Discussion of Intense Tropical Cyclones

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Re: Discussion of Intense Tropical Cyclones

#681 Postby InfernoFlameCat » Tue Dec 07, 2021 2:01 pm

Foxfires wrote:Okay this is unrelated to what's currently being discussed but I was wondering what everyone's intensity estimates for these typhoons are and if you agree with the JMA's estimate.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198824/bd/512x512/GMS388100412.198824.jpg
Typhoon Nelson 1988. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198908/bd/512x512/GMS389071512.198908.jpg
Typhoon Gordon. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198902/bd/512x512/GMS389042106.198902.jpg
Typhoon Andy 1989. The JMA estimated peak intensity at 920mb.

There're probably other satellite pics like microwave imagery that would help but I can't find those anywhere.

Gordon would probably be around 915mb IMO with the CMG ring and good presentation. Being in the Pacific is why I don't account those rather cold cloud tops that might suggest something like 905-900mb in the Atlantic. However for Nelson that system is most likely below 900mb IMO. It is symmetric with CDG ring and a warm eye(can't zoom in but think I see wmg. So that is my vote. Typhoon Andy is difficult. It has a very thick CDG ring but the eye is not very warm in contrast with most intense cyclones and the eye is not as symmetric either. This has me leaning towards 915 - 920mb. just my opinion though.
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Re: Discussion of Intense Tropical Cyclones

#682 Postby mrbagyo » Wed Dec 08, 2021 8:02 am

InfernoFlameCat wrote:
Foxfires wrote:Okay this is unrelated to what's currently being discussed but I was wondering what everyone's intensity estimates for these typhoons are and if you agree with the JMA's estimate.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198824/bd/512x512/GMS388100412.198824.jpg
Typhoon Nelson 1988. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198908/bd/512x512/GMS389071512.198908.jpg
Typhoon Gordon. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198902/bd/512x512/GMS389042106.198902.jpg
Typhoon Andy 1989. The JMA estimated peak intensity at 920mb.

There're probably other satellite pics like microwave imagery that would help but I can't find those anywhere.

Gordon would probably be around 915mb IMO with the CMG ring and good presentation. Being in the Pacific is why I don't account those rather cold cloud tops that might suggest something like 905-900mb in the Atlantic. However for Nelson that system is most likely below 900mb IMO. It is symmetric with CDG ring and a warm eye(can't zoom in but think I see wmg. So that is my vote. Typhoon Andy is difficult. It has a very thick CDG ring but the eye is not very warm in contrast with most intense cyclones and the eye is not as symmetric either. This has me leaning towards 915 - 920mb. just my opinion though.


Gordon's eye is the warmest of the three and it maintained that full symmetrical CMG ring for almost 24 hours leading up to its Luzon Landfall - Gordon's microwave is also hot. IMO, it's on par with Meranti
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Re: Discussion of Intense Tropical Cyclones

#683 Postby NotoSans » Wed Dec 08, 2021 11:28 am

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Re: Discussion of Intense Tropical Cyclones

#684 Postby Iceresistance » Wed Dec 08, 2021 11:37 am



Does that mean that Goni's first peak my have been at 200 mph?
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Re: Discussion of Intense Tropical Cyclones

#685 Postby MarioProtVI » Wed Dec 08, 2021 2:16 pm

Iceresistance wrote:


Does that mean that Goni's first peak my have been at 200 mph?

Goni’s first and arguably true peak is underestimated - I think it’s in the range of 165-175 kt (leaning towards the middle-high end bracket here) given its pinhole eye that was very dry and was very similar in appearance structure-wise to Nepartak 2016 and Hagibis 2019 which were both underestimated storms and likely >165 kt even in post analysis by JTWC). The official “peak” is conversely overestimated given I do not see how 170 kt can go with an eye that wasn’t that warm at all and was actually more of a wet eye. More on the premises of 155 kt for peak 2.
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Re: Discussion of Intense Tropical Cyclones

#686 Postby Yellow Evan » Wed Dec 08, 2021 4:13 pm

Foxfires wrote:Okay this is unrelated to what's currently being discussed but I was wondering what everyone's intensity estimates for these typhoons are and if you agree with the JMA's estimate.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198824/bd/512x512/GMS388100412.198824.jpg
Typhoon Nelson 1988. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198908/bd/512x512/GMS389071512.198908.jpg
Typhoon Gordon. The JMA estimated peak intensity at 915mb.

http://agora.ex.nii.ac.jp/digital-typhoon/wnp/by-name/198902/bd/512x512/GMS389042106.198902.jpg
Typhoon Andy 1989. The JMA estimated peak intensity at 920mb.

There're probably other satellite pics like microwave imagery that would help but I can't find those anywhere.


