ATL: HARVEY - Post-Tropical - Discussion

[wxman57]

They are predicting this to become a category 1 Hurricane as of now !

They went with the statistical SHIPS guidance for intensity. It's often quite poor. Dynamic models aren't developing it much. Most guidance is clustered around 40 kts for peak intensity. A few ensemble members indicate up to hurricane strength.

What's your take on it ?

If it tracks north of Honduras toward Belize, then I wouldn't rule out hurricane strength. I'd forecast below hurricane strength for now.

[Aric Dunn]

I am not surprised in the least.. moderate TS into islands tomorrow..

[RL3AO]

Probably the most I've seen the NHC ignore the GFS and Euro when they agree. They're very skeptical of the models right now. After Gert (and the entire life-span of 99L), I can see why.

[p1nheadlarry]

If I had to guess, I would say the circulation is closed. Would like to see an ASCAT pass though to confirm. This disturbance has exceeded my expectations so far. I agree with the NHC in raising the development percentages. This case also closely follows Dr. Michael Ventrice's research that TC genesis is likely 2 days after the passage of a convectively coupled Kelvin wave.

Makes some sense, there are westerlies that eventually rise on the west side of the cckw right?

[psyclone]

Looks like Franklin V 2.0 late in the forecast.

[Aric Dunn]

Recon likely to find a 50mph TS.

[GCANE]

Cumulus Nimbus filling in on the N & NE of the CoC.
Perhaps from forced updraft.

[Thetxhurricanemaster]

Recon likely to find a 50mph TS.

I think they will find a 40KT tropical storm maybe 45KT

[RL3AO]

Makes some sense, there are westerlies that eventually rise on the west side of the cckw right?

I haven't had a chance to dig into much, but I'd guess the large scale ascent in the eastern Atlantic helped the wave overcome the anomalously dry air present. Of course how much of that ascent was due to the MJO/Kelvin wave is impossible to answer and hard enough to guess at.

[chaser1]

I think the forecast seems quite Beliz-able. Probably does struggle some under the still strong easterly shear unless the low level COC can remained aligned with it's mid level. Not a particularly large convective envelope to protect itself thus far. Better upper conditions and a more moist environment might better allow for greater intensification at the time it reaches the W. Caribbean. Though minimal, i'd guess that if there were any threat to the U.S. that it could possibly be to the lower Texas coastline. Too far out to really see whether this system will maintain its integrity all the way to the W. Caribbean yet or whether it'll gain a bit of latitude during that time.

[Thetxhurricanemaster]

I think the forecast seems quite Beliz-able. Probably does struggle some under the still strong easterly shear unless the low level COC can remained aligned with it's mid level. Not a particularly large convective envelope to protect itself thus far. Better upper conditions and a more moist environment might better allow for greater intensification at the time it reaches the W. Caribbean. Though minimal, i'd guess that if there were any threat to the U.S. that it could possibly be to the lower Texas coastline. Too far out to really see whether this system will maintain its integrity all the way to the W. Caribbean yet or whether it'll gain a bit of latitude during that time.

I agree 100%

[chaser1]

Fragile vertical structure largely in part to its fast motion and pulsating convection not withstanding, I really believe that the forecast itself underplays the potential deepening that could occur with this system (even within the E. Caribbean). Of course should that happen, chances are that the models will suddenly latch on to the storm with reasonable forecasts to follow).

On another note, this was the first time that the new Potential Tropical Cyclone designation was used that I found to be far more appropriate manner, and with some near term manner (aircraft) intended to verify either way what the intensity and overall structure is.

[GCANE]

Wider radius of west winds kicking in quickly.

[Aric Dunn]

Wider radius of west winds kicking in quickly.

yeah we have a deepening TC. still going with a moderate TS into islands. mostly do to the forward motion and shear. has enough convergence and low level moisture so that the dry air won't have too much of an impact.

[chaser1]

Wider radius of west winds kicking in quickly.

yeah we have a deepening TC. still going with a moderate TS into islands. mostly do to the forward motion and shear. has enough convergence and low level moisture so that the dry air won't have too much of an impact.

I"m with you guys as far as overall appearance. I'm still on the fence though whether a closed circulation fully exists at the surface. The more I look at this the more evident how small the core is. If that convection that is seemingly right over (or to the left of) the COC goes through any diurnal minimum any time soon, it just might be fragile and small enough to not maintain vertical integrity yet. On the other hand, if this system can manage to build a more convective envelop today/tomorrow, than it may well be off to the races. Vortex message and sampling of the environment will be pretty telling.

[SouthDadeFish]

It's pretty clear to me that PTC 9 is actually a TC now. The low-level circulation continues to become better defined on visible satellite imagery. There are also some signs of banding starting to form in the northern semicircle.

[Hammy]

Not sure why they went with a PTC here since it's clearly closed already based on satellite, and has been since at least early this morning.

Recon likely to find a 50mph TS.

I think they will find a 40KT tropical storm maybe 45KT

When's the plane fly out?

[SouthDadeFish]

GMI got a nice pass on PTC 9 earlier this morning. Although convection isn't particularly robust, you can tell the structure was there.

[Aric Dunn]

Not sure why they went with a PTC here since it's clearly closed already based on satellite, and has been since at least early this morning.

Recon likely to find a 50mph TS.

I think they will find a 40KT tropical storm maybe 45KT

When's the plane fly out?

Just took off from barbados it looks like. so a short flight out there.

[GCANE]

SW Outflow quickly kicking in.
All from the Convection.
No ULLs equatorward that would be assisting this.