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TropicalAnalystwx13

Cat 5 Major Hurricane Patricia

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Thanks gynx snewx, wxeyeNH, ncforecaster89 and all of you. The decision to leave the station was partly made on the info I was reading right here at the forum and the NHC advisories, so I am really grateful to you all.

News on the anemometer tilt: last Wednesday we were visited by people from CONAGUA, they got a message from NHC regarding the reliability of those readings and they came to check for themselves the state of the sensor and the whole station. They have thought about the wind tunnel test too, winterymix. The Biological station has already contacted people from the Engineering Institute at UNAM, they have a new wind tunnel and they are already in contact with CONAGUA and through them to NHC, either to perform the tests or to help them decide if it is worth doing. And yes, bdgwx, the anemometer was not only tilted, but the boom where it sits was rotated, so the junction box now it is due SW instead of S (approximately, they did not want me to climb the tower). Two of the three guy wires of the tower were loosen quite a bit, too. Luckily, they agree to leave the anemometer at its current position until more assessment is done. Hopefully the NHC interest exerts some pressure on them to stay on top of this.

I also looked at data (not publicly available, sorry) from a Met-One cup anemometer that is installed almost on the same spot, at around 4 m above ground. The highest reading there is 202 kph (125 mph) at 17:50 pm (CST), and it recorded winds >100 kph from 17:00 to 19:00. I understand these sensors have a lower upper range of measurement.

In the pictures you can see some of the damage we captured in the highway and what happened at the station too (hope the link works).

Finally, Roger Smith, regarding the Copa del Sol: It is a weird structure built by an excentric millionaire that owns a lot of land around here. It is supposed to serve as a point of contact with UFOs (!) and he celebrates some sort of re-energizing ritual up there. Excentricities apart, it is the largest concrete structure near the point of landfall, so we are trying to reach a biologist who works for this guy in order to visit the structure and report the damages it shows, if any. Truth is right now the communications with people in nearby villages is harder than reaching people like you, thousands of miles away.

Some towns around here took a big hit. They are mostly fishermen villages, the houses are poorly constructed, and most top roofs are gone and therefore all their stuff got damped and they lost the few things they had. Luckily, the abscense of flash floods meant that Emiliano Zapata and other towns that did very badly during Jova were spared of severe damage this time around, but people in poorer towns are suffering. On top of it, today and yesterday it has been raining and the Cuixmala river and others are swelling quickly. One can only hope there will be no flooding.

Going offline now. Read you later!

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I also looked at data (not publicly available, sorry) from a Met-One cup anemometer that is installed almost on the same spot, at around 4 m above ground. The highest reading there is 202 kph (125 mph) at 17:50 pm (CST), and it recorded winds >100 kph from 17:00 to 19:00. I understand these sensors have a lower upper range of measurement.

 

Hey, Maru-- thanks for the information-- it's very interesting. I was in Emiliano Zapata during the storm-- not far from you.

 

Do you mean 17:50 CST or CDT? Local time was CDT on the day of the hurricane.

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Hey, Maru-- thanks for the information-- it's very interesting. I was in Emiliano Zapata during the storm-- not far from you.

 

Do you mean 17:50 CST or CDT? Local time was CDT on the day of the hurricane.

Hi Josh! so nice to get in contact with you. I know you were in EZ, I follow your work since Jova, I even took the liberty to show and explain your youtube video on Jova to locals during an Open House at the station in 2011. It was a talk about safety during hurricanes.

 

I understood from the guy in charge of the data it was CST. I know we were still on DT last Friday but it seems they keep their timestamps on winter time, but I will double check with him and will let you know.

 

Your chases are really cool!

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Hi Josh! so nice to get in contact with you. I know you were in EZ, I follow your work since Jova, I even took the liberty to show and explain your youtube video on Jova to locals during an Open House at the station in 2011. It was a talk about safety during hurricanes.

 

I understood from the guy in charge of the data it was CST. I know we were still on DT last Friday but it seems they keep their timestamps on winter time, but I will double check with him and will let you know.

 

Your chases are really cool!

