ATL: Ex-Tropical Storm GASTON - Discussion

[BigA]

The last time I checked it, I think Sunday or Saturday, Gaston had vorticity on 850,700,500. Look at him now, low-level only.

This is correct. Interestingly, however the 1800 vorticity map just came out, showing that Gaston has recovered some of his 700mb vorticity and the 850 mb vorticity has increased a good deal in strength. Vorticity as of now looks to be centered southeast of St. Croix, which may explain why it isn't showing up on Puerto Rican radar, as it is too distant.

[vbhoutex]

there is a weak LLC here....low level turning is evident....not as vigorous as it once was but its still there...it needs to sustain convection into the evening and night....if it does that then it might be a go...

Agree!
I'd say it is a "go" too.
20% chance of it.
80% chance it is a wave with no future over the next 48 hours or so.
100% chance that some posters will say that it will still regenerate[/quote]


You still seem to have a problem (sense you continually point it out) when a poster thinks regeneration will occur. We are here to throw out potential and possibilities. If you or any other poster feels the opposite, feel free to post it but stop posting your issue with other posters who point out the potential. This goes for anyone.

We will not go down this road again and derail this thread. If anyone has an issue please revert to PM.

I am backing Michael up on this post + more. This thread has been derailed more than once by what sounds like a bunch of little hens pecking at each other with a few personal attacks thrown in here and there. I have been busy cleaning up the thread as best I can. This type of behavior must stop and it must STOP NOW. Warnings and/or suspensions will follow if it doesn't. I don't know how to make it any clearer for EVERYONE. STAY ON THE TOPIC, not who said what when or how. As I repeat myself once again. We have absolutely no problem with posters disagreeing with each other in a respectful manner. That is how we learn. It isn't, nor will it ever be, about who said what when where and how. Now please get back to discussing ex-Gaston.

[Bailey1777]

is his circulation center wear that hook is in red tops as seen on ir?

[cycloneye]

I dont see a well defined circulation there,maybe a very weak reflection south of Puerto Rico.

[Aric Dunn]

is his circulation center wear that hook is in red tops as seen on ir?

well the circ is opened up now... there is some SW winds but no west winds atm but the convection if it maintains should eventually cause the pressure to fall and we should see the LLC slowly come back if convection dies again it will have to start all over again.. lol

[BigA]

I don't think that the center of vorticity has come into radar range yet. It still looks to be southeast of St. Croix, well southeast of Puerto Rico.



Uploaded with ImageShack.us

Vorticity 3 hours ago



Increase in vorticity between 3 hours ago and now probably due to increase in convection, which starts the process that Aric described above. Whether it continues is another matter entirely.

[Aric Dunn]

yeah those carts are sometimes ambiguous and often lag behind actually whats occurring. but either way the vorticity is still present just had some issue with eastern carrib..

[ColinDelia]

19z. 850 mb vorticity

[Aric Dunn]

19z. 850 mb vorticity

[img]http://linkification.com/wx/2010/gaston/19z.jpg[/img

thats better..

[Bailey1777]

aric suppose we do get some developement what do you see going on as far as steering?

[supercane]

Steve made some good posts about vertical instability. Does anyone have a link to good explanation of what vertical instability is or a link to any graphs or charts detailing it?

Not exactly the same, but close, the vorticity. http://cimss.ssec.wisc.edu/tropic2/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor That's the 850mb, also have 700,500,200. The last time I checked it, I think Sunday or Saturday, Gaston had vorticity on 850,700,500. Look at him now, low-level only.

Not the same at all. In the CIRA Tropical Cyclone Formation Probability Product graphics you referred to, the Product Description defines vertical instability as:

VERTICAL INSTABILITY: The vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment, for each 5° by 5° sub-region.

An easy definition for stability, taken from COMET MetEd, is:

Stability is simply the resistance of the atmosphere to vertical motion. More precisely, it is the degree to which vertical motion in the atmosphere is enhanced or suppressed.

A discussion of instability usually goes into lapse rates to examine whether a parcel of air will continue to rise and uses a Skew-T diagram. Not sure how much you want to get into these things, but if so, I can provide links.

