Discussion of Intense Tropical Cyclones

[1900hurricane]

Nida '09 is another that I hold in very high regard. It also intensified explosively (albeit without a pinhole eye), and in addition to having the rare cold dark grey ring encompassing much of the CDO, Nida also had the warmest eye measured from geostationary satellite that I've been able to find through old ADT data (excluding some of the very likely erroneously high eye temps spit out during the early MTSAT-1R days). JTWC operationally actually went with 160 kt winds for Nida, which prior to Haiyan, may as well have been their 8.0 intensity, but then revised downwards to 155 kt for their final best track data, which I believe was a mistake.

[FireRat]

[youtube]http://www.youtube.com/watch?v=sCYe8VINQWA[/youtube]



Nida from 2009 is another good candidate. It's one of those 155 knot STY playing catchup to dvorak and we all know dvorak is low bias on these powerful storms.

Thanks for that post euro6208, that was one of the most fascinating loops I've ever seen. Wow, that storm's explosive intesification on 11/25 was jaw dropping! It was such a large storm as well, definitely up there with the other legends like Haiyan and Tip. Nida was a textbook example of what a Monster is! IMO this beast peaked at 165 - 170 kts just basing on its appearance and savage spin on that satellite loop. I wish we had recon in there, I'm sure they would have found something truly astounding!

[CrazyC83]

Honestly I really hate the Dvorak technique now, especially those of JTWC and SAB. While low-cost to forecasting weak or mid-strength storms in areas where recon is not available, it’s a complete crap when comes to determine the actual intensity of intense hurricane. There are many unsolved problems even with recon (fl to sfc wind relationship, reliability of high SFMR winds etc.). How can we just take two set of satellite image and say which one is stronger? Recon for strong storms in the past ten years include Wilma, Felix, Megi, and Patricia have revealed how little we know about TC windspeeds. Although currently no better technique is introduced, IMO there're more things we need to keep in mind when looking at Dvorak numbers.

Dvorak isn't that bad when it comes to Cat 1/2/3 hurricane and is okay when it comes to tropical storms, but it definitely has a low bias when it comes Category 4 and 5's. Still, it's a good starting point for determining intensity, but other stuff like ADT, microwave, and storm symmetry need to be factored in IMO and be adjusted upward accordingly.

Even at T6.0 and T6.5, overall, the Dvorak estimates seem to do fairly well. It's at the uppermost end where it has a low bias, really from T7.0 upwards. Also we have learned that the scale can and does get maxed out that a T8.5 and T9.0 classification is probably appropriate as well for the rare, extreme storms that max out beyond cold dark gray. Haiyan at peak intensity was likely a T8.5, with T9.0 representing storms with even more perfect appearances, purple/white tops all the way around, which I have never seen.

I'd restructure the upper end (note these are satellite derived intensities and ignore the presence of Recon):

T6.5 --> 127 knots

T7.0 --> 140 knots (examples: Katrina at peak, Igor at peak)

T7.5 --> 152 knots (examples: Jangmi at peak, Rita at peak)

T8.0 --> 165 knots (examples: Nida at peak, Patricia at peak)

T8.5 --> 180 knots (examples: Haiyan at peak)

T9.0 --> 195 knots (no known cases)

[Yellow Evan]

Not possible unless you modify the Black Dvorak color scheme. Also, in it's current form, I'm not sure if there's a way to tell the difference between Rita, Katrina, Jangmi, and Igor. All of them had W rings and WMG eye's.

[1900hurricane]

:uarrow: Not possible unless you modify the Black Dvorak color scheme. Also, in it's current form, I'm not sure if there's a way to tell the difference between Rita, Katrina, Jangmi, and Igor. All of them had W rings and WMG eye's.

Yeah, the warm medium grey eye embedded in the white CDO is the most often seen case of a T7.0, and it does make them somewhat difficult to sort through all of them and rank them by intensity. Just using these four storms as an example, how would you rank them against each other (and if you're feeling ambitious, what intensity would you assign each) just using IR?



Katrina (alternate image here)



Rita



Jangmi



Igor

[Yellow Evan]

Yeah, the warm medium grey eye embedded in the white CDO is the most often seen case of a T7.0, and it does make them somewhat difficult to sort through all of them and rank them by intensity. Just using these four storms as an example, how would you rank them against each other (and if you're feeling ambitious, what intensity would you assign each) just using IR?

http://www.nrlmry.navy.mil/tcdat/tc05/A ... N-887W.jpg

Katrina

http://www.nrlmry.navy.mil/tcdat/tc05/A ... N-868W.jpg

Rita

http://www.nrlmry.navy.mil/tcdat/tc08/W ... E.64pc.jpg

Jangmi

http://www.nrlmry.navy.mil/tcdat/tc10/A ... W.46pc.jpg

Igor

If I had to guess without recon, I'd say Rita 150 Jangmi 145 Katrina 140 Igor 140.

