PV thinking with Sandy - Trough interaction

[OKpowdah]

Because this has been ignored in the main thread, I thought I would start a new thread open for discussion (perhaps short if someone has a straight up answer).

As cyclonic PV anomalies tend to repel / resist merging, is this significant in how readily a stronger Sandy will phase with incoming trough?

From a PV perspective, closed cyclonic anomalies tend to repel / rotate around each other until one weakens and is absorbed by the stronger anomaly.

Will a stronger Sandy tend to resist phasing in fact remain very separate from the incoming trough?

[OKpowdah]

Interestingly, I just saw the BOX disco is hinting toward this direction (outside of PV thinking...)

[N. OF PIKE]

yes this threw a monkey wrench in my thinking /understanding of how this would work out. i haven't heard this mentioned at all by mets on here, and wondered how significant the effects were and wether the people who understand this phenomena better would be better able to interpret the models and what their bias would be

[CoastalWx]

Because this has been ignored in the main thread, I thought I would start a new thread open for discussion (perhaps short if someone has a straight up answer).

As cyclonic PV anomalies tend to repel / resist merging, is this significant in how readily a stronger Sandy will phase with incoming trough?

From a PV perspective, closed cyclonic anomalies tend to repel / rotate around each other until one weakens and is absorbed by the stronger anomaly.

Will a stronger Sandy tend to resist phasing in fact remain very separate from the incoming trough?

I always thought that if it remained separate, it could still be captured easily so long as the S/W was strong enough. I suppose size does matter though, so that may also depend. I think in the end, it still may not totally phase, but could still keep tropical characteristics longer. I'm surely no expert though.

[NaoPos]

ANy weenies dare venture in here, there would be suicide! Lol.

That's a very interesting notion though. 4-5 days, we might as well be 10.

[OKpowdah]

I always thought that if it remained separate, it could still be captured easily so long as the S/W was strong enough. I suppose size does matter though, so that may also depend. I think in the end, it still may not totally phase, but could still keep tropical characteristics longer. I'm surely no expert though.

A study on TCs phasing in the W Pacific found that the strength of the incoming trough had little effect on whether the storm phased and the final intensity; just the timing (and thus relative position of the two features) mattered.

The stronger Sandy becomes, I think the greater resistance to ET and phasing ... I think...

[CT Rain]

I always thought that if it remained separate, it could still be captured easily so long as the S/W was strong enough. I suppose size does matter though, so that may also depend. I think in the end, it still may not totally phase, but could still keep tropical characteristics longer. I'm surely no expert though.

Probably depends on the size of each PV anomaly.

PV is conserved in adiabatic flow which makes it so powerful as a tool but with the amount of latent heat involved in TCs and the odd distribution when a TC is undergoing ET I'm not sure how that manifests itself.

We do see models get "phase happy" with TCs interacting with jets here in the northeast. Maybe the models are having trouble resolving both PV anomalies, their fujiwhara interaction, and the generation/distrubution of diabatically induced PV?

[OKpowdah]

Probably depends on the size of each PV anomaly.

PV is conserved in adiabatic flow which makes it so powerful as a tool but with the amount of latent heat involved in TCs and the odd distribution when a TC is undergoing ET I'm not sure how that manifests itself.

We do see models get "phase happy" with TCs interacting with jets here in the northeast. Maybe the models are having trouble resolving both PV anomalies, their fujiwhara interaction, and the generation/distrubution of diabatically induced PV?

It's a really powerful tool for that conservation property. In TCs, the latent heat release is maximized in the upper troposphere ... and where the warm core is situated ... this creates PV in the lower to mid troposphere, and destroys PV above the warm core. The stronger the hurricane, not only the stronger the vorticity, but the greater the warm core and thus the stronger the cyclonic PV in the low to mid levels of the troposphere. If we consider phasing the PV anomalies in the middle troposphere, there must be a lot of resistance.

[N. OF PIKE]

i would think the mega block and intensifying sandy may pump the ridge so much that (w/ the info in this thread) a later capture than model'd (instead of an escpae OTS) may be favored (i.e a further north solution) , particularly where/when one would expect sandy to begin extra tropical transition and be more open to phasing or being injested/injesting the other low. But i am no expert that is for certain, just an observation. i will step back and let smarter people handle the rest

[CoastalWx]

A study on TCs phasing in the W Pacific found that the strength of the incoming trough had little effect on whether the storm phased and the final intensity; just the timing (and thus relative position of the two features) mattered.