 

Wow, thank you, Maru! That is so nice of you. :) And I'm so glad my JOVA video was helpful to your community. :) Thanks also for following my work. :wub:

 

It's been interesting to read your posts about the weather station there-- I'm so grateful to read you posts about it.

 

The highest winds at our location in Emiliano Zapata happened between 18:35 and about 19:00 CDT. The period of peak winds was very distinct where we were-- very sharply defined. It came and went like a tornado. So if your peak wind was 17:50 CDT, that would suggest a malfunction, whereas I suppose 17:50 CST (18:50 CDT) would make more sense. Is that peak wind sustained or gust? If gust, it seems very low-- even taking into account that the instrument height is very low (only 4 m instead of standard 10 m above ground).

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Very interesting reports and pictures. Thanks for sharing.

 

I have just found several videos on facebook and youtube. One is from "the orchard" in Chamela where a resident is talking about severe damage there in his demolished shanty, he's saying there has been very little assistance so far. This and one other video are recently posted on the Punta Perula facebook site (type in Punta Perula Huerta Jalisco to get to the right facebook page, and go down, they have an old touristy video pinned to the top). These two videos plus the pictures from Maru would appear to confirm at least cat-4 damage to trees, maybe the some of the Chamela structures would have gone down in any category of hurricane winds and obviously the dense tree cover in some places must absorb a lot of the damage at higher elevations off the ground than one-storey buildings (assuming they don't fall onto the buildings).

 

Then there's a report from a Reuters journalist on youtube showing substantial damage to the exclusive Costa Careyes resort. It's really difficult from the panoramic shots to say what category of damage is actually shown at the resort but it would appear that the place needs a year to recover, and has lost a lot of its trees.

 

Well, let's hope the local governments and ongoing fundraising combine to give those poor folk in Chamela some help. I gather one of the videos was shot in Punta Perula, there it basically looks like everyone's picking up the pieces and putting them back together. But I'm sure that cat-3 or even cat-2 winds would probably have done that sort of damage there, just a few miles further west.

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Josh, one thing to consider is that, if you clipped the eye, then that means that part of eyewall was eroded, hence you only had one period of maximum winds, instead of two, and that was on the backside. That means that west of the eye they might have had the max winds prior to your location, though, by the translation speed it probably would have been of no more than 20-30 minutes.

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Josh, one thing to consider is that, if you clipped the eye, then that means that part of eyewall was eroded, hence you only had one period of maximum winds, instead of two, and that was on the backside. That means that west of the eye they might have had the max winds prior to your location, though, by the translation speed it probably would have been of no more than 20-30 minutes.

It's also conceivable that Josh was actually just inside the eye as it was collapsing in on itself. This would certainly be consistent with his description of the clearing he observed while the winds didn't appear to decrease below gale-force, and the shrinkage of the eye visible in satellite imagery.

Since the maximum winds were consistently observed by Recon in the SE quadrant of the eyewall (IIRC), and Josh said the strongest winds were definitely on the backside of the storm (SE quadrant), it seems rather unlikely that the strongest winds were in the western portion of the eyewall.

By your theory (not completely discounting it), what evidence do you have to support the assumption that the eyewall was any more intact on the west side?

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These two videos plus the pictures from Maru would appear to confirm at least cat-4 damage to trees, maybe the some of the Chamela structures would have gone down in any category of hurricane winds and obviously the dense tree cover in some places must absorb a lot of the damage at higher elevations off the ground than one-storey buildings (assuming they don't fall onto the buildings).

Then there's a report from a Reuters journalist on youtube showing substantial damage to the exclusive Costa Careyes resort. It's really difficult from the panoramic shots to say what category of damage is actually shown at the resort but it would appear that the place needs a year to recover, and has lost a lot of its trees.

Well, let's hope the local governments and ongoing fundraising combine to give those poor folk in Chamela some help. I gather one of the videos was shot in Punta Perula, there it basically looks like everyone's picking up the pieces and putting them back together. But I'm sure that cat-3 or even cat-2 winds would probably have done that sort of damage there, just a few miles further west.

