Atlantic Hurricanes: Reanalyzed

[Srain]

Yeah, what I find most amazing is that if it weren't for the Indianola 1886 cyclone, Victoria would the the biggest population center in TX-- not Houston.

TX history is riddled with all kinds of big, juicy 'cane events. It's had everything but a Cat 5.

Don’ forget Isaac’s Storm of September, 1875.

[am19psu]

Don’ forget Isaac’s Storm of September, 1875.

I thought that was the Galveston Hurricane?

[Srain]

I thought that was the Galveston Hurricane?

A nice review...sorry to hijack your thread, Josh...

This storm was the first of two that struck Indianola and is described in a book Isaac's Storm by Erik Larson (Vintage 2000), 81-83:

"The first storm struck Indianola on September 16, 1875. Gale-force winds had come ashore the previous day and gained velocity throughout the night. By 5:00 P.M. on the sixteenth the wind was blowing at eighty-two miles an hour. The wind continued to strengthen until by midnight, according to Sgt. C. A. Smith, the Signal Corps observer on dusty, "it must have been fully 100 miles an hour."

The storm raised an immense dome of water and shoved it through Indianola, pushing the waters of the Gulf and Matagorda Bay inland "until for 20 miles the back country of prairie was an open sea." Residents fled their homes in boats and gathered in the town's strongest buildings. Shortly after midnight, Smith reported, the tide changed. The survivors believed the worst was over. "This evidence of abatement was hailed with shouts of joy, and was confirmed in a few minutes by the action of the wind, which gradually backed to the north and northwest."

Their joy was premature. The wind again began shoveling water, this time back toward Matagorda Bay, and created an "ebb surge," a mesoscale version of what happens on any beach when water brought ashore by a wave rushes back out to sea, undermining anything in the way. "The tide now swept out toward the bay with terrific force, the wind having but slightly abated, and it was at this time that the greatest destruction to life and property occurred. The buildings remaining had been so loosened and racked by northeast wind and tide that the moment the tremendous force was changed in a cross-direction dozens of them toppled in ruins and were swept into the bay."

The initial storm surge had poured into Matagorda Bay over the course of eighteen hours. It exited in six.

The devastation was stunning. "Fully three-fourths of all the buildings had entirely disappeared from the scene, and of those remaining, a large part were in utter runins," Smith wrote. "Many of those remaining had been swept from their original foundation - some but a few yards, others several blocks."

The storm killed 176 people. ... Gen. Adlphus Greely [head of the Signal Corps], who visited Indianola six months after the storm, estimated the death toll amounted to one-fifth the city's population. The storm left a schooner high and dry five miles inland and killed fifteen thousand sheep and cattle. All this, Greely observed, despite the fact that Indianola occupied a sheltered niche on the Texas coast fourteen miles from the Gulf and behind a broken plume of barrier lands that might have been expected to blunt the force of any oncoming storm. Even six months afterward, the damage was obvious and vivid. The hurricane had destroyed not only the superficial structures made by men, Greely found, but also God's own topography. "The striking physical changes were the formation of a large lake in the rear of the town and the plowing of numerous bayous inland, five connecting across the solid land of an elevation ranging between 10 and 20 feet above the level of Matagorda Bay, on which the town was built. One of these bayous was nearly 20 feet deep at the time of my visit."

http://www.alvyray.c...s/Indianola.htm

[Scott747]

I thought that was the Galveston Hurricane?

It is.

Not sure what Srain is talking about.

[Scott747]

Great write up Josh.

Haven't had much time to look yet but did you happen to come across that paper on the microbursts in Celia. Fairly certain it was in pdf format on Eastern. I'll have some time here in a bit to look for it.

[HurricaneJosh]

Great write up Josh.

Haven't had much time to look yet but did you happen to come across that paper on the microbursts in Celia. Fairly certain it was in pdf format on Eastern. I'll have some time here in a bit to look for it.

Thanks, Scott! Do you agree with the verdict-- 120 kt? Jorge says he's pretty on board with it-- or at least 115 kt (still Cat 4).

P.S. I'll look for that document now.

[Srain]

It is.

Not sure what Srain is talking about.

