ATL GUSTAV: Tropical Depression - Discussion

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ROCK
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#961 Postby ROCK » Sun Aug 24, 2008 8:53 pm

Ed Mahmoud wrote:JB's latest video says 95L, which is two waves merging, per JB, will deflect 94L more Northward than mean steering would indicate. JB sees possibly 3 threats to SE US, 94L, 95L and wave coming off Africa.


JB's thoughts have changed since yesterday then. Going against current model runs...I love that guy... :D
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#962 Postby Sanibel » Sun Aug 24, 2008 8:54 pm

there is no zone of death in the Carib. A bad myth that ahs been dispelled many times in recent years



Perhaps not "death" but 94L has had organization problems in the east half of the Caribbean.
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Clipper96

Re: Re:

#963 Postby Clipper96 » Sun Aug 24, 2008 8:56 pm

HOUR AGO:
Image
LATEST:
Image

The LLC is NOT the dark area, but just southeast of it, near the southwest edge of the new cells that are developing on the east end of the bulb of the "6". These new cells should increase in intensity while the outer banding convection diminishes.

(Does anyone know how to save that IR2 loop in Firefox?)
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Re: Re:

#964 Postby wxman57 » Sun Aug 24, 2008 9:00 pm

Derek Ortt wrote:
Dean4Storms wrote:Well it is currently in the Zone of Death of the Carib. but once it gets west of 70W lookout.


there is no zone of death in the Carib. A bad myth that has been dispelled many times in recent years


What is referred to as the "death zone" in the eastern Caribbean is not entirely mythical, and it's easily explained. There is a region to the south of the average center of the Bermuda high where easterly trades reach their peak. Typically, this is somewhere near the eastern Caribbean. In this area, easterly trade winds accelerate a bit, reducing low-level convergence (as we saw with 94L). Farther west, in the western Caribbean and farther from the high center, trade winds generally relax, leading to increased low-level convergence. That's why more TCs tend to develop in the NW Caribbean than in the eastern Caribbean. Of course, these are generalizations. This pattern of increased easterly trades in the eastern Caribbean isn't always present.
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#965 Postby BigA » Sun Aug 24, 2008 9:00 pm

I thought there wasn't really an LLC yet. There certainly was an MLC per visible, and I wouldn't disagree with you about its location, but I'm not sure if an LLC exists yet
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Re: Re:

#966 Postby ROCK » Sun Aug 24, 2008 9:01 pm

Clipper96 wrote:HOUR AGO:
Image
[/quote]

LATEST:
Image

The LLC is NOT the dark area, but just southeast of it, near the southwest edge of the new cells that are developing on the east end of the bulb of the "6". These new cells should increase in intensity while the outer banding convection diminishes.

(Does anyone know how to save that IR2 loop in Firefox?)[/quote]

I would agree if in fact it has a LLC......
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Ed Mahmoud

Re: ATL: Invest 94L in Eastern Caribbean Sea

#967 Postby Ed Mahmoud » Sun Aug 24, 2008 9:08 pm

Maybe no LLC yet, but deep storms much closer to area of apparent rotation/MLC, so that is where I'd guess one would form, and if deep storms keep up all night, I think airplane will find a storm, not a depression, tomorrow.

Unofficially.
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#968 Postby Sanibel » Sun Aug 24, 2008 9:09 pm

Heck, this is obvious trouble if it gets in the Gulf.
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Re: Re:

#969 Postby RattleMan » Sun Aug 24, 2008 9:09 pm

Clipper96 wrote:(Does anyone know how to save that IR2 loop in Firefox?)

Go to http://www.ssd.noaa.gov/goes/flt/t2/img/ then manually "right-click save" the images you want.
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Re: Re:

#970 Postby jconsor » Sun Aug 24, 2008 9:13 pm

wxman57 wrote:
Derek Ortt wrote:one thing we do need... as of 2100 UTC the low level convergence was not very good at all.

Remember that with Fay and Dolly (the last 94L)... we did not see development until the low level convergence became well-established


It's hard to get low-level convergence when the forward speed is so high. It'll have to slow down, first.


Past few GFDL runs have been showing a slowdown in forward speed to about 8-10 kt by Monday night and Tuesday. However, the GFDL, like nearly all models, has been verifying too slow on the forward speed of 94L.
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#971 Postby AtlanticWind » Sun Aug 24, 2008 9:18 pm

http://www.ssd.noaa.gov/goes/east/carb/loop-rb.html

Covection firing over what appears to be the center
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#972 Postby wxman57 » Sun Aug 24, 2008 9:18 pm

Sanibel wrote:Heck, this is obvious trouble if it gets in the Gulf.


