Discussion of Intense Tropical Cyclones

[Weather Dude]

Super Typhoon Goni vs Hurricane Eta, just two days apart. Both have achieved raw T#s of 8.0 or greater. We'll soon know which is the stronger of the two.
https://i.imgur.com/A0dRQz8.png
https://i.imgur.com/fugshdZ.png

Turns out it's not even a debate...

[aspen]

Super Typhoon Goni vs Hurricane Eta, just two days apart. Both have achieved raw T#s of 8.0 or greater. We'll soon know which is the stronger of the two.
https://i.imgur.com/A0dRQz8.png
https://i.imgur.com/fugshdZ.png

Turns out it's not even a debate...

Eta does really raise the question of whether or not extremely cold cloud tops are indicative of true intensity. Going off of Dvorak appearance, anything from 160-185 kt and <900 mbar seemed possible, but at most it was 140-145 kt and 915-920 mbar. It’s entirely possible Goni was also over-estimated at some point in its life. If any data from landfall survived, though, we could actually have direct measurements of its peak.

[TyphoonNara]

Super Typhoon Goni vs Hurricane Eta, just two days apart. Both have achieved raw T#s of 8.0 or greater. We'll soon know which is the stronger of the two.
https://i.imgur.com/A0dRQz8.png
https://i.imgur.com/fugshdZ.png

Turns out it's not even a debate...

Eta does really raise the question of whether or not extremely cold cloud tops are indicative of true intensity. Going off of Dvorak appearance, anything from 160-185 kt and <900 mbar seemed possible, but at most it was 140-145 kt and 915-920 mbar. It’s entirely possible Goni was also over-estimated at some point in its life. If any data from landfall survived, though, we could actually have direct measurements of its peak.

I would argue that Goni's actual intensity is closer to its Dvorak estimates than that of Eta, solely because Goni managed to maintain T numbers of over 7.5 for over 36 hours, while Eta failed to hold on to its peak. It has been proven numerous times that actual wind speed has a tendency to lag behind satellite appearance. So Goni's much longer peak would imply its real intensity is closer to its satellite appearance. Of course, without recon in Goni all of these are just guesswork.

Regarding the question of whether or not extremely cold cloud tops are indicative of true intensity, I would say there are many other indicators that could affect a storm's intensity. That's why SATCON, which is a metric that follows many different properties of a storm, has proven to be much more accurate in following recon than Dvorak, especially in storms like Irma and Dorian.

[Weather Dude]

Super Typhoon Goni vs Hurricane Eta, just two days apart. Both have achieved raw T#s of 8.0 or greater. We'll soon know which is the stronger of the two.
https://i.imgur.com/A0dRQz8.png
https://i.imgur.com/fugshdZ.png

Turns out it's not even a debate...

Eta does really raise the question of whether or not extremely cold cloud tops are indicative of true intensity. Going off of Dvorak appearance, anything from 160-185 kt and <900 mbar seemed possible, but at most it was 140-145 kt and 915-920 mbar. It’s entirely possible Goni was also over-estimated at some point in its life. If any data from landfall survived, though, we could actually have direct measurements of its peak.

The difference is Goni actually got a true T8.0 rating while Eta only had ridiculous raw T's. I feel like Goni's 170 kt estimate is pretty close. Goni also had much more time to establish itself as a Cat 5 before really ramping up to that 170kts. Goni had the eye cleared for a long time before that T8.0 estimate. Eta only had the eye cleared for a couple hours, and it wasn't as warm as Goni's was. Eta is a storm like we've never seen before in November in the Atlantic so it was tough to know that it was actually weaker than we all thought. If Eta was to form in peak season it likely wouldn't have those insanely cold cloud tops like it did.

[aspen]

Turns out it's not even a debate...

Eta does really raise the question of whether or not extremely cold cloud tops are indicative of true intensity. Going off of Dvorak appearance, anything from 160-185 kt and <900 mbar seemed possible, but at most it was 140-145 kt and 915-920 mbar. It’s entirely possible Goni was also over-estimated at some point in its life. If any data from landfall survived, though, we could actually have direct measurements of its peak.

I would argue that Goni's actual intensity is closer to its Dvorak estimates than that of Eta, solely because Goni managed to maintain T numbers of over 7.5 for over 36 hours, while Eta failed to hold on to its peak. It has been proven numerous times that actual wind speed has a tendency to lag behind satellite appearance. So Goni's much longer peak would imply its real intensity is closer to its satellite appearance. Of course, without recon in Goni all of these are just guesswork.