Indianola History. Some seem to forget that this was the main entry point for European Immigrants that settled across the State, prior to those events.

[Scott747]

Thanks, Scott! Do you agree with the verdict-- 120 kt? Jorge says he's pretty on board with it-- or at least 115 kt (still Cat 4).

P.S. I'll look for that document now.

I've just been hung up on this unique microbust event for years instead of looking at it as being a legit four. However you won't get much of an argument from me on any eventual upgrade. Any four is special territory.

You also have the 16 and 19 storms that could have been fours as well when talking about Corpus history. Heck of a one two punch in such short duration.

[Scott747]

Don’ forget Isaac’s Storm of September, 1875.

Indianola History. Some seem to forget that this was the main entry point for European Immigrants that settled across the State, prior to those events.

?

Neither Indianola storm was ever referred to as "Isaac's Storm." That has always been the 1900 storm.

[HurricaneJosh]

I've just been hung up on this unique microbust event for years instead of looking at it as being a legit four. However you won't get much of an argument from me on any eventual upgrade. Any four is special territory.

You also have the 16 and 19 storms that could have been fours as well when talking about Corpus history. Heck of a one two punch in such short duration.

Yeah, it was an odd wind pattern-- but really, isn't the eyewall of any intense, rapidly deepening 'cane just a chain of these same localized convective processes anyway? Also, it wasn't just like one microburst-- it was a swarm of them across the metro region. The Fujita wind swath shows wide coverage of very destructive winds.

P.S. So you're saying you would or wouldn't argue with an upgrade? Or... If someone held a gun to you head, what would you call Celia?

[am19psu]

I've just been hung up on this unique microbust event for years instead of looking at it as being a legit four. However you won't get much of an argument from me on any eventual upgrade. Any four is special territory.

You also have the 16 and 19 storms that could have been fours as well when talking about Corpus history. Heck of a one two punch in such short duration.

The whole microburst thing is such a touchy subject. Andrew being a 5 at landfall relies on the winds near Homestead being representative of the circulation rather than a microburst/mesovortex. I'm not entirely sure how one can reach a conclusion what is and is not due to microbursts and what is part of the mesoscale eyewall.

[HurricaneJosh]

The whole microburst thing is such a touchy subject. Andrew being a 5 at landfall relies on the winds near Homestead being representative of the circulation rather than a microburst/mesovortex. I'm not entirely sure how one can reach a conclusion what is and is not due to microbursts and what is part of the mesoscale eyewall.

Bingo. See my post above. Like, where do you draw the line between winds that do and don't represent the overall system's intensity?

[Scott747]

Yeah, it was an odd wind pattern-- but really, isn't the eyewall of any intense, rapidly deepening 'cane just a chain of these same localized convective processes anyway? Also, it wasn't just like one microburst-- it was lots of streaks across the metro region. The Fujita wind swath shows wide coverage of very destructive winds.

P.S. So you're saying you would or wouldn't argue with an upgrade? Or... If someone held a gun to you head, what would you call Celia?

Just from reading some of the accounts over the years there was always these descriptions of there being areas where there was literally no damage and then a block away there was complete destruction with tornadic like characteristics and why I've just sorta lived with it being a high end three.

Looking at the data though I can believe that it was a legit four at landfall.

[am19psu]

Bingo. See my post above. Like, where do you draw the line between winds that do and don't represent the overall system's intensity?

It's something I've always had issues with. I'd guess there probably needs to be some sort of size distinction, but that seems totally arbitrary to me. It's obviously a characteristic of rapidly deepening storms to have mesovortices that have higher winds than the normal P-W relationships would allow, sometimes even greater than the MPI. I'm not sure how to reconcile that.

[HurricaneJosh]

Just from reading some of the accounts over the years there was always these descriptions of there being areas where there was literally no damage and then a block away there was complete destruction with tornadic like characteristics and why I've just sorta lived with it being a high end three.

Looking at the data though I can believe that it was a legit four at landfall.

Fair enough. Makes sense. Granted, the streakiness of the damage was very weird.

One thing I do find a little disturbing is that the N eyewall was apparently not totally closed at landfall-- something you'd kind of expect from a rapidly-deepening major. But the MWR attributes that to the structural instability of a system that's rapidly changing intensity.

