ATL: LESLIE - Advisories

[cycloneye]

BULLETIN
Tropical Depression Thirteen Advisory Number 1
NWS National Hurricane Center Miami FL AL132024
200 PM CVT Wed Oct 02 2024

...NEW TROPICAL DEPRESSION FORMS IN THE FAR EASTERN TROPICAL
ATLANTIC...
...COULD BECOME A HURRICANE BY THIS WEEKEND...


SUMMARY OF 200 PM CVT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...10.6N 29.1W
ABOUT 430 MI...690 KM SW OF THE SOUTHERNMOST CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


Tropical Depression Thirteen Discussion Number 1
NWS National Hurricane Center Miami FL AL132024
200 PM CVT Wed Oct 02 2024

The system we have been monitoring several hundred miles to the
southwest of the southernmost Cabo Verde Islands has become
gradually better organized this morning with some curved bands
organizing to the west of the estimated center. Visible satellite
images show that at least a broad closed circulation has developed.
Based on the latest subjective Dvorak fixes of T2.5/35-kt from TAFB
and T1.5/25-kt from SAB, advisories are being initiated on Tropical
Depression Thirteen, with an initial intensity in between these
estimates at 30 kt.

The depressions initial motion appears to be slowly due west, at
270/6 kt. Over the next day or two this motion should continue,
though some of the track guidance actually shows a south of due west
motion, partially related to the steering flow and also the
possibility that the center might try to reform underneath deep
convective bursts in the southern semicircle. After 48 h, the
guidance shows TD13 turning west-northwestward and then
northwestward by the end of the forecast as mid-level ridging
becomes more eroded on its northwestern side while a large long-wave
trough becomes established over the Northwest Atlantic. The initial
NHC track forecast has opted to favor a track close to the consensus
aid TVCN. Interestingly, both the GFS and ECMWF are on the east side
of the guidance, while HCCA is on the western side by the end of the
forecast period.

Intensity wise, initial strengthening could be on the slower end, as
the system has to deal with some northwesterly shear related of the
outflow from the much larger Hurricane Kirk impinging upon the
system. However, the guidance insists this shear will soon decrease,
especially after 24-36 h where the upper-level flow seems to split
off into a cutoff low to the southwest, and a upper-level trough
that shifts east of the depression, leaving the depression in a more
favorable upper-level diffluent pattern. After TD13's inner core
become better defined, the rate of intensification could increase
after 36 h, and the latest NHC intensity forecast forecasts the
depression to become a hurricane in 3 days. Additional
intensification is forecast after that point as long as the cyclone
tracks far enough away from the cold ocean wake left behind by Kirk.
This forecast is roughly in the mean of the intensity guidance
envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 02/1500Z 10.6N 29.1W 30 KT 35 MPH
12H 03/0000Z 10.5N 29.8W 35 KT 40 MPH
24H 03/1200Z 10.2N 30.8W 40 KT 45 MPH
36H 04/0000Z 10.2N 31.9W 45 KT 50 MPH
48H 04/1200Z 10.4N 33.3W 55 KT 65 MPH
60H 05/0000Z 11.0N 34.6W 60 KT 70 MPH
72H 05/1200Z 11.7N 35.8W 65 KT 75 MPH
96H 06/1200Z 13.5N 38.1W 75 KT 85 MPH
120H 07/1200Z 16.5N 41.0W 80 KT 90 MPH

$$
Forecaster Papin

[cycloneye]

BULLETIN
Tropical Depression Thirteen Advisory Number 2
NWS National Hurricane Center Miami FL AL132024
800 PM CVT Wed Oct 02 2024

...TROPICAL DEPRESSION THIRTEEN COULD BECOME A HURRICANE
IN A COUPLE OF DAYS...


SUMMARY OF 800 PM CVT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...10.5N 29.7W
ABOUT 465 MI...745 KM SW OF THE SOUTHERNMOST CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 260 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES[




Tropical Depression Thirteen Discussion Number 2
NWS National Hurricane Center Miami FL AL132024
800 PM CVT Wed Oct 02 2024

Tropical Depression Thirteen has become a little better organized
since the last advisory, with improving circulation definition and
convection continuing to curve cyclonically in a banded fashion on
its western side. However, Dvorak intensity estimates have not
changed much this afternoon, still at T2.5/35-kt from TAFB and
T1.5/25-kt from SAB, so the initial intensity will remain 30 kt.

The depression appears to be moving just south of due west following
along from previous fixes with a current estimated motion at 260/7
kt. This motion has resulted in a slight southward track shift from
the previous forecast but remains close to the consensus aid TVCN.
This motion should continue over the next day or so guided by a
steering ridge to the north and enhanced convection along the
southern semicircle potentially pulling it southward as the
depression organizes. Track guidance then shows TD13 turning
west-northwestward after 48 hours and ultimately northwestward
towards the end of the forecast period as the ridge steering becomes
more eroded on its western side. The track guidance was very
similar to the previous cycle, albeit a touch further south in 5
days, and the latest NHC track has been nudged a bit further south
towards the end of the forecast.

The forecast for this cycle shows a somewhat faster intensification
rate than the prior advisory, with the system now becoming a
hurricane in 48 hours, and peaking at 80 kt in 72 hours, due to
decreasing shear and plenty of warm ocean waters and moisture early
on in the forecast. The intensity guidance then proceeds to show the
intensity plateauing after 72 hours as the system could encounter
the edge of Hurricane Kirk's large area of ocean upwelling. Both
HAFS-A/B show this potentially limiting the intensity in the longer
term, but the NHC intensity forecast could be conservative if TD13
ends up tracking further south than forecasted.


