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iCyclone & Patricia

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Hey Josh,

 

Hey is some photo documentation of Cat 5 destruction just NW of your en-stormed location.

 

attachicon.gifchamela.jpg

 

http://www.eluniversal.com.mx/articulo/english/2015/10/25/chamela-village-hurricane-patricia-swept-away

Honestly, that looks like a poorly-constructed wooden shack without proper trussing and anchoring. The tree damage in the background is quite comparable to what I witnessed in Southeast Florida (Boca Raton) following low-end Category 1 conditions in Wilma (2005). In that storm, most palms retained their foliage, and many mature, deciduous trees were only partly defoliated at best. That is what you see in the background. My visual estimates of low-end Category 1 winds in that storm are consonant with official observations, radar estimates, and judgments by the NHC (see Wilma's post-seasonal report).

 

By contrast, I have seen numerous images and descriptions of true Category 4/5 impacts from the inner cores of Andrew, Charley, STY Haiyan, Hugo, 1926 Miami, 1928 San Felipe II/Okeechobee (in Guadeloupe, Puerto Rico, and South FL), 1930 Dominican Republic, 1935 Labor Day, Janet, Gilbert, David, Iniki, and Dean. (I could argue for 1945 Homestead, but I haven't seen enough evidence to judge. For other Category 4/5 hits, inside or outside the U.S., I haven't seen enough data either.) The visual evidence for true Category 4/5 damage was very strong, compared to that in other storms.

The tree damage was immensely more severe in those cases, with shredding/snapping of mature, hard pines and coconut palms, among other species. Species that defoliate easily, especially in the seasonally dry (sub-)tropical forests of Mexico, the Caribbean, and South Florida, were completely stripped of leaves in several of the cases that I noted. (For good U.S. examples, see North Captiva Island and the Deering Estate after Charley and Andrew, respectively; Google or read up on the "Seaward Explorer" for the latter.) In the '35 hurricane, I've even seen photos in publications showing debarking of entire mangrove forests at Cape Sable and within the inner core on the Keys--something that I've yet to see in any other tropical cyclone.

 

To be honest, the Category 4/5 storms that I've mentioned are among a relative handful for which I've seen conclusive visual evidence to support the official NHC designations at landfall. For many "official" Category 4/5 landfalls like Carla, Camille, Audrey (which will almost certainly be downgraded), Hazel, 1900/1915 Galveston, 1916 Texas, and others, I have yet to see convincing structural or vegetative, wind-caused damage to substantiate their official wind speeds. This is especially true for storms that made landfall north of the latitude of southern Florida, with the notable exception of Hugo in South Carolina.

For instance, images from Pass Christian, Mississippi, which experienced the peak winds of Camille, show only modest tree damage a few blocks inland, outside the surge zone, with only some mature trees closest to the water exhibiting classic denuding/removal of large limbs. Images of Pass Christian after Katrina, a much weaker storm, showed the same phenomenon. Official reports on Camille showed that most mature pines inland were uprooted rather than snapped, despite Camille's rather quick forward speed. In short, there is little, if any, visual evidence to support anything close to the official 150-kt landfall winds for Camille, despite its impressive radar presentation at the time.

Hazel is another egregious case that may hold some relevance for Patricia's. Hazel was an accelerating tropical cyclone ahead of a mid-latitude system that encountered increasing shear as it neared the North Carolina/SC border, albeit from baroclinic forcing. Like Sandy and the 1938 hurricane, Hazel was broadening and undergoing extratropical transition/deepening as it neared the coast; the winds in the former two weakened as they did so. I have seen many images from the NC coast after Hazel, and not a single image that I can recall shows significant tree/structural damage away from the immediate beachfront. As in Camille/Katrina, most damage was from coastal erosion, waves, and surge.