It's something I've always had issues with. I'd guess there probably needs to be some sort of size distinction, but that seems totally arbitrary to me. It's obviously a characteristic of rapidly deepening storms to have mesovortices that have higher winds than the normal P-W relationships would allow, sometimes even greater than the MPI. I'm not sure how to reconcile that.

Yeah, I wonder.

With regard to Celia, what do you think of those extreme wind bursts in the S eyewall-- 1) indicative of a very severe hurricane or 2) freak localized events?

[am19psu]

Fair enough. Makes sense. Granted, the streakiness of the damage was very weird.

One thing I do find a little disturbing is that the N eyewall was apparently not totally closed at landfall-- something you'd kind of expect from a rapidly-deepening major. But the MWR attributes that to the structural instability of a system that's rapidly changing intensity.

That would also be explainable through frictionally enhanced convergence into the mesovortex that we've already been discussing. By enhancing the convergence into the mesovortex, you have to rob it from somewhere else. Obviously, that's not verifiable without some sort of numerical simulation.

Yeah, I wonder.

With regard to Celia, what do you think of those extreme wind bursts in the S eyewall-- 1) indicative of a very severe hurricane or 2) freak localized events?

Can't it be both? I mean, that's kind of what I was getting at above. Almost by definition, those wind bursts are going to be a property of any landfalling, rapidly deepening hurricane. I guess, gun to my head and given the upgrade to Andrew, I'd go for a 4.

[HurricaneJosh]

That would also be explainable through frictionally enhanced convergence into the mesovortex that we've already been discussing. By enhancing the convergence into the mesovortex, you have to rob it from somewhere else. Obviously, that's not verifiable without some sort of numerical simulation.

Hmmm-- interesting. I didn't even think of that.

Can't it be both? I mean, that's kind of what I was getting at above. Almost by definition, those wind bursts are going to be a property of any landfalling, rapidly deepening hurricane. I guess, gun to my head and given the upgrade to Andrew, I'd go for a 4.

Yeah, I gotcha. So I guess what you're getting at is, if the winds happened, they are somehow indicative of the overall cyclone's severity. I would tend to agree.

[am19psu]

Yeah, I gotcha. So I guess what you're getting at is, if the winds happened, they are somehow indicative of the overall cyclone's severity. I would tend to agree.

Yeah, over the years, that's become my position, which is probably due to my job in the private sector versus being an academic. It's a helluva lot more pragmatic to take the observations of winds than to make arguments about what is and isn't part of the hurricane circulation. If you'd have asked me three years ago, I'd bet I'd have a different answer.

[HurricaneJosh]

Yeah, over the years, that's become my position, which is probably due to my job in the private sector versus being an academic. It's a helluva lot more pragmatic to take the observations of winds than to make arguments about what is and isn't part of the hurricane circulation.

Totally. And, like you, I see it as really problematic to try to separate or draw a distinction between winds that represent the cyclone and winds that don't.

(Of course, I'll concede than an actual confirmed tornado is a separate entity and not representative of the parent cyclone's intensity.)

[Scott747]

One thing that has always stayed with me is that the 'microburst' event was in a small timeframe and why I looked at it as a separate part of the storm and why they didn't originally make it a four.

It could be a odd upgrade when you go by the description. Is the upgrade warranted due too actual sustained winds or will it incorrectly be upgraded because of the strange microburst event and incredibly higher gusts relative to the storm itself....

http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1970-prelim/celia/prelim05.gif

[am19psu]

Totally. And, like you, I see it as really problematic to try to separate or draw a distinction between winds that represent the cyclone and winds that don't.

I could see how it is possible if you use some sort of simulation to figure out the winds due to WISHE and the winds due to other convective features, but what's the point from a classification standpoint. The people whose houses in Corpus that got blown away couldn't care less (and isn't that the point of the S-S scale in the first place?). Now, if you are trying to figure out the dynamics of mesovortices to better forecast them, that's a whole different story, but that's a scientific question and not really the one I think we're asking here.

/hurricane philosophical nonsense

[HurricaneJosh]

One thing that has always stayed with me is that the 'microburst' event was in a small timeframe and why I looked at it as a separate part of the storm and why they didn't originally make it a four.

