ATL: ELSA - Post-Tropical - Discussion

[Evenstar]

Here is a dumb question to add to my other "useful contributions" to this forum...

Does Elsa's early formation portend a more active season overall or is she a one off? I am not asking y'all to predict the future. I'm just looking for educated guesses.

***I imagine someone at some point already asked this question, but I am shamelessly lazy and don't want to go through 226 pages of discussion to check...

****I apologize if this is not the right place to ask this question, but I did include "Elsa" in my question in order to pretend I am not off topic.

It does; only two other seasons have had a hurricane take a similar track as Elsa this early in the year: 1933 and 2005.

Thanks!!

Sorry. Annoying double post AND several thank you's. But I can't not say thank you to anyone who puts in the time to answer my question.

[abajan]

It seems like Tropical Storm Elsa has officially made landfall in Florida, and the people in South Florida get to dodge another bullet.

Some in South Florida may beg to differ. Just a hunch.

[Evenstar]

Here is a dumb question to add to my other "useful contributions" to this forum...

Does Elsa's early formation portend a more active season overall or is she a one off? I am not asking y'all to predict the future. I'm just looking for educated guesses.

***I imagine someone at some point already asked this question, but I am shamelessly lazy and don't want to go through 226 pages of discussion to check...

****I apologize if this is not the right place to ask this question, but I did include "Elsa" in my question in order to pretend I am not off topic.

There is data that shows a potential link between July E Carib Hurricane activity and active seasons. The sample size is very small though but pretty eye opening. A list of other seasons that included E Carib July Hurricanes includes, 1996, 1926, 1933, 1961, 2005, and 2020. 5 of those are some of the most impressive seasons all-time and 1996 had a high ratio of Hurricanes and major Hurricanes.

We can't definitively say if this predicts an active season but if it does end up being active it is a very interesting correlation.

Thank you very much!!

[Steve]

As pondered a few days ago, Elsa joins other systems presenting themselves better as they come up into the subtropics. I've been watching, and we'll see if this continues. It doesn't bode well for future 2021 landfalls south of 42-43N. It really shows that we could see more storms organizing and possibly strengthening at or near landfall.

https://www.tropicaltidbits.com/sat/sat ... =truecolor

[cycloneye]

 https://twitter.com/TropicalTidbits/status/1412816422011473920

[Shell Mound]

It was an East wind, pretty hard to get an East wind on the western side of a cyclone in the northern hemisphere. https://www.ndbc.noaa.gov/station_page.php?station=42023

Take it up with Stewart

Elsa's center also passed just barely to the east of Buoy 41023
around 2100 UTC, producing a sustained wind of 49 kt at 3-meters
elevation, which equals a 10-meter wind speed of 55 kt on the west
side of the cyclone.

Never saw any recon report with that strong a wind on the west side of this and he'd have to explain how it received a due East wind with that gust

The observations from the buoy indicate that winds veered from east to southwest, with the minimum MSLP of 1001 mb coincident with 19-kt SSW MSW at 3 m. The data from the buoy suggest that the centre passed almost directly overhead, that the station was inside the RMW, and that the central pressure was probably closer to 999 mb rather than 996 mb at the time of Elsa’s closest proximity to the buoy. Moreover, an elongated LLC passing just to the west of the buoy would normally generate a wind shift from an easterly to a southwesterly direction, and neither the low- nor mid-level circulation was aligned particularly well at the time, so perhaps the NHC was struggling to pinpoint the exact centre amid sub-vortices rotating around inside, or perhaps the LLC indeed passed just to the west. The observations best correspond to a close passage west of the station. I’m not sure as to why the discussion claims the centre passed “just east” of the buoy. It should read “just west,” given the coordinates of the buoy and the centre.

[ronjon]

Getting some of my worst weather from Elsa in Hernando Beach with winds gusting to 40 mph, heavy rain, and tides now running about 1-2 ft above normal. We're under a flood warning till 3 pm as this rather persistent feeder band keeps training over us.

[Sciencerocks]

[StPeteMike]

The lack of stronger shear did help bring down the threat of tornadoes, didn’t see as much warnings as I expected on the peninsula.

[ZipWx]

https://imagizer.imageshack.com/img922/5662/pXx8Iu.gif

Can someone weigh in on these high streaming clouds fanning out and away from Elsa as the inner convection collapses?

Energy transfer?