My hunch is that Hazel may have been substantially weaker than its official 115-kt landfall winds indicate, a contention bolstered by recent cases like Sandy. I also feel that Hazel's leaving the Gulf Stream brought it over the cooler shelf waters closer to the NC/SC coast, just as Camille would have begun encountering lower oceanic heat content after bypassing the Mississippi Delta. Storms like Camille, which had undergone an eyewall replacement several hours before landfall, and Hazel, both of which were expanding in size, may have had more trouble translating their winds to the surface, given a weaker gradient, lower OHC, and/or (as in Hazel's case) increasing vertical shear. Carla and Audrey likely faced similar conditions.

 

The point is that even lower OHC can potentially affect how well a storm's peak winds translate to the surface, even when other conditions are seemingly conducive for an intense hurricane. It's possible that Camille's winds may have not strengthened from 135 to 150 kt as it neared MS in its final hours, even though its central pressure dropped from 919 to 900 mb. Similarly, Carla could have deepened to 931 mb, and Hazel to 938 mb, at landfall, yet without a corresponding increase in winds. (Sandy deepened to 940 mb even as its winds decreased a bit from 85 to 80 kt. As for Audrey, I have serious doubts that it was still deepening as it hit, given its evident structural deterioration on radar.)

Hazel and Camille both had near-average or smaller-than-average radii of maximum winds as they made U.S. landfalls. If my hypothesis is correct, even though those storms deepened before landfall, their winds may have stayed the same or even decreased. Similarly, even as Patricia maintained a small inner core as it made landfall, the effects of increasing shear and downsloping off the mountainous terrain likely reduced the ratio between flight-level and surface wind speeds, resulting in a lower conversion to standard 10-m elevation. In that case, its winds could have easily decreased to 125-135 kt (or perhaps even a bit lower) before landfall.

While a small but sheared storm may be able to retain a high conversion for some hours, the combination of shear and dry air/downsloping has been shown to rapidly affect even well-developed, compact hurricanes. Plus, forecasting experience has shown that small, extremely intense hurricanes are more vulnerable to sudden changes in environmental parameters than are large storms. Dry air intrusion and increasing shear would have induced rapid weakening a cyclone like Patricia, which is what we indeed observed. That could explain the steady warming of the CDO before landfall, coincident with the shifting of the strongest convection to the western quadrant.

 

If my hypothesis is correct, and we are justified in assuming that many (if not most) of our estimated intensities for intense tropical cyclones over land are incorrect, then it amply illustrates the weakness of our historical records and how much we still need to know about complex structural dynamics and interactions between the atmosphere and ocean surface(s) in tropical cyclones undergoing changing environmental parameters at different latitudes/longitudes. Unfortunately, without more recon and other remote sampling of intense cyclones, we won't be able to develop supercomputers able to resolve these issues, much less improve our reanalysis efforts.

 

In short, even taking into account recon and satellite estimates, along with land observations, does not necessarily tell the whole story about maximum sustained winds at 10 m in a tropical cyclone. My preliminary analysis indicates that we may be only reasonably certain about the winds at landfall in a handful (13 or so) of the many "official" Category 4/5 tropical cyclones on record, at least in the Atlantic and North Pacific basins. These cases had support from visual images and/or descriptions of wind-caused damage as well as scientific observations (recon, satellite, surface/ships, etc.). These storms, since 1900, are as follows, with my unofficial estimates of sustained winds included:

  • 1926 Miami hurricane: 120–130 kt (South FL)
  • 1928 Okeechobee: 120–130 kt (Guadeloupe), 130–140 kt (Puerto Rico), 120–130 kt (South FL)
  • 1930 San Zenón: 135–145 kt (Dominican Republic)
  • 1935 Labor Day: 170–185 kt (South FL [Keys])
  • Janet 1955: 140–150 kt (Islas del Cisne/Swan Is., Honduras), 150–165 kt (Quintana Roo, Yucatán)
  • David 1979: 130–140 kt (Dominica), 145–155 kt (Dominican Republic)
  • Gilbert 1988: 115–125 kt (Jamaica), 140–150 kt (Quintana Roo, Yucatán)
  • Hugo 1989: 120–130 kt (Guadeloupe), 110–120 kt (Puerto Rico), 125–135 kt (SC)
  • Andrew 1992: 145–155 kt (South FL)
  • Iniki 1992: 120–130 kt (Kauai, Hawaii)
  • Charley 2004: 125–135 kt (southern FL)
  • STY Haiyan 2013: 165–175 kt (strongest near Guiuan, Eastern Samar, Philippines)
  • Dean 2007: 145–155 kt (Quintana Roo, Yucatán)

Note that my strict standards leave off a number of "official" or probable cases, such as Felix 2007 (due to lack of documentary evidence for Category 4/5 wind damage) and the 1959 Mexican hurricane.

