Neoguri has a highly unusual origin. Forming due to the convective activity below a cut off TUTT, eventually turning into a cutoff low. In fact, it was the same cut-off TUTT cell that was the death of Hurricane Kiko earlier in the month! As the cutoff low proceeded westward, convective activity slowly increased, and the system gained the moniker 91W.

On September 17th the storm became more compact as outflow organized further, and convective activity increased as evident by the cooling cloud tops. Around mid-day on the 18th, the storm was looking even better, and thus it received the name Neoguri from JMA.

The system had became quite isolated due to its nature as an ULL-origin storm, and once a low level core got going, outflow expanded radially from the storm’s center, which looked particularly pleasing to the eye on infrared satellite image loops.

Original forecasts from JTWC were quite low intensity wise, as there was a lot of spread in model output as to how strong the storm would get, however it quickly became evident due to the storm’s high degree of organization, as well as ample outflow that Neoguri would become quite a strong system.

Early on the 19th of September, Neoguri began quickly intensifying. Microwave imagery revealed that the system began building a low and mid level core. Satellite image loops showed that the storm was organizing further, as convective coverage increased and rotational motion became much more apparent.

Official forecasts quickly jumped in forecast intensity, as JTWC upped its peak from 80kt to 115kt within one advisory. Neoguri was poised for rapid intensification, which ended up being even stronger than originally predicted.

A very big question regarding Neoguri’s future was whether the storm would recurve or not. As the storm drifted north west, a small trough would approach from the west, and depending on its position relative to Neoguri, it would swing it northeast, or, in a less likely scenario, not manage to “grab” the storm and have it recurve south west as a ridge built over Japan.

In reality, neither of these scenarios played out. The storm did recurve southwest somewhat, however the ridge didn’t push it over far enough where the next trough wouldn’t sweep it up, causing the typhoon to do a little loop before the 2nd trough slingshot it towards Alaska.

In the case of a recurve, Neoguri would have entered a sublime environment, likely strengthening more than its first peak, and possibly impacting Japan - as interesting as it would have been if it had occurred, it’s for the better that Neoguri remained a fish storm.

Later on the 19th, Neoguri made began clearing an eye. As vortical hot towers began rapidly curling around the storm’s core, subsidence increased in the center. This did not succeed in the short term, however as larger, less organized CBs covered the nascent eye feature, although this issue would not last long. We’re proud of you Neoguri!

Worthy of note, at this time a satellite produced a microwave image of Neoguri’s core, indicating that the system was quite healthy under the hood - something all western pacific Weenies knew would come in 2025, although we had to wait for it for quite some time.

Strengthening of Neoguri continued into the 20th as the large CBs blocking its eye finally organized into localized VHTs (Vortical hot towers). The eye eventually cleared enough for positive temps to show up on the floater, all the while becoming drier.

Despite Neoguri being an average sized tropical cyclone, both in terms of CDO and eye size, it was dwarfed by the massive typhoon Ragasa farther southwest, which is especially evident in basin-wide imagery.

This was not the end of the road for Neoguri of course, as the system continued strengthening throughout the day, with the eye becoming more and more stable as the CDO organized into a smoother shape around it.

Microwave passes from near noon on the 20th show that the storm had developed a VERY healthy core, with a thick ring of red on the color89 pass - indicative of a healthy eyewall.

Neoguri was now approaching peak intensity, however there is still lots to cover. At this point, Neoguri’s eye was as stable as it gets in this business, central dense overcast becoming more and more axis-symmetric, and eye was still drying - all of the core signs that signal that you’ve got an extremely strong TC on your hands.

Satellite data analysis was quickly approaching category 4 levels, however subjective analysis showed that the typhoon may have been approaching T7.0 already - the Dvorak threshold for a category 5 storm.

The typhoon, our beloved Neoguri peaked around 18z-19z on the 20th of September. What characteristics did Neoguri poses at the time, that made it so powerful, as well as beautiful on satellite imagery?