FORECAST POSITIONS AND MAX WINDS

INIT 02/2100Z 10.5N 29.7W 30 KT 35 MPH
12H 03/0600Z 10.2N 30.3W 35 KT 40 MPH
24H 03/1800Z 10.1N 31.3W 45 KT 50 MPH
36H 04/0600Z 10.2N 32.5W 55 KT 65 MPH
48H 04/1800Z 10.6N 33.8W 65 KT 75 MPH
60H 05/0600Z 11.1N 35.1W 75 KT 85 MPH
72H 05/1800Z 11.8N 36.4W 80 KT 90 MPH
96H 06/1800Z 13.8N 38.8W 80 KT 90 MPH
120H 07/1800Z 16.5N 42.0W 80 KT 90 MPH

$$
Forecaster Torres-Vazquez/Papin

[cycloneye]

BULLETIN
Tropical Storm Leslie Advisory Number 3
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Wed Oct 02 2024

...LESLIE FORMS OVER THE TROPICAL EASTERN ATLANTIC...
...EXPECTED TO BECOME A HURRICANE IN A COUPLE OF DAYS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...10.4N 30.1W
ABOUT 490 MI...790 KM SW OF THE SOUTHERNMOST CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 265 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES




Tropical Storm Leslie Discussion Number 3
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Wed Oct 02 2024

Geostationary satellite and microwave images indicate that the
system has become better organized with convective bands wrapping
about two-thirds of the way around the center. A partial ASCAT pass
from around 2230 UTC showed winds very close to tropical storm
force northeast of the center. Since the system has continued to
become organized since the ASCAT pass, the initial intensity is
increased to 35 kt, making the cyclone Tropical Storm Leslie.
This intensity estimate is also in agreement with a 2.5 Dvorak
classification from TAFB.

Leslie is moving slowly to the west at about 5 kt. A continued slow
westward to west-northwestward motion is expected during the next 2
to 3 days as Leslie remains steered by a weak mid-level ridge to its
north. Beyond that time, a slightly faster motion to the northwest
is predicted as the storm moves on the western periphery of the
ridge and approaches a broad trough over the central Atlantic. The
models are in fair agreement overall, and the NHC track forecast
lies near the middle of the guidance envelope.

Leslie is currently in a moderate wind shear environment due to the
outflow from major Hurricane Kirk to its northwest. However, the
shear is expected to lessen while Leslie remains over warm waters
and in a moist environment. These condition should support steady
strengthening during the next few days, and the official intensity
forecast is a little higher than the previous one. Beyond a few
days, Leslie is predicted to move over Kirk's prior track and
associated cool wake, and into a slightly drier air mass. These
conditions could cause the intensity to level off. The new
forecast is in best agreement with the latest HCCA guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0300Z 10.4N 30.1W 35 KT 40 MPH
12H 03/1200Z 10.2N 30.8W 40 KT 45 MPH
24H 04/0000Z 10.2N 31.9W 50 KT 60 MPH
36H 04/1200Z 10.4N 33.1W 60 KT 70 MPH
48H 05/0000Z 10.8N 34.5W 70 KT 80 MPH
60H 05/1200Z 11.4N 35.8W 80 KT 90 MPH
72H 06/0000Z 12.2N 37.0W 85 KT 100 MPH
96H 07/0000Z 14.3N 39.6W 85 KT 100 MPH
120H 08/0000Z 17.0N 42.9W 85 KT 100 MPH

$$
Forecaster Bucci/Cangialosi

[cycloneye]

TCDAT3

Tropical Storm Leslie Discussion Number 4
NWS National Hurricane Center Miami FL AL132024
500 AM AST Thu Oct 03 2024

The satellite structure of Leslie has changed little since the
previous advisory, with small curved bands of convection primarily
on the eastern side of the storm. Upper-level outflow from distant
Hurricane Kirk continues to impinge on the western portion of the
circulation. The initial intensity is held at 35 kt, in best
agreement with a T2.5/35-kt TAFB subjective Dvorak classification.

Leslie is moving slowly westward (265/5 kt) to the south of a
subtropical ridge over the eastern Atlantic. A gradual turn to the
west-northwest and northwest, along with a slight increase in
forward speed, is forecast on Friday and over the weekend while the
storm moves around the western extent of the ridge. The models are
in reasonably good agreement on this scenario through the 5-day
forecast period. The updated NHC prediction is virtually unchanged
from the previous one, and lies near or in between the multi-model
consensus aids HCCA and TVCA.

As the distance between Kirk and slow-moving Leslie grows, the wind
shear over Leslie should diminish. This will provide a more
conducive environment for the storm to steadily strengthen within a
moist environment over warm waters. There is some spread in the
intensity guidance regarding how much strengthening will occur
during the next 2-3 days, with the HAFS-A/B models much higher than
the global models and statistical-dynamical aids. Given the storm's
current structure and slow forward speed, the NHC forecast remains
near the middle of the guidance envelope, closest to the IVCN simple
consensus aid. This forecast brings Leslie to hurricane strength by
early Saturday. As previously noted, the intensity of Leslie could
plateau thereafter if it follows a similar track to Kirk and
encounters the cool wake left behind by the hurricane.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 10.3N 30.5W 35 KT 40 MPH
12H 03/1800Z 10.1N 31.2W 40 KT 45 MPH
24H 04/0600Z 10.2N 32.3W 50 KT 60 MPH
36H 04/1800Z 10.5N 33.6W 60 KT 70 MPH
48H 05/0600Z 11.1N 35.0W 70 KT 80 MPH
60H 05/1800Z 11.8N 36.4W 80 KT 90 MPH
72H 06/0600Z 12.7N 37.6W 85 KT 100 MPH
96H 07/0600Z 15.3N 40.4W 85 KT 100 MPH
120H 08/0600Z 18.0N 44.0W 90 KT 105 MPH

$$
Forecaster Reinhart

[cycloneye]

Tropical Storm Leslie Discussion Number 5
NWS National Hurricane Center Miami FL AL132024
1100 AM AST Thu Oct 03 2024

Leslie is becoming better organized this morning. An earlier
microwave pass depicted a more well-defined center with better
defined curved banding features. Recent satellite-derived wind data
depicts max winds around 38-40 kt. Subjective and objective Dvorak
satellite intensity estimates range from 35-40 kt. Given the
improved organizational structure and satellite trends will lean
towards the higher end of these estimates with an initial intensity
of 40 kt.

