ATL: LARRY - Post-Tropical - Discussion

[AlphaToOmega]

105 knots/958 millibars

AL, 12, 2021090500, , BEST, 0, 177N, 475W, 105, 958, HU

[Ubuntwo]

Thats interesting that it was developed off of West Pacific storms. If the Atlantic varies a bit, you’d think they could have a specific technique for the Atlantic. A lot of Atlantic storms get recon and so they get accurate wind data. That data plus the Dvorak number could easily create a more accurate Atlantic scale.


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There’s variation in part of the basin and time of year which would complicate that. ETA was a really late season hurricane in the Western Caribbean so it was far weaker than Dvorak/cloud top temps would indicate. Vice versa here.

[Yellow Evan]

https://cdn.discordapp.com/attachments/733552978572869632/883769747546734642/50c49ebd-d8b7-420a-9900-448acdcba6cf.png

Still T5.0. Not convinced this is as strong as the NHC or well Papin says tbh.

Tropopause temperature is about -65C which matches up with the light grey cdo. Only the strongest updrafts are getting into the stratosphere which we can see with the blacks and whites rotating cyclonically. With the mediocre OHC I'm not sure this will get the cdo of -70 or -75 cloud tops. However since most of the Dvorak technique was developed based on West Pacific storms or off storms in the warmer parts of the Atlantic, I wouldn't be surprised if recon finds winds higher than the Dvorak estimates would suggest.

Does anyone remember if some of these category 4/5 storms in this part of the ocean like Isabel that have received recon have matched up with their Dvorak estimates?

I believe Isabel achieved an average T7.0 on September 11. Dropped down to T6.5 the following day, September 12.

https://i.imgur.com/sf4XmrX.png

Isabel didn’t have Recon at its first peak (which in truth was probably on the 11th) and quite frankly wouldn’t surprise me if it was quite similar to Irma/Dorian in intensity at its time just based on eye definition and overall symmetry. High end and warm eye open Atlantic storms can be weird like that because the tropopause is relatively warm. Isabel at its annular peak was a Recon confirmed Cat 5 despite just having a B ring along with a 17C eye (so probably T6.0).

However, there’s a major difference between this and Isabel. The eye is nowhere near as round despite similar CDO rings and even comparable eye temperatures. Not to mention Isabel’s CDO is definitely more smooth it.

[TheDreamTraveler]

https://imagizer.imageshack.com/img924/9426/Pdo4pv.gif

Yeah we're in annular territory lol

Larry is shedding what's left of the spiral banding it has left

[Yellow Evan]

[supercane4867]

Tropopause temperature is about -65C which matches up with the light grey cdo. Only the strongest updrafts are getting into the stratosphere which we can see with the blacks and whites rotating cyclonically. With the mediocre OHC I'm not sure this will get the cdo of -70 or -75 cloud tops. However since most of the Dvorak technique was developed based on West Pacific storms or off storms in the warmer parts of the Atlantic, I wouldn't be surprised if recon finds winds higher than the Dvorak estimates would suggest.

Does anyone remember if some of these category 4/5 storms in this part of the ocean like Isabel that have received recon have matched up with their Dvorak estimates?

I believe Isabel achieved an average T7.0 on September 11. Dropped down to T6.5 the following day, September 12.

https://i.imgur.com/sf4XmrX.png

Isabel didn’t have Recon at its first peak (which in truth was probably on the 11th) and quite frankly wouldn’t surprise me if it was quite similar to Irma/Dorian in intensity at its time just based on eye definition and overall symmetry. High end and warm eye open Atlantic storms can be weird like that because the tropopause is relatively warm. Isabel at its annular peak was a Recon confirmed Cat 5 despite just having a B ring along with a 17C eye (so probably T6.0).

However, there’s a major difference between this and Isabel. The eye is nowhere near as round despite similar CDO rings and even comparable eye temperatures. Not to mention Isabel’s CDO is definitely more smooth it.

Satellite presentation of Isabel at her initial CAT5 peak FWIW. Isabel was one of the only 2 Atlantic hurricanes upgraded to CAT5 operationally based solely on Dvorak estimates (the other one being Lorenzo whose overall symmetry was a far cry from Isabel). The fact that she made NHC forecasters to pull the rare CAT5 trigger without any recon support, which was unprecedented at the time, really tells you something about her potential.

[Hypercane_Kyle]

Starting to see some deeper convection going. Still feeling some shear though.

[CyclonicFury]

No longer expected to become a Category 4.

[supercane4867]

Gonna give HWRF big credit for nailing the structure of Larry, but with the current structure in place it would be hard to see additional strengthening.

18z HWRF run keeps wind speed steady for the next 48hrs.

[Sciencerocks]

[Teban54]

I remember last year, at one point when Teddy was a Cat 2, it was also no longer forecast to become a Cat 4. So there's still a chance for Larry to intensify further.

That said, Larry's current appearance doesn't resemble a strengthening cyclone. Despite the stronger southern eyewall as per microwave, its eye remains ragged and CDO broken to the SW all day. Shear is likely having a bigger impact than expected.

