EPAC: KIKO - Hurricane - Discussion

[cycloneye]

Kiko has so far ACE of 27.0 and can add a lilltle bit more.

[tropicwatch]

It would be nice if Kiko came in closer to the islands. They could use the rain.

[cycloneye]

 https://x.com/MadrigalWxViz/status/1964868338066047088

[cycloneye]

BULLETIN
Hurricane Kiko Advisory Number 32
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
500 PM HST Sun Sep 07 2025

...KIKO REMAINS A CATEGORY 2 HURRICANE...
...EXPECTED TO PASS NORTH OF THE HAWAIIAN ISLANDS ON TUESDAY AND
WEDNESDAY...


SUMMARY OF 500 PM HST...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...18.9N 146.6W
ABOUT 555 MI...895 KM E OF HILO HAWAII
ABOUT 750 MI...1210 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...974 MB...28.77 INCHES


Hurricane Kiko Discussion Number 32
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
500 PM HST Sun Sep 07 2025

An Air Force Reserve Hurricane Hunter aircraft investigating Kiko
this afternoon measured a minimum central pressure of 974 mb and a
maximum flight-level wind of 103 kt. The satellite presentation has
held fairly steady since, though some deterioration of the southwest
quadrant has been noted as southwesterly shear of around 20 kt has
started to affect the cyclone. Recent aircraft fixes also suggest a
slight northeastward tilt of the vortex in response to the shear.
Subjective Dvorak estimates ranged from T4.5/77 kt at SAB and JTWC
to T5.0/90 kt at HFO, while objective estimates from UW-CIMSS were
between 77 and 88 kt. Based on a blend of these data and the modest
satellite changes, the initial intensity has been lowered to 90 kt
for this advisory.

The initial motion is northwestward, or 305/12 kt, with Kiko
remaining on the southwestern periphery of a mid-level ridge. Based
on this steering pattern, Kiko is expected to pass north of the
Hawaiian Islands on Tuesday and Wednesday, and the most reliable
track models remain in good agreement on this scenario. The official
forecast is nearly identical to the previous NHC forecast and
remains close to the consensus aids. Given the new forecast and
accounting for typical errors, there is currently less than a 10
percent chance of tropical-storm-force winds occurring at any
location in the Hawaiian Islands, and tropical storm watches are not
required or expected at this time.

Cooler waters and increasing shear supports additional weakening
during the next 12–24 hours, with Kiko likely to fall below
hurricane strength by late Monday or Monday night. The shear is
forecast to peak near 30–35 kt between 24 and 48 hours, which should
accelerate the weakening trend. If Kiko is able to withstand that
period, some moderation in the weakening rate is possible later in
the forecast as the cyclone moves over slightly warmer waters near
27 C while also accompanied by a decrease in vertical wind shear.
The current intensity forecast lies near the middle of the guidance
envelope.


Key Messages:

1. Kiko is forecast to pass north of the Hawaiian Islands on Tuesday
and Wednesday. While the risk of direct impacts on the islands
appears to be decreasing, interests there should continue to monitor
Kiko's progress and the latest forecast.

2. Swells generated by Kiko are expected to gradually build and are
forecast to peak along east-facing exposures of the Hawaiian Islands
late Monday through midweek, potentially producing life-threatening
surf and rip currents. Listen for later advisories and possible
warnings from the National Weather Service in Honolulu, Hawaii.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 18.9N 146.6W 90 KT 105 MPH
12H 08/1200Z 19.7N 148.1W 75 KT 85 MPH
24H 09/0000Z 20.9N 150.4W 65 KT 75 MPH
36H 09/1200Z 22.1N 152.9W 55 KT 65 MPH
48H 10/0000Z 23.3N 155.5W 50 KT 60 MPH
60H 10/1200Z 24.2N 158.1W 45 KT 50 MPH
72H 11/0000Z 25.2N 160.5W 40 KT 45 MPH
96H 12/0000Z 27.0N 165.0W 40 KT 45 MPH
120H 13/0000Z 28.6N 168.2W 35 KT 40 MPH

$$
Forecaster Gibbs (CPHC)

[cycloneye]

BULLETIN
Hurricane Kiko Advisory Number 33
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
1100 PM HST Sun Sep 07 2025

...KIKO WEAKENS SLIGHTLY BUT REMAINS A CATEGORY 2 HURRICANE...
...EXPECTED TO PASS NORTH OF THE HAWAIIAN ISLANDS ON TUESDAY AND
WEDNESDAY...


