ATL: HARVEY - Models

[HurricaneBrain]

I would say it's the dry air to the west that causes the GFS to open it into a wave, but the dry air around Harvey right now is already drier than what's west of it...

I'm looking closer at the GFS and trying to figure out why it opens up the system into a wave.




I'm perplexed. We have a tropical storm entering the Caribbean with ever increasing mid-level moisture, decreasing shear, and an unstable environment. Even the VP anomalies show divergence over the Caribbean in the GFS forecast.

It appears to be producing limited convection unlike the waves in the eastern Atlantic which it has been over-doing convection with. I'm lost. Any other mets have an idea?

[NDG]

The model to follow is the HWRF, IMO.

[tolakram]

GFS running.

[tolakram]

Here is the trend GIF.

[Hurricaneman]

Here is the trend GIF.

Definitely stronger this run

[NDG]

As usual the GFS finally starts picking up the system late, but better than never.

[tolakram]

Weakening after 32 hours, Shear climbing ... uh, no, depends on where I place cursor of course.

[tolakram]

Significantly stronger than previous run.

[NDG]

No open wave on the latest run from the GFS, BTW the hr 12z GFS run only had it completely open for just a few hours in the central Caribbean.

[tolakram]

Open again past 72 hours.

[Blown Away]

No open wave on the latest run from the GFS, BTW the hr 12z GFS run only had it completely open for just a few hours in the central Caribbean.

Maybe a TD at 78 hours... GFS still keeping system weak..

[Alyono]

GFS somehow starts weakening the storm once it moves under the upper high. It's like it cannot handle barotropic dynamics and can only intensify systems in shear environments with troughs

[wxmann_91]

I'm looking closer at the GFS and trying to figure out why it opens up the system into a wave.




I'm perplexed. We have a tropical storm entering the Caribbean with ever increasing mid-level moisture, decreasing shear, and an unstable environment. Even the VP anomalies show divergence over the Caribbean in the GFS forecast.

It appears to be producing limited convection unlike the waves in the eastern Atlantic which it has been over-doing convection with. I'm lost. Any other mets have an idea?

At least in the first image it looks like there's 25kt around 300mb so there's some mid-level shear there. But yeah, it's a bit perplexing. Maybe they're capturing some inhibition for robust convective development and sustainment. This is the deep tropics, which tend to be less favorable for TC development than the subtropics, so I don't think we'll see another model failure like what we saw for Gert.

[tolakram]

[Blown Away]

18z GFS... Keeps Harvey, maybe a TD/Weak TS up to @66 hrs and then TW into CA...

[tolakram]

This is where the Euro re-develops, GFS squashes.

[Kingarabian]

Well let's not forget that the GFS completely busted on Franklin in the very same area.

[Thetxhurricanemaster]

Well let's not forget that the GFS completely busted on Franklin in the very same area.

As of now I'm discounting the GFS because it only intensifys storms if they are in a 30%humidity environment and a 40KT shear environment it's a laughing stock

[stormreader]

Models seem to be trending North

Yeah, wondering about the GOM. Franklin was forced back west (and even south of west) in the GOM. Interesting to see the angle it takes in the Yucatan area. We will be in late August when "potential Harvey" arrives in GOM (if forecast bears out). Depends on conditions, but I think climo would call for at least some northerly component in the GOM if it makes a central to north Yucatan crossing. Not necessarily, but more likely than Franklin.

Some models like the EURO show a very complex steering pattern at day 5 through 8 which can slow the system and maybe even stall it !

Since I don't access the models, this is the kind of informative post I need to hear. A stalled system in the southern GOM is a different kind of animal. Seems like years ago, we had more of that. With a system then threatening a more NNW or N move toward the northern gulf coast. Thanks. Getting to that time of year when that is more in line with climo too.

[stormreader]

GFS somehow starts weakening the storm once it moves under the upper high. It's like it cannot handle barotropic dynamics and can only intensify systems in shear environments with troughs

You mean its got it "bassackwards!" lol