WPAC, Indian Ocean, and Southern Hemisphere Tropical Cyclones

[Windspeed]

Well, that escalated quickly. Gaemi is now a powerful Super Typhoon with a very intense eyewall and evolving concentric structure. Most likely, this concentric banding structure will result in an ERC prior to landfall and hopefully bring down intensity prior to crossing the shoreline. Hopefully, any such cycle will not be completed with haste to allow reintensification, but Gaemi is no doubt going to be a powerful strike on Taiwan regardless.

[Windspeed]

Gaemi has thrown on the brakes and made a hard left turn down the eastern coastline. It's absolutely incredible to see such a scenario unfold in real-time.

[Windspeed]

We've seen these crazy cyclonic loops in the past in interaction with the mountainous island of Taiwan. It's still quite eye-opening, no pun intended.

[Chinook]

Typhoon Ampil (category-3, 105 knots) is east of Tokyo. This is kind of interesting that it has many parallels to Hurricane Ernesto. It should be peaking. It is traveling north. It's much closer to the Japan coastline than Ernesto is to the American coastline. I wonder if the storm energy eventually affects the eastern United States in 10 days

Quote

INITIAL POSITION: 35.0N 142.0E

INITIAL INTENSITY: 105 KTS

GEOGRAPHIC REFERENCE:

114 NM EAST OF YOKOSUKA, JAPAN

MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 12 KTS

SIGNIFICANT WAVE HEIGHT: 38 FEET

 

[gallopinggertie]

Tropical storm Shanshan is currently forecast to make landfall on southern Honshu as a 120mph typhoon. Major hurricane-equivalent strikes on Japan are not that common.

[gallopinggertie]

Typhoon Shanshan is looking pretty serious for Japan. It’s now forecast to make landfall as a strong Cat 3 or low-end 4 equivalent near Nagoya.

[NorthHillsWx]

9 hours ago, gallopinggertie said:

Typhoon Shanshan is looking pretty serious for Japan. It’s now forecast to make landfall as a strong Cat 3 or low-end 4 equivalent near Nagoya.

I’ll believe it when I see it. This is a notorious track for a weakening 70-85 kt storm after a week of major hurricane hits on models. Shear and cooler waters ensure this will be weakening into landfall the only question is how much. Still a serious storm, don’t get me wrong, but this won’t be close to cat 4, and I STRONGLY doubt cat 3

[gallopinggertie]

44 minutes ago, NorthHillsWx said:

I’ll believe it when I see it. This is a notorious track for a weakening 70-85 kt storm after a week of major hurricane hits on models. Shear and cooler waters ensure this will be weakening into landfall the only question is how much. Still a serious storm, don’t get me wrong, but this won’t be close to cat 4, and I STRONGLY doubt cat 3

I found a map showing SSTs are 28-30 C over that part of the Pacific. Seems plenty warm though I’m not sure about shear. 
 

https://www.ospo.noaa.gov/products/ocean/sst/contour/

Shanshan is forecast to still be a 70 mph tropical storm when it reaches Hokkaido, which is unusually strong for that far north. I wonder if it will be extratropical by then.

 

 

[NorthHillsWx]

Shanshan looks extremely ragged this morning. Not sure this was expected 

[Windspeed]

Shanshan looks extremely ragged this morning. Not sure this was expected 

Shanshan's mid-level vortex is being stretched due to close proximity to the mid-to-upper cutoff, which is now an intensifying ULL. The ULL has been evolving while imparting substantial shear across the TC the past few days. Interestingly, though shear has a negative impact in preventing Shanshan's core from developing a stable eyewall, strong diffluence (spreading wind vectors) around the ULL has already been aiding in strong convective bursting to keep the low-level vortex vigorously organized, and it is exactly this phenomenon that favors future rapid intensification. As the ULL retrogrades to the WSW and gains separation from Shanshan, it will flip from unfavorable to exceptionally favorable in mid-to-upper flow. The 400-200 hPa jet pivots away to create a mass sink to evacuate air. Diffluence remains, but you now have divergence aloft with poleward and westward channels. Simultaneously, Shanshan moves over relatively untouched SSTs with deep heat potential. So we're all looking at this thing with apprehension because, based on the evolving and modeled steering layer, this TC has the potential to be the most powerful typhoon to make landfall in Japan in decades. I am not saying it will. But you may still be dismissive of the high-end modeling (which is probably overdoing it) and are certainly justified to worry of an intense and destructive landfall.