The tropical storm is moving slowly westward at an estimated motion
of 260/4 kt to the south of a subtropical ridge over the eastern
Atlantic. As we move into Friday and this weekend the system will
gradually turn west-northwestward then northwestward increasing its
forward speed rounding the subtropical ridge. Model guidance is
tightly clustered and in fairly good agreement. The NHC track
forecast is very near the previous, and lies near the simple and
corrected consensus aids.

The system is still feeling some of the effects of the outflow of
Kirk, however as Kirk begins to move further away shear is forecast
to weaken. The oceanic and atmospheric environmental conditions are
conducive for steady strengthening with warm sea surface temperature
and plenty of moisture. The NHC intensity forecast lies near the
upper-end of the guidance envelope given the improved structure and
favorable environment, and lies near the HCCA corrected consensus.
Towards the end of the forecast period the intensity forecast
plateaus given the system is forecast to track behind the cold wake
of Hurricane Kirk.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 10.1N 30.8W 40 KT 45 MPH
12H 04/0000Z 10.1N 31.5W 50 KT 60 MPH
24H 04/1200Z 10.4N 32.8W 60 KT 70 MPH
36H 05/0000Z 10.8N 34.2W 70 KT 80 MPH
48H 05/1200Z 11.4N 35.7W 75 KT 85 MPH
60H 06/0000Z 12.3N 37.0W 80 KT 90 MPH
72H 06/1200Z 13.3N 38.2W 85 KT 100 MPH
96H 07/1200Z 15.9N 41.1W 90 KT 105 MPH
120H 08/1200Z 18.6N 44.6W 95 KT 110 MPH

$$
Forecaster Kelly/E.Adams

[cycloneye]

Tropical Storm Leslie Discussion Number 6
NWS National Hurricane Center Miami FL AL132024
500 PM AST Thu Oct 03 2024

Leslie is becoming better organized this afternoon, but continues to
battle wind shear due to the outflow from Hurricane Kirk. The center
is becoming more well-defined on visible satellite imagery and
convection is increasing along the southern semi-circle. Subjective
Dvorak satellite estimates from TAFB and SAB show a Data-T number of
3.0, corresponding with the initial intensity of 45 kt.

The tropical storm is drifting westward at 270/5 kt along the
southern periphery of a subtropical ridge in the eastern Atlantic.
Leslie is forecast to move slowly westward over the next day or so
before gradually turning west-northwestward, then accelerating to
the northwest this weekend. Model guidance has shifted slightly
westward, and the official NHC track forecast has followed suit and
lies near the simple consensus aids.

Leslie has been slowly strengthening today. Steady strengthening is
expected over the next 36-48 hr as the shear from Hurricane Kirk
lessen, and Leslie moves through a more favorable atmospheric and
oceanic environment. The spread in model intensity guidance has
increased this afternoon, and the hurricane models have suggested
the potential for rapid strengthening. The official NHC intensity
forecast lies near the simple consensus aids, although it still
lies below some of the regional hurricane models and HCCA. The
intensity forecast will plateau by the end of the forecast period
as Leslie moves into the cold wake of Kirk.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 10.1N 31.5W 45 KT 50 MPH
12H 04/0600Z 10.2N 32.3W 55 KT 65 MPH
24H 04/1800Z 10.5N 33.6W 65 KT 75 MPH
36H 05/0600Z 10.9N 35.0W 75 KT 85 MPH
48H 05/1800Z 11.7N 36.5W 80 KT 90 MPH
60H 06/0600Z 12.6N 37.7W 85 KT 100 MPH
72H 06/1800Z 13.7N 39.0W 85 KT 100 MPH
96H 07/1800Z 16.3N 42.1W 90 KT 105 MPH
120H 08/1800Z 19.3N 45.6W 100 KT 115 MPH

$$
Forecaster Kelly/E.Adams

[cycloneye]

Tropical Storm Leslie Discussion Number 7
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Thu Oct 03 2024

There has been little change in Leslie's appearance this evening.
Based on the CIMSS-UW satellite wind analyses, the storm is still
being sheared by the outflow from Hurricane Kirk. Convection
continues to pulse near the center with a curved band wrapping
around the southern portion of the circulation. Subjective
satellite intensity estimates have held steady this cycle and the
initial intensity remains at 45 kt.

Leslie is moving slowly just south of due west at 265/5 kt. A
subtropical ridge centered over the eastern Atlantic is forecast to
slowly move Leslie westward overnight and then gradually turn the
storm west-northwestward on Friday. By the end of the weekend,
Leslie is expected to accelerate and turn northwestward. The latest
NHC track forecast have been nudged slightly westward from the
previous prediction, largely due to a more westward initial
position.

Despite the vertical wind shear caused by Hurricane Kirk, Leslie is
expected to steadily strengthen in next couple of days due to warm
ocean waters and sufficient mid-level moisture. As the shear abates
in 48-72 h, Leslie could strengthen more quickly, however the spread
in model guidance is rather large as these forecast hours. Factors
such as how long Leslie is over Kirk's cold wake could slow or stall
intensification. For now, the NHC intensity forecast is unchanged
from the earlier advisory and lies near the top of the guidance
envelope, closest to the corrected consensus aid, HCCA.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 10.0N 32.0W 45 KT 50 MPH
12H 04/1200Z 10.1N 32.8W 55 KT 65 MPH
24H 05/0000Z 10.5N 34.2W 65 KT 75 MPH
36H 05/1200Z 11.0N 35.6W 75 KT 85 MPH
48H 06/0000Z 11.8N 36.9W 80 KT 90 MPH
60H 06/1200Z 12.8N 38.2W 85 KT 100 MPH
72H 07/0000Z 14.0N 39.5W 85 KT 100 MPH
96H 08/0000Z 16.8N 43.0W 90 KT 105 MPH
120H 09/0000Z 19.9N 46.6W 100 KT 115 MPH

$$
Forecaster Bucci

[cycloneye]

Tropical Storm Leslie Discussion Number 8
NWS National Hurricane Center Miami FL AL132024
500 AM AST Fri Oct 04 2024

A 0421 UTC GMI microwave pass showed that Leslie has developed a
well-defined low-level structure, along with what appears to be an
attempt at an eyewall feature south of the center. This asymmetry
in the convection is the result of continued moderate shear out of
the north-northeast. ASCAT-C data from several hours ago showed
several 44-kt wind barbs northwest of the center. Given the
typical undersampling of this instrument, and the storm's improved
structure despite the shear, the initial intensity is estimated to
be 50 kt.

