Ground Scouring

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  1. Maru González, First, thank you for your excellent firsthand reports from the area. Some questions: Do you care to share an update regarding the state of the anemometer? Has it been left in place? Is it going to be tested via wind tunneling? Also, have you sent in your data and images of the aftermath to the NHC? Have you heard from the biologist regarding Copa del Sol? Best wishes to you and the residents still recovering from the storm!
  2. Based on my post here, I'd like to point out that many U.S. Category 4/5 hits may well have been much weaker than even indicated in reanalysis. I'd specifically highlight 1900/1915 Galveston, 1916 Texas, Hazel 1954, Audrey 1957, Carla 1961, and Camille 1969, for which there is abundant photographic evidence from the landfall area (meaning areas that would have been impacted by the estimated maximum winds) failing to show wind-caused damage even proximate to that implied by the official landfall designation. I'd propose downgrading at least a few, if not all, of these. Thoughts and comments in the other thread (or here!) are welcome.
  3. Just out of curiosity, I'd like to know what your personal feelings are about the strength of Patricia at landfall.
  4. 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.
  5. The Haiyan images that I've seen mostly showed coconut palms uprooted or snapped, but with their fronds intact, with some spotty exceptions. I could have missed other images and descriptions, of course, so I could very well be wrong. But as far as intensity is concerned, Josh explicitly said that the pressure would likely have been around 930 mb at landfall if the landfall location (~2 nm to his west) was correct. Given the extreme pressure gradient that he also mentioned, even a slight difference in the landfall location could mean a pressure 5-10 mb lower. (See wxmx's posts.) In his discussion with Dr. Postel, both seemingly agreed that Patricia will keep its Category-5 status at landfall when post-analysis is completed. Now, that does not mean that Patricia actually was a Category 5 at landfall, but if not, it was almost certainly fairly close (within 10 kt or so). As for the anemometer, the initial 161-kt reading could have been accurate; the real anomalies indicating malfunction may have occurred just afterward, with the 141 kt for 19 consecutive minutes. Of course, given surrounding terrain, even if the 161-kt reading were accurate, whether it is representative of the storm's strength is another matter. There are good, scientific, meteorological cases for and against Patricia's maintaining at least 140 kt at landfall. Personally, I would go with 125-135 kt at landfall, but 140 kt is quite plausible, in my opinion.
  6. Here's the first view I've found of Costa Careyes, apparently taken just after the peak winds arrived. The image appears to show extreme shredding of coconut palms in the background, with similar decapitation of several royal palms on the right. Apparently the concrete structures in the resort village survived the storm, but vegetative damage is extreme.
  7. The middle image looks quite similar to the damage that some areas sustained in Haiyan. In both cases the coconut palms often retained their fronds while other vegetation was violently shredded nearby. I'm not saying that this was as intense as Haiyan was, but I would hesitate to make judgments one way or another. Vegetative damage is notoriously subjective and dependent on variables such as density, hardwood vs. softwood, depth of roots, soil type, etc. The surrounding area looks hilly, and in a compact but weakening system, the circulation was likely producing very intense winds just above the standard 10-m elevation. Terrain would have further enhanced such winds. So even if the system was below Category 5 status at landfall, sustained winds just above 10 m likely still retained 140+ kt. A conversion to 10 m would likely still yield 125-135 kt (if not 140 kt) at landfall, meaning a storm at least as strong as Madeline 1976 (125 kt), which is the strongest eastern Pacific landfall on record. I also think that the pressure reports from both iCyclone and the biological station support a landfall value pretty close to the preliminary NHC estimate of 920 mb, given both sites' inland locations, the brief lull (far from a true calm) at each site, and the small size of the RMW. An application of the Schloemer (1954) equation actually yields 918 mb at landfall based on the 948 mb (27.98") peripheral sea-level reading from the biological station. Keep in mind that the system was moving rather quickly at landfall, so, given the compact size, areas at or inside the RMW would have only experienced the most extreme conditions for a very brief period. (To be honest, based on the data that have come out, I think that my initial landfall estimate of 115-120 kt is substantially too low, even if Patricia was just short of 140 kt as it hit.)
  8. I still don't see any reports from areas that experienced the inner core. And iCyclone still hasn't reported in.
  9. To be honest, given that this system has weakened even faster than it intensified, plus the fact that I've never seen a 130+ kt cyclone without an intact inner core, I think that this is 115-120 kt tops at landfall with a central pressure in the low to mid 940s (based on extrapolation from the recon data and filling rate, plus satellite/radar trends). It's basically comparable to Kenna 2002, which attained Category 5 status but then rapidly weakened to a 120-kt hurricane before landfall. This system may even be a bit weaker than Kenna.