Gordon is basically Meranti with a slightly larger eye. Probably around 170, with the summer tropopause holding the cloud tops back, and thus making it look weaker than it currently is. Andy and Nelson are probably both slightly weaker, though not by much.
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Re: Discussion of Intense Tropical Cyclones

#687 Postby Foxfires » Mon Dec 13, 2021 6:37 am

I feel like some official/agency stuff about Typhoon Judy (1979) is just.. weirdly false for some reason

On the 19th of August at 22:45, aircraft reconnaissance recorded a pressure of 887mb was recorded in the storm according to the JTWC's ATCR. Some time earlier, the warmest eye temperature (at 700mb height) ever recorded in a tropical cyclone (34C) was also recorded when the storm's barometric was at 889mb.

I went to look through satellite images of Judy from the JMA database out of curiosity
Why does it state the pressure at 910mb
that's not even rounded to the nearest 5mb or anything
Image

I also looked through the IBTrACS database for the other agency estimates
Image
It feels odd that agencies aren't paying attention to aircraft recon observations sometimes (or maybe they don't trust them idk)
you wouldn't be able to know about Judy's actual pressure if you didn't read the JTWC's ATCR

Anyways, because the JTWC used AH77 (Atkinson-Holiday wind pressure relationship 1977) for winds, which apparently tends to underestimate wind speed for stronger storms, I was wondering: what does everyone here think Judy's peak winds were? I'm not an expert but I'd say >=160kt from the pressure alone.
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Re: Discussion of Intense Tropical Cyclones

#688 Postby mrbagyo » Mon Dec 13, 2021 7:40 am

Foxfires wrote:I feel like some official/agency stuff about Typhoon Judy (1979) is just.. weirdly false for some reason

On the 19th of August at 22:45, aircraft reconnaissance recorded a pressure of 887mb was recorded in the storm according to the JTWC's ATCR. Some time earlier, the warmest eye temperature (at 700mb height) ever recorded in a tropical cyclone (34C) was also recorded when the storm's barometric was at 889mb.

I went to look through satellite images of Judy from the JMA database out of curiosity
Why does it state the pressure at 910mb
that's not even rounded to the nearest 5mb or anything
https://media.discordapp.net/attachments/887577983508967455/919879276759744522/unknown.png?width=990&height=427

I also looked through the IBTrACS database for the other agency estimates
https://media.discordapp.net/attachments/887577983508967455/919880223577755668/unknown.png
It feels odd that agencies aren't paying attention to aircraft recon observations sometimes (or maybe they don't trust them idk)
you wouldn't be able to know about Judy's actual pressure if you didn't read the JTWC's ATCR

Anyways, because the JTWC used AH77 (Atkinson-Holiday wind pressure relationship 1977) for winds, which apparently tends to underestimate wind speed for stronger storms, I was wondering: what does everyone here think Judy's peak winds were? I'm not an expert but I'd say >=160kt from the pressure alone.


1900hurricane (author of this thread) - reanalyzed Judy at 165 knots

JMA is notorious at ignoring ground / actual obs from other agency - a station in Legazpi City, Albay once recorded a minimum pressure of 909.5hPa during Typhoon Nina (1987) but JMA's database puts the mslp at 930 hPa

JMA's mslp for Rammasun is still 935 hpa despite a sub-900 hPa reading in Quizou Island
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Re: Discussion of Intense Tropical Cyclones

#689 Postby aspen » Mon Dec 13, 2021 10:29 am

mrbagyo wrote:
Foxfires wrote:I feel like some official/agency stuff about Typhoon Judy (1979) is just.. weirdly false for some reason

On the 19th of August at 22:45, aircraft reconnaissance recorded a pressure of 887mb was recorded in the storm according to the JTWC's ATCR. Some time earlier, the warmest eye temperature (at 700mb height) ever recorded in a tropical cyclone (34C) was also recorded when the storm's barometric was at 889mb.

I went to look through satellite images of Judy from the JMA database out of curiosity
Why does it state the pressure at 910mb
that's not even rounded to the nearest 5mb or anything
https://media.discordapp.net/attachments/887577983508967455/919879276759744522/unknown.png?width=990&height=427

I also looked through the IBTrACS database for the other agency estimates
https://media.discordapp.net/attachments/887577983508967455/919880223577755668/unknown.png
It feels odd that agencies aren't paying attention to aircraft recon observations sometimes (or maybe they don't trust them idk)
you wouldn't be able to know about Judy's actual pressure if you didn't read the JTWC's ATCR

Anyways, because the JTWC used AH77 (Atkinson-Holiday wind pressure relationship 1977) for winds, which apparently tends to underestimate wind speed for stronger storms, I was wondering: what does everyone here think Judy's peak winds were? I'm not an expert but I'd say >=160kt from the pressure alone.


