ATL: ISAIAS - Post-Tropical - Discussion

[CourierPR]

The latest satellite images seem to suggest the system is getting better organized with increasing convection.

[HurricaneFrances04]

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

Multiple storms have survived "the shredder" as other factors are often involved. Fay in 2008 spent the beginning part of its life over the length of Hispaniola and was no worse off

[Evil Jeremy]

Stewart is the GOAT. Can he be a bit aggressive with his forecasts? Sometimes. Do I hold that against him? No. He's had his eye on every storm that's RI'd for decades. Well, except for the nearly 2 years he spent in Iraq with the Navy, right in the middle of his NHC tenure. I don't blame him for forecasting with upside in mind. And he more than justifies his decisions in the discussions. He is detail oriented, and leaves nothing behind, while also writing in an engaging fashion.

[toad strangler]

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

Multiple storms have survived "the shredder" as other factors are often involved. Fay in 2008 spent the beginning part of its life over the length of Hispaniola and was no worse off

https://upload.wikimedia.org/wikipedia/commons/6/63/Fay_2008_track.png

Well developed cyclones have much more to lose over those mountains.

[SFLcane]

From the discussion:

Although the GFS-and ECMWF-based SHIPS intensity
guidance shows considerable southwesterly vertical wind shear of
20-30 kt in the 72-96 h period when the disturbance is over the
Straits, the global model fields show that this is self-induced
shear caused by the SHIPS model incorporating the system's
impressive upper-level outflow winds in its shear calculations. As a
result, this is not being considered a negative intensity factor
compared to land interaction.

was just going to post this.

means the models are messed up on intensity..

Is this something that happens frequently? I've been paying close attention to the tropics (including on this forum) for 16 years now and I can't remember hearing that SHIPS or any intensity guidance was incorporating "self-induced" shear.

Stacy means that the way they average it, some of the outflow from the TC itself is being incorrectly counted as shear in SHIPS.

[BobHarlem]

Trying to figure out what the intensity section of that discussion is implying, is Stewart basically saying that the massive size of the system is causing the intensity models to feedback on the outflow and create modeled shear that doesn't really exist, and that the intensity forecast may be on the low side once past Hispaniola? Shredder works on organized systems, something this massive and disheveled may not be impacted quite so much.

If so It's nice that Stacy likes to share a lot about the fake shear with the sheer size of the system,

[Hd444]

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

Hispanola helps tropiccal waves consolidate as it slows the axis down. This is not a tropical system yet, think before you knock Stewart. He is the best one there.

[sma10]

The NHC’s 11pm update was not what I was expecting. PTC-9 is forecast to turn north and go through the Greater Antilles. However, it passes right over the DR, and the NHC bumps its peak intensity to 55 kt.

I was anticipating either death by DR or a Caribbean Crusier, potentially trying to make landfall in Cuba.

Interaction with DR is very tricky. There's a theory that it's more harmful to a system (relatively speaking) when it has an established core than it is to a nascent system. We'll see. Additionally, it doesn't hurt PTC 9's cause if it is still skipping along at a very brisk pace during the encounter

[Craters]

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

If it were a disorganized thing before Hispaniola, it would be a disorganized thing after Hispaniola. What would be the difference, really? It'd still have to organize itself one way or the other -- shredder or no shredder.

[MGC]

As I suspected, a shift to the left of the forecast track. Would not be surprised if the track is shifted even further west. PTC9 will have a hard time closing off until it slows down in a day or two......MGC

[floridasun78]

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

Hispanola helps tropiccal waves consolidate as it slows the axis down. This is not a tropical system yet, think before you knock Stewart. He is the best one there.

Stewart been nhc for years he one best at nhc

[blp]

This is finally consolidating.

[toad strangler]

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

If it were a disorganized thing before Hispaniola, it would be a disorganized thing after Hispaniola. What would be the difference, really? It'd still have to organize itself one way or the other -- shredder or no shredder.

A lot can be said about momentum. A well developed cyclone is shocked slamming into high mountainous terrain. That negative unraveling momentum is much more difficult to turn around and ramp back up. The weak system doesn't have to overcome it's own negative unraveling to tighten up.

[Vdogg]

Gotta love Stewart.

Stewart is by far the most bullish at NHC, it seems.

That would explain his forecast. How can it survive the shredder?? This thing is all but certain to die before it reaches 20N.

Nothing, in any way, is certain at this point.

[WxEp]

was just going to post this.

means the models are messed up on intensity..

Is this something that happens frequently? I've been paying close attention to the tropics (including on this forum) for 16 years now and I can't remember hearing that SHIPS or any intensity guidance was incorporating "self-induced" shear.

Stacy means that the way they average it, some of the outflow from the TC itself is being incorrectly counted as shear in SHIPS.

I got that - thanks. My question is does TC outflow frequently get incorrectly counted as shear in SHIPS or other intensity guidance? I have not heard of this happening before today.

[sma10]

This is finally consolidating.

https://i.ibb.co/qrXK6KN/mimictpw-natl-latest.gif

Levi had mentioned he expected the circulation to take on a more rounded, north-south orientation tonight ...

[CM2]

So something that has to be stated from the NHC Discussion https://www.nhc.noaa.gov/mobile/refresh/MIATCDAT4+html/MIATCDAT4_290253.html

the GFS-and ECMWF-based SHIPS intensity guidance shows considerable southwesterly vertical wind shear of 20-30 kt in the 72-96 h period when the disturbance is over the Straits, the global model fields show that this is self-induced shear caused by the SHIPS model incorporating the system's impressive upper-level outflow winds in its shear calculations.

So essentially, all the models are very wrong and are infact giving quite conservative intensification forecasting because there is forcasted shear that doesn't exist.

Truly a crazy time we live in.

[Hurricaneman]

My new forecast for this is that it goes just south of Puerto Rico but over Hispaniola as a disorganized system but forms a low north of Hispaniola and makes landfall in Key West and moves north to make a second landfall just north of Tampa

Intensity is the hardest part as I don’t think much comes of this before Hispaniola but I’m going along with the intensity models afterwards but a little more conservative than those models

Now. PTC 40mph
12hrs PTC. 40mph
24hrs. TS. 40mph South of Puerto Rico
36hrs. TD 35mph over Hispaniola
48hrs. TD. 35mph reforms N of western Hispaniola
72hrs. TS. 50mph
96hrs. TS. 65mph near Key West
120hrs. C1. 80mph Tampa
144hrs. TD. 35mph over Georgia

I see this as most plausible

[CM2]

Double post :/

[tropicwatch]

Is this something that happens frequently? I've been paying close attention to the tropics (including on this forum) for 16 years now and I can't remember hearing that SHIPS or any intensity guidance was incorporating "self-induced" shear.

Stacy means that the way they average it, some of the outflow from the TC itself is being incorrectly counted as shear in SHIPS.

I got that - thanks. My question is does TC outflow frequently get incorrectly counted as shear in SHIPS or other intensity guidance? I have not heard of this happening before today.

In this case I can see it due to high above PTC Nine and the ULL to its northwest.