EPAC: ILEANA - Remnants - Discussion

[wxman57]

Went to look at it on satellite this morning and see a convectionless swirl. Bye Ileana.

[cycloneye]

Tropical Storm Ileana Discussion Number 9
NWS National Hurricane Center Miami FL EP092024
800 AM MST Sat Sep 14 2024

Satellite imagery shows that Ileana is being affected by increasing
southwesterly shear. A large burst of convection that occurred in
the early morning hours has moved northeast of the exposed
low-level center, while new convection is forming to the north and
southeast of the center. The initial intensity is held at 35 kt
based on various satellite intensity estimates and earlier surface
data from Topolobampo, Mexico.

The initial motion is just east of due north or 010/6 kt. This
general motion should continue for the next 6 hours or so, bringing
the center near or over the coast of Mexico near Topolobampo and Los
Mochis today. After that, Ileana should begin a slow motion toward
the northwest over the Gulf of California roughly parallel to the
coast of Mexico, with this motion continuing until the system
dissipates. The new track forecast is nudged to the north and east
of the previous track and lies near the various consensus models.

Ileana is expected to weaken below tropical-storm strength later
today due to a combination of shear and land interaction. However,
before that happens, the cyclone should bring tropical storm
conditions to portions of the northern coast of Sinaloa and
southern coast of Sonora through this afternoon. The system is
expected to degenerate to a remnant low between 12-24 h, with the
remnant low dissipating over the central Gulf of California on
Monday.


Key Messages:

1. Tropical Storm Ileana will bring heavy rainfall to portions of
coastal Sinaloa, Mexico through this weekend. This heavy rainfall
will bring a risk of flash flooding and mudslides to portions of the
area.

2. Tropical storm conditions are expected within the warning area
of northern Sinaloa and southern Sonora through this afternoon.


FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 24.9N 108.9W 35 KT 40 MPH
12H 15/0000Z 25.6N 109.2W 30 KT 35 MPH...NEAR COAST
24H 15/1200Z 26.3N 109.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 16/0000Z 26.9N 110.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 16/1200Z 27.7N 111.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 17/0000Z...DISSIPATED

$$
Forecaster Beven

[Sciencerocks]

[cycloneye]

Tropical Storm Ileana Discussion Number 11
NWS National Hurricane Center Miami FL EP092024
800 PM MST Sat Sep 14 2024

Ileana has stalled near the coast of northwestern Mexico, offshore
of the state of Sinaloa. All of the deep convection has moved
inland, as indicated by both the radar and satellite imagery,
leaving the low-level circulation exposed. Surface observations
from Topolobampo and Los Mochis recently measured sustained winds of
39 kt, with higher gusts. Based on these data, the initial
intensity for this cycle is raised to 40 kt.

The storm is drifting with an uncertain motion of 360/1 kt. Ileana
is still expected to turn northwestward soon and gradually
accelerate, bringing the center across the northern coastal region
of Sinaloa during the next 12 h. By Sunday, the cyclone is forecast
to be near the coast of southern Sonora and stay roughly parallel to
the coast of Mexico over the Gulf of California until the system
dissipates. The new track forecast is again nudged to the north and
east of the previous track and lies near the various consensus
models.

Despite strong southwesterly vertical wind shear decoupling
Ileana's surface circulation from its deep convection, the surface
winds have yet to weaken. Global models indicated that deep
organized convection should not reform and therefore Ileana is
expected to become a post-tropical cyclone by Sunday. The system
should gradually weaken due to the interaction with land and
surrounding dry air and strong vertical wind shear. The official
forecast shows Ileana dissipating by late Monday, though some
numerical guidance suggests this could occur sooner.


Key Messages:

1. Tropical Storm Ileana will bring heavy rainfall to portions of
coastal Sinaloa, Mexico through this weekend. This heavy rainfall
will bring a risk of flash flooding and mudslides to portions of the
area.

2. Tropical storm conditions are expected within the warning area
of northern Sinaloa and southern Sonora through Sunday.


FORECAST POSITIONS AND MAX WINDS

INIT 15/0300Z 25.5N 109.0W 40 KT 45 MPH
12H 15/1200Z 25.7N 109.2W 35 KT 40 MPH...POST-TROPICAL
24H 16/0000Z 26.4N 109.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 16/1200Z 27.4N 110.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 17/0000Z...DISSIPATED

$$
Forecaster Bucci

[cycloneye]

Tropical Depression Ileana Discussion Number 12
NWS National Hurricane Center Miami FL EP092024
200 AM MST Sun Sep 15 2024

All of Ileana's deep convection dissipated yesterday afternoon, and
all that is left now is a swirl of low clouds off the coast of
northern Sinaloa. An ASCAT-C pass from 0410 UTC showed maximum
winds near 30 kt over the Gulf of California near northern Sinaloa,
and a weather station in Topolobampo is no longer reporting winds to
tropical storm force. As a result, Ileana is now designated as a
30-kt tropical depression, and all coastal warnings in Mexico have
been discontinued.

Ileana has been meandering, but the longer-term motion is
west-northwestward, or 300/2 kt. Model guidance indicates that the
cyclone should turn northwestward later today but maintain a
generally slow motion while moving over the Gulf of California.
Due to strong southwesterly shear and a very dry atmosphere, deep
convection is not expected to redevelop, and it's likely that
Gordon will be declared a remnant low later this morning. The
remnant low is expected to dissipate on Monday.


FORECAST POSITIONS AND MAX WINDS

INIT 15/0900Z 25.5N 109.3W 30 KT 35 MPH
12H 15/1800Z 25.8N 109.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 16/0600Z 26.5N 110.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 16/1800Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

Post-Tropical Cyclone Ileana Discussion Number 13
NWS National Hurricane Center Miami FL EP092024
800 AM MST Sun Sep 15 2024

Ileana has been devoid of deep convection since yesterday afternoon,
as the system has been within a strong wind shear and very dry
environment. Given the lack of convection, the system is being
designated as a post-tropical remnant low. An ASCAT-C pass from
late last night depicted winds near 30 kt over the Gulf of
California near northern Sinaloa. Given this, will hold the
intensity at 30 kt for this advisory, although that may be generous.

The system has been meandering over the Gulf of California with a
motion of 310/3 kt. The remnant low will increase forward speed
later today as it continues northwestward. The remnant low will
continue to weaken throughout the day, and is forecast to dissipate
on Monday.

This is the last advisory on this system. For additional
information on the remnant low please see High Seas Forecasts issued
by the National Weather Service, 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 15/1500Z 25.7N 109.6W 30 KT 35 MPH...POST-TROPICAL
12H 16/0000Z 26.1N 110.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 16/1200Z 27.3N 111.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 17/0000Z...DISSIPATED

$$
Forecaster Kelly