1900hurricane (author of this thread) - reanalyzed Judy at 165 knots

JMA is notorious at ignoring ground / actual obs from other agency - a station in Legazpi City, Albay once recorded a minimum pressure of 909.5hPa during Typhoon Nina (1987) but JMA's database puts the mslp at 930 hPa

JMA's mslp for Rammasun is still 935 hpa despite a sub-900 hPa reading in Quizou Island

I really dislike how the JMA runs things in the WPac. Keeping pressure estimates at intervals of 5mb is bad enough, but not even bothering to take into account other estimates — JWTC, Dvorak, or ground-based observations — just makes things worse. The pressure differences between the JMA and JTWC intensity estimates can exceed 40 mb in some cases.

Using 10-minute sustained winds is also a poor choice because it can make a storm seem weaker to the public eyes than it actually is. One of the worst offenders is “Severe Tropical Storm” Usagi in 2018, which peaked as a 90 kt Cat 2 typhoon but had 10-minute sustained winds of 60 kt. The JMA also said it was only 990mb, when in actuality it was likely sub-970mb.

The JMA did well with Surigae’s pressure (890mb vs 888mb from JTWC), but storms like Hagibis and Halong still have 15-25mb pressure discrepancies between agencies.
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Re: Discussion of Intense Tropical Cyclones

#690 Postby Iceresistance » Mon Dec 13, 2021 11:27 am

Is is possible to get a weighted average on the Sea-Level Pressure between the JMA & JTWC?
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Re: Discussion of Intense Tropical Cyclones

#691 Postby Foxfires » Tue Dec 14, 2021 7:51 am

mrbagyo wrote:1900hurricane (author of this thread) - reanalyzed Judy at 165 knots

JMA is notorious at ignoring ground / actual obs from other agency - a station in Legazpi City, Albay once recorded a minimum pressure of 909.5hPa during Typhoon Nina (1987) but JMA's database puts the mslp at 930 hPa

JMA's mslp for Rammasun is still 935 hpa despite a sub-900 hPa reading in Quizou Island


Ah well I'm not surprised considering they refuse to go sub-900mb a lot of the time despite the history of the basin they're monitoring (literally storms dethroning each other at an alarming rate) and seem to only give it for T8.0 storms. It's like they think it's too extreme or something which is incredibly weird. I mean, the JMA literally has so much more reason to assign a storm sub-890mb without recon but for some reason it's the FMS that's willing to do it.
Storms like Zeb are almost certainly sub-900mb, and the weird AH77 derived pressure from the JTWC may actually be closer to its actual pressure. And don't get me started on storms like Angela and Mike (I mean like, at least JMA gave 900mb to Zeb; how did they end up with 910mb and 915mb for Angela and Mike??).


aspen wrote:I really dislike how the JMA runs things in the WPac. Keeping pressure estimates at intervals of 5mb is bad enough, but not even bothering to take into account other estimates — JWTC, Dvorak, or ground-based observations — just makes things worse. The pressure differences between the JMA and JTWC intensity estimates can exceed 40 mb in some cases.

Using 10-minute sustained winds is also a poor choice because it can make a storm seem weaker to the public eyes than it actually is. One of the worst offenders is “Severe Tropical Storm” Usagi in 2018, which peaked as a 90 kt Cat 2 typhoon but had 10-minute sustained winds of 60 kt. The JMA also said it was only 990mb, when in actuality it was likely sub-970mb.

The JMA did well with Surigae’s pressure (890mb vs 888mb from JTWC), but storms like Hagibis and Halong still have 15-25mb pressure discrepancies between agencies.


(JMA actually gave Surigae 895mb btw)
It's not really that the JMA uses 10-min sustained winds that's the problem, it's more on the fact that you can't convert the winds and get a result that makes sense with the pressure (The highest conversion I know of is x1.14) for stronger storms (at least cat 4+ intensity), and that's what makes people potentially underestimate storms because some people only pay attention to the winds (why). Take for example, Typhoon Rita 1978: the storm had a pressure of 878mb (rounded to 880mb by the JMA but whatever), but was estimated to have winds of 120kt; convert that and you get 135kt. This would imply TCs Winston (884mb), Pam (896mb), Monica (916mb), and Orson (904mb) are stronger than the 878mb storm in terms on winds. The chances of Rita being weaker than Winston are lower than the chances of Rammasun being 935mb imo. Imagine thinking a storm is a cat 4, preparing for it adequately, only to be met with something that virtually makes almost every other storm on record look like a joke... same problem with PAGASA; the chances of Haiyan being 125kt aren't exactly in the agency's favor.

Can't compare it to other storms in other basins that use 10-min winds either without making the WPAC look weak even though it's the opposite.
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Re: Discussion of Intense Tropical Cyclones

#692 Postby Yellow Evan » Tue Dec 14, 2021 1:51 pm

Why are we even looking at the JMA’s data for anything? They’re pressures are rounded in the Recon era, use of AH77 has created false pressure-wind relationship, and their use of the Koba Scale causes them to grossly underestimate high end intensities.
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Re: Discussion of Intense Tropical Cyclones

#693 Postby InfernoFlameCat » Wed Dec 15, 2021 2:47 pm

Image
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Re: Discussion of Intense Tropical Cyclones

#694 Postby NotoSans » Fri Dec 17, 2021 2:32 pm

The Koba table is developed to ensure continuity in best track data after the recon era, but one could reasonably question how maximum winds during the recon era were estimated by JMA in the first place.