A recent convective burst with -70C tops is trying to make it to the SW as I'm typing this... So we'll see how it goes.


Edit: Looks like that convective burst managed to wrap around and form a black ring, even though it might be unstable.

[Yellow Evan]

T6.0.

[Kingarabian]

I believe Isabel achieved an average T7.0 on September 11. Dropped down to T6.5 the following day, September 12.

https://i.imgur.com/sf4XmrX.png

Isabel didn’t have Recon at its first peak (which in truth was probably on the 11th) and quite frankly wouldn’t surprise me if it was quite similar to Irma/Dorian in intensity at its time just based on eye definition and overall symmetry. High end and warm eye open Atlantic storms can be weird like that because the tropopause is relatively warm. Isabel at its annular peak was a Recon confirmed Cat 5 despite just having a B ring along with a 17C eye (so probably T6.0).

However, there’s a major difference between this and Isabel. The eye is nowhere near as round despite similar CDO rings and even comparable eye temperatures. Not to mention Isabel’s CDO is definitely more smooth it.

Satellite presentation of Isabel at her initial CAT5 peak FWIW. Isabel was one of the only 2 Atlantic hurricanes upgraded to CAT5 operationally based solely on Dvorak estimates (the other one being Lorenzo whose overall symmetry was a far cry from Isabel). The fact that she made NHC forecasters to pull the rare CAT5 trigger without any recon support, which was unprecedented at the time, really tells you something about her potential.

https://i.imgur.com/zJxuzaU.gif

https://i.imgur.com/nXXAehR.gif

[url]https://i.imgur.com/lNvuial.gif[/rl]

That's pretty much a W ring in BD imagery. With an eye that well defined and warm, Dvorak estimates had to have been at 7.0. I read somewhere thats what the consensus was near its peak.

[Yellow Evan]

Isabel didn’t have Recon at its first peak (which in truth was probably on the 11th) and quite frankly wouldn’t surprise me if it was quite similar to Irma/Dorian in intensity at its time just based on eye definition and overall symmetry. High end and warm eye open Atlantic storms can be weird like that because the tropopause is relatively warm. Isabel at its annular peak was a Recon confirmed Cat 5 despite just having a B ring along with a 17C eye (so probably T6.0).

However, there’s a major difference between this and Isabel. The eye is nowhere near as round despite similar CDO rings and even comparable eye temperatures. Not to mention Isabel’s CDO is definitely more smooth it.

Satellite presentation of Isabel at her initial CAT5 peak FWIW. Isabel was one of the only 2 Atlantic hurricanes upgraded to CAT5 operationally based solely on Dvorak estimates (the other one being Lorenzo whose overall symmetry was a far cry from Isabel). The fact that she made NHC forecasters to pull the rare CAT5 trigger without any recon support, which was unprecedented at the time, really tells you something about her potential.

https://i.imgur.com/zJxuzaU.gif

https://i.imgur.com/nXXAehR.gif

[url]https://i.imgur.com/lNvuial.gif[/rl]

That's pretty much a W ring in BD imagery. With an eye that well defined and warm, Dvorak estimates had to have been at 7.0. I read somewhere thats what the consensus was near its peak.

Yeah it’s one of two Atlantic FT’s of T7.0 ever that didn’t receive Recon, other being Igor.

[Yellow Evan]

T5.5. B ring broke.

[supercane4867]

With the ongoing symmetrization, 115-120kt peak by tomorrow seems reasonable

[InfernoFlameCat]

That was a short lived weakening phase. Larry back on intensification now.

[Yellow Evan]

TXNT27 KNES 050541
TCSNTL

A. 12L (LARRY)

B. 05/0531Z

C. 18.5N

D. 48.4W

E. ONE/GOES-E

F. T5.5/5.5

G. IR/EIR/SWIR

H. REMARKS...A WMG EYE SURROUNDED BY LG AND EMBEDDED IN LG YIELDS A
DT OF 5.5 AFTER AN EYE ADJ OF +0.5. MET IS EQUAL TO 6.0 AND PT IS EQUAL
5.5 BASED ON A DEVELOPMENT TREND IN THE LAST 24 HOURS. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...TUGGLE

[Sciencerocks]

nice broad view! Kind of reminds me of Igor 2010, Bill 2009

[Teban54]

I remember last year, at one point when Teddy was a Cat 2, it was also no longer forecast to become a Cat 4. So there's still a chance for Larry to intensify further.

That said, Larry's current appearance doesn't resemble a strengthening cyclone. Despite the stronger southern eyewall as per microwave, its eye remains ragged and CDO broken to the SW all day. Shear is likely having a bigger impact than expected.

A recent convective burst with -70C tops is trying to make it to the SW as I'm typing this... So we'll see how it goes.


Edit: Looks like that convective burst managed to wrap around and form a black ring, even though it might be unstable.

So intensification resumed right after I made the reply... Oof.