Regarding the question of whether or not extremely cold cloud tops are indicative of true intensity, I would say there are many other indicators that could affect a storm's intensity. That's why SATCON, which is a metric that follows many different properties of a storm, has proven to be much more accurate in following recon than Dvorak, especially in storms like Irma and Dorian.

What was SATCON estimating for Eta?

[Ed_2001]

Makes me think. Goni's SATCON and AMSU estimates were both off the charts and would put it in Patricia territory, though the JTWC estimate is probably reasonable and I imagine it would be extremely hard to justify upgrading any storm to 200mph + without more concrete evidence, because they are just so rare.

[euro6208]

Super Typhoon Goni vs Hurricane Eta, just two days apart. Both have achieved raw T#s of 8.0 or greater. We'll soon know which is the stronger of the two.

Goni actually had Dvorak fixes of 8.0 from PGTW/KNES.

Eta is only at 6.5.

Pretty sure it got up to 8.4

7.0 is Cat 5. I'm pretty sure it would be upgraded operationally had it reach that.

[cheezyWXguy]

Goni actually had Dvorak fixes of 8.0 from PGTW/KNES.

Eta is only at 6.5.

Pretty sure it got up to 8.4

https://i.imgur.com/gra3KhV.png

7.0 is Cat 5. I'm pretty sure it would be upgraded operationally had it reach that.

At one point final T got to 7.2, but recon never supported anything above 135kt. Maybe they’ll reconsider in the TCR, but if they do, I don’t think dvorak will decide it.

[Weather Dude]

I think Eta is going to go down as one of those "probable" Cat 5's where it likely reached 140kts at some point between the recon missions, but the recon never supported it while it was there. We'll see what they do in the TCR but it's hard to upgrade without any solid evidence

[mrbagyo]

Interesting insight from a University of the Philippines-Diliman structural engineer (wind engineer) on the intensity of Haiyan / Yolanda.
This is the first time I heard that Tacloban station did record a 279.2 kph gust while Bantayan island recorded an even higher speed of 281 kph.
Research author's estimate of Typhoon Haiyan intensity are 290 kph (10 minutes ) / 351 kph (1 minutes) and a minimum pressure of 872.2 mbar

"Estimating Typhoon Haiyan's Wind Speeds Using Windicators"


 https://twitter.com/JoshuaCAgar/status/1325135888511164416




 https://twitter.com/JoshuaCAgar/status/1325135901492613124




 https://twitter.com/JoshuaCAgar/status/1325137472418836480




 https://twitter.com/JoshuaCAgar/status/1325140748472258560




 https://twitter.com/JoshuaCAgar/status/1325141683286142977




 https://twitter.com/JoshuaCAgar/status/1325146435864596483




 https://twitter.com/JoshuaCAgar/status/1325147057322012678




 https://twitter.com/JoshuaCAgar/status/1325148887263322112

[euro6208]

Who would have thought.

[Hayabusa]

Interesting insight from a University of the Philippines-Diliman structural engineer (wind engineer) on the intensity of Haiyan / Yolanda.
This is the first time I heard that Tacloban station did record a 279.2 kph gust while Bantayan island recorded an even higher speed of 281 kph.
Research author's estimate of Typhoon Haiyan intensity are 290 kph (10 minutes ) / 351 kph (1 minutes) and a minimum pressure of 872.2 mbar

"Estimating Typhoon Haiyan's Wind Speeds Using Windicators"


https://twitter.com/JoshuaCAgar/status/1325135888511164416?s=20

https://twitter.com/JoshuaCAgar/status/1325135901492613124?s=20

https://twitter.com/JoshuaCAgar/status/1325137472418836480?s=20

https://twitter.com/JoshuaCAgar/status/1325140748472258560?s=20

https://twitter.com/JoshuaCAgar/status/1325141683286142977?s=20

https://twitter.com/JoshuaCAgar/status/1325146435864596483?s=20

https://twitter.com/JoshuaCAgar/status/1325147057322012678?s=20

https://twitter.com/JoshuaCAgar/status/1325148887263322112?s=20

Very interesting they concluded 190 knots 1 minute sustained winds while this different paper concludes that the minimum pressure was 860 mb but no wind estimate.

In the three scenarios, the minimum pressure estimated in the eye of Haiyan has values of 866.5, 861 and 855.5hPa, respectively – lower than the world record of 870hPa recorded in Typhoon Tip in October 1979. The most likely scenario for Haiyan would correspond to a rounded value of 860hPa.

In a study aimed at estimating the intensity of the ten most intense cyclones of the satellite era, Velden et al. (2016) found an 878hPa pressure associated with a maximum sustained wind of 176kn for Haiyan using the Advanced Dvorak Technique. This pressure remains higher than the 860hPa estimated in our study of Haiyan. The next step will be to better estimate the maximum sustained winds generated by a typhoon whose pressure was around 860hPa.

