ATL: KIRK - Remnants - Discussion

[TheStormExpert]

I smell Bones getting ready to make his appearance! Kirk is on life-support.

[TheStormExpert]

Some humor.

Kirk VS. The Shear! (I think we know who will win in this case. )

[GCANE]

[chaser1]

( Jeez, I've always loved Star Trek from a really young age, but looking back to some of those Aliens costumes and character fight sequences..... just give me the biggest laughs! )

[wxman57]

St. Lucia is reporting a 25kt SE wind. No evidence of any TS winds in the surface obs over the past 6 hours, regardless of what SFMR might suggest. I still don't trust those SFMR winds. Kirk would not rate an upgrade to a tropical depression based on its current state of organization.

[hipshot]

( Jeez, I've always loved Star Trek from a really young age, but looking back to some of those Aliens costumes and character fight sequences..... just give me the biggest laughs! )

That is exactly what I was thinking when I saw that post!!!

[Craters]

I have a question arising from complete ignorance that I'd like to throw out there in the hopes that one of you Weather Wizards® would have the time and inclination to answer it.

What mechanism (or mechanisms?) is keeping the LLC of Kirk intact for so long? There's obviously a low-pressure center at the surface, but why/how can it persist for so long with no obvious convection to support it? Anybody who's even casually watched the tropics for a while knows that this certainly isn't an unusual event. If somebody asked me how the LLC could survive after decoupling from the massive convection, though, I'd have to admit that I don't know.

Duh.

Thanks!

[wxman57]

I have a question arising from complete ignorance that I'd like to throw out there in the hopes that one of you Weather Wizards® would have the time and inclination to answer it.

What mechanism (or mechanisms?) is keeping the LLC of Kirk intact for so long? There's obviously a low-pressure center at the surface, but why/how can it persist for so long with no obvious convection to support it? Anybody who's even casually watched the tropics for a while knows that this certainly isn't an unusual event. If somebody asked me how the LLC could survive after decoupling from the massive convection, though, I'd have to admit that I don't know.

Duh.

Thanks!

It has momentum. The air is flowing around the weak low center. Once the inflow stops, the air is still rotating. It takes a while for the "top" to spin-down. These swirls can persist for days.

[GCANE]

[Craters]

I have a question arising from complete ignorance that I'd like to throw out there in the hopes that one of you Weather Wizards® would have the time and inclination to answer it.

What mechanism (or mechanisms?) is keeping the LLC of Kirk intact for so long? There's obviously a low-pressure center at the surface, but why/how can it persist for so long with no obvious convection to support it? Anybody who's even casually watched the tropics for a while knows that this certainly isn't an unusual event. If somebody asked me how the LLC could survive after decoupling from the massive convection, though, I'd have to admit that I don't know.

Duh.

Thanks!

It has momentum. The air is flowing around the weak low center. Once the inflow stops, the air is still rotating. It takes a while for the "top" to spin-down. These swirls can persist for days.

I guess that gets to the core of my question. With the inflow stopped, where's the centripetal force that's keeping the rotation going? The way I'm thinking -- and please correct that, because it's obviously wrong! -- no inflow would remove the centripetal component of a parcel's velocity, right? That would then mean that the only forces on the parcel, ignoring buoyancy, would be from any remaining regional pressure gradient and frictional effects, no? Or is there a feedback-type thing going on here, with the rotational momentum itself actually sustaining the low pressure in the center of the circulation until frictional effects eventually kill it?

Thanks, wxman -- I don't mean to beat a dead horse, here, because I can easily see it working for a solid object (the top). I'm having trouble visualizing it for a fluid, though...

[GCANE]

I have a question arising from complete ignorance that I'd like to throw out there in the hopes that one of you Weather Wizards® would have the time and inclination to answer it.

What mechanism (or mechanisms?) is keeping the LLC of Kirk intact for so long? There's obviously a low-pressure center at the surface, but why/how can it persist for so long with no obvious convection to support it? Anybody who's even casually watched the tropics for a while knows that this certainly isn't an unusual event. If somebody asked me how the LLC could survive after decoupling from the massive convection, though, I'd have to admit that I don't know.

Duh.

Thanks!

It has momentum. The air is flowing around the weak low center. Once the inflow stops, the air is still rotating. It takes a while for the "top" to spin-down. These swirls can persist for days.

I guess that gets to the core of my question. With the inflow stopped, where's the centripetal force that's keeping the rotation going? The way I'm thinking -- and please correct that, because it's obviously wrong! -- no inflow would remove the centripetal component of a parcel's velocity, right? That would then mean that the only forces on the parcel, ignoring buoyancy, would be from any remaining regional pressure gradient and frictional effects, no? Or is there a feedback-type thing going on here, with the rotational momentum itself actually sustaining the low pressure in the center of the circulation until frictional effects eventually kill it?

Thanks, wxman -- I don't mean to beat a dead horse, here, because I can easily see it working for a solid object (the top). I'm having trouble visualizing it for a fluid, though...

The Coriolis force imparted from an updraft creates the counter-clockwise motion seen in any given altitude.
Two factors create an updraft: Convection and Hadley Circulation.
There is still convection therefore still an updraft.
Its displaced to the east of the surface center of circulation.
As you go up in altitude, the center of circulation moves east due primarily to shear (and to some extent 355K PV).
Therefore if you look at 850mb, 700mb, and 500mb they respectively are east of the lower one.
The vort column in this case is said to be tilted.
So, it is still being driven in large part by convection and in some smaller extent by Hadley.

[GCANE]

A small amount of convection firing off the naked swirl and pressure turning south.

[Aric Dunn]

like I mentioned last night. its only hope would be to continue to sporadically have burst of convection near the center if that stops then goodbye until western carrib in a week and the trough meanders around for awhile.


there is some hints in the models that kirk might slowly come back to life with some other piece of energy next week.

[Aric Dunn]

yeah all of the 12z models now start to slowly organize the remnants of Kirk next week. how much is left of kirk over all will be interesting. might get a new name.

[meriland29]

Especially the FV3-GFS models... very prominent comeback for what I think is Kirk. He slides up the EC, but never hits. Still, that change-up changes things.. if GFS never anticipated him to comeback at all, it's a little scary they anticipate he will be that close to the EC this far out already...

[GCANE]

A lot of the convection moving closer to the CoC.
Vort column losing some of its tilt.

[meriland29]

A lot of the convection moving closer to the CoC.
Vort column losing some of its tilt.

I am still unfamiliar with a lot of meteorologic terms :S sorry lol ..but what does it mean if the Vort column loses its tilt?

[Aric Dunn]

A lot of the convection moving closer to the CoC.
Vort column losing some of its tilt.

I am still unfamiliar with a lot of meteorologic terms :S sorry lol ..but what does it mean if the Vort column loses its tilt?

the column is the atmosphere from the surface up. what you want is all the vorticity or circulations in all levels of the atmosphere to be vertically aligned... stacked on top of each other in a way. its more fluid than actual distinct separations but just in general....

you dont want the convection that builds to look like this lol

[meriland29]

Ah I see, so being that it is tilting (as well as COC bursts) suggests Kirk is trying to thrive?

[Aric Dunn]

Ah I see, so being that it is tilting (as well as COC bursts) suggests Kirk is trying to thrive?

right in a way. the shear is way too high for it actually do anything. but as long as there is surface convergence and convection building over the center it can keep a closed circ and survive longer.

the longer it does the more the models are likely going to show the remnants organize again in the western carrib.