Looking at the pics you referenced, I don't see any damage that couldn't have been caused by category-three hurricane conditions. In general, it's the higher wind gusts that cause most of the worst wind damage. That said, I certainly don't think Patricia weakened below category-four intensity...but, the more I analyze the various data and examine the pics posted on the internet, the more confident I am in suggesting that Patricia did indeed drop to below category-five status (likely in the 125-130 kt. range).

If it did weaken to 125 kt., for example, it still would've been capable of producing wind gusts exceeding 155 knots! Just imagine how much damage that can cause. Not to mention, the relative increase in wind speeds at higher elevations. Taking these things into consideration, one could just as easily argue it's possible it may have even been a little weaker than that.

All that being said, I still respectfully argue for a 125-130 kt. Cat 4 designation with a corresponding lowest central pressure of 930 mb. This would still place hurricane Patricia at the number 1 spot amongst the most intense EPAC hurricane landfalls in recorded history!

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Those pressure changes reported by Josh are quite impressive. Hell of an isoballaric gradient in there, despite the weakening. The inner eye started collapsing some hours before landfall, as evidenced by the radar, but there did appear to be a decent outer eyewall in development as it came in for landfall, so it's possible he simply experienced that as it came ashore. A mesovortex is also a possibility.

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Some towns around here took a big hit. They are mostly fishermen villages, the houses are poorly constructed, and most top roofs are gone and therefore all their stuff got damped and they lost the few things they had. Luckily, the abscense of flash floods meant that Emiliano Zapata and other towns that did very badly during Jova were spared of severe damage this time around, but people in poorer towns are suffering. On top of it, today and yesterday it has been raining and the Cuixmala river and others are swelling quickly. One can only hope there will be no flooding.

Going offline now. Read you later!

Hi Maru! Your posts and corresponding observations are a huge addition to not only this thread, but likely in helping the NHC determine just how intense hurricane Patricia may have been at landfall. Obviously, the same thing applies to Josh's data and personal observations, as well.

For me, I just simply care alot about the accuracy and integrity of the HURDAT databases and sincerely hope that all of the respective storms are properly assessed. Naturally, there will always be a measure of subjectivity involved, due to the inexact nature of the science, but I feel that should always be the ultimate goal in the reanslysis process of all storms.

I understand that my personal opinion that Patricia had weakened below category-five intensity isn't going to be the most popular sentiment around here, but my completely unbiased and objective review of the data leads me to that conclusion. Even so, that has zero baring on the fact that your region has suffered a major calamity and I pray that the current suffering of your fellow citizens will not be exacerbated by any additional flooding.

Thanks again for your very informative and thoughtful posts. I'm sure I can speak for everyone else here by saying that we will be looking forward to additional updates at a time that's truly most convenient for you.

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Those pressure changes reported by Josh are quite impressive. Hell of an isoballaric gradient in there, despite the weakening. The inner eye started collapsing some hours before landfall, as evidenced by the radar, but there did appear to be a decent outer eyewall in development as it came in for landfall, so it's possible he simply experienced that as it came ashore. A mesovortex is also a possibility.

Excellent post! I too have been pondering the same thing given that microwave imagery seemed to suggest an ERC was occurring, and if so, that would also accelerate the collapse of the inner eyewall.

Mesovortises can't be discounted, but I suspect the strongest winds were more likely the result of category-five wind gusts...which would be expected with any hurricane of mid-range category-four strength. No matter how one looks at it, there's very little doubt that Patricia was a very severe hurricane...regardless of its eventual categorical designation following post-storm analysis.

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The theory Re: an inner-eyewall collapse is contradicted by what I observed on the ground: by far the most extreme winds were confined very, very close to the center and didn't last long. The destruction was not caused by some secondary, outer wind max. In fact, damaging winds didn't even start until the center was maybe an hour from its closest approach, and the peak winds lasted about 20 minutes. Also, the most-extreme pressure gradients-- in one place over 10 mb/n mi (!!!)-- were very near the center. This was not a KATRINA situation with rapidly expanding wind radii and a flattening pressure field.

 

 I hope to release my full report and data today. When I do, I'll post a link here.

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

Great post. I couldn't agree more with everything you said.