Presented without comment:

"The initial intensity is being held at 65 kt just in case convection redevelops
around the ragged eye feature later tonight."

Really curious as to what caused the almost instantaneous collapse right as it was in ramp up mode. Fascinating

Essentially it was a two-pronged attack. Elsa was experiencing SW shear, which consistently displaced the MLC the NE throughout the day, leaving the SW quadrant of Elsa devoid of sustainable convection. 18z HWRF analysis was Elsa at her peak:
https://i.imgur.com/L4D2LKz.png

However, if we start to look at the RH for 400-700mb, we can begin to see issues. In the image below, the LLC and MLC are the best stacked we've seen Elsa since the storm crossed Barbados. However, tiny cores are susceptible to dry air intrusion, and we can see this has begun:
https://i.imgur.com/saJidN4.png

Shear from the west is starting to drive mid-level dry air into the center of Elsa, in fact RH values directly to the west of the center were at 57% (to the east we had RH values in the 85-90% range):
https://i.imgur.com/Ec20UjZ.png

At the same time, Elsa is ramping up, her tiny core is finally vertically stacked and the wind field begins to expand. There is no sustained convection on the western/southwestern quadrant of Elsa, and this eventually entrains dry air in the vertical air column of Elsa's circulation. This disrupts vorticity, and Elsa responds by becoming elongated from the east to west (essentially the LLC has become squashed and elongated). At the same time, the MLC becomes decoupled and races off to the NE, away from the LLC. We can see this in the 00z HWRF forecast (8PM ET):
https://i.imgur.com/mVF7X8C.png

We can begin to see this occur in the last frames of visible imagery, as the outflow boundaries creates a fanning of the cloud tops to the north and northwest:
https://i.imgur.com/vBZ1mCx.gif

Here are the last 130 radar frames saved as a video to see this occur in real-time:
https://youtu.be/kSzM0Q3zH1Y

Wow. Just wow. What a beautiful reply. Thanks so much.

However...I fear I am about to express what may be a (life long) character defect--when I want/need to know something, I'm like a dog worry'n a bone...

What is the mechanism, smaller scale dynamics of cells, I presume, that would cause such a dramatic exhaust event when convection collapses? I guess this may be less a tropical cyclone question, and more a general meteorology question.

If the convection is collapsing and the heat/energy pump engine is breaking, why THEN the big exhaust out the top?

Or, what process is balancing, or holding in check said exhaust when (yes, I know we can observe an exhaust process in healthy, ventilating sysrems) the storm engine is chugging along?

Perhaps my puzzlement has to do with a matter of degree (bad weather joke, sorry), that is, how dramatic in scale were the exhaust cloud fans, and how perfectly (seemingly) timed to appear associated causally with the dryair, shear focussed, convection collapse.

Now beating dead horse with half chewed bone.

[cheezyWXguy]

In all the time that Elsa has been observable on hi def radar, this is the first time I’ve seen the apparent center on reflectivity and velocity actually match up. Figures it would only happen once it’s on land

[Shell Mound]

Take it up with Stewart

Never saw any recon report with that strong a wind on the west side of this and he'd have to explain how it received a due East wind with that gust

https://i.postimg.cc/PrBD3LYG/Ska-rmavbild-2021-07-07-kl-18-48-38.png

The observations from the buoy indicate that winds veered from east to southwest, with the minimum MSLP of 1001 mb coincident with 19-kt SSW MSW at 3 m. The data from the buoy suggest that the centre passed almost directly overhead, that the station was inside the RMW, and that the central pressure was probably closer to 999 mb rather than 996 mb at the time of Elsa’s closest proximity to the buoy. Moreover, an elongated LLC passing just to the west of the buoy would normally generate a wind shift from an easterly to a southwesterly direction, and neither the low- nor mid-level circulation was aligned particularly well at the time, so perhaps the NHC was struggling to pinpoint the exact centre amid sub-vortices rotating around inside, or perhaps the LLC indeed passed just to the west. The observations best correspond to a close passage west of the station. I’m not sure as to why the discussion claims the centre passed “just east” of the buoy. It should read “just west,” given the coordinates of the buoy and the centre.

Maybe someone could email Stacy Stewart and politely ask for some clarification about this. I am curious but would like further information about this.

[aspen]

Why is it that Elsa always seems to look better when it’s well over land? It even has convection popping over its LLC, despite having reached SW Georgia.

