Windspeed
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Everything posted by Windspeed
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With respect to the recent impacts on the Lesser & Greater Antilles and US territories, PBS NOVA is airing a new documentary that focuses on the deadliest Altantic major hurricane in the historical record, The Great Hurricane of 1780. http://player.pbs.org/viralplayer/3005566471/ -
Here is a longer version with footage from the eyewall.
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Here's a blast from the past: Anyone remember Major Hurricane Elena? It is another example of a hurricane that intensified significantly while over the shallow shelf waters of the northern Gulf. Elena reached upper Category 3 intensity with maximum estimated winds of 110 kts, but did weaken slightly to 100 kts in the hours just before landfall near Biloxi, Mississippi. I think we should realize, however, that Elena was its own worst enemy. It spent nearly four days in the same general region of the Gulf. The circulation took on slow and erratic movement ENE before looping sharply back to the WNW. This motion was due to interaction with a fast moving weak upper level shortwave trough that lifted and left Elena behind. The 500 mb weakness filled and allowed a ridge to take the wheel. Prolonged meandering and drift of the circulation likely did upwell cooler water from the previous days. This combined with the core's close proximity to the coast on its WNW track prior to landfall perhaps did prevent Elena from becoming a Category 4. The highest official coastal measurements were 92 kts sustained with 118 kts gust on Dauphin Is., Alabama, and gusts of 105 kts in Gulfport, Miss. Elena is also one of the few early and rare moments where a successful storm chaser was lucky enough to have a quality camera on the ground inside the eye at landfall. The chaser filmed the clear blue sky overhead and the beautiful concave eyewall seen @ 1m 20s. A stunning shot made even more impressive that this was captured in 1985.
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115 kts ... massive wind radiii: Near or at landfall:
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They can handle a Cat 2/3, yes, they have sea walls and well built structures. But that's besides the point. Even a Cat 2, don't take it seriously and it hits a densely populated area, see what happens. And just based on current motion, 15-20kt of weakening is probably close to the mark. It wouldn't be good and it will cause destruction. Nobody was hyping this. Edit: Current intensity is 125 kts and that may even be high. Earlier, when Lan looked a lot better, mind you, I made the 15-20 kt comment based on its appearance versus rapid forward motion. It's down to 125 kts. So give me the benefit of the doubt of 20 kts. You win. It will clearly weaken more than 20 kts. Probably 30 kts by landfall. Congratulations. I apologize for overhyping a 135 kt typhoon based on a worry of rapid motion. A Cat 2/3 landfall was forecast throughout and that is likely what it will be. Never called for anything higher, but you are correct. I insinuated hype with the word "worry" that it wouldn't weaken below Cat 3. It most likely will. Cheers!
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That is your definition of hype? The core is in rapid motion. It's a worry vs I should just call it a windy day and move on?
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Please quote me hyping this typhoon. Quote any words. I beg you. You are ridiculous.
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I just do not see what your point is here. Who has made a call this will landfall as a Super Typhoon? Look at the forecast. It's still serious for Japan.
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Also, NOBODY in this thread has been overhyping Lan. Not in the least. Get real.
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Good thing that's not how we alert the public. You don't downplay a 135kt cyclone. Yes, the core may degrade to absolute crap by landfall. You want to base your advisory on that call. Have you ever been in a Cat 2/3 storm? This will be destructive. Hopefully it will weaken and that destruction will be mitigated.
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Haha. That's clearly your opinion. I see this as a powerful system that is going to make landfalll in a densely populated region. All based on perspective I suppose.
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Perhaps in 8-10 hrs, but the perspective that it's falling apart based on current satellite presentation isn't good sound meteorology. We all knew the system was going to weaken based on the environement. But Lan isn't exactly hot garbage.
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Define "really going downhill"? If convection were falling apart, I'd concede. But this is classic tilting due to mid-level flow. Only, at present, the core is moving rapidly enough to counter it. That northern eyewall must still be quite fierce with such intense convection wrapped around it. Yes, you will have an assymmetrical appearance outside the core with baroclinic influence and increased southwesterly flow, but the core itself around the eyewall remains symmetrical and intact. This is still an intense typhoon. Hopefully it will begin to weaken significantly for the sake of impact on a highly populated region.
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The center may be slightly tilted as well. Southerly flow is screaming. This is still an intense typhoon though. I am a bit worried this won't weaken more than 15-20 kts prior to landfall ue to rapid forward motion.