The stronger Sandy becomes, I think the greater resistance to ET and phasing ... I think...

Probably depends on the size of each PV anomaly.

PV is conserved in adiabatic flow which makes it so powerful as a tool but with the amount of latent heat involved in TCs and the odd distribution when a TC is undergoing ET I'm not sure how that manifests itself.

We do see models get "phase happy" with TCs interacting with jets here in the northeast. Maybe the models are having trouble resolving both PV anomalies, their fujiwhara interaction, and the generation/distrubution of diabatically induced PV?

It's an interesting topic because I did not even think of it until Sam brought it up. I deal with west pac typhoons a lot and many times the models are phase happy. They tended to be east of the extreme solutions when all was said and done, but I can't recall a massive block involved either. Sam's idea does make sense from a physical standpoint.

[CT Rain]

It's a really powerful tool for that conservation property. In TCs, the latent heat release is maximized in the upper troposphere ... and where the warm core is situated ... this creates PV in the lower to mid troposphere, and destroys PV above the warm core. The stronger the hurricane, not only the stronger the vorticity, but the greater the warm core and thus the stronger the cyclonic PV in the low to mid levels of the troposphere. If we consider phasing the PV anomalies in the middle troposphere, there must be a lot of resistance.

Yeah... that's what makes it warm core.... latent heat release detroying PV up top and generating it down low. But it would have to be in the middle troposphere which is probably why it's so challenging.

How the distribution of PV changes when a storm begins to undergo ET probably makes a big different in how the PV anomalies interact. I wonder the impact of this storm remaining a deep warm core/seclusion during ET (you can see that on the cyclone phase space site by comparing upper trop thermal wind to lower trop thermal wind) rather than a more typical shallow warm core seclusion.

[CT Rain]

It's an interesting topic because I did not even think of it until Sam brought it up. I deal with west pac typhoons a lot and many times the models are phase happy. They tended to be east of the extreme solutions when all was said and done, but I can't recall a massive block involved either. Sam's idea does make sense from a physical standpoint.

Which is why I've been thinking all along that the gigantic loop from due east to NW and WNW is just so unlikely. I think a more S-N kinda deal (like the Euro... but maybe farther east) is more likely.

[WXeastern]

Ive always been under the impression that the deeper a TC becomes the more resistance it puts up to any system.. be it a mid latitude one.. or a tropical one? If that is the case..I would think that Sandy tracking over the highest peaks of cuba wouldnt bode too well for a non capture scenario. Nice thread BTW!

[CoastalWx]

Which is why I've been thinking all along that the gigantic loop from due east to NW and WNW is just so unlikely. I think a more S-N kinda deal (like the Euro... but maybe farther east) is more likely.

It's just so hard to get that like we talked about. Something more NW or even NW is a little more sensible.

[CoastalWx]

It's a really powerful tool for that conservation property. In TCs, the latent heat release is maximized in the upper troposphere ... and where the warm core is situated ... this creates PV in the lower to mid troposphere, and destroys PV above the warm core. The stronger the hurricane, not only the stronger the vorticity, but the greater the warm core and thus the stronger the cyclonic PV in the low to mid levels of the troposphere. If we consider phasing the PV anomalies in the middle troposphere, there must be a lot of resistance.

The latent heat release allows for the stretching of isentropes and hence increase PV between these isentropes, correct? So is the reason why PV is destroyed above the warm core is because the isentropes at that level are now compacted and therefore support anticyclonic vorticity?

[CoastalWx]

The latent heat release allows for the stretching of isentropes and hence increase PV between these isentropes, correct? So is the reason why PV is destroyed above the warm core is because the isentropes at that level are now compacted and therefore support anticyclonic vorticity?

I think I have it right.

[Roger Smith]

This trend towards rapid deepening already is also possibly (and I stress conjecture here for my travelling band of critics) the first stage of what will become a steady northward acceleration of a powerful hurricane that will resist extratropical transition until landfall which is the signal that the models were trying to tell us with the 933 mb centre. That's a detail that may yet verify but equally plausible would be a 930 mb hurricane north of the Bahamas Friday night accelerating north. The 00z runs may tell us a lot about this, I've always been saying about this phase potential that the models generally looked far too weak on the rapid phase potential and that Sandy would most likely try to hook up with the front while it was still actively attached to the warm sector rather than in some post-system phase two days later. This current scenario introduces the possibility of an earlier landfall time like late Sunday into early Monday although I wouldn't say that was the most likely outcome. Another thought from my eccentric collection, all the notable hurricanes seem to follow very regular tracks as if they were rotating around some centre of mass. The most likely solution now that we have rapid intensification is probably a long steady merge into the existing SSW jet stream without the strange little loops on the GFS or GEM. After Cuba, there's not a whole lot in the way until the Berkshires.

