The system originated from a tropical wave which entered the basin on late August, tracking westward into the open waters of the Eastern Pacific. By August 29th, the disturbance would begin showing signs of organization, and the next day, it would acquire a look more reminiscent of a tropical cyclone. By the last day of August, NHC classified the disturbance as 11E, which was then promptly named Kiko the next advisory.

Models were quite bullish with Kiko - some members bringing it up to major status on the SSHWS from initialization as a marginal tropical storm, which is quite uncommon, even for hurricane models, and this trend was reflected in the NHC forecast, which even from the first advisory forecasted a solid category 2 storm.

The storm would be initially characterized by a prominent curved band west of the circulation, but deep convection would become more centralized as the day progressed. An ASCAT pass early in Kiko’s life showcased the spiral band structure to the west of its center, which at the time harbored the strongest winds found in the system. During this time, the LLC was somewhat disorganized, and the circulation was not fully closed, which is to be expected with a dominant band structure in a dry environment which disturbed the low level center with outflow boundaries and weak westerly shear.

Worth noting is how high the chances for RI were as poised by the SHIPS model, which predicted a 45% chance for a 55 knot windspeed increase in the span pf 48 hours.

On September 1st the storm would continue organizing at a steady pace, mixing out a dry intrusion and becoming more axis-symmetric. During this time concerns began to arise about the dry air surrounding the storm becoming entrained into Kiko’s core, which in the coming hours would indeed occur.

Around mid-day on the first, the system would be sampled by a satellite which produced microwave images of the storm’s core, in which a core was evidently in the process of forming. A spiral band curled around a nascent eye, poising Kiko for it’s upcoming first peak. First, however, the storm had to deal with the dry air intrusion.

During the afternoon and evening, the aforementioned dry intrusion into the storm’s core did indeed occur, causing Kiko to take on quite a curious satellite appearance. In the community, we refer to this as “shrimping out” due to the resemblance to a fried shrimp of storms which undergo this colloquial process.

What does this mean for the storm though? A core is building, and intensification is soon likely, assuming that the cyclone’s rate of intensification can outrun the dry air choking it from one side and form a moisture bubble. This was the case in Kiko, as the storm managed to fully wrap around with deep, moist convection and closed itself off from dry air enveloping it.

Kiko would strengthen into a hurricane by the next morning, briefly clearing out an eye before an uptick in wind shear made Kiko’s structure lopsided. Non the less, despite a somewhat failed attempt at forming an eye, the storm was looking healthy, and SAR wind profiles did indeed showcase a drastic increase in windspeeds in a mere 24 hours.

Kiko was forecast to remain a solid hurricane, even peaking at major status around midweek, however later in its life cooler sea surface temperatures were expected to weaken the storm quite quickly.

Later in the day, Kiko would make a solid attempt at clearing an eye, which would persist throughout the night. VHTs concentrated in the SE quadrant of the storm, briefly obscuring the eye, however the core would eventually stabilize, allowing for Kiko to intensify into a category 2 storm. Microwave imagery also showcased that the storm had formed a very solid core, another sign of its intensification.

On the evening of the 2nd, the hurricane had attained quite the satellite appearance, looking formidable despite being unusually small in size, mainly due to dry air enveloping the storm not allowing for the formation of many rain bands. This, coupled with axis-symmetric structure and a nascent eye let Kiko strike quite the look.

Despite this, the storm would encounter an environment of higher shear which in turn lead to a weakening period early on the 3rd.

As I mentioned prior, after trying to form an eye the storm encountered some mid level shear, which lead to the eye collapsing and CDO becoming lopsided. Microwave imagery also showed that Kiko’s core structure had eroded on the northern side, and was generally less organized than prior. This brief hiccup would not stop the hurricane for long though, as its first and strongest peak was quickly approaching.

On September 3rd, Kiko had rapidly intensified into a major hurricane, reaching its first peak intensity of 125kt, tying Erick as strongest hurricane of the season by windspeed. Kiko cleared a decently warm eye with a quite cold, well defined CDO. The storm became very symmetric in all quadrants, with satellite estimates ranging from a medium category 3 to a medium category 4, with the upper estimates being deemed more in tune with the reality of the situation.

The hurricane was stunning on satellite imagery, which became a trend for the rest of its life, especially at its peaks in intensity.

During the entire period of its rapid intensification, Kiko exhibited eyewall lightning - a phenomena reserved for upper echelon strengthening, indicative of extreme upward movement in the eyewall.

This peak would not last long, as early on the 4th of September shear would take toll once more, causing the eye to fill temporarily and convection to get stuck again. This hiccup wouldn’t last for long of course, as Kiko was proving to be extremely resilient.

Microwave imagery once again showed that the core had become eroded from the north - a trend that would become more apparent as time went on, shear was mainly striking Kiko from the north. This, in turn, would cause the system to focus its convective activity in the southeast quadrant where it would curl over the eastern eyewall before weakening.

Interestingly enough, the storm was forecast to become steadily weakening with no further peaks as seen in model data. Why is that, seeing how the storm peaked 3 more times?

• Models struggle with low sea surface temperatures
• Models have issues with analyzing weakly sheared, strong storms which exhibit a strong PV+ anomaly, weakening them much faster than in reality
• Kiko had a very stable inner core and some annular features - elements which make storms more resilient and weaken slower.

