ATL: ISAIAS - Post-Tropical - Discussion

[SFLcane]

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.

And there she goes... That dust has been a killer which it usually is this time of the year. Let’s see if it can pop some convection today. Area around the LLC is fairly moist.

[Aric Dunn]

Looks like everything is consolidating around that LLC.

it has started tapping into that huge moisture plume from the South.

seeing increasing curved low level cloud lines feeding into that area.

looks like only a matter of time now.

[SFLcane]

Looks like everything is consolidating around that LLC.

it has started tapping into that huge moisture plume from the South.

seeing increasing curved low level cloud lines feeding into that area.

looks like only a matter of time now.

Aric you might be on to something here..

[MJGarrison]

I was able to see on the water vapor loop where dry air was causing an issue.
But could someone point out the coordinates of the possible consolidation? I’m having trouble seeing that.


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[Aric Dunn]

Looks like everything is consolidating around that LLC.

it has started tapping into that huge moisture plume from the South.

seeing increasing curved low level cloud lines feeding into that area.

looks like only a matter of time now.

Aric you might be on to something here..

https://iili.io/duauQS.gif

https://re.ssec.wisc.edu/s/c1uCUG

[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.

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.

On the other hand:

 https://twitter.com/AndyHazelton/status/1287714862949425152



 https://twitter.com/cyclonicwx/status/1287743979510009856



 https://twitter.com/MJVentrice/status/1287720862788071424



 https://twitter.com/MJVentrice/status/1287721618916225030

[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.

On the other hand:

https://twitter.com/AndyHazelton/status/1287714862949425152
https://twitter.com/cyclonicwx/status/1287743979510009856
https://twitter.com/MJVentrice/status/1287720862788071424
https://twitter.com/MJVentrice/status/1287721618916225030

Sure but it is going to wrap around.... Might be moist now, wouldn't count on that much longer given the huge amount of SAL it sucked in.

[StruThiO]

I know it's been pointed out repeatedly already, but I cannot get over the areal extent of this thing. Tropical waves the size of Texas in July, folks.

[chaser1]

I think we are reaching a point with this particular disturbance that I was most concerned about prior to the start of the season. Particularly strong easterly trades resulting in potent tropical disturbances to remain low latitude until reaching a point further west in the basin. Then, given more conducive conditions development begins to occur resulting in a greater number of storms to develop or track into the Caribbean thus posing an increased landfall threat to the Greater Antilles, Yucatan, and CONUS. 92L has plenty of time to develop and still pose a primary threat to the Leewards and Puerto Rico but I'm worried that the greater threat may be to Cuba and GOM.

[HurricaneEnzo]

I think we are reaching a point with this particular disturbance that I was most concerned about prior to the start of the season. Particularly strong easterly trades resulting in potent tropical disturbances to remain low latitude until reaching a point further west in the basin. Then, given more conducive conditions development begins to occur resulting in a greater number of storms to develop or track into the Caribbean thus posing an increased landfall threat to the Greater Antilles, Yucatan, and CONUS. 92L has plenty of time to develop and still pose a primary threat to the Leewards and Puerto Rico but I'm worried that the greater threat may be to Cuba and GOM.

Maybe we will have to see. It it gets to the E Carib and is still this disorganized I think it gets shredded or suffers a fate similar to Gonzalo.

[toad strangler]

I think we are reaching a point with this particular disturbance that I was most concerned about prior to the start of the season. Particularly strong easterly trades resulting in potent tropical disturbances to remain low latitude until reaching a point further west in the basin. Then, given more conducive conditions development begins to occur resulting in a greater number of storms to develop or track into the Caribbean thus posing an increased landfall threat to the Greater Antilles, Yucatan, and CONUS. 92L has plenty of time to develop and still pose a primary threat to the Leewards and Puerto Rico but I'm worried that the greater threat may be to Cuba and GOM.

Maybe we will have to see. It it gets to the E Carib and is still this disorganized I think it gets shredded or suffers a fate similar to Gonzalo.

Disorganized waves are already shredded. They may float right on by.

[curtadams]

These huge systems always look really impressive, but they tend to take a long time to get going and often never do. Sometimes even when they look like tropical cyclones they have a hard time forming. I remember when Dolly 2008 looked like a cyclone all the way across the Atlantic, with strong model support, but couldn't actually close off a circulation until it reached the Bay of Campeche. That was also in July, BTW. We all jumped when the NHC raised the chances so quickly but I think they just fell into that same trap.

[ouragans]

Looks like everything is consolidating around that LLC.

it has started tapping into that huge moisture plume from the South.

seeing increasing curved low level cloud lines feeding into that area.

looks like only a matter of time now.

I would say tomorrow with it gets to 50W with SSTs around 28c

[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.

On the other hand:

https://twitter.com/AndyHazelton/status/1287714862949425152
https://twitter.com/cyclonicwx/status/1287743979510009856
https://twitter.com/MJVentrice/status/1287720862788071424
https://twitter.com/MJVentrice/status/1287721618916225030

Also, could just be a case of 'the models aren't always right'. Particuarly when it comes to formation and strength. Sure they are a good guide but often miss the mark. Florence was supposed to hit NC as a Cat 4. Michael wasn't supposed to hit Florida as a Cat 5. Harvey wasn't supposed to explode into a Cat 4. Joaquin was supposed to stay weak. The list goes on and on.

[StruThiO]

 https://twitter.com/TropicalTidbits/status/1287757047354855425




 https://twitter.com/TropicalTidbits/status/1287758263551918081

[supercane4867]

It's organized enough to be classified as a TD. Systems like this are fairly common in the WPAC.

[psyclone]

Another system that did this was the precursor to Hermine in 2016. It was a broad, largely convection free swirl all the way to the Gulf. But spinning is winning in this game. I certainly wouldn't write the potential off. It is fair to say development chances have decreased...but from a high baseline. Out of respect for SAL, the calendar, and the present disarray...reduced development odds are highly likely. But out of respect for the season to date, keep checking back.

[HurricaneEnzo]

It's organized enough to be classified as a TD. Systems like this are fairly common in the WPAC.

With all due respect they are pretty lenient with the TD classification over there. The NHC wants to see something significantly better organized than this.

[aspen]

Could the large size of 92L and the nearby dry air potentially cause it to fragment into two or more areas of vorticity, with one taking over to eventually become a TC?

[SFLcane]

Only a matter of time per Levi. Very impressive circulation with this wave indeed.