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The theory Re: an inner-eyewall collapse is contradicted by what I observed on the ground: by far the most extreme winds were confined very, very close to the center and didn't last long. The destruction was not caused by some secondary, outer wind max. In fact, damaging winds didn't even start until the center was maybe an hour from its closest approach, and the peak winds lasted about 20 minutes. Also, the most-extreme pressure gradients-- in one place over 10 mb/n mi (!!!)-- were very near the center. This was not a KATRINA situation with rapidly expanding wind radii and a flattening pressure field.

 

 I hope to release my full report and data today. When I do, I'll post a link here.

Ah, gotcha, thanks for that clarification.

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

The satellite images and observed pressure rises indicate nothing short of a rapidly weakening hurricane. I'd have to look at the microwave data (if there is any at landfall) to better gauge the condition of the inner eyewall as it was coming ashore.

That being said, I would have to respectfully disagree with any notion that Patricia wasn't rapidly weakening during the last 5.5 hours preceding landfall. Even if one were to accept the operational NHC landfall pressure of 920 mb...that corresponds to at least a 41 mb increase in a 5.5 hour period (7.5mb/hr.), which most certainly qualifies as very rapid weakening.

That doesn't even take into consideration the significant degradation of the satellite appearance with the eye becoming virtually cloud-filled and more obscure during the last 3 hours prior to landfall. Unfortunately, there were no Recon obs taken during the last 2.75 hours before the eye reached the coast. It's also important to note that the most notable deteoration of the eye took place following Recon's departure.

With the aforementioned in mind, I'm not sure how one could possibly suggest Patricia was weakening at anything short of a very rapid pace.

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

 

Well said. :)

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

 

Good post. Agreed.

 

Ah, gotcha, thanks for that clarification.

 

You're welcome. I had to weigh in because some of the remarks here seem to completely disregard what was happening at the surface. Obviously, the storm was weakening-- from being by the far the strongest hurricane ever in the Western Hemisphere. The gradient around the core remained jaw-dropping. The wind core was very tight. Like I said, I'll release my report later today, and then y'all can pick over it all you want. :)

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The inner eyewall was still very strong during the last recon leg, all radar images from the aircraft showed so, with an open eyewall in the NNE quadrant. That, of course, could have changed some during the few hours after recon and prior to landfall, but assuming a similar state at landfall, it could be that the front right quadrant of the eyewall could have a weakened and EZ could have felt the full brunt of the rear right quad. Also, there was no indications the western eyewall was anywhere near collapsed on said radar images.

From Josh's account, it looks the inner eyewall held its own, and the hurricane was gradually weakening (vs rapidly weakening in the event of a full inner eyewall collapse).Even the sat imagery was that of a gradually filling hurricane. Compare Patricia's images to that of Kenna at landfall. Kenna was sheared rather badly, and it could still manage winds of a mid end cat 4. Patricia's most probable weakening factor was an ongoing ERC, since it was very symmetric up to landfall.

 

Good post.

 

Ah, gotcha, thanks for that clarification.

 

You're welcome. I don't have any intention of participating in a debate about the cyclone's intensity, but I do feel some of the assumptions here completely disregard what was happening at the surface. When an inner core collapses, you don't have jaw-dropping pressure gradients and extremely violent winds confined to a tiny ring around the center. The eye becoming cloudy doesn't negate that. Satellite imagery is only one angle on this.

 

I'll post my detailed report with all my obs later.

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The satellite images and observed pressure rises indicate nothing short of a rapidly weakening hurricane. I'd have to look at the microwave data (if there is any at landfall) to better gauge the condition of the inner eyewall as it was coming ashore.

I posted this a couple times in here. While the storm was obviously weakening, the strong inner core was still intact even if the eyewall was open on NE side.

http://tropic.ssec.wisc.edu/real-time/mimic-tc/2015_20E/webManager/displayGifsBy12hr_04.html

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I posted this a couple times in here. While the storm was obviously weakening, the strong inner core was still intact even if the eyewall was open on NE side.

http://tropic.ssec.wisc.edu/real-time/mimic-tc/2015_20E/webManager/displayGifsBy12hr_04.html

 

Thanks-- I hadn't seen this. And it perfectly corroborates what I experienced on the ground: tiny, concentrated inner core.

