ATL: ETA - Post-Tropical - Discussion

[wxman57]

Surface obs around Eta indicate it's where it was supposed to be today. I think it'll track NNE for 48-60 hrs then hit a wall of shear across the northern Gulf. Tiny storms like Eta don't tolerate any shear at all. GFS & Euro look like they have a good handle on it. Remnant low by Friday afternoon drifting west or northwest.

[SouthDadeFish]

Nice hole on 37GHz vertical polarization

https://i.imgur.com/GCH7Tra.jpg

I don't think that is an eye. That looks to be a artifact from intense ice scattering associated with the ongoing convective burst. The color-composite imagery also indicates the vortex is tilted and convection is asymmetric.

[wxman57]

Center is clearly visible on that lower image. It's NNW of the convection, around 23N on the lower image, and NW of the big red dot on the top image.

[aspen]

Nice hole on 37GHz vertical polarization

https://i.imgur.com/GCH7Tra.jpg

I don't think that is an eye. That looks to be a artifact from intense ice scattering associated with the ongoing convective burst. The color-composite imagery also indicates the vortex is tilted and convection is asymmetric.

https://i.imgur.com/XjNobnu.jpg

https://i.imgur.com/kZnkQj3.jpg

Yep, it’s a CCC structure. Wasn’t shear supposed to be <10 kt by now?

[wxman57]

Here's the center, nearly exposed NW of the convection. Pardon my crude mouse writing.

[AutoPenalti]

Here's the center, nearly exposed NW of the convection. Pardon my crude mouse writing.

http://wxman57.com/images/center.jpg

It's sheared. So a reformation is possible.

[wxman57]

Here's the center, nearly exposed NW of the convection. Pardon my crude mouse writing.

http://wxman57.com/images/center.jpg

It's sheared. So a reformation is possible.

No, not really. A weakening is more likely. Small storms like Eta don't tolerate an unfavorable environment well.

[jconsor]

Eta getting decapitated by the shear and getting pushed W by the low-level flow is not for sure. There is an alternate scenario that could still bring it NE toward the W coast of FL as a strong TS:

 https://twitter.com/yconsor/status/1326158578823159809

[robbielyn]

Eta getting decapitated by the shear and getting pushed W by the low-level flow is not for sure. There is an alternate scenario that could still bring it NE toward the W coast of FL as a strong TS:

https://twitter.com/yconsor/status/1326158578823159809

Thats the only model that says that HMON. All the ones that have been dead on like HRWF and GFS takes it away from FL. Even HMON has it hit florida just barely on the coast and goes west back out to the GOM so it's only a matter of time for HMON to fall in with the rest of the crowd.

[AutoPenalti]

Here's the center, nearly exposed NW of the convection. Pardon my crude mouse writing.

http://wxman57.com/images/center.jpg

It's sheared. So a reformation is possible.

No, not really. A weakening is more likely. Small storms like Eta don't tolerate an unfavorable environment well.

We've seen this happen already. It's been through dry air and shear and has been able to to hold up, now that could all change if convection begins to collapse at any point during it's trek.

[underthwx]

Eta getting decapitated by the shear and getting pushed W by the low-level flow is not for sure. There is an alternate scenario that could still bring it NE toward the W coast of FL as a strong TS:

https://twitter.com/yconsor/status/1326158578823159809

As the NHC mentions in it's 3 am discussion, how much ETA strengthens will have alot to do with it's near-future fate.. correct?

[wxman57]

Eta getting decapitated by the shear and getting pushed W by the low-level flow is not for sure. There is an alternate scenario that could still bring it NE toward the W coast of FL as a strong TS:

https://twitter.com/yconsor/status/1326158578823159809

As the NHC mentions in it's 3 am discussion, how much ETA strengthens will have alot to do with it's near-future fate.. correct?

Yes, if it can remain a tropical storm, then it's NNE to the FL Panhandle or northern Peninsula. If shear gets it, then it drifts W-NW Fri/Sat as a remnant low. Northern Gulf is dominated by very strong shear. Any movement toward the northern Gulf for a landfall would be suicide. I don't see much of a future for Eta, in terms of U.S. impacts.

[underthwx]

Eta getting decapitated by the shear and getting pushed W by the low-level flow is not for sure. There is an alternate scenario that could still bring it NE toward the W coast of FL as a strong TS:

https://twitter.com/yconsor/status/1326158578823159809

As the NHC mentions in it's 3 am discussion, how much ETA strengthens will have alot to do with it's near-future fate.. correct?

Yes, if it can remain a tropical storm, then it's NNE to the FL Panhandle or northern Peninsula. If shear gets it, then it drifts W-NW Fri/Sat as a remnant low. Northern Gulf is dominated by very strong shear. Any movement toward the northern Gulf for a landfall would be suicide.

I understand, and as always, any reply from you, to gain your perspective on difficult storms such as ETA, is always appreciated, thankyou very much...

[chaser1]

Essentially appears to have more or less completed a small counter-clockwise loop/turn but motion still very slow

[robbielyn]

What does this mean

What is CAPE?

CAPE or Convective Available Potential Energy is the amount of fuel available to a developing thunderstorm. More specifically, it describes the instabilily of the atmosphere and provides an approximation of updraft strength within a thunderstorm. A higher value of CAPE means the atmosphere is more unstable and would therefore produce a stronger updraft.

To better understand this, consider a parcel of air that has been forced upward by some mechanism such as an approaching frontal boundary. Since warm air is less dense (lighter) than cold air, the parcel will continue rising on its own as long as its temperature remains warmer than its surroundings. This is the same concept as a hot air balloon, which uses a heat source to maintain a temperture within the balloon (air parcel) that is warmer than its surroundings. As long as this condition is met, the balloon will continue rising. Once the air temperature within the balloon cools and becomes equal to the air outside the balloon, it will stop rising.

CAPE is calculated by determing the area between the environmental temperature trace and the trajectory of an air parcel that is forced upwards on an atmospheric sounding. The image below shows an atmospheric sounding. The red line is the measured temperature of the surrounding air as you climb through the depth of the atmosphere. The yellow line represents the trajectory of an air parcel that has been forced to rise from the surface. As long as the yellow line (parcel) remains to the right of the red line (environment), the parcel is warmer than its surroundings and will continue to rise. The amount of CAPE in the sounding is therefore the area contained between the red and yellow lines. An atmospheric sounding such as the one below gives forecasters a quick visual way to assess how much fuel is available within the atmosphere.

Robbielyn....Im giving you an A for that!....but seriously...good post...up till your post... I didn't have a clue what CAPE was... Thanks for that...

Haha thank you but this was taken from the the NHC after I googled it. It was way better than what I could have come up with. So how about a C for the effort I put forth to give you an excellent explanation from the NHC?

[Iceresistance]

If the CDO convection sustains itself, will there be a center reformation?

[GCANE]

If this is decapitated, it sure is bleeding like crazy.
Maybe we should call it Zombie Eta.

[cycloneye]

 https://twitter.com/StuOstro/status/1326173402411970562

[AutoPenalti]

Also, smaller storms are prone to rapid intensification as well as rapid weakening.

[Nuno]

Whether zombified or hiding signs of life, Eta will probably steer more showers in the direction of SFL this afternoon.