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Honestly, that looks like a poorly-constructed wooden shack without proper trussing and anchoring. The tree damage in the background is quite comparable to what I witnessed in Southeast Florida (Boca Raton) following low-end Category 1 conditions in Wilma (2005). In that storm, most palms retained their foliage, and many mature, deciduous trees were only partly defoliated at best. That is what you see in the background. My visual estimates of low-end Category 1 winds in that storm are consonant with official observations, radar estimates, and judgments by the NHC (see Wilma's post-seasonal report).

 

By contrast, I have seen numerous images and descriptions of true Category 4/5 impacts from the inner cores of Andrew, Charley, STY Haiyan, Hugo, 1926 Miami, 1928 San Felipe II/Okeechobee (in Guadeloupe, Puerto Rico, and South FL), 1935 Labor Day, Janet, Gilbert, David, Iniki, and Dean. (I could argue for 1945 Homestead, but I haven't seen enough evidence to judge. For other Category 4/5 hits, inside or outside the U.S., I haven't seen enough data either.) The visual evidence for true Category 4/5 damage was very strong, compared to that in other storms.

The tree damage was immensely more severe in those cases, with shredding/snapping of mature, hard pines and coconut palms, among other species. Species that defoliate easily, especially in the seasonally dry (sub-)tropical forests of Mexico, the Caribbean, and South Florida, were completely stripped of leaves in several of the cases that I noted. (For good U.S. examples, see North Captiva Island and the Deering Estate after Charley and Andrew, respectively; Google or read up on the "Seaward Explorer" for the latter.) In the '35 hurricane, I've even seen photos in publications showing debarking of entire mangrove forests at Cape Sable and within the inner core on the Keys--something that I've yet to see in any other tropical cyclone.

 

To be honest, the Category 4/5 storms that I've mentioned are among a relative handful for which I've seen conclusive visual evidence to support the official NHC designations at landfall. For many "official" Category 4/5 landfalls like Carla, Camille, Audrey (which will almost certainly be downgraded), Hazel, 1900/1915 Galveston, 1916 Texas, and others, I have yet to see convincing structural or vegetative, wind-caused damage to substantiate their official wind speeds. This is especially true for storms that made landfall north of the latitude of southern Florida, with the notable exception of Hugo in South Carolina.

For instance, images from Pass Christian, Mississippi, which experienced the peak winds of Camille, show only modest tree damage a few blocks inland, outside the surge zone, with only some mature trees closest to the water exhibiting classic denuding/removal of large limbs. Images of Pass Christian after Katrina, a much weaker storm, showed the same phenomenon. Official reports on Camille showed that most mature pines inland were uprooted rather than snapped, despite Camille's rather quick forward speed. In short, there is little, if any, visual evidence to support anything close to the official 150-kt landfall winds for Camille, despite its impressive radar presentation at the time.

Hazel is another egregious case that may hold some relevance for Patricia's. Hazel was an accelerating tropical cyclone ahead of a mid-latitude system that encountered increasing shear as it neared the North Carolina/SC border, albeit from baroclinic forcing. Like Sandy and the 1938 hurricane, Hazel was broadening and undergoing extratropical transition/deepening as it neared the coast; the winds in the former two weakened as they did so. I have seen many images from the NC coast after Hazel, and not a single image that I can recall shows significant tree/structural damage away from the immediate beachfront. As in Camille/Katrina, most damage was from coastal erosion, waves, and surge.

