ATL GUSTAV: Tropical Depression - Discussion

[ROCK]

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...

[Sanibel]

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.

[Clipper96]

HOUR AGO:

LATEST:


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?)

[wxman57]

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.

[BigA]

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

[ROCK]

HOUR AGO:

[/quote]

LATEST:


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......

[Ed Mahmoud]

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.

[Sanibel]

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

[RattleMan]

(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.

[jconsor]

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.

[AtlanticWind]

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

Covection firing over what appears to be the center

[wxman57]

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.

[abajan]

(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.

[wxman57]

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.

[Derek Ortt]

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

[Clipper96]

(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.)

[Ivanhater]

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..

[Derek Ortt]

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

[cheezyWXguy]

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.

[cheezyWXguy]

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?