The GMI and ASCAT passes helped immensely in locating Leslie's
center, which is a little farther south than previously estimated.
Leslie is moving slowly westward, or 270/5 kt, along the southern
periphery of the subtropical ridge. With the ridge expected to
remain centered over the eastern Atlantic, Leslie is forecast to
gradually turn west-northwestward later today and then toward the
northwest in about 48 hours, with that motion continuing through
the middle of next week. The NHC track forecast is near a blend of
the HCCA and TVCA consensus aids, and any differences from the
previous prediction should be considered negligible.

The deep-layer shear affecting Leslie is likely to abate in about
12 hours. However, there are a few environmental features that
could potentially limit Leslie's rate of intensification.
Mid-level shear and dry air are shown to be the biggest negative
factors in the SHIPS diagnostics, and Leslie may end up moving over
Hurricane Kirk's cold wake. Additional strengthening is still
anticipated, however much of the intensity guidance has come down
on this cycle. The NHC intensity forecast is slightly lower than
the previous forecast to follow this trend, but it lies near or
above the highest intensity models for most of the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 9.8N 32.5W 50 KT 60 MPH
12H 04/1800Z 10.1N 33.4W 55 KT 65 MPH
24H 05/0600Z 10.5N 34.7W 60 KT 70 MPH
36H 05/1800Z 11.0N 36.1W 70 KT 80 MPH
48H 06/0600Z 11.8N 37.3W 75 KT 85 MPH
60H 06/1800Z 13.0N 38.6W 80 KT 90 MPH
72H 07/0600Z 14.5N 40.1W 85 KT 100 MPH
96H 08/0600Z 17.5N 43.6W 90 KT 105 MPH
120H 09/0600Z 20.3N 47.2W 95 KT 110 MPH

$$
Forecaster Berg

[cycloneye]

Tropical Storm Leslie Discussion Number 9
NWS National Hurricane Center Miami FL AL132024
1100 AM AST Fri Oct 04 2024

A recent SSMIS microwave pass depicted that Leslie is continuing to
become better organized and is trying to develop an inner core.
Burst of deep convection have continued to develop mainly on the
southern semi-circle as the system is still battling some deep-layer
northeasterly wind shear. Given the improved convective pattern the
subjective Dvorak intensity estimates have increased this cycle with
a data-T 3.5/55 kt, from both TAFB and SAB. Using these estimates
and the improving structure, the initial intensity is set to 55 kt
for this advisory.

Leslie is moving slowly westward at 280/5 kt, along the southern
periphery of the subtropical ridge. The ridge will continue to
steer Leslie, with a gradual turn west-northwestward then
northwestward as it rounds the ridge. Leslie should continue
north-westward with a slight increase in forward speed through the
end of the forecast period. The NHC track forecast is very near the
previous forecast track, which lies between the HCCA HFIP-corrected
consensus and simple consensus aids.

Northeasterly shear should begin to decrease later today as
Hurricane Kirk continues to pull further away from the system.
Strengthening is then forecast over the next 2-3 days with warm sea
surface temperatures, upper-level divergence and low deep-layer
shear. The intensity guidance, especially the peak has come down
this cycle, and that is a combination of a few factors. In about 3
days, Leslie is forecast to move over the cold wake of Kirk, and
encounter increasing dry air, mid-level shear, and the upper-level
pattern also become a little less diffluent. This should cause the
intensity of Leslie to plateau through the end of the forecast
period. The NHC intensity forecast follows these trends and is
slightly lower than the previous forecast, but lies near the higher
end of the intensity guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 10.0N 33.0W 55 KT 65 MPH
12H 05/0000Z 10.3N 34.0W 65 KT 75 MPH
24H 05/1200Z 10.8N 35.3W 75 KT 85 MPH
36H 06/0000Z 11.4N 36.6W 80 KT 90 MPH
48H 06/1200Z 12.4N 37.8W 80 KT 90 MPH
60H 07/0000Z 13.8N 39.3W 85 KT 100 MPH
72H 07/1200Z 15.3N 40.9W 90 KT 105 MPH
96H 08/1200Z 18.2N 44.4W 85 KT 100 MPH
120H 09/1200Z 20.9N 47.7W 85 KT 100 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Leslie Discussion Number 10
NWS National Hurricane Center Miami FL AL132024
500 PM AST Fri Oct 04 2024

The convective structure of Leslie has become better organized this
afternoon with a more symmetrical convective shield. There have not
been any helpful microwave or scatterometer passes the last several
hours to help evaluate the structure further. The latest subjective
Dvorak satellite intensity estimates were T/3.5 and T/4.0, from TAFB
and SAB respectively. Using a blend of these estimates, the initial
intensity is set to 60 kt for this advisory.

Leslie is moving slowly west-northwestward at 290/6 kt, and this
motion is expected to continue as the storm rounds the subtropical
ridge anchored over the east Atlantic. Leslie should continue
west-northwestward then turn more northwestward by the end of the
weekend with a slight increase in forward speed through the end of
the forecast period. The track guidance is fairly well clustered and
the NHC track lies near the consensus aids.