  10. I don't think that the decrease in winds necessarily saved many lives. Even in the 1935 Labor Day hurricane, most of the deaths were from surge, not directly related to the extreme (160+ kt) winds. Remember how relatively few people died in Andrew, Charley, Dean, etc.--the intensely windy micro-monsters--compared to those who died in weaker or weakening but larger storms like Katrina, Ike, Sandy, 1915 New Orleans, Rita, etc. And the majority of those deaths were from water. People forget time and time again that the deadliest killers, even in the most powerful cyclones, have been storm surge and inland flooding. Most of Mexico's deadliest tropical cyclone-related disasters, including the 1959 hurricane (1,000+ deaths), were from mudslides and flash flooding due to heavy rainfall, not extreme winds. Patricia will likely deliver inland rainfall of 20-25"+ in some areas, especially over mountainous terrain. This is the story that should be getting at least as much play as the winds. And as others have mentioned, a weaker but larger wind field still retains considerable energy and would produce more/higher storm surge over a larger area than would a tightly wound, 150+ kt monster.
  11. I think you're focusing too much on the winds. Most of Mexico's deadliest tropical cyclone-related disasters have resulted from flash floods/heavy rainfall, not extreme winds (including the 1959 hurricane, most of whose 1,000+ deaths were from mudslides).
  12. Actually, it looks as if the more westerly short-term track caused it to track outside the most favorable upper-level conditions and into an area of stronger southerly shear near the jet entrance region. The small inner core has yet to feel the full influence of the mountains, so I doubt that land interaction has played much of a role in the rapid weakening. I'd say shear plus ERC has done Patricia in, though it will still be a strong Category 4 hurricane at landfall (125-130 kt) in the post-seasonal analysis, most probably.
  13. The ERC simply won't have time to induce substantial weakening given the faster movement. I'd say a Haiyan-style landfall (160-165 kt, perhaps even a bit stronger) looks very likely now. This would put the storm in contention for the strongest landfall on record, rivaling or exceeding Haiyan and the 1935 Labor Day hurricane.
  14. Dean and Felix both made landfall at 150 kt, as did Janet 1955. Typhoon Zeb (1998) hit the Philippines at 155 kt, if I recall correctly. And that 204-kt flight-level wind likely means that this storm will be upgraded in post-seasonal analysis to a peak of 180-185 kt (90% reduction yields ~184 kt 10-m winds).
  15. By maximum one-minute sustained winds, Haiyan (165 kt) holds the record, if I recall correctly. The 1935 Labor Day hurricane (160 kt) is second.
  16. No doubt this was in Tip's league several hours earlier overnight...given the 878 mb extrapolated pressure even with a warmer CDO.
  17. Early call: landfall around 20Z ~20 mi W of Manzanillo at 155 kt with major wind/surge destruction to the east of the center.
  18. I think that this is likely to deviate to the right of the forecast track up until landfall. Satellite data over the past few hours indicate that the trend is not a jog, but rather a definite turn to the north-northeast and eventually northeast. Layer mean analysis at 500-850 mb indicates southwest to northeast flow as the mid-level jet becomes more zonal, so Patricia is likely beginning a sharp turn to the northeast, much as Charley did in 2004, that would bring the center to the coast within 20-30 mi of Manzanillo.
  19. Considering the continued warming and contraction of the small eye, the incoming mission may well find a pressure in the upper 870s, likely in the range of 877-879 mb. This may well be as strong as it was at the time of last night's historic final pass, though peak intensity likely occurred some hours earlier. My guess is that the winds in post-analysis will be bumped up to 180 kt, based on SFMR data and the possible findings of this mission.
  20. This is another contender by iCyclone...really showing the power of even a storm much weaker (110 kt) than Patricia. (Personally, I suspect that Odile may have been 115 kt--low-end Category 4--at landfall.)
  21. My original expectations for weakening to 130-135 kt before landfall look to go down the drain. Because the cyclone is heading parallel to the shear vectors and is south of the jet entrance region, any increase in vertical shear should not impact the core very much before landfall this afternoon. If anything, the storm may be stronger now than it's ever been, at least in terms of central pressure. The only things that may preclude landfall at 175+ kt are likely the possibility of an ERC and/or frictional effects from land, but the former looks less likely to get much underway before landfall. Plus, given satellite indicators that the movement is just east of due north, this looks to make landfall earlier, as has been mentioned previously. I can't see any reason as to why this won't make landfall as a formidable Category 5 (I'm thinking 150-155 kt, but this could be a bit conservative in the end).
  22. ATCF has 165 kt/886 mb for the 06Z fix. This makes Patricia only the third case in which the NHC operationally (in its advisories) classed a cyclone at 165 kt or higher, after Camille and Allen. Patricia now only has to conquer Wilma's 882 mb for the Western Hemispheric record, which I think is a very good likelihood.