ATL: MARGOT - Advisories

[cycloneye]

BULLETIN
Tropical Depression Fourteen Advisory Number 1
NWS National Hurricane Center Miami FL AL142023
200 PM CVT Thu Sep 07 2023

...DEPRESSION FORMS OVER THE EASTERN TROPICAL ATLANTIC...


SUMMARY OF 200 PM CVT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...15.7N 26.4W
ABOUT 160 MI...260 KM W OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES




Tropical Depression Fourteen Discussion Number 1
NWS National Hurricane Center Miami FL AL142023
200 PM CVT Thu Sep 07 2023

Visible and infrared satellite imagery depicts that showers and
thunderstorms have become better organized around a well-defined
low-level center associated with the low pressure area (AL96) that
NHC has been tracking the past few days. Subjective satellite
Dvorak intensity estimates from TAFB and SAB were both T2.0/30 kt.
Given the better defined low-level center and these satellite
estimates, advisories are being initiated on Tropical Depression
Fourteen over the far eastern Atlantic, with an initial intensity
of 30 kt.

The depression is moving generally west-northwest and this
motion is forecast to continue over the next few days, with a
decrease in forward speed and a turn to the north at the end of the
forecast period, into a weakness in the tropical ridge. The
guidance envelope is in fairly good agreement and the NHC track
forecast lies between the HCCA and TVCA consensus aids.

Tropical Depression Fourteen is forecast to be over warm sea surface
temperatures near 28-29 degrees Celsius during the next several
days. However, the depression will encounter some northerly vertical
wind shear, and drier mid-level relative humidities along the
current forecast track. Given the mixed environmental conditions the
NHC forecast calls for gradual strengthening during the early part
of the forecast but brings the system to hurricane strength before
the end of the period. The NHC intensity forecast lies near the HCCA
and IVCN intensity consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 15.7N 26.4W 30 KT 35 MPH
12H 08/0000Z 16.4N 28.6W 35 KT 40 MPH
24H 08/1200Z 17.3N 31.7W 40 KT 45 MPH
36H 09/0000Z 18.5N 34.6W 50 KT 60 MPH
48H 09/1200Z 19.8N 37.0W 55 KT 65 MPH
60H 10/0000Z 21.0N 38.9W 60 KT 70 MPH
72H 10/1200Z 22.4N 40.4W 65 KT 75 MPH
96H 11/1200Z 26.1N 41.7W 75 KT 85 MPH
120H 12/1200Z 30.2N 42.7W 80 KT 90 MPH

$$
Forecaster Kelly/Camposano

[cycloneye]

BULLETIN
Tropical Storm Margot Advisory Number 2
NWS National Hurricane Center Miami FL AL142023
800 PM CVT Thu Sep 07 2023

...DEPRESSION BECOMES TROPICAL STORM MARGOT...


SUMMARY OF 800 PM CVT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...16.8N 28.3W
ABOUT 290 MI...465 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

Tropical Storm Margot Discussion Number 2
NWS National Hurricane Center Miami FL AL142023
800 PM CVT Thu Sep 07 2023

Visible and infrared satellite imagery have shown increasingly
organized convection, with some convective bursts and curved banding
features around the low-level center. Dvorak classifications from
TAFB and SAB have increased to T2.5/35 kt. Therefore, the initial
intensity is set at 35 kt, making the system a tropical storm.

Tropical Storm Margot is currently moving west-northwestward, and
this motion is forecast to continue over the next couple days. A
decrease in forward speed and a turn to the north is indicated by
the end of the forecast period as a weakness develops in the
subtropical ridge over east-central Atlantic. The track guidance is
in general agreement, and the NHC track forecast once again lies
between the HCCA and TVCA consensus aids.

Sea surface temperatures remain in the vicinity of 28C, but Margot
could encounter moderate wind shear and drier mid-level relative
humidities later in the forecast period. In general, these
conditions are not expected to be too hostile, and gradual
strengthening is indicated. The NHC wind speed forecast brings
Margot to hurricane strength in two to three days. The NHC intensity
forecast lies near the HCCA and IVCN intensity consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 16.8N 28.3W 35 KT 40 MPH
12H 08/0600Z 17.5N 30.6W 40 KT 45 MPH
24H 08/1800Z 18.5N 33.6W 45 KT 50 MPH
36H 09/0600Z 19.8N 36.1W 50 KT 60 MPH
48H 09/1800Z 21.1N 38.3W 60 KT 70 MPH
60H 10/0600Z 22.6N 39.9W 65 KT 75 MPH
72H 10/1800Z 24.4N 41.0W 70 KT 80 MPH
96H 11/1800Z 28.0N 42.4W 75 KT 85 MPH
120H 12/1800Z 31.5N 43.1W 80 KT 90 MPH

$$
Forecaster Kelly/Camposano

[cycloneye]

Tropical Storm Margot Discussion Number 3
NWS National Hurricane Center Miami FL AL142023
200 AM CVT Fri Sep 08 2023

The convective organization of Margot has changed little tonight.
The storm is producing some sheared convection to the north of its
center with modest signs of curvature. An earlier 37 GHz GMI
microwave image of Margot suggested the low-level center was a bit
south of previous estimates, and this is consistent with the now
partially exposed center that has emerged in recent proxy-visible
imagery. The satellite intensity estimates are unchanged from
earlier today, and the intensity remains 35 kt for this advisory.