SUMMARY OF 1100 PM HST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.6N 147.6W
ABOUT 490 MI...785 KM E OF HILO HAWAII
ABOUT 675 MI...1090 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES





Hurricane Kiko Discussion Number 33
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
1100 PM HST Sun Sep 07 2025

An Air Force Reserve Hurricane Hunter aircraft investigating Kiko
this evening measured a minimum central pressure of 982 mb and a
maximum flight-level wind of 96 kt. These data indicate that Kiko
has continued to weaken, with satellite imagery showing the
low-level center near the southwestern edge of the deep convection
in response to about 25 to 30 kt of southwesterly shear. Based on a
blend of the aircraft data, satellite trends, and the various
intensity estimates, the initial intensity is set at a
possibly generous 85 kt.

The initial motion is northwestward, or 305/12 kt, with Kiko
remaining on the southwestern periphery of a mid-level ridge. This
steering pattern should keep the cyclone on a general
west-northwestward to northwestward trajectory through the next
couple of days. Kiko is expected to pass north of the Hawaiian
Islands on Tuesday and Wednesday, and the most reliable track models
remain in good agreement on this scenario. The official forecast is
essentially unchanged from the previous cycle and remains close to
the consensus aids. Based on the new forecast and accounting for
typical errors, there is currently less than a 10 percent chance of
tropical-storm-force winds occurring at any location on the Hawaiian
Islands, and tropical storm watches are not required or expected at
this time.

Kiko is expected to continue weakening at an accelerated rate during
the next 24 hours as southwesterly shear strengthens to 30–35 kt
while the cyclone remains over marginal sea surface temperatures.
Under these increasingly hostile conditions, the system should
weaken to tropical storm strength by late Monday. If Kiko is
able to withstand the peak shear period, some moderation in the
weakening rate is possible later in the forecast as it moves over
slightly warmer waters near 27 C and vertical wind shear decreases.
The current intensity forecast lies near the middle of the guidance
envelope.


Key Messages:

1. Kiko is forecast to pass north of the Hawaiian Islands on Tuesday
and Wednesday. While the risk of direct impacts on the islands
appears to be decreasing, interests there should continue to monitor
Kiko's progress and the latest forecast.

2. Swells generated by Kiko are expected to gradually build and are
forecast to peak along east-facing exposures of the Hawaiian Islands
late Monday through midweek, potentially producing life-threatening
surf and rip currents. Listen for later advisories and possible
warnings from the National Weather Service in Honolulu, Hawaii.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 19.6N 147.6W 85 KT 100 MPH
12H 08/1800Z 20.5N 149.2W 70 KT 80 MPH
24H 09/0600Z 21.7N 151.6W 55 KT 65 MPH
36H 09/1800Z 22.9N 154.1W 50 KT 60 MPH
48H 10/0600Z 23.9N 156.7W 45 KT 50 MPH
60H 10/1800Z 24.7N 159.1W 40 KT 45 MPH
72H 11/0600Z 25.3N 161.4W 40 KT 45 MPH
96H 12/0600Z 26.8N 165.2W 35 KT 40 MPH
120H 13/0600Z 28.8N 168.3W 30 KT 35 MPH

$$
Forecaster Gibbs (CPHC)

[Hayabusa]

Latest JMA 12Z restrengthens Kiko as it enters the WPAC

[cycloneye]

BULLETIN
Hurricane Kiko Advisory Number 34
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
500 AM HST Mon Sep 08 2025

...KIKO NOW A CATEGORY 1 HURRICANE...
...FORECAST TO PASS NORTH OF THE HAWAIIAN ISLANDS LATER THIS WEEK
BRINGING SURF AND RIP CURRENT IMPACTS TO PORTIONS OF THE ISLANDS...