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I posted this a couple times in here. While the storm was obviously weakening, the strong inner core was still intact even if the eyewall was open on NE side.

http://tropic.ssec.wisc.edu/real-time/mimic-tc/2015_20E/webManager/displayGifsBy12hr_04.html

 Just remember, though, that that animation is composed of both microwave data (taken at most only twice per day) and model data to fill in the gaps, so it may not be a realtime picture of what was happening at landfall.

 

http://tropic.ssec.wisc.edu/real-time/mimic-tc/description.html

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The satellite images and observed pressure rises indicate nothing short of a rapidly weakening hurricane. I'd have to look at the microwave data (if there is any at landfall) to better gauge the condition of the inner eyewall as it was coming ashore.

That being said, I would have to respectfully disagree with any notion that Patricia wasn't rapidly weakening during the last 5.5 hours preceding landfall. Even if one were to accept the operational NHC landfall pressure of 920 mb...that corresponds to at least a 41 mb increase in a 5.5 hour period (7.5mb/hr.), which most certainly qualifies as very rapid weakening.

That doesn't even take into consideration the significant degradation of the satellite appearance with the eye becoming virtually cloud-filled and more obscure during the last 3 hours prior to landfall. Unfortunately, there were no Recon obs taken during the last 2.75 hours before the eye reached the coast. It's also important to note that the most notable deteoration of the eye took place following Recon's departure.

With the aforementioned in mind, I'm not sure how one could possibly suggest Patricia was weakening at anything short of a very rapid pace.

Weakening to the point of winds lowering by 40+ knots in such a short period of time with what appears to be a still very energetic inner eyewall? There should be much stronger evidence of such weakening, than what has been presented,IMO.

My personal opinion is that the operational winds will be lowered to around 135-140 knots.

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The satellite images and observed pressure rises indicate nothing short of a rapidly weakening hurricane. I'd have to look at the microwave data (if there is any at landfall) to better gauge the condition of the inner eyewall as it was coming ashore.

That being said, I would have to respectfully disagree with any notion that Patricia wasn't rapidly weakening during the last 5.5 hours preceding landfall. Even if one were to accept the operational NHC landfall pressure of 920 mb...that corresponds to at least a 41 mb increase in a 5.5 hour period (7.5mb/hr.), which most certainly qualifies as very rapid weakening.

That doesn't even take into consideration the significant degradation of the satellite appearance with the eye becoming virtually cloud-filled and more obscure during the last 3 hours prior to landfall. Unfortunately, there were no Recon obs taken during the last 2.75 hours before the eye reached the coast. It's also important to note that the most notable deteoration of the eye took place following Recon's departure.

With the aforementioned in mind, I'm not sure how one could possibly suggest Patricia was weakening at anything short of a very rapid pace.

Weakening to the point of winds lowering by 40+ knots in such a short period of time with what appears to be a still very energetic inner eyewall? There should be much stronger evidence of such weakening, than what has been presented,IMO.

My personal opinion is that the operational winds will be lowered to around 135-140 knots. Again, anything below that will require much more evidence that would support such extraordinary wind weakening. Scattered surface observations and satellite imagery aren't just enough,IMO. The pressure gradient is currently not supportive of that, and that's probably the reason the NHC is very interested in that data.

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 Just remember, though, that that animation is composed of both microwave data (taken at most only twice per day) and model data to fill in the gaps, so it may not be a realtime picture of what was happening at landfall.

 

http://tropic.ssec.wisc.edu/real-time/mimic-tc/description.html

 

Even then, you can clearly see that the eyewall really opens up right as the eye is coming ashore.  Interestingly, it's the back half of the eyewall that's most lacking in that image as it crosses the coastline.  Regardless, I still believe all the available evidence doesn't imply an intensity less than 125 kt.  OTOH, I'll reiterate the available evidence also doesn't suggest Patricia retained category-five intensity, either.

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Weakening to the point of winds lowering by 40+ knots in such a short period of time with what appears to be a still very energetic inner eyewall? There should be much stronger evidence of such weakening, than what has been presented,IMO.