[TorSkk]

I think that Eta demonstrates quite convincingly why Dvorak constraints are out there

[aspen]

I think that Eta demonstrates quite convincingly why Dvorak constraints are out there

Imagine if Eta was in the WPac and the JTWC went with 130 kt like the NHC. We would be going berserk that they didn’t upgrade it to 160-180 kt, not knowing that even 145 kt is an aggressive estimate.

[Weather Dude]

I think that Eta demonstrates quite convincingly why Dvorak constraints are out there

Imagine if Eta was in the WPac and the JTWC went with 130 kt like the NHC. We would be going berserk that they didn’t upgrade it to 160-180 kt, not knowing that even 145 kt is an aggressive estimate.

That makes me doubt the intensity of some November/December storms like Kammuri. I don't even think Kammuri was a Cat 4 honestly

[aspen]

I think that Eta demonstrates quite convincingly why Dvorak constraints are out there

Imagine if Eta was in the WPac and the JTWC went with 130 kt like the NHC. We would be going berserk that they didn’t upgrade it to 160-180 kt, not knowing that even 145 kt is an aggressive estimate.

That makes me doubt the intensity of some November/December storms like Kammuri. I don't even think Kammuri was a Cat 4 honestly

I think duration needs to be taken into account. Eta hit raws of T#8.5, but it’s massive CDG CDO only lasted for 12 hours maximum. By comparison, last year’s Halong, which also occurred in early November, had extremely deep convection from day 1 and throughout its RI phase, and it hit T#7.5 and higher on ADT for most of the day on November 5th. It wasn’t a sudden T#7.5-8.0 like Eta, so it had enough time to get close to the official 165 kt/888 mbar estimate.

If I recall correctly, Kammuri didn’t have much ground-based evidence to support a Cat 4 intensity, and pressure readings near the center only down down to the 960s.

[Weather Dude]

Imagine if Eta was in the WPac and the JTWC went with 130 kt like the NHC. We would be going berserk that they didn’t upgrade it to 160-180 kt, not knowing that even 145 kt is an aggressive estimate.

That makes me doubt the intensity of some November/December storms like Kammuri. I don't even think Kammuri was a Cat 4 honestly

I think duration needs to be taken into account. Eta hit raws of T#8.5, but it’s massive CDG CDO only lasted for 12 hours maximum. By comparison, last year’s Halong, which also occurred in early November, had extremely deep convection from day 1 and throughout its RI phase, and it hit T#7.5 and higher on ADT for most of the day on November 5th. It wasn’t a sudden T#7.5-8.0 like Eta, so it had enough time to get close to the official 165 kt/888 mbar estimate.

If I recall correctly, Kammuri didn’t have much ground-based evidence to support a Cat 4 intensity, and pressure readings near the center only down down to the 960s.

Yeah I agree. If Eta would have been able to hold that structure for a few more hours it would have been insane. Thankfully for CA the ERC happened but it was still a disaster.

[aspen]

That makes me doubt the intensity of some November/December storms like Kammuri. I don't even think Kammuri was a Cat 4 honestly

I think duration needs to be taken into account. Eta hit raws of T#8.5, but it’s massive CDG CDO only lasted for 12 hours maximum. By comparison, last year’s Halong, which also occurred in early November, had extremely deep convection from day 1 and throughout its RI phase, and it hit T#7.5 and higher on ADT for most of the day on November 5th. It wasn’t a sudden T#7.5-8.0 like Eta, so it had enough time to get close to the official 165 kt/888 mbar estimate.

If I recall correctly, Kammuri didn’t have much ground-based evidence to support a Cat 4 intensity, and pressure readings near the center only down down to the 960s.

Yeah I agree. If Eta would have been able to hold that structure for a few more hours it would have been insane. Thankfully for CA the ERC happened but it was still a disaster.

The pinhole remained intact for like 3 hours after the final recon pass, which would’ve been enough time for it to go sub-915. It probably did, but we’ll never know.

I hope 2021 doesn’t have as many recon issues...

[NotoSans]

Iota is another example of intense TC following closely w/ Dvorak estimates (recon finds 140kt when FT reaches 7.0). It seems Dvorak in general does a good job for Gulf and Caribbean systems (Maria, Michael, just to name a few), but less well for storms in the eastern Atlantic (Dorian and Irma, in particular).

[CrazyC83]

Eta kind of reminds me of Parma in 2009(?) in the WPAC. Ramped up to crazy town with cloud tops, but didn't hold them long enough to register really intense winds and had an eye that wasn't quite warm enough.