SUMMARY OF 500 AM HST...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...20.3N 148.8W
ABOUT 410 MI...660 KM E OF HILO HAWAII
ABOUT 590 MI...950 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES




Hurricane Kiko Discussion Number 34
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
500 AM HST Mon Sep 08 2025

Before departing, the final Air Force Reserve Hurricane Hunter
aircraft fix into Kiko showed that the hurricane's structure
continues to degrade, with the dropsonde launched at 1104 UTC
showing increasing tilt with height between the surface center and
flight level center. Maximum flight level winds from earlier in the
mission were still 94 kt at 700 mb, but the structure has degraded
further since that time. In fact satellite-based intensity estimates
are much lower, and only support an intensity of 55 to 75 kt. The
initial intensity of Kiko this advisory is being lowered to 75 kt,
on the higher end of the satellite estimates, in deference to the
earlier recon data.

Kiko continues to move west-northwestward, with its estimated motion
at 300/13 kt. For the next 12-24 hours this motion should continue
as Kiko remains vertically deep, and is steered along the
southwestern periphery of a subtropical ridge. However, the
hurricane is quickly approaching a large deep-layer trough, which is
imparting significant southwesterly mid- to upper-level flow. At
this juncture, this flow is expected to significantly shear the
cyclone, making it more vertically shallow, and it will become
increasingly steered by the mid- to low-level flow which still has
an anticyclone to its north. Thus, the west-northwestward motion is
expected to continue beyond 24 hours too, and may even turn slightly
leftward in days 3-4. The track guidance remains is good agreement
on this scenario, and the latest NHC track forecast is very close
to the prior one, blending the reliable consensus aids HCCA and
TVCE with the Google Deep-Mind ensemble mean (GDMI). On the
forecast track, Kiko is expected to pass north of the Hawaiian
islands later this week and at this time no tropical storm watches
are necessary for the island chain.

The hurricane now appears to be feeling the effects of southwesterly
vertical wind shear, which is now above 25 kt and expected to
increase further over the next 24 hours. In addition, very dry air
as seen on GOES-18 water vapor imagery is located in that upshear
direction, and will likely be imported into Kiko's small inner core.
Thus, weakening is anticipated to continue, and Kiko will likely
weaken below hurricane intensity even as the cyclone starts to move
over warmer sea-surface temperatures in 24-48 hours. There is a
brief period where the shear weakens in 2-3 days before it increases
again out of the east. Given the latest guidance, it seems more
likely Kiko's structure will not allow the cyclone to recover much,
and slow weakening is still forecasted through the end of the
forecast period. The latest NHC intensity forecast is close to the
middle of the guidance envelope through the 5 day period.


Key Messages:

1. Kiko is forecast to pass north of the Hawaiian Islands on Tuesday
and Wednesday. While the risk of direct impacts on the islands
continues to decrease, interests there should continue to monitor
Kiko's progress and the latest forecast.

2. Swells generated by Kiko are expected to gradually build and are
forecast to peak along east-facing exposures of the Hawaiian Islands
late today through the middle of the week, potentially producing
life-threatening surf and rip currents. Listen to the latest updates
and potential High Surf Warnings issued from the National Weather
Service in Honolulu, Hawaii.


FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 20.3N 148.8W 75 KT 85 MPH
12H 09/0000Z 21.2N 150.5W 65 KT 75 MPH
24H 09/1200Z 22.4N 152.9W 55 KT 65 MPH
36H 10/0000Z 23.4N 155.6W 50 KT 60 MPH
48H 10/1200Z 24.3N 158.0W 45 KT 50 MPH
60H 11/0000Z 25.0N 160.4W 40 KT 45 MPH
72H 11/1200Z 25.9N 162.6W 40 KT 45 MPH
96H 12/1200Z 27.3N 166.4W 35 KT 40 MPH
120H 13/1200Z 29.1N 168.7W 35 KT 40 MPH

$$
Forecaster Papin/Shieh

[cycloneye]

BULLETIN
Hurricane Kiko Advisory Number 35
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
1100 AM HST Mon Sep 08 2025

...RECONNAISSANCE FINDS THAT KIKO REMAINS A CATEGORY ONE
HURRICANE...
...FORECAST TO PASS NORTH OF THE HAWAIIAN ISLANDS LATER THIS WEEK
BRINGING SURF AND RIP CURRENT IMPACTS TO PORTIONS OF THE ISLANDS...