[JaxGator]

Here in Valdosta GA, its been mainly rain, but in the last hour, winds have been increasing with some gusts. I'm thankful Elsa didn't have the time (more like the ability) to consolidate and intensify further more than "she" did. Family and friends in Jacksonville will have to deal with Elsa's rainbands a little bit longer though.

[LarryWx]

Why is it that Elsa always seems to look better when it’s well over land? It even has convection popping over its LLC, despite having reached SW Georgia.

From normal daytime heating? The storm, itself, continues to gradually weaken.

[JaxGator]

Why is it that Elsa always seems to look better when it’s well over land? It even has convection popping over its LLC, despite having reached SW Georgia.

One guess would be swamps or Elsa is just being fickle.

[Steve]

Why is it that Elsa always seems to look better when it’s well over land? It even has convection popping over its LLC, despite having reached SW Georgia.

I still have a hunch that in 2021 it has something to do with storms coming up into more favorable dynamics farther north. I don’t expect that will play out for every system. And I don’t know if there is a magical latitude or a variable range. We have seen it before, but it’s too early to say if there will be any memorable trends that pan out.

[chaser1]

Can someone weigh in on these high streaming clouds fanning out and away from Elsa as the inner convection collapses?

Energy transfer?

Really curious as to what caused the almost instantaneous collapse right as it was in ramp up mode. Fascinating

Essentially it was a two-pronged attack. Elsa was experiencing SW shear, which consistently displaced the MLC the NE throughout the day, leaving the SW quadrant of Elsa devoid of sustainable convection. 18z HWRF analysis was Elsa at her peak:
https://i.imgur.com/L4D2LKz.png

However, if we start to look at the RH for 400-700mb, we can begin to see issues. In the image below, the LLC and MLC are the best stacked we've seen Elsa since the storm crossed Barbados. However, tiny cores are susceptible to dry air intrusion, and we can see this has begun:
https://i.imgur.com/saJidN4.png

Shear from the west is starting to drive mid-level dry air into the center of Elsa, in fact RH values directly to the west of the center were at 57% (to the east we had RH values in the 85-90% range):
https://i.imgur.com/Ec20UjZ.png

At the same time, Elsa is ramping up, her tiny core is finally vertically stacked and the wind field begins to expand. There is no sustained convection on the western/southwestern quadrant of Elsa, and this eventually entrains dry air in the vertical air column of Elsa's circulation. This disrupts vorticity, and Elsa responds by becoming elongated from the east to west (essentially the LLC has become squashed and elongated). At the same time, the MLC becomes decoupled and races off to the NE, away from the LLC. We can see this in the 00z HWRF forecast (8PM ET):
https://i.imgur.com/mVF7X8C.png

We can begin to see this occur in the last frames of visible imagery, as the outflow boundaries creates a fanning of the cloud tops to the north and northwest:
https://i.imgur.com/vBZ1mCx.gif

Here are the last 130 radar frames saved as a video to see this occur in real-time:
https://youtu.be/kSzM0Q3zH1Y

Wow. Just wow. What a beautiful reply. Thanks so much

What is the mechanism, smaller scale dynamics of cells, I presume, that would cause such a dramatic exhaust event when convection collapses? I guess this may be less a tropical cyclone question, and more a general meteorology question.

If the convection is collapsing and the heat/energy pump engine is breaking, why THEN the big exhaust out the top?

So, good questions, and kudos for UStropics for a great response.

A succinct answer to how upper level outflow might continue in spite of a broad collapse of convection, applies to the very nature of a tropical cyclone's vertical heat engine. Regardless of significant convective activity, established surface inflow (convergence) continues to result in moist warm air to enter and rise within the vertical column. That moist air continues to condensate as it's evacuated outward from the column. Sometimes this is well displayed in a circular manner where an established upper level anticyclone is already in place or begins to develop. Other times, these upper level clouds are prominent through "outflow jets"; Often a result of a shear pattern or more volatile upper air conditions. Hope that answers your second question

[Sciencerocks]

[OuterBanker]

This storm has been puzzling from the start. It should have decoupled days ago. I started to breathe a sigh of relief when all the models shifted to the west. According to the models even the rain will be minor. But, after looking at the latest visible and IR it seems to be expanding to the east. It looks like the heights are dropping over the center and a second mlc circulation is forming near the Ga coast. Almost like it’s making a run to the coast. Not sure what to make of it.