It could be a odd upgrade when you go by the description. Is the upgrade warranted due too actual sustained winds or will it incorrectly be upgraded because of the strange microburst event and incredibly higher gusts relative to the storm itself....

http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1970-prelim/celia/prelim05.gif

It's true that most of the bursts apparently occurred across Corpus Christi within a 15-min timeframe-- but, when you take into account that it was a small cyclone moving quite briskly, it's reasonable to expect that the highest winds would be short-lived in any one city.

According to the reports, the gusts-- which I think must have approached (or maybe even exceeded) 150 kt to do some of that damage-- happened atop a "base wind" of 60 or 70 kt. Averaging over a minute could yield a Cat-4 value (114 kt), depending on the duration of the higher winds.

[HurricaneJosh]

I could see how it is possible if you use some sort of simulation to figure out the winds due to WISHE and the winds due to other convective features, but what's the point from a classification standpoint. The people whose houses in Corpus that got blown away couldn't care less (and isn't that the point of the S-S scale in the first place?). Now, if you are trying to figure out the dynamics of mesovortices to better forecast them, that's a whole different story, but that's a scientific question and not really the one I think we're asking here.

/hurricane philosophical nonsense

[Scott747]

It's true that most of the bursts apparently occurred across Corpus Christi within a 15-min timeframe-- but, when you take into account that it was a small cyclone moving quite briskly, it's reasonable to expect that the highest winds would be short-lived in any one city.

According to the reports, the gusts-- which I think must have approached (or maybe even exceeded) 150 kt to do some of that damage-- happened atop a "base wind" of 60 or 70 kt. Averaging over a minute could yield a Cat-4 value (114 kt), depending on the duration of the higher winds.

Could you imagine if we set up shop and only had 70 kt winds while a few blocks over all hell was breaking loose with 120 kt winds.

I definitely believe the gusts were that high. There was some new oil derricks at Robstown High that were newly built to withstand winds up to 175 mph with one of them failing.

[HurricaneJosh]

Could you imagine if we set up shop and only had 70 kt winds while a few blocks over all hell was breaking loose with 120 kt winds.

That would be too weird to see that.

Folks who lived in homes very close to but not in the paths of these terrific bursts must have been like "WTF???" when they saw what happened a few houses over.

I definitely believe the gusts were that high. There was some new oil derricks at Robstown High that were newly built to withstand winds up to 175 mph with one of them failing.

Interesting.

Yeah, and the pics I've seen (many of which I posted) along with the vivid damage descriptions in the NHC Preliminary Report suggest very high peak values.

[HurricaneJosh]

Thanks, guys, for the discussion Re: Celia. It seems the core Tropical Dudes mostly agree that there's a strong argument for calling it a Cat 4, despite the structural weirdness of it. Jorge agrees also. Despite his curious silence in this thread, I know he agrees because he told me so in a Skype chat. (Maybe he just doesn't want to go on record as agreeing with me. )

I might reanalyze another cyclone in the 1954-1979 era in the next couple of days, and I promise to make the next one a little shorter. (I got a little carried away with Celia because I'm so into that one.) I'm trying to think of one where I can take a controversial position-- to provoke a spicy discussion.

I encourage anyone else to offer their own proposals for reclassifying past cyclones. Any entries are welcomed, as long as they're well-researched. (Skimming a Wikipedia article doesn't count. )

[k***]

I just read this now. Good discussion.

[HurricaneJosh]

I just read this now. Good discussion.

Thanks-- gad you liked it. I know reanalysis isn't really your thing, so it's nice to see you dropping by.

[k***]

Thanks-- gad you liked it. I know reanalysis isn't really your thing, so it's nice to see you dropping by.

reanalyze something interesting next time!

[Juliancolton]

(Skimming a Wikipedia article doesn't count. )

What about writing one? I did the featured article on Carmen '74 (took several days of work and research, which I guess qualifies), and I'd be interested to see a reanalysis of the storm's intensity between its official upgrade to Cat 4 and its first landfall. The apparent ERC and northern jog suggest there are some undocumented fluctuations in peak winds. Just a thought.