[Aric Dunn]

aric suppose we do get some developement what do you see going on as far as steering?

mostly ridging.. probably end up in the NW Caribbean with possibly a trough picking it up into the gulf or just bending more WNW... this is of course it developed into something significant.....

[BigA]

My maps look like they are a few hours obsolete. Makes more sense that the vorticity maximum is around 16.5 65.5 like the newer map shows

[ColinDelia]

Here's how to get the vorticity map I just posted for anyone that doesn't know

Go this site, click on the map, click vort. Note you can change the image resolution in left-side map if you wish.
http://cimss.ssec.wisc.edu/tropic2/predict/#

It's updated hourly

[xironman]

Steve made some good posts about vertical instability. Does anyone have a link to good explanation of what vertical instability is or a link to any graphs or charts detailing it?

GCANE was posting these maps that looked pretty good (using CAPE)

[5KOVERLIBOR]

Steve made some good posts about vertical instability. Does anyone have a link to good explanation of what vertical instability is or a link to any graphs or charts detailing it?

Not exactly the same, but close, the vorticity. http://cimss.ssec.wisc.edu/tropic2/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor That's the 850mb, also have 700,500,200. The last time I checked it, I think Sunday or Saturday, Gaston had vorticity on 850,700,500. Look at him now, low-level only.

Not the same at all. In the CIRA Tropical Cyclone Formation Probability Product graphics you referred to, the Product Description defines vertical instability as:

VERTICAL INSTABILITY: The vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment, for each 5° by 5° sub-region.

An easy definition for stability, taken from COMET MetEd, is:

Stability is simply the resistance of the atmosphere to vertical motion. More precisely, it is the degree to which vertical motion in the atmosphere is enhanced or suppressed.

A discussion of instability usually goes into lapse rates to examine whether a parcel of air will continue to rise and uses a Skew-T diagram. Not sure how much you want to get into these things, but if so, I can provide links.

Supercane, much thanks. I think this is what I was trying to drive at earlier. I am not qualified in the science of meteorology, but if at the beginning of the day - if these basins can't maintain seasonal vertical instabilities - wouldn't this be the original problem? I am hopefully not oversimplifying this too much, but if you can't get convection, because essentially the heat imbalance isn't large enough (something Steve was driving wrt NA pressures), is there anything else really to talk about? I'm not suggesting there aren't a host of things driving the realization of the 2010 season, but if you can't get a large enough temperature gradient from the surface to 200 MB to support deep sustained convection, would everything else be for not?

[Ivanhater]

6 hours old

[ColinDelia]

Wow, I know it has been off on gaston so far but LGEM, the best intensity models the past 3 years, goes to 141 knots in 120 hours. Using the BAMM track. Very low shear all week long.

ftp://ftp.tpc.ncep.noaa.gov/atcf/stext/ ... _ships.txt

[bvigal]

Not the same at all.... .

Thanks, Supercane, I know it's not the same. By "close" I meant a quick, easy visual of the location, vs using instability products often represented on graphs. I simply thought the vorticity by layer would be helpful.

[Aric Dunn]

Supercane, much thanks. I think this is what I was trying to drive at earlier. I am not qualified in the science of meteorology, but if at the beginning of the day - if these basins can't maintain seasonal vertical instabilities - wouldn't this be the original problem? I am hopefully not oversimplifying this too much, but if you can't get convection, because essentially the heat imbalance isn't large enough (something Steve was driving wrt NA pressures), is there anything else really to talk about? I'm not suggesting there aren't a host of things driving the realization of the 2010 season, but if you can't get a large enough temperature gradient from the surface to 200 MB to support deep sustained convection, would everything else be for not?

You can over come some vertical instability issues if you have a highly divergent or even sheared environment such that there is enough lift to overcome a flat vertical temp gradient. we have seen this happen a few time.... if there is a pre existing surface trough or wave with sufficient surface convergence that moves into such a environment where it is moist in the low levels and highly divergent aloft or high shear then you can see convection build enough to intensify the surface feature enough likely a closed LLC so that it can increase the temp/dew point even more at the surface ( warm core ) so that the vertical temp and dew point gradient is increased enough to support organized convection deep in the atmosphere.