[Chrisrotary12]

So say that we are on to something. That Sandy resists the urge to phase because she is to strong in a sense. Wouldn't that mean that the s/w and Sandy would then tend to Fujiwhara with each other. Which if we believe this to be true and ultimately the Euro ends up being right on position and timing.......then realistically we still take it on the chin from what could potentially still be a very dangerous hurricane.......great. lol.

[CoastalWx]

So say that we are on to something. That Sandy resists the urge to phase because she is to strong in a sense. Wouldn't that mean that the s/w and Sandy would then tend to Fujiwhara with each other. Which if we believe this to be true and ultimately the Euro ends up being right on position and timing.......then realistically we still take it on the chin from what could potentially still be a very dangerous hurricane.......great. lol.

Well phasing and capture aren't completely the same which is why I was saying it could try to move and get caught up in the mid level flow of the approaching wave...yet still maintain itself. At that point though, it will begin to phase and become more extratropical with time.

[OKpowdah]

The latent heat release allows for the stretching of isentropes and hence increase PV between these isentropes, correct? So is the reason why PV is destroyed above the warm core is because the isentropes at that level are now compacted and therefore support anticyclonic vorticity?

Other way around. The latent heat release in the upper levels of the troposphere compacts isentropes in the low to mid levels which creates PV and stretches isentropes above, destroying PV

[Dsnowx53]

Perhaps a much stronger system is more initially resistant to phasing.

But when you combine that factor with enhanced downstream ridging, I would think it would mean a later and further NORTH phase, but not a further EAST phase, since the stronger ridging downstream would prevent the storm from gaining longitude, but its resistance to phasing might help it gain more latitude. I really don't see this making a wild turn east and then a wild turn west again. I see it more resembling a just east of north track to a just west of north track...kinda like what Ryan was saying before.

This is what I said in the other thread.

Good thread btw, Sam. I've learned a lot tonight.

[CoastalWx]

Other way around. The latent heat release in the upper levels of the troposphere compacts isentropes in the low to mid levels which creates PV and stretches isentropes above, destroying PV

But if you stretch an isentrope, by definition with vorticity being conserved, aren't you going to generate it?

[CT Rain]

Other way around. The latent heat release in the upper levels of the troposphere compacts isentropes in the low to mid levels which creates PV and stretches isentropes above, destroying PV

warm bowls and cold domes is how I remember lol

[CoastalWx]

warm bowls and cold domes is how I remember lol

Same here, but it had me thinking. Although Qg theory says heights would fall below warming level, so I didn't think of it like that.

[OKpowdah]

But if you stretch an isentrope, by definition with vorticity being conserved, aren't you going to generate it?

Ertel potential vorticity in isentropic coords is given by P = (abs vort) * (-g * d(theta)/dp)

As isentropes are stretched in the vertical, -d(theta)/dp becomes smaller. Given constant vorticity, P decrease --> PV is destroyed

[OKpowdah]

Same here, but it had me thinking. Although Qg theory says heights would fall below warming level, so I didn't think of it like that.

Yeah, so both through a thickness perspective and a PV perspective, warming creates PV below and destroys PV above

[CoastalWx]

Yeah, so both through a thickness perspective and a PV perspective, warming creates PV below and destroys PV above

I went about looking at it from a different way. But it makes sense, because it's a similar idea from stratospheric intrusion...totally looked at it the wrong way. Too much model watching.

[capecod04]

Arent we looking at some significant shear that shes gonna run into in about 48 hrs?

[CoastalWx]

Sometimes it is best to break out the math again. Dust off the cobwebs, thanks Sam I am.

[OKpowdah]

Arent we looking at some significant shear that shes gonna run into in about 48 hrs?

So, it may run into that shear and weaken enough that the forces of the incoming trough can overcome resisting forces and absorb the hurricane. However, as Sandy becomes stronger (and larger) it tends to 1) resist the baroclinic zone and 2) become less susceptible to shear. Something to keep in mind as we watch it intensify tonight .