[tatertawt24]

:uarrow: Not possible unless you modify the Black Dvorak color scheme. Also, in it's current form, I'm not sure if there's a way to tell the difference between Rita, Katrina, Jangmi, and Igor. All of them had W rings and WMG eye's.

Yeah, the warm medium grey eye embedded in the white CDO is the most often seen case of a T7.0, and it does make them somewhat difficult to sort through all of them and rank them by intensity. Just using these four storms as an example, how would you rank them against each other (and if you're feeling ambitious, what intensity would you assign each) just using IR?



Katrina (alternate image here)



Rita



Jangmi



Igor

I'm curious, where did you get these images?

[1900hurricane]

I got them from the NRL page. Here is the index for their images.

I'd probably go in the order of Rita, Jangmi, Katrina, Igor. Of note though is Katrina and Rita's eye temps of well over 20*C as measured by geostationary satellite, which is very rare. Storms like those two are why I personally like to watch eye temp trends when trying to assess if a storm is strengthening or weakening. Even if convection is warming up a little, but the eye continues to warm, I wouldn't bet against a storm at least maintaining intensity.

[Ptarmigan]

Here's a classic example of how IR imagery can be misleading, and with recon support

Typhoon Jangmi when recon measured 140kt and 906mb




Hurricane Katrina when recon measured 150kt and 902mb



They are similar in both size and structure but Katrina is confirmed to be the stronger one despite looks a lot weaker on satellite.
Higher latitude and background pressure in GOM is likely the reason in this case

Closer to the equator, pressure tends to be lower. I remember Wilma had 892 millibars and 135 kt winds. That type of pressure/wind setup happens more often in the West Pacific than in the Atlantic. It was also in a tropical latitude that time.

[Ptarmigan]

Some guesses in terms of winds (knts) based off of memory of how they looked:

Haiyan 185
Patricia 180
Gay 180
June 180
Angela 175
Megi 175
Monica 170
Zeb 170
Ivan 170
Joan 170
Nida 170
Andy 165
Linda 165
Nuri 165
Allen 165
Wilma 165

Wilma at its peak was 160 knots or 185 mph winds. It was based on recon. As for the other storms, I would not be surprised they were that strong.

[Ptarmigan]

I also noticed that it seems like these intense tropical cyclones behave differently than your average category 5 storm. They seem to be able to hold their intensity longer and go through EWRCs very quickly and efficiently. Both Haiyan and Patricia were able to hold their small eye and very cold cloud tops until land interaction.

Which storm do you all think was the most powerful in the world? Was it Tip or perhaps Gay, Angela, June, or Patricia?

I believe Patricia reached its extreme intensity due to a favorable trough interaction. It was not underneath the anti-cyclone. The upper high was displaced well east of the eye. It was being pulled by the trough, and I believe the interaction initially was such that there was no shear, only outflow enhancement. As Patricia approached the coast, it was sheared causing the rapid weakening before landfall.

My suspicion is that most extreme storms with a pressure had trough enhancement. Haiyan likely did not have a pressure as low as Patricia (it may have been higher than Megi's as well), though it likely had the highest winds of any TC because of the fact that there was a strong ridge just north of Haiyan that was sending west at 20 kts. I still think Haiyan had winds around 185 kts at landfall (and Guiuan did NOT get those winds, Haiyan was that small that those winds remained just offshore)

I noticed Haiyan produce high storm surge. They behaved like a tsunami. Looking at Haiyan on satellite, I think 185 knots or 215 mph sounds about right. On land with the 15 percent reduction that is 183 mph winds, which is strong! Multiply a factor of 1.5 to get gust, the gusts go as high as 274 mph!

[Yellow Evan]

Wilma at its peak was 160 knots or 185 mph winds. It was based on recon. As for the other storms, I would not be surprised they were that strong.

which didn't have SFMR and likely peaked between Recon flights.

[Ptarmigan]

Wilma at its peak was 160 knots or 185 mph winds. It was based on recon. As for the other storms, I would not be surprised they were that strong.

which didn't have SFMR and likely peaked between Recon flights.

No doubt in my mind. I suspect the pressure was lower as well.

Speaking of that, I think the same happened with Hurricane Gilbert.

22 19.40 -82.50 09/13/18Z 140 905 HURRICANE-5
23 19.70 -83.80 09/14/00Z 160 888 HURRICANE-5
24 19.90 -85.30 09/14/06Z 155 889 HURRICANE-5
25 20.40 -86.50 09/14/12Z 145 892 HURRICANE-5

http://weather.unisys.com/hurricane/atl ... /track.dat

Notice that between 00Z and 06Z, the pressure only rises by 1 millibar. I suspect Gilbert could of had peaked at 165 knots or 190 mph and pressure dropped below 888 millibars.