My hunch is that Hazel may have been substantially weaker than its official 115-kt landfall winds indicate, a contention bolstered by recent cases like Sandy. I also feel that Hazel's leaving the Gulf Stream brought it over the cooler shelf waters closer to the NC/SC coast, just as Camille would have begun encountering lower oceanic heat content after bypassing the Mississippi Delta. Storms like Camille, which had undergone an eyewall replacement several hours before landfall, and Hazel, both of which were expanding in size, may have had more trouble translating their winds to the surface, given a weaker gradient, lower OHC, and/or (as in Hazel's case) increasing vertical shear. Carla and Audrey likely faced similar conditions.

 

The point is that even lower OHC can potentially affect how well a storm's peak winds translate to the surface, even when other conditions are seemingly conducive for an intense hurricane. It's possible that Camille's winds may have not strengthened from 135 to 150 kt as it neared MS in its final hours, even though its central pressure dropped from 919 to 900 mb. Similarly, Carla could have deepened to 931 mb, and Hazel to 938 mb, at landfall, yet without a corresponding increase in winds. (Sandy deepened to 940 mb even as its winds decreased a bit from 85 to 80 kt. As for Audrey, I have serious doubts that it was still deepening as it hit, given its evident structural deterioration on radar.)

Hazel and Camille both had near-average or smaller-than-average radii of maximum winds as they made U.S. landfalls. If my hypothesis is correct, even though those storms deepened before landfall, their winds may have stayed the same or even decreased. Similarly, even as Patricia maintained a small inner core as it made landfall, the effects of increasing shear and downsloping off the mountainous terrain likely reduced the ratio between flight-level and surface wind speeds, resulting in a lower conversion to standard 10-m elevation. In that case, its winds could have easily decreased to 125-135 kt (or perhaps even a bit lower) before landfall.

While a small but sheared storm may be able to retain a high conversion for some hours, the combination of shear and dry air/downsloping has been shown to rapidly affect even well-developed, compact hurricanes. Plus, forecasting experience has shown that small, extremely intense hurricanes are more vulnerable to sudden changes in environmental parameters than are large storms. Dry air intrusion and increasing shear would have induced rapid weakening a cyclone like Patricia, which is what we indeed observed. That could explain the steady warming of the CDO before landfall, coincident with the shifting of the strongest convection to the western quadrant.

 

If my hypothesis is correct, and we are justified in assuming that many (if not most) of our estimated intensities for intense tropical cyclones over land are incorrect, then it amply illustrates the weakness of our historical records and how much we still need to know about complex structural dynamics and interactions between the atmosphere and ocean surface(s) in tropical cyclones undergoing changing environmental parameters at different latitudes/longitudes. Unfortunately, without more recon and other remote sampling of intense cyclones, we won't be able to develop supercomputers able to resolve these issues, much less improve our reanalysis efforts.

 

In short, even taking into account recon and satellite estimates, along with land observations, does not necessarily tell the whole story about maximum sustained winds at 10 m in a tropical cyclone. My preliminary analysis indicates that we may be only reasonably certain about the winds at landfall in a handful (13 or so) of the many "official" Category 4/5 tropical cyclones on record, at least in the Atlantic and North Pacific basins. These cases had support from visual images and/or descriptions of wind-caused damage as well as scientific observations (recon, satellite, surface/ships, etc.). These storms, since 1900, are as follows, with my unofficial estimates of sustained winds included:

  • 1926 Miami hurricane: 120–130 kt (South FL)
  • 1928 Okeechobee: 120–130 kt (Guadeloupe), 130–140 kt (Puerto Rico), 120–130 kt (South FL)
  • 1935 Labor Day: 170–185 kt (South FL [Keys])
  • Janet 1955: 140–150 kt (Islas del Cisne/Swan Is., Honduras), 150–165 kt (Quintana Roo, Yucatán)
  • David 1979: 130–140 kt (Dominica), 145–155 kt (Dominican Republic)
  • Gilbert 1988: 115–125 kt (Jamaica), 140–150 kt (Quintana Roo, Yucatán)
  • Hugo 1989: 120–130 kt (Guadeloupe), 110–120 kt (Puerto Rico), 125–135 kt (SC)
  • Andrew 1992: 145–155 kt (South FL)
  • Iniki 1992: 120–130 kt (Kauai, Hawaii)
  • Charley 2004: 125–135 kt (southern FL)
  • STY Haiyan 2013: 165–175 kt (strongest near Guiuan, Eastern Samar, Philippines)
  • Dean 2007: 145–155 kt (Quintana Roo, Yucatán)