SUMMARY OF 1100 AM HST...2100 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.0N 149.9W
ABOUT 350 MI...560 KM ENE OF HILO HAWAII
ABOUT 515 MI...830 KM E OF HONOLULU HAWAII
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES




Hurricane Kiko Discussion Number 35
NWS Central Pacific Hurricane Center Honolulu HI EP112025
Issued by NWS National Hurricane Center Miami FL
1100 AM HST Mon Sep 08 2025

The convective structure of Hurricane Kiko continues to degrade,
with IR satellite imagery depicting a gradual warming of cloud tops,
with convection become more ragged. Furthermore, a WSF-M microwave
pass at 1625 UTC showed the core of the circulation tilting with
height toward the north. The most recent Air Force Reserve Hurricane
Hunter aircraft observed maximum flight-level winds of 88 kt at 700
mb in the northeast quadrant, suggesting that Kiko has maintained
its intensity, despite the continued structural degradation.
Assuming a slightly lower than typical 0.85 reduction factor at 700
mb, the intensity for this advisory is maintained at 75 kt, which is
higher than both Dvorak and objective satellite intensity estimates.
The most recent aircraft pass through the northwest quadrant
indicated a strongly tilted vortex, with enhanced convection in the
downshear-left quadrant.

Kiko continues to move west-northwestward, with its estimated motion
at 305/13 kt. For the next 12-24 hours this motion should continue
as Kiko continues to be steered around the southwestern periphery of
a subtropical ridge. However, as Kiko continues to experience strong
southwesterly vertical wind shear, the vertical depth of the system
is expected to decrease, with the more shallow circulation becoming
subsequently steered by the low- to mid-level subtropical ridge to
the north. This evolution is forecast to result in a gradual
leftward turn but still west-northwestward as Kiko passes the
longitude of the Hawaiian islands. The track guidance remains in
good agreement, and the latest NHC track forecast is very close to
the prior forecast, remaining close to a blend of the HCCA and TVCE
consensus and Google Deep Mind ensemble mean (GDMI).

The strong southwesterly vertical wind shear above 25 kts is
expected to continue through 48 hours. Beyond that, SHIPS guidance
suggests a brief decrease in shear from 48 to 72 hours, after which
the shear increases again but shifting 180 degrees from
southwesterly to northeasterly. Dry air continues to surround the
circulation of Kiko, particularly upshear, which in light of the
current shear, will accelerate the ventilation of the core
convection. Weakening is forecast through the forecast period. The
latest NHC intensity forecast is close to the middle of the guidance
envelope through the 5 day period.


Key Messages:

1. Kiko is forecast to pass north of the Hawaiian Islands on Tuesday
and Wednesday. While the risk of direct impacts on the islands
continues to decrease, interests there should continue to monitor
Kiko's progress and the latest forecast.

2. Swells generated by Kiko are expected to gradually build and are
forecast to peak along east-facing exposures of the Hawaiian Islands
late today through the middle of the week, potentially producing
life-threatening surf and rip currents. Listen to the latest updates
and potential High Surf Warnings issued from the National Weather
Service in Honolulu, Hawaii.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 21.0N 149.9W 75 KT 85 MPH
12H 09/0600Z 21.8N 151.7W 60 KT 70 MPH
24H 09/1800Z 23.0N 154.2W 50 KT 60 MPH
36H 10/0600Z 23.9N 156.7W 45 KT 50 MPH
48H 10/1800Z 24.8N 159.4W 45 KT 50 MPH
60H 11/0600Z 25.5N 161.6W 45 KT 50 MPH
72H 11/1800Z 26.1N 163.8W 40 KT 45 MPH
96H 12/1800Z 27.5N 167.6W 35 KT 40 MPH
120H 13/1800Z 29.5N 169.5W 30 KT 35 MPH

$$
Forecaster Shieh/Papin