To be fair to JMA - in 2018, the agency wrote a paper emphasising the need to revisit the Koba relationship. But given the lack of "ground truth" data in WPAC, such revision is practically impossible, not to mention the need to reanalyse the whole best track dataset if a revision is indeed conducted.
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Re: Discussion of Intense Tropical Cyclones

#695 Postby Foxfires » Tue Dec 21, 2021 9:33 am

Ok, I'm going to try starting a discussion on how intense Typhoon Rai was, since that's kind of the point of this forum
(I've tried spurring the discussion elsewhere
Twitter is much too rude for my taste, and people seem unable to accept that the JTWC or just other people in general can have their own opinion and that that's ok, and also the limit for wordcount is too tight for any kind of proper discussion
I've tried in the forum here about Rai but I think there's other stuff that should also be focused on there
but I decided to go with another Storm2K forum because people here seem to be more civil)

The topic of the discussion is simple: how strong was Rai at both its first (Philippine Sea) and second peak (South China Sea), and how intense was it throughout the Philippines? Most people I've seen can generally agree on 135-140kt for its first peak (high-end cat 4 to low-end cat 5), but there's a lot, lot, more debate on its second peak.


As for it's first peak, I don't know of any direct measurements from stations or barometers on Siargao or the Dinagat Islands that didn't stop recording mid-way through. However, I believe Rai was trying to undergo an eyewall replacement cycle and weakened to category 4 intensity soon after landfall anyways (based on the JTWC's estimate). But for this peak, most people can agree on 140kt (some 135kt but that's barely a difference), which is the JTWC's intensity estimate.


For the intensity throughout the Philippines, I've found some direct measurements. There was 950.5mb recorded north of the eye in Maasin City (Southern Leyte) at 18:00 PST (10:00 UTC) (thanks to user Imran_doomhaMwx for the information).

After looking through Philsensors data I found some other stuff (all recordings listed will be for 16 Dec unless stated otherwise). For Southern Leyte, a station in Malitbog recorded 988.7mb (1000.9mb at SLP assuming stated elevation of 107 is in meters) at 14:18 PST (6:18 UTC).

For Bohol, a station in Dagohoy recorded 954.78mb at 19:45 (11:45 UTC), Dangay Elementary School at Alburquerque recorded 975.83mb at 20:45 PST (12:45 UTC), DOST PSTC Bohol, Tagbilaran recorded 984.07mb at 21:45 PST (13:45 UTC), and San Miguel Municipal Hall, San Miguel recorded 971.13mb at 19:45 PST (11:45 UTC); all measurements were south of the eye and are station pressures (elevation unknown).

For Cebu, Motorpool Cansaga, Consolacion recorded 985.54mb (it says 98554.0 but I think that's an error) at 21:00 PST (13:00 UTC), BRGY. Canjue, Argao, recorded 908.1mb at 22:00 PST (14:00 UTC), 960.68mb and 973.9mb was recorded at Toledo City by two different sensors at 20:00 PST (12:00 UTC) and 19:00 PST (11:00 UTC) respectively, BRGY. Hall Manipis, Talisay City recorded 939.05mb at 20:00 PST (12:00 UTC), BRGY. Poblacion, Ginatilan recorded 987.55mb at 00:00 PST on 17 Dec (16:00 UTC 16 Dec), Catmon Seaside Park Flores, Catmon recorded 996.17mb at 19:45 PST (11:45 UTC), Cordova Municipal Hall recorded 969.34mb on 21:30 PST (13:30 UTC) (elevation is stated at 30, I'm assuming meters, but no temperature), DOST VII, Cebu City recorded 976.12mb at 21:30 PST (13:30 UTC) (elevation is stated at 62; no temp), Moalboal recorded 968.73mb at 22:30 PST (14:30 UTC) (elevation is stated at 1; no temp), Ollfi, Sibonga recorded 967.59mb at 21:30 PST (13:30 UTC) (elevation is stated at 88; no temp), Pasil, Santander recorded 989.73mb at 22:45 PST (14:45 UTC) (elevation is stated at 19; no temp), Pinamungajan, Pandacan recorded 982.35mb 22:00 PST (14:00 UTC) (elevation is stated at 29; no temp), Central Visayas Campus, Argao recorded 951.45mb at 22:30 PST (14:30 UTC), and Cabancalan-Canduman Bridge, Mandaue City recorded 980.7mb at 20:40 PST (12:40 UTC). All aforementioned readings are station level pressure.

There's more places but it's taking forever to sort through them. It doesn't look like that much but most of the stations are non-operational and I have to look through those as well.