[gallopinggertie]

Shanshan only forecast to be cat 2 at landfall now. Still shown as a typhoon over the Sea of Japan though which is quite rare.

[gallopinggertie]

9 hours ago, gallopinggertie said:

Shanshan only forecast to be cat 2 at landfall now. Still shown as a typhoon over the Sea of Japan though which is quite rare.

Now the forecast is back up to a 125-mph landfall, further to the west in central Shikoku island. There’s a major city there, Kochi, with 2 million people in the urban area, hopefully they are not too prone to storm surge if it does hit there.

*Edit: I misread, it’s forecast to hit Shikoku at 110-mph. 

[Windspeed]

Shanshan has positioned itself in a more favorable environment now for rapid intensification. The features that were holding it in check are now aiding in ventilation. Over the past few hours, intense convection has wrapped the core of the typhoon. Hopefully, the TC doesn't go too crazy and become a super typhoon prior to landfall.

[olafminesaw]

Huge corrections from all models. Now many models have it slowing down prior to landfall which may give it an opportunity to go through ERC before landfall 

[NorthHillsWx]

1 hour ago, olafminesaw said:

Huge corrections from all models. Now many models have it slowing down prior to landfall which may give it an opportunity to go through ERC before landfall 

I’m not sure the westward corrections are finished either. It’s already trending west of track today 

[WxWatcher007]

2 hours ago, NorthHillsWx said:

I’m not sure the westward corrections are finished either. It’s already trending west of track today 

Seems like there have been several instances of models struggling to keep up in the tropical realm this season.

[Windspeed]

Shanshan completed an ERC and now has a larger diameter eye. For now, it looks like the Kagoshima Prefecture will take the brunt of landfall. There is also potential for a stall inland over Kyushu before moving back out over open water. Modeling has not performed the greatest with Shanshan up to this point, however, not handling the steering layer well around large features such as the typhoon's interaction with the mid-to-upper cutoff and weak steering flow with a potential block to the north.

[Windspeed]

Shanshan is now a Category 4 typhoon. The storm is crawling, but its large symmetrical eye is maintaining a very stable and steady state. It is churning up deeper water, but not feeling its own effects of upwelling due to the 26°C isotherm being over 100 meters deep currently in that part of the NW Pacific. High TCHP is critical for slow-moving large TCs to maintain such intensity for long durations.

[Rjay]

Lol

 

[NorthHillsWx]

Due likely to upwelling and westerly shear, Shanshan is a shell of its former self. Massive flooding impacts likely, but this will be a cat 1, minimal cat 2 landfall. It’s so hard to get a high end landfall in mainland Japan. As for flooding, this could be catastrophic given the topography of that area and the slow movement of the system. I do not want to mitigate the impact by stating the LF intensity will be significantly lower than feared 

[Windspeed]

Due likely to upwelling and westerly shear, Shanshan is a shell of its former self. Massive flooding impacts likely, but this will be a cat 1, minimal cat 2 landfall. It’s so hard to get a high end landfall in mainland Japan. As for flooding, this could be catastrophic given the topography of that area and the slow movement of the system. I do not want to mitigate the impact by stating the LF intensity will be significantly lower than feared 

I'm not convinced that westerly shear is the culprit for weakening here. I think the problem a TC experiences in its current location is downsloping off of Kyushu's mountainous terrain. About 12 hours ago, there was a pass that showed significant deformation in the eyewall and a replacement cycle in progress. Then, the entire western band disintegrated as the northern circulation moved over the greater Kyushu landmass. If you watch satellite and radar animation through the same timeframe, it's rather neat to see the landmass of Kyushu having effects on Shanshan's structure. I agree we're looking at a Cat 1-2 in windspeeds, most likely. But in hindsight, this is a massive typhoon and large circulation. A dangerous situation is unfolding if it continues to crawl at a slow pace through landfall and progresses slowly over the Kagoshima prefecture. Precipitation amounts may lead to a historical event, unfortunately.