The intensity forecast has become a little more uncertain with
varying model solutions the last few model cycles, especially with
the peak intensity and potential weakening towards the middle to end
of the period. Northeasterly shear from Kirk has started to weaken
over the system this afternoon, and that has likely aided the
improved convective pattern. Leslie will be within a favorable
atmospheric and oceanic environment for steady strengthening over
the next 2 days or so. Beyond that time models begin to plateau the
strengthening or start a weakening trend, as Leslie encounters some
westerly shear and a drier air mass. There is a notable difference
between the GFS and ECMWF in how hostile the environment will be by
five days, with the ECMWF showing more shear, a much drier air
mass, and a much weaker Leslie. One other issue is that the
forecast track is expected to take Leslie over the cold wake left
behind from Hurricane Kirk. Given the lowering intensity guidance
and varying model solutions, the NHC intensity forecast has been
adjusted downward, but still lies at the higher end of the guidance
envelope. Additional adjustments to the intensity forecast may be
needed on later advisories.


FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 10.3N 33.6W 60 KT 70 MPH
12H 05/0600Z 10.7N 34.6W 70 KT 80 MPH
24H 05/1800Z 11.2N 35.9W 75 KT 85 MPH
36H 06/0600Z 12.2N 37.1W 80 KT 90 MPH
48H 06/1800Z 13.5N 38.3W 80 KT 90 MPH
60H 07/0600Z 14.9N 39.8W 80 KT 90 MPH
72H 07/1800Z 16.3N 41.6W 75 KT 85 MPH
96H 08/1800Z 19.0N 45.0W 75 KT 85 MPH
120H 09/1800Z 21.5N 48.2W 70 KT 80 MPH

$$
Forecaster Kelly

[cycloneye]

Hurricane Leslie Discussion Number 11
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Fri Oct 04 2024

Leslie continues to become better organized this evening. An SSMIS
microwave pass from 1946 UTC showed that Leslie had a small inner
core with a well-defined mid-level center. Subjective satellite
intensity guidance has held steady while objective guidance has
increased significantly, creating a wide range of possible
intensities (56-84 kt). For this advisory, the maximum sustained
winds have been increased to 65 kt, which is closest to the SAB T4.0
classification. Leslie is the eighth hurricane in the Atlantic this
season.

A subtropical ridge over the eastern Atlantic Ocean is steering the
hurricane slowly to the west-northwest at 290/6 kt. There has been
no changes to the track reasoning. The ridge should be the dominant
steering feature through the entire forecast period, turning Leslie
northwestward by Saturday and continue this motion through the
middle of next week. Only minor updates were made to the latest NHC
track forecast.

Based on the UW-CIMSS satellite wind analysis, Leslie is on the edge
of a shear gradient, with the core in an area of moderate-to-weak
vertical wind shear. Global models suggest environmental conditions
will be conducive for about a day and half before the shear begins
to increase and Leslie moves into a drier airmass. These conditions
should induce gradual weakening. There is still a large spread in
the intensity guidance envelope, which seems related to the strength
of the vertical wind shear Leslie could encounter. Overall, the
guidance has once shifted downward this cycle, and the NHC intensity
forecast has been lowered at 60 h and beyond. The forecast still
lies at the high end of the intensity aids and additional
adjustments may be needed in later advisories.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0300Z 10.4N 34.2W 65 KT 75 MPH
12H 05/1200Z 10.8N 35.2W 70 KT 80 MPH
24H 06/0000Z 11.6N 36.4W 75 KT 85 MPH
36H 06/1200Z 12.7N 37.6W 80 KT 90 MPH
48H 07/0000Z 14.1N 38.9W 80 KT 90 MPH
60H 07/1200Z 15.4N 40.6W 75 KT 85 MPH
72H 08/0000Z 16.9N 42.4W 70 KT 80 MPH
96H 09/0000Z 19.5N 45.9W 70 KT 80 MPH
120H 10/0000Z 21.8N 48.7W 70 KT 80 MPH

$$
Forecaster Bucci

[cycloneye]

Hurricane Leslie Discussion Number 12
NWS National Hurricane Center Miami FL AL132024
500 AM AST Sat Oct 05 2024

A 0552 UTC SSMIS microwave pass showed that Leslie still has a
well-defined mid-level eye, and deep convection continues to burst
over the center. Dvorak estimates from TAFB and SAB are both
T4.0/65 kt, while objective numbers are overall a bit higher than
that. Therefore, Leslie's intensity is now estimated to be 70 kt.

Leslie continues to move slowly west-northwestward (290/6 kt), with
the cyclone still located along the southern periphery of the
subtropical ridge. The ridge is expected to remain entrenched and
strengthen over the eastern Atlantic during the next several days,
which should cause Leslie to move northwestward and accelerate a
bit by Tuesday and Wednesday. The NHC forecast is close to a blend
of the TVCA and HCCA consensus aids, and nearly lies on top of the
previous prediction.

The intensity forecast is the most challenging part of this
advisory. Deep-layer shear is relatively low at the moment and
should remain so for the next 24 hours or so. This is the period
where the NHC forecast shows additional strengthening, and is close
to the statistical-dynamical models near the top end of the
guidance. Increased shear, combined with Leslie potentially moving
over Kirk's cold wake, could cause some weakening after 24 hours.
All of the intensity models support this scenario, however they
differ significantly in how much weakening will occur. The NHC
forecast continues to show Leslie maintaining hurricane status
through day 5, mainly following the SHIPS model. However, the IVCN
and HCCA consensus aids, as well as several of the hurricane
regional models, suggest that Leslie could weaken below hurricane
intensity by 48 hours. Downward adjustments to the intensity
forecast may be required in future advisories if this trend
continues.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0900Z 10.7N 34.8W 70 KT 80 MPH
12H 05/1800Z 11.2N 35.7W 75 KT 85 MPH
24H 06/0600Z 12.1N 36.8W 80 KT 90 MPH
36H 06/1800Z 13.2N 38.1W 75 KT 85 MPH
48H 07/0600Z 14.6N 39.6W 70 KT 80 MPH
60H 07/1800Z 15.9N 41.3W 70 KT 80 MPH
72H 08/0600Z 17.4N 43.1W 70 KT 80 MPH
96H 09/0600Z 20.2N 46.7W 65 KT 75 MPH
120H 10/0600Z 22.3N 49.5W 65 KT 75 MPH

$$
Forecaster Berg

[cycloneye]

Hurricane Leslie Discussion Number 13
NWS National Hurricane Center Miami FL AL132024
1100 AM AST Sat Oct 05 2024

Deep convection continues to burst over the center of Leslie this
morning. Some of the latest satellite images depict a little bit of
shear starting to impact the system, with a sharper convective edge
on the western side. Subjective and objective satellite intensity
estimates range from 65 to 75 kt. Using a blend of these estimates,
the initial intensity is held at 70 kt for this advisory.