For the second peak, this is what people cannot agree on. The JTWC put the intensity at 145kt, but I believe they changed it to 140kt. Now, Most people, specifically on Twitter, think it was 125-130kt at second peak intensity (I think I saw someone say 135kt-140kt and another 140kt) and that the JTWC was overestimating it due to Dvorak.

At 15:05 Vietnam Time (8:05 UTC) on the 18th of October, 953mb was recorded on Southwest Cay (possibly in the eye), and, I quote: "The wind recorded at 13:52 was 45.61m/s; wind gust 56.79m/s." (I got the info from a YT reply and I would like to give this person credit however I'm not sure if they're comfortable with it). Twitter user Joshua C. Agar stated in a tweet that (about the station readings): "Second photo is the simulated 10-min sustained winds, with max 10-min wind estimate to be 49.35 m/s at 14:00 (GMT+7). Max. gust projected was 60.7 m/s. #Rai doesn't sound like Cat. 5." I'm assuming this was supposed to debunk the JTWC's category 5 estimate; ironically, this actually supports their estimate for the time, which was 110-115kt (110kt on 06:00 UTC and 115kt at 12:00 UTC), and they upgraded Rai to a category 5 nearly 10 hours (around 18:00 UTC) after the 953mb reading was recorded and 11 hours after the simulated wind speeds. Unfortunately, as far as I know, there was nothing to directly record Rai's intensity at 18:00 UTC.

All of this of course, is very confusing, and so my question is: is it possible that Rai reached category 5 intensity in the South China Sea?


(Also a little note: From what I've seen, there are a number of tropical cyclones that really don't follow the look, at least on like, Dvorak (and even visible), for intense tropical cyclones (Typhoon Flo 1990 and Typhoon Tip 1979 at peak size for example). On the other side of the spectrum, there're also storms that look more intense than they actually are, like Hurricane Eta 2020 and Typhoon Vera 1979 (but then again most of Eta's ADT estimates were like T6.2-6.3 and the only thing that was T8.3 was the Raw T, in contrast to Rai where the FinalT, AdjT, and CI number were all T7+). I don't understand microwave imagery and other things enough so maybe that's a thing to consider.)

Anyways sorry if I wasted your time or something
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Re: Discussion of Intense Tropical Cyclones

#696 Postby Weather Dude » Tue Dec 21, 2021 11:11 am

Foxfires wrote:Ok, I'm going to try starting a discussion on how intense Typhoon Rai was, since that's kind of the point of this forum
(I've tried spurring the discussion elsewhere
Twitter is much too rude for my taste, and people seem unable to accept that the JTWC or just other people in general can have their own opinion and that that's ok, and also the limit for wordcount is too tight for any kind of proper discussion
I've tried in the forum here about Rai but I think there's other stuff that should also be focused on there
but I decided to go with another Storm2K forum because people here seem to be more civil)

The topic of the discussion is simple: how strong was Rai at both its first (Philippine Sea) and second peak (South China Sea), and how intense was it throughout the Philippines? Most people I've seen can generally agree on 135-140kt for its first peak (high-end cat 4 to low-end cat 5), but there's a lot, lot, more debate on its second peak.


As for it's first peak, I don't know of any direct measurements from stations or barometers on Siargao or the Dinagat Islands that didn't stop recording mid-way through. However, I believe Rai was trying to undergo an eyewall replacement cycle and weakened to category 4 intensity soon after landfall anyways (based on the JTWC's estimate). But for this peak, most people can agree on 140kt (some 135kt but that's barely a difference), which is the JTWC's intensity estimate.


For the intensity throughout the Philippines, I've found some direct measurements. There was 950.5mb recorded north of the eye in Maasin City (Southern Leyte) at 18:00 PST (10:00 UTC) (thanks to user Imran_doomhaMwx for the information).

After looking through Philsensors data I found some other stuff (all recordings listed will be for 16 Dec unless stated otherwise). For Southern Leyte, a station in Malitbog recorded 988.7mb (1000.9mb at SLP assuming stated elevation of 107 is in meters) at 14:18 PST (6:18 UTC).

For Bohol, a station in Dagohoy recorded 954.78mb at 19:45 (11:45 UTC), Dangay Elementary School at Alburquerque recorded 975.83mb at 20:45 PST (12:45 UTC), DOST PSTC Bohol, Tagbilaran recorded 984.07mb at 21:45 PST (13:45 UTC), and San Miguel Municipal Hall, San Miguel recorded 971.13mb at 19:45 PST (11:45 UTC); all measurements were south of the eye and are station pressures (elevation unknown).

