nor is this season dead.

Everyone just watched a broad mess of crap turn into nearly a CAT 2 in a couple days.

This happens every year.. if it is not perfect nearly everyone flip flops with every model run and puff of cloud..

[TheStormExpert]

Is normal, back in 2017 late July through the third week of August the middle of the MDR was very dusty, the reason the Atlantic's MDR didn't really got going until late August.

https://i.imgur.com/BX9gk5N.png

Ok. It just seems like it’s been relentless over the past month or so. Not to mention there’s been a lot of mid-level dry air which I assume is due highly in part to the SAL?

Yes, it is due to the SAL outbreaks, for the most part.

Ok, thanks for the insight!

[ouragans]

 https://twitter.com/tropicalupdate/status/1287736259696353280

[ouragans]

PTC at 15z?

 https://twitter.com/268Weather/status/1287733370471030785

[cycloneye]

12a Best Track: 12.0N-45.0W

AL, 92, 2020072712, , BEST, 0, 120N, 450W, 25, 1009, DB, 34, NEQ, 0, 0, 0, 0, 1011, 180, 150, 35, 0, L, 0, , 0, 0, INVEST, S

[alan1961]

I believe the flow from the ITCZ is keeping this from completely fizzling out,
if it stays close enough to that feed of moisture then it can build into something
better, its certainly getting a move on and it may end up going a touch more south
and weaker than the models seem to show.

[wxman57]

It is failing to consolidate. Ingesting a lot of dry Saharan air. Moving too quickly. Less model support for development and strengthening today. NHC will begin gradually lowering development chances, which I agree with. Perhaps I will be able to take some of the 5 comp days I've accrued over the past 2 weeks.

[HurricaneEnzo]

Amazing to see the forum turn so bearish on an objectively strong feature

Agreed, this is an incredible invest in which professionals are labeling as a 90% chance of development. The invest nor is this season dead.

Nobody is saying the season is dead because we are skeptical this invest forms....

Massive circulations like this often have trouble consolidating in the best of conditions. Just look at Hanna, while it overperformed in the end it wasn't until it neared the Texas coast that it really got its act together in a big way. Hanna had conditions more favorable than this invest is in.

This huge circulation just pulled in a massive amount of SAL in on its Western side. It is largely unorganized and devoid of any significant convection and model enthusiasm is waning. I don't blame anyone who is currently skeptical of formation.

[gatorcane]

92l looks to be succumbing to the SAL and mid-level dry air as I thought it probably would from the very beginning when it rolled off Africa. It may still find some favorable conditions further west later this week and into the weekend but development chances looks low for the next several days if not longer. Be cautious using the upgraded ECMWF and long-range ensembles as this invest has proven!

[Shell Mound]

Let’s assume, hypothetically, that 92L somehow ends up doing nothing. If that were the case, then why would the global models overestimate 92L but underestimate the precursor to Hanna, which was similarly expansive? Why, for instance, would the GFS consistently underestimate Hanna but overestimate 92L, given that PWATs were generally higher in association with Hanna’s vs. 92L’s environment? So far I can’t find a logical explanation for this discrepancy. Given that Hanna presumably was in a more conducive environment than 92L has been, why would the global models underestimate Hanna but overestimate 92L? Something doesn’t add up.

[HurricaneEnzo]

Let’s assume, hypothetically, that 92L somehow ends up doing nothing. If that were the case, then why would the global models overestimate 92L but underestimate the precursor to Hanna, which was similarly expansive? Why, for instance, would the GFS consistently underestimate Hanna but overestimate 92L, given that PWATs were generally higher in association with Hanna’s vs. 92L’s environment? So far I can’t find a logical explanation for this discrepancy. Given that Hanna presumably was in a more conducive environment than 92L has been, why would the global models underestimate Hanna but overestimate 92L? Something doesn’t add up.

My theory is the models are missing a huge portion of data because of significantly reduced flights because of the pandemic and it is causing them some big issues. Sure they have hit on some stuff but also been wildly inconsistent lately.