Leslie continues to move slowly west-northwestward (295/6 kt),
steered by a mid-level subtropical ridge over the eastern Atlantic.
The ridge will continue to steer Leslie the next several days with a
turn more northwestward, with an increase in forward speed by the
middle of the forecast period. The NHC track forecast is very close
to the previous, and lies near the simple and corrected consensus
aids.

The intensity forecast continues to trend downward with Leslie. The
system has about 12-24 hours left within a favorable environment
where some slight additional strengthening may occur. By Sunday,
increased shear, drier mid-level, and the track taking Leslie over
Kirk's cold wake, this could cause some weakening after 24 hours.
There is better agreement with the weakening trend, however they
differ on how significantly and how quickly weakening will occur.
Therefore, downward adjustments were made to the NHC intensity
forecast and now has Leslie weakening below hurricane strength
beyond 48 h. If trends continue further downward adjustments may be
required in future advisories.

FORECAST POSITIONS AND MAX WINDS

INIT 05/1500Z 11.1N 35.4W 70 KT 80 MPH
12H 06/0000Z 11.7N 36.2W 75 KT 85 MPH
24H 06/1200Z 12.7N 37.4W 75 KT 85 MPH
36H 07/0000Z 13.8N 38.7W 70 KT 80 MPH
48H 07/1200Z 15.0N 40.3W 65 KT 75 MPH
60H 08/0000Z 16.4N 42.1W 60 KT 70 MPH
72H 08/1200Z 17.8N 44.0W 60 KT 70 MPH
96H 09/1200Z 20.4N 47.7W 55 KT 65 MPH
120H 10/1200Z 22.4N 50.4W 55 KT 65 MPH

$$
Forecaster Kelly

[cycloneye]

Hurricane Leslie Discussion Number 14
NWS National Hurricane Center Miami FL AL132024
500 PM AST Sat Oct 05 2024

Leslie continues to produce deep convection this afternoon. Although
the convective pattern depicts some southwesterly shear
starting to impact the system. Subjective and objective Dvorak
satellite intensity estimates range from 55-70 kt. Given the deep
convection over the center still, the initial intensity is held at
70 kt for this advisory, although that could be a little generous.

The hurricane continues to move slowly west-northwestward at 300/7
kt, steered along the southwestern portion of a mid-level
subtropical ridge over the eastern Atlantic. The ridge will continue
to steer Leslie the next several days with a turn more
northwestward, with an increase in forward speed the next several
days. Model track guidance still remains fairly tightly clustered
and the NHC track forecast is very close to the previous one.

Leslie may be able to fend off the shear over the next 12 hours or
so, however by Sunday, the system will start to move into increasing
wind shear and mid-level dry air. The NHC forecast track also takes
Leslie over Kirk's cold wake. There continues to be some model
differences on how significantly, and quickly weakening will occur.
The NHC forecast follows the latest consensus aids downward trends,
and is slightly lower than the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 11.6N 36.0W 70 KT 80 MPH
12H 06/0600Z 12.3N 36.8W 70 KT 80 MPH
24H 06/1800Z 13.4N 38.0W 65 KT 75 MPH
36H 07/0600Z 14.7N 39.6W 65 KT 75 MPH
48H 07/1800Z 16.0N 41.3W 60 KT 70 MPH
60H 08/0600Z 17.3N 43.0W 55 KT 65 MPH
72H 08/1800Z 18.7N 45.0W 55 KT 65 MPH
96H 09/1800Z 21.0N 48.3W 50 KT 60 MPH
120H 10/1800Z 22.9N 51.0W 50 KT 60 MPH

$$
Forecaster Kelly

[cycloneye]

Hurricane Leslie Discussion Number 15
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Sat Oct 05 2024

Leslie is holding steady this evening. Geostationary imagery
shows a growing Central Dense Overcast (CDO) with periodic burst
of embedded deep convection. An ASCAT pass from earlier showed
that has a small core with the center near the southern side of
the deep convection. Objective and subjective satellite estimates
range from 50 to 77 kt. The initial intensity is held at an
uncertain 70 kt, favoring the SAB and TAFB estimates.

The hurricane is moving at an estimated 310/8 kt. A subtropical
ridge centered over the eastern Atlantic has turned Leslie to the
northwest, and this motion is expected to continue, with a slight
increase in forward speed, for the entire forecast period. Model
guidance is in relatively good agreement about this forecast and
only small adjustments have been made to the latest NHC track
prediction.

According to the SHIP diagnostics, Leslie only has a few more hours
in the low vertical wind shear environment. On Sunday, increasing
wind shear and dry mid-level humidities should induce a gradual
weakening trend for the entire forecast period. Some model
guidance is showing that Leslie could weaken quicker than forecast,
and adjustments to the intensity forecast could be necessary in
subsequent advisories. The latest NHC forecast has been nudged
downward, slightly above the consensus aid IVCN.


FORECAST POSITIONS AND MAX WINDS

INIT 06/0300Z 12.4N 36.9W 70 KT 80 MPH
12H 06/1200Z 13.2N 37.8W 70 KT 80 MPH
24H 07/0000Z 14.4N 39.3W 65 KT 75 MPH
36H 07/1200Z 15.5N 40.9W 60 KT 70 MPH
48H 08/0000Z 16.8N 42.6W 60 KT 70 MPH
60H 08/1200Z 18.2N 44.4W 55 KT 65 MPH
72H 09/0000Z 19.5N 46.3W 50 KT 60 MPH
96H 10/0000Z 21.7N 49.3W 50 KT 60 MPH
120H 11/0000Z 23.4N 51.2W 50 KT 60 MPH

$$
Forecaster Bucci

[cycloneye]

Hurricane Leslie Discussion Number 16
NWS National Hurricane Center Miami FL AL132024
500 AM AST Sun Oct 06 2024

The center of Leslie was embedded within a cold, asymmetric central
dense overcast for much of the overnight hours. But recently,
geostationary satellite images indicate an eye feature is trying to
emerge, with a warm spot in infrared imagery surrounded by a ring of
deep, cold convection. Based on these satellite trends, the initial
intensity is raised to 75 kt, in best agreement with T4.5 Dvorak
estimates from TAFB and SAB.