Note that my strict standards leave off a number of "official" or probable cases, such as Felix 2007 (due to lack of documentary evidence for Category 4/5 wind damage) and the 1959 Mexican hurricane.

Is anyone willing to comment on this? I'd be interested in hearing other views. :)

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Here's my comment:  Any list like this that leaves off Ivan in Grand Cayman is a crappy list.

The wind damage on Grand Cayman in Ivan, while severe, does not compare to that in the other cases that I listed. Most of the trees stripped bare on the island were deciduous trees that shed leaves readily, such as Australian pines (Casuarina) and Terminalia trees. Many other trees seem to have been uprooted and stripped by storm surge rather than wind. Moreover, I haven't seen coconut palms--a signature tree--stripped bare, unlike in the other storms that I've listed, even though, over the long run, more Category 4/5 cyclones have likely impacted Grand Cayman, given its location, than those that hit the U.S. I've seen images showing numerous coconut palms stripped in Cabo San Lucas after Odile (2014), a storm that officially is 110 kt--high-end Category 3--at landfall in Mexico, though I believe that it should be 115 kt (low-end Category 4) instead.

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The wind damage on Grand Cayman in Ivan, while severe, does not compare to that in the other cases that I listed. Most of the trees stripped bare on the island were deciduous trees that shed leaves readily, such as Australian pines (Casuarina) and Terminalia trees. Many other trees seem to have been uprooted and stripped by storm surge rather than wind. Moreover, I haven't seen coconut palms--a signature tree--stripped bare, unlike in the other storms that I've listed, even though, over the long run, more Category 4/5 cyclones have likely impacted Grand Cayman, given its location, than those that hit the U.S. I've seen images showing numerous coconut palms stripped in Cabo San Lucas after Odile (2014), a storm that officially is 110 kt--high-end Category 3--at landfall in Mexico, though I believe that it should be 115 kt (low-end Category 4) instead.

 

As you imply, part of that is the winnowing effect of past storms in the Caymans   IIRC (and I don't have the reports handy but I've reviewed them in the past) the property damage in Grand Cayman was concluded to be Cat 4+: and keep in mind that construction standards there are quite high.

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The tree damage was immensely more severe in those cases, with shredding/snapping of mature, hard pines and coconut palms, among other species. Species that defoliate easily, especially in the seasonally dry (sub-)tropical forests of Mexico, the Caribbean, and South Florida, were completely stripped of leaves in several of the cases that I noted. (For good U.S. examples, see North Captiva Island and the Deering Estate after Charley and Andrew, respectively; Google or read up on the "Seaward Explorer" for the latter.) In the '35 hurricane, I've even seen photos in publications showing debarking of entire mangrove forests at Cape Sable and within the inner core on the Keys--something that I've yet to see in any other tropical cyclone.

 

 

Hey, this is really interesting! Do you have a link or some other form of reference that you could send me? I would love to see it.

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Hey, this is really interesting! Do you have a link or some other form of reference that you could send me? I would love to see it.

The reference is the book Gladesmen: Gator Hunters, Moonshiners, and Skiffers by Glen Simmons and Laura Ogden (Gainesville: University Press of Florida, 1998). Chapter 4, "Flamingo and the Cape" (pp. 122-163), contains a number of images taken within a few years of the 1935 hurricane's passage over Cape Sable, now within the southwestern part of Everglades National Park on the South Florida mainland. Pages 126, 145, and 157 contain images showing how the 1935 hurricane literally stripped bare and even partly debarked black mangrove forests in the area.

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