[znel52]

Wilma at its peak was 160 knots or 185 mph winds. It was based on recon. As for the other storms, I would not be surprised they were that strong.

which didn't have SFMR and likely peaked between Recon flights.

No doubt in my mind. I suspect the pressure was lower as well.

Speaking of that, I think the same happened with Hurricane Gilbert.

22 19.40 -82.50 09/13/18Z 140 905 HURRICANE-5
23 19.70 -83.80 09/14/00Z 160 888 HURRICANE-5
24 19.90 -85.30 09/14/06Z 155 889 HURRICANE-5
25 20.40 -86.50 09/14/12Z 145 892 HURRICANE-5

http://weather.unisys.com/hurricane/atl ... /track.dat

Notice that between 00Z and 06Z, the pressure only rises by 1 millibar. I suspect Gilbert could of had peaked at 165 knots or 190 mph and pressure dropped below 888 millibars.

Agreed, could have dropped to around 885 or so in my opinion.

Wilma was also a storm still strengthening when recon left. Could have been sub 880 in the 878-879 range.

[1900hurricane]

Here's a classic example of how IR imagery can be misleading, and with recon support

Typhoon Jangmi when recon measured 140kt and 906mb

[image removed]


Hurricane Katrina when recon measured 150kt and 902mb

[image removed]

They are similar in both size and structure but Katrina is confirmed to be the stronger one despite looks a lot weaker on satellite.
Higher latitude and background pressure in GOM is likely the reason in this case

Closer to the equator, pressure tends to be lower. I remember Wilma had 892 millibars and 135 kt winds. That type of pressure/wind setup happens more often in the West Pacific than in the Atlantic. It was also in a tropical latitude that time.

To be fair though, 135 kt/892 mb is something that wasn't seen commonly in the Western Pacific either. For Wilma, those disproportionately low winds were likely due to the onset of eyewall replacement completely blowing up the pressure gradient. The core went from a small tight one to a larger one in a relatively short time. The microwave images below are only 10 hours and 31 minutes apart.

[1900hurricane]

Probably the most difficult type of storm to assign an intensity to is one that explosively intensifies and then collapses just as fast. Without recon or ground truth, these types of storms are a nightmare to figure out how intense they actually got before falling apart, and perhaps the best example I can think of is Super Typhoon Parma from 2009. The storm developed a tiny pinhole eye perhaps even smaller than Wilma's and explosively intensified on September 30th, even attaining a full cold dark grey CDO by sunrise, before collapsing on October first.



On October 29th, around the time of the local sunrise, Parma is clearly strengthening, but it's hard to fathom the explosive intensification to come just by looking at IR.



12 hours later, a small eye is evident, and things begin to go down.



Near sunrise the next day, Parma is likely near peak intensity. Extremely small pinhole eye surrounded by a CDO colder than -80*C speaks for itself really.



About six hours after daybreak, the CDO shrinks considerably and the eye begins to fill.



Another six hours later, the core has essentially completely collapsed.

JTWC estimated max winds of 135 kt, but I wouldn't be surprised if it was quite a bit stronger than that very briefly, although such a claim is basically impossible to verify. On my recon wish list, Parma would definitely be a top 5 storm.

[euro6208]

I remember Parma very well.

Another view of this "Top 5".

[SapphireSea]

Actually one thing I can gather from the deep storms is the warming trend of clouds as it comes into the eye. Katrina had warmer and warmer clouds further from the eye and still surrounded by cold tops. This should indicate that the depth is large in a wider area and the center should be that much deeper. In the end maybe deeper storms are not necessarily more intense due to ambient pressure and other factors since weather under the deeper convection is that much more severe compared to the eyewall.

[1900hurricane]

I remember Parma very well.

Another view of this "Top 5".

[image removed]

By the time of that sat pass, Parma was already on the decline after likely peaking near sunrise. Notice how small the CDO diameter had become in this image.

I'd also like to clarify that Parma is on my top 5 recon wish list not because I necessarily believe it was a top 5 storm in terms of intensity. It could be for all I know, but I'm not going to pretend like I know how strong (or not) Parma actually was at peak intensity. The extreme rate at which it first intensified and then promptly weakened makes it a nightmare to assess, and that's exactly why I would have loved recon for this storm. Parma very well could have been a data goldmine for both tropical cyclone explosive intensification and explosive collapse.

[Ptarmigan]

To be fair though, 135 kt/892 mb is something that wasn't seen commonly in the Western Pacific either. For Wilma, those disproportionately low winds were likely due to the onset of eyewall replacement completely blowing up the pressure gradient. The core went from a small tight one to a larger one in a relatively short time. The microwave images below are only 10 hours and 31 minutes apart.

Sounds about right. Normally 892 millibars is Category 5. The 1935 Labor Day Hurricane had a pressure measured at landfall of 892 millibars. However, I read it may had a pressure as low as 880 millibars.