EPAC: KRISTY - Remnants - Discussion

[cycloneye]

Hurricane Kristy Discussion Number 19
NWS National Hurricane Center Miami FL EP122024
200 AM PDT Sat Oct 26 2024

Kristy continues to weaken this morning. While the hurricane is
still producing an area of fairly deep convection, this convection
is becoming stretched poleward as south-southwesterly vertical wind
shear steadily increases over the tropical cyclone. Subjective
Dvorak estimates are constrained from decreasing faster this
morning, but taking a blend of subjective and objective intensity
estimates yields an intensity of 85 kt for this advisory. The shear
diagnosed by SHIPS guidance and UW-CIMSS analysis is now up to 30
kt, and is forecast to increase above 40 kt in 24 h. In addition,
Kristy is now crossing the 26 C isotherm and heading for even cooler
ocean waters. This combination should continue to result in rapid
weakening, with the hurricane likely to vertically decouple later
today. The NHC intensity forecast continues to blend the previous
forecast with the latest consensus aids, showing Kristy weakening
below hurricane intensity by this evening. Remnant low status is
likely not far behind on Sunday as the cyclone ceases to produce
organized deep convection, as depicted by both global and
regional-hurricane models. The remnant low low should finally open
up into a trough on Monday.

The hurricane has maintained a northwestward motion this morning at
320/13 kt. While the prominent subtropical mid-level ridge over Baja
California steering Kristy should remain in place, the tropical
cyclone's vertically deep vortex will likely decouple over the next
24 h. This decoupling will result in the mid-level vortex leaving
behind Kristy's surface circulation, which should quickly slow down
and turn westward as it becomes primarily influenced by strong
low-level ridging to its north. The track guidance continues to be
in relative good agreement with the prior forecast track, and only
minor adjustments were made from the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 18.7N 127.6W 85 KT 100 MPH
12H 26/1800Z 20.0N 128.5W 65 KT 75 MPH
24H 27/0600Z 21.8N 129.5W 45 KT 50 MPH
36H 27/1800Z 22.6N 130.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 28/0600Z 22.4N 131.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 28/1800Z...DISSIPATED

$$
Forecaster Papin

[cycloneye]

Hurricane Kristy Discussion Number 20
NWS National Hurricane Center Miami FL EP122024
800 AM PDT Sat Oct 26 2024

Kristy is rapidly weakening. Satellite images show the center of
the hurricane on the southern edge of the central dense overcast,
with the southern part of the circulation exposed due to strong
shear. The current intensity is set to 65 kt, consistent with
the latest estimates. Further rapid weakening is anticipated due
to a continuation of strong shear and Kristy moving over cooler
waters. The new intensity forecast is reduced from the previous
one, similar to the intensity consensus aids. Kristy should
become post-tropical without any organized convection in about 24 h.

The hurricane continues to move northwestward at about 12 kt
this morning. This general motion is expected until late today
when the mid-level circulation of the cyclone becomes decoupled
with the low-level center. Kristy should then turn westward on
Sunday and southwestward late that day as a remnant low. Very
little change was made to the previous forecast, which remains
steady in showing this course.


FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 19.7N 128.4W 65 KT 75 MPH
12H 27/0000Z 21.1N 129.2W 50 KT 60 MPH
24H 27/1200Z 22.3N 130.0W 35 KT 40 MPH...POST-TROPICAL
36H 28/0000Z 22.5N 131.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 28/1200Z 21.9N 132.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 29/0000Z...DISSIPATED

$$
Forecaster Blake

[cycloneye]

Tropical Storm Kristy Discussion Number 21
NWS National Hurricane Center Miami FL EP122024
200 PM PDT Sat Oct 26 2024

The cloud pattern of Kristy continues to decay, with the low-level
center now exposed to the south of what remains of the mid-level
circulation due to strong shear. The current intensity is set to 55
kt using a blend of the most recent Dvorak estimates. A
continuation of this shear along with cool water temps should
lead to further weakening, and Kristy is forecast to become a
remnant low early on Sunday. The new intensity forecast is similar
to the previous one and the latest consensus aids.

The storm continues to move northwestward at about 12 kt. Kristy
should turn more westward overnight as the circulation becomes more
vertically shallow and steered by a low-level ridge. Other than
a small westward adjustment, little change was made to the NHC
track forecast, and the new prediction lies just west of the
consensus guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 20.7N 129.2W 55 KT 65 MPH
12H 27/0600Z 21.7N 129.9W 45 KT 50 MPH
24H 27/1800Z 22.3N 130.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 28/0600Z 22.0N 132.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 28/1800Z...DISSIPATED

$$
Forecaster Blake

[cycloneye]

Tropical Storm Kristy Discussion Number 22
NWS National Hurricane Center Miami FL EP122024
800 PM PDT Sat Oct 26 2024

Kristy's low-level cloud field is starting to lose some definition,
but there has still been bursting of deep convection to the north of
the center. Dvorak CI numbers of 3.5 from TAFB and 3.0 from SAB,
combined with objective satellite estimates, support a current
intensity of 50 kt. Due to the expected continuation of very strong
southerly shear, as well as sea surface temperatures of 23-24
degrees Celsius, Kristy is forecast to weaken below tropical storm
strength and become a remnant low during the day on Sunday. Model
fields show the circulation opening up into a trough by 36 hours,
and that is when dissipation is now shown.

Kristy has turned north-northwestward and slowed down further
(330/10 kt). However, now that the circulation is becoming
increasingly shallow, low-level ridging to the north will cause the
cyclone to turn back toward the northwest and west tonight and on
Sunday before it dissipates.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 21.5N 129.5W 50 KT 60 MPH
12H 27/1200Z 22.2N 130.1W 35 KT 40 MPH
24H 28/0000Z 22.3N 131.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 28/1200Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

The end is here but she reached cat 5.

Post-Tropical Cyclone Kristy Discussion Number 24
NWS National Hurricane Center Miami FL EP122024
800 AM PDT Sun Oct 27 2024

Very strong southwesterly vertical wind shear, dry air entrainment,
and cool waters have taken a toll on Kristy. The storm has lacked
organized deep convection since about 03Z, and it has generally
consisted of a low-level cloud swirl since that time. Therefore,
Kristy no longer meets the criteria of a tropical cyclone, and this
is the last advisory on this system. The initial wind speed is
lowered to 40 kt, assuming some decrease in winds from the ASCAT
pass overnight that showed maximum winds close to 50 kt.

The gale-force low is still moving north-northwestward at about 7
kt, but it is expected to turn to the west and west-southwest later
today and Monday when it moves in the low-level flow. The
post-tropical cyclone is also expected to continue to weaken and
dissipate completely on Monday.

This is the last NHC advisory on Kristy. For more details on this
system, including gale warnings, see High Seas Forecasts issued by
the National Weather Service. This information can be found under
AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at
ocean.weather.gov/shtml/NFDHSFEPI.php


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 22.6N 129.8W 40 KT 45 MPH...POST-TROPICAL
12H 28/0000Z 22.7N 130.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 28/1200Z 22.2N 131.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 29/0000Z...DISSIPATED

$$
Forecaster Cangialosi

[Kingarabian]

Was a nice storm. Till next time.