All of this taken into consideration, the storm was still forecast to weaken, and its upcoming peaks exceeded expectations.

A pause from the struggle occurred as Kiko’s eye reemerged on satellite imagery, sustaining itself and even strengthening once more as a category 4, arguably as its second peak (although still weaker than the 1st peak.) What’s interesting is that the storm looked mostly the same as during its first peak, becoming somewhat of a Deja Vu of what happened the previous day.

We were now deep in the highly scientific KikoCycle. What’s that, you may ask? Well, it’s basically Kiko strengthening against all reason, looking gorgeous for a few hours, then rapidly weakening due to a blast of northerly shear. It’s quite interesting how despite the storm being fully isolated with dry air all around, the main issue was shear, not entrainment.

The storm once again repeated what happened the day before and weakened quickly as its eye collapsed, convection became asymmetric to the east and generally disorganized. As usual with Kiko, this weakening trend did not last long, and soon enough the system began recovering.

By the first hours of September 5th, Kiko’s overall appearance once again began recovering, strong CBs would begin rotating rapidly around the core, and the eye began clearing for the third time. The CDO maintained its cold temperature, and outflow increased, clear signs of intensification.

Once Kiko organized properly, the storm had an absolutely stunning satellite appearance - a well defined warm eye, a very cold CDO covered in spikey transverse cirrus bands. You can find more imagery down in the gallery section, as it is hard to not overfill this article with how gorgeous this storm was :)

The storm at this time also once again exceeded expectations, intensifying much more than models had expected. Most models has the storm weakening to a category 2 if not lower, while in reality it became a category 4 for the 2nd time (2nd peak was still C4 from the first peak!)

As the sun went down on the 6th of September, Kiko showed clear signs of weakening. The CDO degraded, thinning out dramatically in the northern quadrants while the eye became more wobbly. This was once again due to northerly shear as evident in how the asymmetry developed, starting on the northern edge of the storm.

In spite of the weakening, the eye remained unusually warm around 15C, as well as quite dry, seemingly uncaring of the degrading eyewall around it. This weakening was not as drastic as the previous times Kiko struggled, mainly due to the pre-existing PV+ anomaly and stability of the core, as well as a much more stable structure broadly thanks to its annular features.

Late on September 6th, Kiko unexpectedly rebounded drastically, the CDO vastly thickened as deeper convection smoothly wrapped around the eye. CPHC issued two TCUs to catch up to Kiko’s sudden intensification, re-upgrading Kiko to a category 4 hurricane, marking its fourth, and final peak.

The storm met sunset as a stunning, powerful hurricane while entering cooler waters. The storm looked quite unusual for a category 4 - the CDO was extremely smooth, yet somewhat warm, harboring temperatures around -70C, whilst most category 4 storms hover around -80C. The eye was also of note, as it was as stable as the strongest systems recorded, noting satellite temperature readings of up to 18C.

Breaking the KikoCycle, the storm did not begin rapidly weakening after reaching its 4th peak, instead weakening at a veeeery slow pace, its CDO shrinking and warming over the course of many hours.

Worth noting is that this fourth peak was occurring over pretty cool waters - averaging around 25C while Emanuel’s MPI (Maximum potential intensity) hovered around 80kt/975mb. Needless to say, this storm was an absolute anomaly in all the best ways, staying out to sea while remaining incredibly beautiful on satellite imagery. An aberration, which we all had the pleasure of tracking.

Recon missions began that same night (early on the 7th), and despite a more anemic appearance, aircraft data showed Kiko resiliently sustained itself as a major over sub-26°C waters. The aircraft reported a central pressure of 959 millibars and flight level winds of 115 knots in the north west quadrant of the system, placing it as a category 3 storm.

This unusually slow weakening trend would continue throughout the coming day or two, with the extremely warm and dry eye finally faltering as cold waters took its toll on the system.

Kiko slowly faltered while traversing the cold waters of the Central Pacific, eventually encountering an increasingly hostile environment. Non the less, when recon sampled the storm later on the 7th it was still a solid category 2 hurricane, albeit weakening more drastically now, mainly due to a dry air intrusion into the western eyewall.

This time, the weakening was terminal, and subsequent passes into Kiko showed it increasingly weaker and weaker. This time however, it was southerly shear, which coupled with cool seas below killed the hurricane. Maybe Kiko was just vaccinated against northerly shear, and this new variant knocked it off its legs.

Recon found that the storm had weakened drastically in its southern quadrant, barely holding tropical storm force winds, while its northern side was a solid category 1 hurricane.

Kiko passed its last two days as a sheared, moribund tropical cyclone. A strong, well modeled convective burst would attempt and briefly succeed at covering the low level circulation, however this CB would soon get heavily sheared as well. On September 10th, Kiko finally succumbed to the surrounding environment, degenerating into a remnant low over the anomalously warm waters of the Central Pacific subtropics.

A very noteworthy aspect of Kiko, which says a lot considering how deeply unusual this storm had been, was its tiny size. Attached below are examples of how tiny the storm was, all to scale.

Gallery of valuable data, imagery and extra stuff.#

Sorry for not much stuff here folks, this article was a beast to write and I am TIRED, haha.