Leslie is moving northwestward (310/9 kt) while being steered by a
subtropical ridge centered to the north and northeast of the
hurricane. This ridge is expected to build eastward over the eastern
Atlantic and remain the primary steering feature for much of the
5-day forecast period. As a result, the NHC forecast shows a
continued northwestward motion, remaining near the center of the
track guidance envelope. Only small right-of-track adjustments
were made to the previous forecast, mainly beyond 48 h.

Some near-term intensity fluctuations are possible today, depending
on whether Leslie is able to fully clear out an eye this morning.
But overall, the environmental conditions are still forecast to
become less favorable for further development in the coming days.
Drier mid-level air, a more convergent upper-level environment, and
increasing southwesterly shear should induce at least a gradual
weakening trend in the coming days, and this is reflected in the
latest NHC prediction. Since Leslie is a relatively small tropical
cyclone, it could be more susceptible to these negative factors and
weaken even faster than the NHC forecast later in the period, as
suggested by the regional hurricane models.


FORECAST POSITIONS AND MAX WINDS

INIT 06/0900Z 12.9N 37.3W 75 KT 85 MPH
12H 06/1800Z 13.7N 38.4W 80 KT 90 MPH
24H 07/0600Z 14.9N 39.9W 75 KT 85 MPH
36H 07/1800Z 16.2N 41.5W 65 KT 75 MPH
48H 08/0600Z 17.5N 43.2W 55 KT 65 MPH
60H 08/1800Z 18.9N 45.0W 50 KT 60 MPH
72H 09/0600Z 20.2N 46.6W 50 KT 60 MPH
96H 10/0600Z 22.2N 49.1W 50 KT 60 MPH
120H 11/0600Z 24.0N 50.5W 50 KT 60 MPH

$$
Forecaster Reinhart

[cycloneye]

Hurricane Leslie Discussion Number 17
NWS National Hurricane Center Miami FL AL132024
1100 AM AST Sun Oct 06 2024

Leslie has continued to produce a deep ring of convection around the
center, with a faint eye becoming more apparent on infrared and
visible satellite imagery, and GLM lightning data depicts lightning
occuring in the northern eyewall. These satellite trends all
depict Leslie is still strengthening within a marginally favorable
environment. Dvorak subjective and objective satellite intensity
estimates have continued to increase this cycle and range from 70
to 85 kt. Based on these satellite data, the initial intensity
is raised to 80 kt.

Leslie is moving northwestward (310/8 kt) while being steered by a
subtropical ridge centered to the northeast of the hurricane. The
ridge will remain anchored over the eastern Atlantic and continue to
steer the hurricane northwestward throughout the forecast period. As
a result, model guidance is fairly tightly clustered with only a few
slight leftward adjustments made towards the end of the forecast
period, closer to the HCCA corrected consensus.

The hurricane has been able to maintain its core even though wind
shear is gradually increasing over the system. Leslie has about 12
more hours before it begins to move into an increasingly unfavorable
environment. In the near term the forecast allows for some
additional strengthening, especially if Leslie's eye can clear.
However, drier mid-level air is nearby as is depicted on water vapor
imagery, as well as a less difluent upper-level pattern, and
southwesterly shear will persist. The latest NHC forecast follows
the latest model trends with gradual weakening beginning on Monday.
Since Leslie is a relatively small tropical cyclone, it could be
more susceptible to these negative factors and weaken even faster
than the NHC forecast later in the period, as suggested by some of
the global and hurricane regional models.


FORECAST POSITIONS AND MAX WINDS

INIT 06/1500Z 13.3N 37.9W 80 KT 90 MPH
12H 07/0000Z 14.2N 39.0W 85 KT 100 MPH
24H 07/1200Z 15.4N 40.5W 75 KT 85 MPH
36H 08/0000Z 16.6N 42.0W 65 KT 75 MPH
48H 08/1200Z 17.9N 43.8W 55 KT 65 MPH
60H 09/0000Z 19.2N 45.4W 50 KT 60 MPH
72H 09/1200Z 20.4N 47.1W 50 KT 60 MPH
96H 10/1200Z 22.2N 49.5W 50 KT 60 MPH
120H 11/1200Z 24.2N 51.0W 50 KT 60 MPH

$$
Forecaster Kelly

[cycloneye]

Hurricane Leslie Discussion Number 18
NWS National Hurricane Center Miami FL AL132024
500 PM AST Sun Oct 06 2024

Leslie's satellite imagery has become a little more ragged as
southwesterly shear has disrupted the overall convective pattern.
The deep inner core convection has become a little more broken the
last few hours. Subjective and objective estimates range from 75 to
85 kt, with a T4.5 from both TAFB and SAB. Based on these
satellite estimates, the initial intensity is held at 80 kt.

Leslie is moving northwestward (310/8 kt) while being steered by a
subtropical ridge over the eastern Atlantic. The ridge will continue
to build to the northeast of the system, which should steer the
hurricane northwestward throughout the forecast period. Models
continue to be in good agreement, the NHC track forecast is very
similar to the previous which remains near the latest consensus
aids.

The hurricane has started to enter a more hostile environment.
Southwesterly shear has started to increase, with drier mid-levels,
and upper-level convergence along the forecast path. The latest NHC
forecast follows the latest model trends with gradual weakening
beginning on Monday. Since Leslie is a relatively small tropical
cyclone, it could be more susceptible to these negative factors and
weaken even faster than the NHC forecast later in the period, as
suggested by some of the global and hurricane regional models.