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It's nice to have some recon surface obs for once in the WPAC to back up satellite estimates. I will say that Lan looks even better than it did when they acquired their dropsonde data yesterday. EDIT: ADT ranged from 5.9 to 6.3 during the time they would have been in the eyewall. At present, ADT CI # is: 6.8 / 922.9mb/134.8kt JTWC 21/2100 discussion:
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I wonder if Lan will be intercepted by reconnaissance aircraft. Last year, there were several publications that members from Nagoya University and the Meteorogical Research Institute were going to conduct missions into powerful typhoons beginning this year. Granted, the 2017 WPAC season has been slow. But if ever there was a typhoon to start data gathering missions, especially considering the threat to Japan, you would think Lan would be it. https://weather.com/news/weather/news/typhoon-observation-western-pacific-recon-aircraft It would be awesome to have a dropsonde in this big powerful eyewall. Sometimes Dvorak underestimates large eyewalls. I recall Irma this year in the Atlantic was underestimated versus some of the recon measurements, though that hurricane was imbedded in a higher background pressure regime. Edit: Well I just stumbled across this info on another board. They did not include any obs but confirms the flight occurred. Article is Japanese, here is the Google translation: https://headlines.yahoo.co.jp/hl?a=20171020-00173308-nbnv-sctch
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I agree that it is a little concerning that both majors have the core coming ashore left of Tokyo and Yokohama. That does increase right front surge potential for Tokyo Bay. But they do have a system of sea walls and dikes to handle tsunamis and surge, though the upper west portion of the bay could have issues if it surpasses 2-3 meters. It would still cause a lot of damage but hopefully not result in casualties. Worst cast would be the right side of the core running directly up the bay. The track would need to be exactly postioned and Lan has that potential. Still, even 40 hrs out, it could shift a bit. Let's see what 24 more hrs of modeling brings with interaction of the southwesterly flow at that positon. Hopefully the JMA is alerting the government and getting people in close promixity to the bay shoreline / water front aware.
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I agree this has the potential to be a big hit for Japan. Though Lan won't hold this intensity, the fast movement will mitigate rapid weakening. This very well could be an upper end Cat 3 landfall for populated areas.
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CI# /Pressure/ Vmax 6.1 / 941.1mb/117.4kt At this rate, it will be Super Typhoon Lan by 00z.
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Lan is rapidly intensifying. ADT CI# is 112 kts and rising fast. Colder tops and the CDO is expanding NW of the 50nm wide eye now, which has warmed significantly the past few hours. Still 24-36 hrs of low-to-moderate shear but with an ever increasing 200mb poleward jet steak. The diameter of the eye will slowly contract some and I suspect ADT will hit 130 kts or more before Lan begins to weaken. JTCW will probably re-up the intensity forecast some. This is a massive-sized core, but perhaps a Super Typhoon is still a possibilty afterall. Edit: Good grief, to be so short, this typhoon's name is plaguing me. I keep hitting the freakin' m key!
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Yeah, Lam likely matures into a large and powerful typhoon with a big stable eye over the next 24-36 hrs.
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You nailed it. That has been the issue. Lam developed as multiple surface circulations formed within a large surface trough. Over the past week, surface vorts have been competing within the large gyre. When you have that scenario, deep convection within one vort can suppress convection or create subsidence that affects parts of the overall core structure. However, it looks like a deep band is getting established and a dominate vortex will take over. The SSTs are plenty warm up to southern Japan. It may not reach Super Typhoon status, but I think it will definitly be a Cat 3/4 before the the typhoon nears Japan. Perhaps holds intensity enough to landfall as a 3.
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My main point was to show that you do not need deep oceanic heat content for a fast moving cyclone. Often times people post these OHC images as evidence for rapid intensification, but in my opinion, it is of far less importance for fast moving hurricanes versus the overall upper-level atmospheric environment. These NOAA maps that show depth of the 26° isotherm and also TCHP in the Gulf of Mexico are far more critical in slow to moderate motion in cyclones where their own upwelling below the shallow surface layer can affect intensity. Another hurricane I completely forgot to mention is Harvey. Here is another example of a hurricane that rapidly intensified over a shallow shelf just off the SE Texas coast. The immediate surface layer was around 30-31° C at the time. But Harvey's core had already moved away from deeper oceanic heat content and a deep warm eddy. See the CIMSS image: http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2017/08/Harvey_track_OHC.jpg The shallow surface layer was essentially overkill to support rapid intensification. The improving upper-level environment became spectacular near the coast however, and the models had been hinting at a favorable 200 mb pattern in the days proceeding Harvey's rapid intensification. The reason I cited Camille in the post above is that it is an example of a Category 5 that actually reintensified over the shallow shelf just east of Louisiana. In late August, the shallow surface layer near eastern Louisiana / southern MS-AL coast would have been around 30-31° C, similar to what we observed under Harvey just off Texas coast. I worry that we will see another Camille again. Granted, October the SSTs have dropped enough. But in the prime GOM months of July and August, I have little doubt a Category 5 can make landfall along the northern Gulf coast. We have developed a preconception of that region of the GOM due to recent examples of major hurricane landfalls. But it just takes the right upper-level environment and storm motion to change or erase that conception.
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