For Cebu, Motorpool Cansaga, Consolacion recorded 985.54mb (it says 98554.0 but I think that's an error) at 21:00 PST (13:00 UTC), BRGY. Canjue, Argao, recorded 908.1mb at 22:00 PST (14:00 UTC), 960.68mb and 973.9mb was recorded at Toledo City by two different sensors at 20:00 PST (12:00 UTC) and 19:00 PST (11:00 UTC) respectively, BRGY. Hall Manipis, Talisay City recorded 939.05mb at 20:00 PST (12:00 UTC), BRGY. Poblacion, Ginatilan recorded 987.55mb at 00:00 PST on 17 Dec (16:00 UTC 16 Dec), Catmon Seaside Park Flores, Catmon recorded 996.17mb at 19:45 PST (11:45 UTC), Cordova Municipal Hall recorded 969.34mb on 21:30 PST (13:30 UTC) (elevation is stated at 30, I'm assuming meters, but no temperature), DOST VII, Cebu City recorded 976.12mb at 21:30 PST (13:30 UTC) (elevation is stated at 62; no temp), Moalboal recorded 968.73mb at 22:30 PST (14:30 UTC) (elevation is stated at 1; no temp), Ollfi, Sibonga recorded 967.59mb at 21:30 PST (13:30 UTC) (elevation is stated at 88; no temp), Pasil, Santander recorded 989.73mb at 22:45 PST (14:45 UTC) (elevation is stated at 19; no temp), Pinamungajan, Pandacan recorded 982.35mb 22:00 PST (14:00 UTC) (elevation is stated at 29; no temp), Central Visayas Campus, Argao recorded 951.45mb at 22:30 PST (14:30 UTC), and Cabancalan-Canduman Bridge, Mandaue City recorded 980.7mb at 20:40 PST (12:40 UTC). All aforementioned readings are station level pressure.

There's more places but it's taking forever to sort through them. It doesn't look like that much but most of the stations are non-operational and I have to look through those as well.


For the second peak, this is what people cannot agree on. The JTWC put the intensity at 145kt, but I believe they changed it to 140kt. Now, Most people, specifically on Twitter, think it was 125-130kt at second peak intensity (I think I saw someone say 135kt-140kt and another 140kt) and that the JTWC was overestimating it due to Dvorak.

At 15:05 Vietnam Time (8:05 UTC) on the 18th of October, 953mb was recorded on Southwest Cay (possibly in the eye), and, I quote: "The wind recorded at 13:52 was 45.61m/s; wind gust 56.79m/s." (I got the info from a YT reply and I would like to give this person credit however I'm not sure if they're comfortable with it). Twitter user Joshua C. Agar stated in a tweet that (about the station readings): "Second photo is the simulated 10-min sustained winds, with max 10-min wind estimate to be 49.35 m/s at 14:00 (GMT+7). Max. gust projected was 60.7 m/s. #Rai doesn't sound like Cat. 5." I'm assuming this was supposed to debunk the JTWC's category 5 estimate; ironically, this actually supports their estimate for the time, which was 110-115kt (110kt on 06:00 UTC and 115kt at 12:00 UTC), and they upgraded Rai to a category 5 nearly 10 hours (around 18:00 UTC) after the 953mb reading was recorded and 11 hours after the simulated wind speeds. Unfortunately, as far as I know, there was nothing to directly record Rai's intensity at 18:00 UTC.

All of this of course, is very confusing, and so my question is: is it possible that Rai reached category 5 intensity in the South China Sea?


(Also a little note: From what I've seen, there are a number of tropical cyclones that really don't follow the look, at least on like, Dvorak (and even visible), for intense tropical cyclones (Typhoon Flo 1990 and Typhoon Tip 1979 at peak size for example). On the other side of the spectrum, there're also storms that look more intense than they actually are, like Hurricane Eta 2020 and Typhoon Vera 1979 (but then again most of Eta's ADT estimates were like T6.2-6.3 and the only thing that was T8.3 was the Raw T, in contrast to Rai where the FinalT, AdjT, and CI number were all T7+). I don't understand microwave imagery and other things enough so maybe that's a thing to consider.)

Anyways sorry if I wasted your time or something

Rai is exactly what happens when there's no recon in the WPAC...
So basically the short answer is no one knows for sure without recon, but as much as we rag on JTWC for getting some operational intensities off in higher end systems, they generally do a pretty good job at revising them, especially in the final post-season best track so it will be interesting to see if they will make any adjustments or not.

For Rai's first peak, I generally agree with the 140kt estimate, the only thing that might drag it down is the eye temp didn't seem to be all that warm but without recon its impossible to know for sure.

For it's second peak I wasn't able to track it real time so I may be missing something but based on what I've seen I would probably lean towards a strong Cat 4 in the SCS. In terms of appearance in the SCS Rai wasn't close to Rammasun so either Rammusun's peak needs to be increased or Rai's second peak needs to be downgraded IMO.