FORECAST POSITIONS AND MAX WINDS

INIT 06/2100Z 14.0N 38.6W 80 KT 90 MPH
12H 07/0600Z 14.9N 39.7W 80 KT 90 MPH
24H 07/1800Z 16.2N 41.3W 70 KT 80 MPH
36H 08/0600Z 17.6N 43.0W 60 KT 70 MPH
48H 08/1800Z 19.0N 44.7W 55 KT 65 MPH
60H 09/0600Z 20.3N 46.4W 55 KT 65 MPH
72H 09/1800Z 21.2N 47.7W 55 KT 65 MPH
96H 10/1800Z 22.5N 50.0W 50 KT 60 MPH
120H 11/1800Z 24.1N 51.7W 50 KT 60 MPH

$$
Forecaster Kelly

[cycloneye]

Hurricane Leslie Discussion Number 19
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Sun Oct 06 2024

Leslie has been more or less status quo this evening, with the
hurricane characterized by a small central dense overcast that
occasionally has a warm spot appearing on infrared images.
Subjective Dvorak estimates from TAFB and SAB remain unchanged for
00 UTC, while the objective intensity estimates are a tad lower
than earlier. For now, Leslie's intensity will be held at 80 kt
until there is a more distinct degradation in its satellite
appearance.

Leslie continues to move northwestward, with its motion estimated at
315/10 kt this advisory. The hurricane has been primarily steered by
a mid-level ridge to its northeast which should continue for the
next several days, followed by a turn to the north-northwest or
north by the end of the forecast period as it reaches the westward
extent of the ridge. There has been a slight rightward shift in the
guidance this cycle, and the NHC track forecast is a little north
and east of the prior track forecast, roughly in between the latest
TVCA and HCCA consensus aids.

There are a couple of negative factors likely to influence Leslie's
intensity over the next few days. First, while 200-850 mb vertical
wind shear is forecast to be fairly low, undercutting this outflow
layer is stronger 20-25 kt mid-level southwesterly shear. This shear
appears likely to import some very dry mid-level air, seen on water
vapor GOES-16 imagery southwest of Leslie, into the hurricane's
small inner core. At the same time, sea-surface temperatures along
Leslie's path are likely to be at least somewhat cooler thanks in
part to upwelling from Hurricane Kirk last week. The intensity
guidance, especially the regional-hurricane models, show quite a bit
of weakening due to these negative factors, and the NHC intensity
forecast also will show weakening through the forecast period. In
fact, the latest NHC forecast shows a bit more weakening than the
prior advisory, as Leslie's small core could be more prone to these
negative conditions. However, this forecast is still a little above
the latest HAFS-A/B forecasts which show more rapid weakening over
the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 15.0N 39.4W 80 KT 90 MPH
12H 07/1200Z 16.0N 40.7W 75 KT 85 MPH
24H 08/0000Z 17.4N 42.3W 65 KT 75 MPH
36H 08/1200Z 18.8N 44.1W 55 KT 65 MPH
48H 09/0000Z 20.2N 45.7W 50 KT 60 MPH
60H 09/1200Z 21.2N 47.1W 50 KT 60 MPH
72H 10/0000Z 21.9N 48.2W 45 KT 50 MPH
96H 11/0000Z 23.4N 50.0W 45 KT 50 MPH
120H 12/0000Z 25.0N 50.5W 40 KT 45 MPH

$$
Forecaster Papin

[cycloneye]

Hurricane Leslie Discussion Number 20
NWS National Hurricane Center Miami FL AL132024
500 AM AST Mon Oct 07 2024

Conventional satellite imagery indicates that Leslie's cloud
pattern has changed little during the past few hours. A fortuitous
SSMIS microwave image revealed a compact inner core with the
eyewall partially open in the south side. Most of the
convective curve bands remain confined to the north side of the
cyclone. The TAFB and SAB subjective and the UW-CIMSS objective
satellite intensity estimates support holding the initial intensity
at 80 kt for this advisory.

Although the statistical GFS/ECMWF SHIPS intensity models
indicate a low-shear surrounding environment through the 60 hr
period, the global model forecast sounding reveals 15-20 kt of
400-250 mb mid-tropospheric westerly shear undercutting the
diffluent flow aloft. This mid-level disrupting flow could force
the drier, stable air identified in the water vapor imagery into
Leslie's deep convective core. This negative thermodynamic
contribution, along with gradually decreasing oceanic surface
temperatures ahead of the cyclone's predicted path should cause
Leslie to weaken through the period. The ECMWF and GFS model
simulated infrared forecast now indicates that Leslie will lose its
organized convection within inhibiting environmental conditions and
become a post-tropical cyclone by day 5, and the NHC intensity
forecast follows suit.

Based on the above-mentioned microwave pass, the initial motion is
estimated to be northwestward, or 315/11 kt, just a little left of
the previous track. Leslie is expected to move around the
southwestern periphery of a subtropical ridge to the northeast of
the cyclone and turn gradually north-northwestward to northward
toward the end of the week. The official forecast is an update of
the previous one and closely follows the various consensus aids.

Leslie's wind radii were adjusted based on an earlier CSA/RCM-3 SAR
overpass.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 15.6N 40.4W 80 KT 90 MPH
12H 07/1800Z 16.6N 41.7W 75 KT 85 MPH
24H 08/0600Z 18.1N 43.4W 60 KT 70 MPH
36H 08/1800Z 19.6N 45.2W 55 KT 65 MPH
48H 09/0600Z 20.9N 46.7W 50 KT 60 MPH
60H 09/1800Z 21.7N 47.9W 50 KT 60 MPH
72H 10/0600Z 22.4N 48.9W 45 KT 50 MPH
96H 11/0600Z 23.9N 50.1W 40 KT 45 MPH
120H 12/0600Z 25.8N 49.9W 40 KT 45 MPH...POST-TROPICAL

$$
Forecaster Roberts