Windspeed

Also, NOBODY in this thread has been overhyping Lan. Not in the least. Get real.

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.

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.

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.

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.

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.

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:

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

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.

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.

JTWC now up to 130 kts and forecast to peak at 140 kts over the next 12 hrs.

CI# /Pressure/ Vmax 6.1 / 941.1mb/117.4kt At this rate, it will be Super Typhoon Lan by 00z.

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!

Not too shabby...

Yeah, Lam likely matures into a large and powerful typhoon with a big stable eye over the next 24-36 hrs.

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.

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.

Much has been discussed in various tropical cyclone threads on this forum and the old predecessor Eastern Wx forums over the past 17 years about the northern Gulf of Mexico and its unfavorability in sustaining major hurricane landfalls. Even as recently a Hurricane Nate, the discussion was brought up again. Though Nate was not a major hurricane, nor was it forecast to be, it was forecast by the NHC to reach 90 kts / 105 mph by landfall. Nate did not reach Category 2 intensity however, and even appeared to weaken more significantly than the official advisory prior to landfall; though we will need reanalysis to perhaps know for certain just how much weakening occurred. Either way, it is clear Nate did not strengthen or maintain its structure into landfall. Convection waned, the core appeared to collapse and the NE eyewall barely held its curved banding into the MS coastline. As such, discussion linked Nate to the unfavorability that exists there. I disagree with this conception, however. Hurricane Nate is not a good example of a cyclone sustaining intensity due to SST environmental conditions. Nate was a hurricane with a small core that was under a extremely fast steering regime. Convective mesos would form, rotate to the western half of the circulation and collapse. This happened at a near constant rate as its forward motion increased until it couldn't manage to close off its eyewall vortex. At multiple points on track, an eyewall would develop only to pivot around into a new intensifying meso. I think recon may have measured hurricane force winds within the stronger east side of these mesos, but I am not so sure Nate ever held a steady state intensity for prolonged periods. It's quite possible the core would reattain hurricane force during each meso, but an eyewall band had trouble establishing overall dominance as the core vortex feature. Whether the shallower heat content had an effect I believe is insignificant compared to the unfavorable flow against the western half of the hurricane. Perhaps radial convergence and evaporation feed of heat flux really was suffered by Nate. The storm was just moving way too fast for it to take advantage of any immediate sea surface heat layer, much less heat content at depth (regardless of its presence). Understand that I have been skeptical of forward motion, low-level convergence and heat flux being a significant factor, but I am now wondering if this is a critical to sustainment of eyewall convective banding as upper-level divergence over LLC core may be overwhelmed or disrupted with meso scale vortices updrafts within the inner periphery of the low-level vortex in rapidly moving systems such as Nate. This may not have been as much a negative factor for an already well-organized surface vortex, but Nate seemed to be struggling with this process even as a hurricane. We also have plenty of examples of hurricanes intensifying at landfall in the northern Gulf over the shallow surface layer to contend with the hurricanes that weakened. Alicia, Fredrick and Camille (after completing an ERC) are some of the more notable cyclones. The most intense major hurricane to be shown to have reintensified by landfall in reanalysis is Camille. Though it weakened during an ERC SSE of the mouth of the Mississippi River when the tiny inner eyewall finally collapsed, a bright outter ring representing the outter eyewall contracted quite rapidly. It did not lose its structure and in fact appears to have sustained nearly a 360° 12 nm closed band right at landfall at Waveland, MS. See linked animation .gif of landfall and PDF of reanalysis. Now clearly, shallow surface layer SSTs in August near the northern Gulf coastline are warmer than in October. We typically observe 29-31° C shallow surface water by late August without any significant frontal interaction. By October, the shelf typically drops a few degrees. But 28° were still being observed in Nate's track. That would have been sufficient to support a major hurricane, especially a fast mover. Unfortunately, Nate was moving so fast, it began to collapse before the shallow layer even mattered. We have seen rapid motion in major hurricanes before. Charley was moving around 20 mph when it underwent rapid intensification from 95 to 125 kts and a 27 mb pressure drop in less than 8 hours. But when Charley's core gained faster forward motion, it already had a well organized and symmetrical core. Interestingly, though it did not cross over the northern Gulf shallow shelf, it was crossing the shallow shelf off of SW Florida, north of the Keys. Wilma also intensified crossing this shallow shelf. OTOH, Nate was in the process of developing its core vortex the entirety of its track across the W. Caribbean and GOM between 22 and 26 mph. These are purely tropical cyclone examples. We can also cite the rapid motion of the 1938 Long Island Hurricane; however, this storm was likely undergoing rapid baroclinic forcing as well, which likely sustained intense convection and major hurricane force winds/surge straight inland. Some majors that weakened at landfall are obviously noteworthy. Katrina, Rita and Ivan are mentioned frequently. But every one of these systems were battling significant shear as well. Ivan is an interesting case as it managed to remain 105 kts Category 3 even with 30 kts of mid-level shear advecting dry stable air into its core. The northern and eastern eyewall band held together quite well. With past hurricane examples of intensifying storms into the northern Gulf coast, these systems were all in a more favorable upper-level environment. Even though Nate was in a low shear environment, the western circulation northerly flow was hampered by such strong opposing directional mid-level flow. I think if Nate had been a slower moving storm, being a purely tropical entity, it would have been able to reach Category 2 intensity at landfall. Perhaps even strengthen all the way into landfall. But this is speculative. I'm only wanting to point out that the sea surface environmental aspects were not its doom. Edit: I initially intended to preview and correct typos, but I accidentally submitted the entire post prematurely. If you read this post within the first hour of submission, you may want to reread before commenting. Thanks!

Often times posters will discuss, compare and contrast historical tropical cyclones and their climatology during an active event thread, but these posts end up buried amongst the overall meteorological storm discussion for obvious reasons. I am opening this thread for current and future discussion as it relates to past tropical cyclone events and their peer-reviewed reanalysis projects. If any person wishes to post about, reminisce or debate past tropical cyclones, regardless of oceanic basin or sea, perhaps they carry that on in this thread so we may have an easier flow of information and archive of such discussion. I have quite a few cyclones to discuss myself and existing preconceptions / misconceptions about a particular region of the Atlantic to flesh out. My first post will be later this evening. But don't wait on me.

This would be the place.

Looks like the ERC occurred in best case scenario with landfall.

I think they might be a little too north in their forecast track. Of course it could gain a more WNW motion between now and landfall, but it really looks to be bullseyeing the mouth of the Palanan River.

The forecasted location of landfall receives more severe landfalling cyclones than any place on Earth. That combined with the mountainous terrain of the region probably has a lot to do with the far less densely populated geography as compared to the rest of the Philippines. However, there are small villages and townships still located along the coastline of northeastern Luzon. Hopefully the center makes landfall where one of those villages aren't located. Additionally, you are correct about the threat of inland flooding. This typhoon has a powerful circulation with a very low pressure. As it pushes west, it will be a big threat to higher populated regions of central and western Luzon. That risk can certainly not be downplayed. Edit: Divilacan Bay has several small coastal townships that are the closest to the current projected landfall point. That area was also blasted by Super Typhoon Megi in 2010. Inland flooding from that typhoon displaced 200,000 people as it moved across Luzon. https://en.m.wikipedia.org/wiki/Divilacan,_Isabela https://en.m.wikipedia.org/wiki/Maconacon,_Isabela

Ok, great! It wasn't showing any changes for several hours. Glad they're up. Anxious to see what they have to report besides.

Data equipment and communications obviously failed at the airport on Itbayat.