My personal opinion is that the operational winds will be lowered to around 135-140 knots. Again, anything below that will require much more evidence that would support such extraordinary wind weakening. Scattered surface observations and satellite imagery aren't just enough,IMO. The pressure gradient is currently not supportive of that, and that's probably the reason the NHC is very interested in that data.

 

Yeah, I am finding some jaw-dropping pressure gradients very close to the center. The highest I've found in my data is 11.4 mb over 1 n mi! I've been working with Adam Moyer on the analysis. Besides being a meteorologist, he's a statistics/math dude and has vetted my methodology.

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Weakening to the point of winds lowering by 40+ knots in such a short period of time with what appears to be a still very energetic inner eyewall? There should be much stronger evidence of such weakening, than what has been presented,IMO.

My personal opinion is that the operational winds will be lowered to around 135-140 knots.

 

I'd be remiss if I didn't make a point of stating that I genuinely respect everyones personal opinion, whether they agree with my assessment or not.  That aside, I most definitely believe that the incredible rise in the pressure (somewhere in the range of 41-51 mb) in the last 5.5 hours prior to landfall, would easily cause a decrease in the MSW by at least 40 knots.  If you examine the microwave imagery more closely, you will see that the eyewall really opens up right at the shoreline...after the eye had been rapidly filling during the preceding 5.5 hours.  If you look at the infrared imagery, it will also show the eye collapsing and becoming more elongated at landfall. 

 

I would also reiterate that it's not too unusual to see such abrupt changes in intensity with such small hurricane eyewalls and they typically weaken much more rapidly (in both pressure and winds) than their much larger counterparts.

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Weakening to the point of winds lowering by 40+ knots in such a short period of time with what appears to be a still very energetic inner eyewall? There should be much stronger evidence of such weakening, than what has been presented,IMO.

My personal opinion is that the operational winds will be lowered to around 135-140 knots. Again, anything below that will require much more evidence that would support such extraordinary wind weakening. Scattered surface observations and satellite imagery aren't just enough,IMO. The pressure gradient is currently not supportive of that, and that's probably the reason the NHC is very interested in that data.

 

I can completely understand your reasoning.  From my personal perspective, I can't fathom how a 45-50 mb increase in the central pressure wouldn't decrease the winds by at least 40 kt.  A full 5.5 hours is plenty of time for that attendant pressure gradient to manifest itself in the ascribed weakening of the winds.  

 

As I've stated from the outset, I also doubt the NHC will lower the operational winds below 140 kt. The main reason being that they don't have RECON observations from the last 2.75 hours prior to landfall, to give a much better estimate of the true landfall intensity.  Given they assessed it at 145 kt. operatonally, I highly doubt they'd make more than a 5-10 kt. reduction...which is right in line with your expectation.

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Yeah, I am finding some jaw-dropping pressure gradients very close to the center. The highest I've found in my data is 11.4 mb over 1 n mi! I've been working with Adam Moyer on the analysis. Besides being a meteorologist, he's a statistics/math dude and has vetted my methodology.

That's amazing! Thanks for sharing.

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I can completely understand your reasoning.  From my personal perspective, I can't fathom how a 45-50 mb increase in the central pressure wouldn't decrease the winds by at least 40 kt.  A full 5.5 hours is plenty of time for that attendant pressure gradient to manifest itself in the ascribed weakening of the winds.  

 

As I've stated from the outset, I also doubt the NHC will lower the operational winds below 140 kt. The main reason being that they don't have RECON observations from the last 2.75 hours prior to landfall, to give a much better estimate of the true landfall intensity.  Given they assessed it at 145 kt. operatonally, I highly doubt they'd make more than a 5-10 kt. reduction...which is right in line with your expectation.

 

A downgrade to high-end Cat 4 is certainly possible. They're weighing all the evidence. There are mixed signals, and arguments can be made either way. Whatever verdict they come to is what I'll live by.

 

Either way-- the core was tight and intact as it came ashore. I know because I measured it, experienced it, shot it, and documented it. The SE eyewall was the angriest and most sharply-defined I've been in.

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