Maybe, but let's look at the mid-level steering pattern for late this coming week should it track as the GFDL is predicting (toward the northern Yucatan by Friday). We can use the latest run of the GFS and plot 700-400mb streamlines/winds (10,000-20,000 ft) and see where a system near the northern Yucatan might be steered. We'll have to make a big assumption that the GFS has a clue about the pattern across the Gulf in the wake of Fay.

I plotted where the GFDL puts 94L at the time of the map. Now if a low center is there, near 23N/87W and there's high pressure to the north, it has to track westward. Again, lots of assumptions.

Image
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Re: Re:

#973 Postby abajan » Sun Aug 24, 2008 9:19 pm

RattleMan wrote:
Clipper96 wrote:(Does anyone know how to save that IR2 loop in Firefox?)

Go to http://www.ssd.noaa.gov/goes/flt/t2/img/ then manually "right-click save" the images you want.
I'm sure there must be an easier way. Google it and see what you can find, Clipper96. I'll do some googling on the matter myself.
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Re: Re:

#974 Postby wxman57 » Sun Aug 24, 2008 9:19 pm

jconsor wrote:
wxman57 wrote:
Derek Ortt wrote:one thing we do need... as of 2100 UTC the low level convergence was not very good at all.

Remember that with Fay and Dolly (the last 94L)... we did not see development until the low level convergence became well-established


It's hard to get low-level convergence when the forward speed is so high. It'll have to slow down, first.


Past few GFDL runs have been showing a slowdown in forward speed to about 8-10 kt by Monday night and Tuesday. However, the GFDL, like nearly all models, has been verifying too slow on the forward speed of 94L.


That's right, it's moving more quickly than the models have forecast, indicating stronger than predicted easterly steering currents. That would seem to argue against a northwest turn.
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Derek Ortt

Re: ATL: Invest 94L in Eastern Caribbean Sea

#975 Postby Derek Ortt » Sun Aug 24, 2008 9:21 pm

Sanibel wrote:Could there be a ULL over it giving those false centers?


Highly untrue, Sanibel



While it did get some lagging disruption from Hispaniola it is my opinion that it had enough time to go stronger than the 60mph it entered Cuba at. I'm too lazy to do the research, but I suspect you could find similar tracks over those prime south of Cuba SST's where storms took the same time and did much better. A good example would be Fay's structure quirks near Key West. The environment was too hostile for potential peak intensity - which was the point to begin with. In fact I would even entertain doubts whether an overwater track would have done too much better.


we'd have had at least a cat 1 out of Fay had it not have crossed Hispaniola and Cuba. Quite possibly a cat 2 due to the intensification near the coast
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Clipper96

Re: Re:

#976 Postby Clipper96 » Sun Aug 24, 2008 9:23 pm

RattleMan wrote:
Clipper96 wrote:(Does anyone know how to save that IR2 loop in Firefox?)
Go to http://www.ssd.noaa.gov/goes/flt/t2/img/ then manually "right-click save" the images you want.
Well, yes; but it's inconvenient. (Pity the site doesn't have an archive. It'd be unrealistic to keep every pic of every invest forever, but retaining them for a week or month would be great.)
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Re: ATL: Invest 94L in Eastern Caribbean Sea

#977 Postby Ivanhater » Sun Aug 24, 2008 9:24 pm

Huh? Im not seeing any blocking high in the gulf when the gfdl indicates 94L to be getting int the gulf..all I see is a building high to the west blocking any west movement..all assuming if the gfs and gfdl are correct..

Image

Image
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Derek Ortt

#978 Postby Derek Ortt » Sun Aug 24, 2008 9:26 pm

isn't there a little weakness in those GFS forecast fields? I would think that would mean WNW, possibly followed by due west. regardless... still looks like a Mexican landfall if this misses the weakness predicted at 75W
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Re: Re:

#979 Postby cheezyWXguy » Sun Aug 24, 2008 9:26 pm

Well I think the northwest turn will occur, but later on. Note that steering currents are strong now in the east caribbean, but drop off in about 2 days or so. By then we might have a tropical cyclone, and if it does begin its nw turn in the nw caribbean as opposed to right now, there is a serious potential for RI and a track into the GOM looks plausible.
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Re:

#980 Postby cheezyWXguy » Sun Aug 24, 2008 9:27 pm

Derek Ortt wrote:isn't there a little weakness in those GFS forecast fields? I would think that would mean WNW, possibly followed by due west. regardless... still looks like a Mexican landfall if this misses the weakness predicted at 75W

What about the weakness from fay? And that diagram wxman posted appears to show a weakness between the 2 highs...am i correct?
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