Just my opinion of course.
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Re: Discussion of Intense Tropical Cyclones

#697 Postby aspen » Tue Dec 21, 2021 4:30 pm

Weather Dude wrote:
Foxfires wrote:Ok, I'm going to try starting a discussion on how intense Typhoon Rai was, since that's kind of the point of this forum
(I've tried spurring the discussion elsewhere
Twitter is much too rude for my taste, and people seem unable to accept that the JTWC or just other people in general can have their own opinion and that that's ok, and also the limit for wordcount is too tight for any kind of proper discussion
I've tried in the forum here about Rai but I think there's other stuff that should also be focused on there
but I decided to go with another Storm2K forum because people here seem to be more civil)

The topic of the discussion is simple: how strong was Rai at both its first (Philippine Sea) and second peak (South China Sea), and how intense was it throughout the Philippines? Most people I've seen can generally agree on 135-140kt for its first peak (high-end cat 4 to low-end cat 5), but there's a lot, lot, more debate on its second peak.


As for it's first peak, I don't know of any direct measurements from stations or barometers on Siargao or the Dinagat Islands that didn't stop recording mid-way through. However, I believe Rai was trying to undergo an eyewall replacement cycle and weakened to category 4 intensity soon after landfall anyways (based on the JTWC's estimate). But for this peak, most people can agree on 140kt (some 135kt but that's barely a difference), which is the JTWC's intensity estimate.


For the intensity throughout the Philippines, I've found some direct measurements. There was 950.5mb recorded north of the eye in Maasin City (Southern Leyte) at 18:00 PST (10:00 UTC) (thanks to user Imran_doomhaMwx for the information).

After looking through Philsensors data I found some other stuff (all recordings listed will be for 16 Dec unless stated otherwise). For Southern Leyte, a station in Malitbog recorded 988.7mb (1000.9mb at SLP assuming stated elevation of 107 is in meters) at 14:18 PST (6:18 UTC).

For Bohol, a station in Dagohoy recorded 954.78mb at 19:45 (11:45 UTC), Dangay Elementary School at Alburquerque recorded 975.83mb at 20:45 PST (12:45 UTC), DOST PSTC Bohol, Tagbilaran recorded 984.07mb at 21:45 PST (13:45 UTC), and San Miguel Municipal Hall, San Miguel recorded 971.13mb at 19:45 PST (11:45 UTC); all measurements were south of the eye and are station pressures (elevation unknown).

For Cebu, Motorpool Cansaga, Consolacion recorded 985.54mb (it says 98554.0 but I think that's an error) at 21:00 PST (13:00 UTC), BRGY. Canjue, Argao, recorded 908.1mb at 22:00 PST (14:00 UTC), 960.68mb and 973.9mb was recorded at Toledo City by two different sensors at 20:00 PST (12:00 UTC) and 19:00 PST (11:00 UTC) respectively, BRGY. Hall Manipis, Talisay City recorded 939.05mb at 20:00 PST (12:00 UTC), BRGY. Poblacion, Ginatilan recorded 987.55mb at 00:00 PST on 17 Dec (16:00 UTC 16 Dec), Catmon Seaside Park Flores, Catmon recorded 996.17mb at 19:45 PST (11:45 UTC), Cordova Municipal Hall recorded 969.34mb on 21:30 PST (13:30 UTC) (elevation is stated at 30, I'm assuming meters, but no temperature), DOST VII, Cebu City recorded 976.12mb at 21:30 PST (13:30 UTC) (elevation is stated at 62; no temp), Moalboal recorded 968.73mb at 22:30 PST (14:30 UTC) (elevation is stated at 1; no temp), Ollfi, Sibonga recorded 967.59mb at 21:30 PST (13:30 UTC) (elevation is stated at 88; no temp), Pasil, Santander recorded 989.73mb at 22:45 PST (14:45 UTC) (elevation is stated at 19; no temp), Pinamungajan, Pandacan recorded 982.35mb 22:00 PST (14:00 UTC) (elevation is stated at 29; no temp), Central Visayas Campus, Argao recorded 951.45mb at 22:30 PST (14:30 UTC), and Cabancalan-Canduman Bridge, Mandaue City recorded 980.7mb at 20:40 PST (12:40 UTC). All aforementioned readings are station level pressure.

There's more places but it's taking forever to sort through them. It doesn't look like that much but most of the stations are non-operational and I have to look through those as well.


For the second peak, this is what people cannot agree on. The JTWC put the intensity at 145kt, but I believe they changed it to 140kt. Now, Most people, specifically on Twitter, think it was 125-130kt at second peak intensity (I think I saw someone say 135kt-140kt and another 140kt) and that the JTWC was overestimating it due to Dvorak.