[NorthHillsWx]

30 minutes ago, Windspeed said:

50 minutes ago, NorthHillsWx said:

Due likely to upwelling and westerly shear, Shanshan is a shell of its former self. Massive flooding impacts likely, but this will be a cat 1, minimal cat 2 landfall. It’s so hard to get a high end landfall in mainland Japan. As for flooding, this could be catastrophic given the topography of that area and the slow movement of the system. I do not want to mitigate the impact by stating the LF intensity will be significantly lower than feared 

I'm not convinced that westerly shear is the culprit for weakening here. I think the problem a TC experiences in its current location is downsloping off of Kyushu's mountainous terrain. About 12 hours ago, there was a pass that showed significant deformation in the eyewall and a replacement cycle in progress. Then, the entire western band disintegrated as the northern circulation moved over the greater Kyushu landmass. If you watch satellite and radar animation through the same timeframe, it's rather neat to see the landmass of Kyushu having effects on Shanshan's structure. I agree we're looking at a Cat 1-2 in windspeeds, most likely. But in hindsight, this is a massive typhoon and large circulation. A dangerous situation is unfolding if it continues to crawl at a slow pace through landfall and progresses slowly over the Kagoshima prefecture. Precipitation amounts may lead to a historical event, unfortunately.

That theory could definitely hold weight, we see that all the time with storms that approach high elevation areas in the pacific. However this storm has been dealing with westerly shear to varying degrees for some days now, even when it was at its peak, and it seemed that once the central convection began to wane, likely due to upwelling and not getting the same interaction with ULL including the difluent flow over top and ventilation, the shear was able to really rip the western eyewall apart quickly. I’m not sure what the cause is but modeling consistently overestimates LF intensity in this region really unlike anywhere else that is frequently impacted by typhoons. I’d say that overall, landmasses in this area probably are not modeled correctly in terms of their impact on impeding cyclonic flow for high intensity storms. This one’s been fun to watch, another storm that spent most of its life in radar range. We’ve been spoiled by these this season 

[Windspeed]

That theory could definitely hold weight, we see that all the time with storms that approach high elevation areas in the pacific. However this storm has been dealing with westerly shear to varying degrees for some days now, even when it was at its peak, and it seemed that once the central convection began to wane, likely due to upwelling and not getting the same interaction with ULL including the difluent flow over top and ventilation, the shear was able to really rip the western eyewall apart quickly. I’m not sure what the cause is but modeling consistently overestimates LF intensity in this region really unlike anywhere else that is frequently impacted by typhoons. I’d say that overall, landmasses in this area probably are not modeled correctly in terms of their impact on impeding cyclonic flow for high intensity storms. This one’s been fun to watch, another storm that spent most of its life in radar range. We’ve been spoiled by these this season 

Yes, instead of one negative factor versus another (700-500 hPa shear versus downslopping), or slow motion and upwelling, it's more a combination of all factors weakening the typhoon too much convectively to sustain the higher-end TC modeling outputs from previous days. Interestingly, Shanshan did maintain a stable peak and large eye while in what was essentially a 24-to-36-hour stall in the Amami islands. It was not much of a surprise since that region of sea had a much deeper 26°C isotherm of over 100 meters.

[NorthHillsWx]

Though the storm degraded significantly before landfall, it still had a ferocious NE eyewall that unfortunately hit/is hitting a large swath of coastline. No doubt a large area seeing 100+ mph gusts. 

[NorthHillsWx]

Also- looks like Josh scored at least part of the eye. Given the layout of that coastline and variable forecast that’s a pretty impressive score for him

[gallopinggertie]

52 minutes ago, NorthHillsWx said:

Though the storm degraded significantly before landfall, it still had a ferocious NE eyewall that unfortunately hit/is hitting a large swath of coastline. No doubt a large area seeing 100+ mph gusts. 

The angle of approach combined with the slow speed doesn’t seem great. I saw there are some mandatory evacuations, and Toyota and Honda are closing their factories for the storm. Kumamoto is on a large bay, so hopefully storm surge isn’t an issue. 

[tamarack]

As of earlier this AM, some spots in southern Kyushu have received a half meter if rain, with some landslide fatalities, and totals over a meter are in play.  My son and his wife live in Nagoya, about 400 miles northeast from the downpours; they probably will get 2-4" if Shanshan ever decides to move.

[gallopinggertie]

Typhoon Yagi is poised to make landfall in southern China. JTWC has it around 135 mph before it crosses the Leizhou peninsula, then around 110 mph before landing in northern Vietnam. 

[olafminesaw]

Some of the wildest banding I've ever seen. Well on it's way to cat 5

[hlcater]

Beast emerging in the south china sea