• Entirely clear eye
• 20C temp stable in the eye
• Cold, symmetric CDO
• Radial outflow
• Pretty dry (-20C) eye
• Isolation from other mesoscale features around it.

Needless to say, Neoguri was a beast, however its peak was soon coming to an end.

Very soon after Neoguri peaked, signs of weakening began to show through the cracks. The mechanism by which the typhoon’s peak came to an end was not shear or dry air, but rather a mix of them combined with an eyewall replacement cycle.

The CDO began to falter as warmer temps creeped up. On top of that, the eye began to softly wobble - common signs of an approaching EWRC. As the day progressed these features continued to become more pronounced, and eventually due to a weakness in the storm’s core, a dry air intrusion formed a dry slot on the eastern side. Not looking good for Neoguri!

The weakening trend continued further as the EWRC fully set in. Eventually, the dry slot became more of a moat between the two eyewalls, and the eye began to wobble troichodally.

While Neoguri falters in the back, let’s talk about its intensification. JTWC, sadly, as usual, did a pretty poor job forecasting this storm, keeping it weaker than it actually was for most of its life, as well as forecasting a weaker peak than expected and even lowering their peak substantially while the storm was beginning RI. The graph below shows model forecasts for Neoguri, as well as its (likely) maximum intensity.

The following day was rough for the typhoon. The eye fully collapsed, CDO became disorganized, and on top of that I’ve heard reports that Neoguri dropped its ice cream cone. Sad!

Not much changed for the following 2 days, so I won’t ramble on about it as it is simply put quite uninteresting. Non the less, this was soon going to change.

The following 3 days were much of the same: periods of brief strengthening, followed by convective collapse, only to become more compact and fire another CB. At one point, the storm even attempted to form an eye as it conserved a low level core, however this did not last long.

Honestly? We all thought Neoguri was cooked and just stuck in purgatory at this point, waiting for the next trough to sweep it up and slingshot it to Alaska. Oh how wrong we were…

The 27th of September was Neoguri’s big comeback. It began when the storm’s outflow got fully connected with the jet stream to its north, and began accelerating northeast. Due to the storm’s small size, and pre-existing LLC, Neoguri was able to quickly take advantage of the increased upper level divergence and rebuild its CDO.

Thanks to the dry air surrounding the storm, as well as its pre existing PV+ anomaly, the storm entrained some drier air into its core, which quickly became surrounded by deep moist convection, allowing for the formation of a nascent eye.

As the eye began to clear and warm, outflow raced northward due to the jet interaction. Neoguri was in the process of rapidly intensifying at 35N, a feat almost never achieved by any prior tropical cyclone, once again proving how unique and unusual Neoguri was.

As the eye crept into positive temps, and quickly afterwards into the teens, it was evident that Neoguri became a major equivalent typhoon, with the JTWC supporting that claim.

Worth noting that the typhoon was achieving this while being at a similar latitude to the Mediterranean sea or Rome. The storm well and truly rapidly intensified, as evident in the Dvorak analysis.

Sadly, this absolutely gorgeous and anomalous peak did not last long. After about 15 hours of looking like a gorgeous donut, the storm’s CDO began to falter, eventually succumbing to the dry air being forced into its core, as well as extremely high wind shear.

Non the less, Neoguri maintained itself for a bit more, before finally becoming extratropical early on the 29th of September.

The 2nd peak of Neoguri was truly anomalous, and a great example of climate change driven weather-weirdness. Were it not for the extremely high sea surface temperature anomaly in the northern Pacific, Neoguri would have likely not intensified - a testament to our changing climate.

On a final note, it is worth mentioning that Neoguri was one of the very few storms which were sampled by JMA’s recon aircrafts, netting us readings of a MSLP of 920mb. Very cool stuff!

Gallery of valuable data, imagery and extra stuff.#