At 15:05 Vietnam Time (8:05 UTC) on the 18th of October, 953mb was recorded on Southwest Cay (possibly in the eye), and, I quote: "The wind recorded at 13:52 was 45.61m/s; wind gust 56.79m/s." (I got the info from a YT reply and I would like to give this person credit however I'm not sure if they're comfortable with it). Twitter user Joshua C. Agar stated in a tweet that (about the station readings): "Second photo is the simulated 10-min sustained winds, with max 10-min wind estimate to be 49.35 m/s at 14:00 (GMT+7). Max. gust projected was 60.7 m/s. #Rai doesn't sound like Cat. 5." I'm assuming this was supposed to debunk the JTWC's category 5 estimate; ironically, this actually supports their estimate for the time, which was 110-115kt (110kt on 06:00 UTC and 115kt at 12:00 UTC), and they upgraded Rai to a category 5 nearly 10 hours (around 18:00 UTC) after the 953mb reading was recorded and 11 hours after the simulated wind speeds. Unfortunately, as far as I know, there was nothing to directly record Rai's intensity at 18:00 UTC.

All of this of course, is very confusing, and so my question is: is it possible that Rai reached category 5 intensity in the South China Sea?


(Also a little note: From what I've seen, there are a number of tropical cyclones that really don't follow the look, at least on like, Dvorak (and even visible), for intense tropical cyclones (Typhoon Flo 1990 and Typhoon Tip 1979 at peak size for example). On the other side of the spectrum, there're also storms that look more intense than they actually are, like Hurricane Eta 2020 and Typhoon Vera 1979 (but then again most of Eta's ADT estimates were like T6.2-6.3 and the only thing that was T8.3 was the Raw T, in contrast to Rai where the FinalT, AdjT, and CI number were all T7+). I don't understand microwave imagery and other things enough so maybe that's a thing to consider.)

Anyways sorry if I wasted your time or something

Rai is exactly what happens when there's no recon in the WPAC...
So basically the short answer is no one knows for sure without recon, but as much as we rag on JTWC for getting some operational intensities off in higher end systems, they generally do a pretty good job at revising them, especially in the final post-season best track so it will be interesting to see if they will make any adjustments or not.

For Rai's first peak, I generally agree with the 140kt estimate, the only thing that might drag it down is the eye temp didn't seem to be all that warm but without recon its impossible to know for sure.

For it's second peak I wasn't able to track it real time so I may be missing something but based on what I've seen I would probably lean towards a strong Cat 4 in the SCS. In terms of appearance in the SCS Rai wasn't close to Rammasun so either Rammusun's peak needs to be increased or Rai's second peak needs to be downgraded IMO.

Just my opinion of course.

It’s ridiculous that the JMA has kept Rammusun’s official peak pressure at 935mb for over half a decade despite the valid 888mb reading. That pressure would support winds of 155-165kt, maybe 150 kt at the lowest due to the generally lower background pressures in the WPac.

I do believe that the very cold tropopause was resulting in high-biased ADT estimates, at least for Rai’s second peak. Its first Cat 5 peak is a little dubious for the same reason, but Rai was clearly undergoing a phase of ERI so a Cat 5 peak is not unreasonable despite its similarities to Eta.
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Re: Discussion of Intense Tropical Cyclones

#698 Postby Yellow Evan » Tue Dec 21, 2021 4:39 pm

For those of you who think Rai’s first peak is a Category 5, I have a challenge. Find me an OW eye Recon-confirmed Category 5 where the eye is well resolved.
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Re: Discussion of Intense Tropical Cyclones

#699 Postby Foxfires » Wed Dec 22, 2021 1:06 am

Yellow Evan wrote:For those of you who think Rai’s first peak is a Category 5, I have a challenge. Find me an OW eye Recon-confirmed Category 5 where the eye is well resolved.


OW? what does that stand for?
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Re: Discussion of Intense Tropical Cyclones

#700 Postby Foxfires » Wed Dec 22, 2021 1:18 am

aspen wrote:It’s ridiculous that the JMA has kept Rammusun’s official peak pressure at 935mb for over half a decade despite the valid 888mb reading. That pressure would support winds of 155-165kt, maybe 150 kt at the lowest due to the generally lower background pressures in the WPac.

I do believe that the very cold tropopause was resulting in high-biased ADT estimates, at least for Rai’s second peak. Its first Cat 5 peak is a little dubious for the same reason, but Rai was clearly undergoing a phase of ERI so a Cat 5 peak is not unreasonable despite its similarities to Eta.


the 899.2mb reading is potentially due to an eyewall mesovortex, but even then, the reading before that was like 908mb or something, so Rammasun's min pressure would probably be 905-900mb at least, so Rammasun being 150-155kt is definitely very reasonable. I think it should probably be reanalyzed, at least by the JMA because they're WPAC's RSMC.

For the comparison of Rai and Eta... I've seen talk about it but Eta and Rai aren't really the same in terms of the ADT. Eta was not rated as a category 5 operationally by the ADT. Everyone pointed out the T8.3 but that was raw T (not sure what the significance of that is but I heard it's bad for TC intensity) and everyone was kind of not paying attention to the rest of the screen because the FinalT & AdjT were 6.2 and 6.3 respectively iirc, and the CI was around 119kt/942mb. Rai, on the other hand, got T7.0+ for everything I believe. I don't know if this changes anything but that's just something to note.
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