The SSTs along Margot's track are plenty warm enough to support some
intensification over the next few days. On the other hand, there is
a good amount of dry air in the surrounding environment, and
southwesterly deep-layer shear is forecast to increase over Margot
during the next several days in association with an upper-level
trough over the central Atlantic. Interestingly, the increased shear
diagnosed from the SHIPS guidance occurs around the same time as
increasing upper-level divergence over the cyclone. This seems to
suggest that some of the intensification in the global models could
be driven by positive interaction with the upper trough. Since most
of the global and regional hurricane models show Margot becoming a
hurricane during the next few days, the NHC forecast follows suit
and shows slow strengthening throughout the period. This forecast
lies between the latest HCCA and IVCN multi-model aids.

Margot is moving west-northwestward at 295/14 kt around a ridge over
the eastern Atlantic. This general motion should continue for the
next couple of days, followed by a turn toward the northwest and
north-northwest at a slightly slower forward speed at days 3-5 as a
weakness develops in the subtropical ridge. The track model
consensus this cycle has trended slower and to the left of the
previous prediction. As a result, the updated NHC track forecast has
been adjusted accordingly.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 16.8N 29.3W 35 KT 40 MPH
12H 08/1200Z 17.5N 31.6W 40 KT 45 MPH
24H 09/0000Z 18.6N 34.4W 45 KT 50 MPH
36H 09/1200Z 19.9N 36.8W 50 KT 60 MPH
48H 10/0000Z 21.2N 38.7W 55 KT 65 MPH
60H 10/1200Z 22.7N 40.1W 60 KT 70 MPH
72H 11/0000Z 24.5N 41.0W 65 KT 75 MPH
96H 12/0000Z 28.0N 42.5W 75 KT 85 MPH
120H 13/0000Z 31.0N 43.0W 80 KT 90 MPH

$$
Forecaster Reinhart

[cycloneye]

Tropical Storm Margot Discussion Number 4
NWS National Hurricane Center Miami FL AL142023
500 AM AST Fri Sep 08 2023

Deep convection has been gradually increasing near and to the north
of the center of Margot during the past few hours. The satellite
intensity estimates range from 30 to 38 kt, and based on that data,
the initial wind speed is held at 35 kt.

Margot is moving to the west-northwest at about 14 kt on the
southwest side of a mid-level ridge. The storm is expected to
gradually turn to the northwest and then the north as it moves
toward a weakness in the ridge induced by a mid- to upper-level low
over the central subtropical Atlantic. The models are in fairly
good agreement, but there are some differences on where and when
Margot makes the northward turn. The NHC track forecast is similar
to the previous one and near the middle of the guidance envelope.

Global models show Margot strengthening for unconventional reasons.
While there are sufficiently warm ocean water along the forecast
track, deep-layer vertical wind shear is expected to be strong to
moderate as the storm nears an upper-level low pressure. Typically,
increased shear would lead to a weakening cyclone, but Margot could
be positioned beneath an area of diffluence leading to increased
convection and therefore, strengthening. The NHC intensity forecast
is similar to the previous one and near the IVCN and HCCA consensus
models.

FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 17.4N 30.8W 35 KT 40 MPH
12H 08/1800Z 18.2N 33.1W 40 KT 45 MPH
24H 09/0600Z 19.4N 35.7W 45 KT 50 MPH
36H 09/1800Z 20.6N 37.8W 50 KT 60 MPH
48H 10/0600Z 21.9N 39.5W 55 KT 65 MPH
60H 10/1800Z 23.5N 40.5W 60 KT 70 MPH
72H 11/0600Z 25.2N 41.4W 65 KT 75 MPH
96H 12/0600Z 28.3N 42.5W 75 KT 85 MPH
120H 13/0600Z 31.4N 43.1W 80 KT 90 MPH

$$
Forecaster Bucci/Cangialosi

[cycloneye]

Tropical Storm Margot Discussion Number 5
NWS National Hurricane Center Miami FL AL142023
1100 AM AST Fri Sep 08 2023

Margot has not changed much this morning. Deep convection has
persisted throughout the morning to the north and east of the
low-level center. Subjective and objective satellite intensity
estimates from SAB/TAFB and UW-CIMMS range from 30 to 40kt for
this cycle. Using a blend of these estimates, the intensity is
held at 35 kt for this advisory.

The tropical storm is moving west-northwestward at about 15 kt as
it traverses the southern edge of a mid-level ridge. Margot is
expected to continue this general motion for the next day or so,
after which it is expected to gradually turn northwestward this
weekend and then northward by early next week. Global and regional
models are in generally good agreement for the next several days,
but toward the end of the forecast period the track guidance
diverges significantly as uncertainty in the steering flow
increases. The official track forecast is similar to the previous
advisory, and lies near the center of the guidance envelope.

The intensity forecast is complex. Sea surface temperatures are
sufficiently warm along the forecast track, but vertical wind shear
is expected to increase during the next day or so and remain strong
throughout much of the forecast period. Despite the vertical wind
shear, global and regional hurricane models are in generally good
agreement that Margot will gradually intensify throughout the
forecast period. The official intensity forecast is similar to the
prior advisory and represents a blend of the consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 18.0N 32.5W 35 KT 40 MPH
12H 09/0000Z 18.9N 34.7W 40 KT 45 MPH
24H 09/1200Z 20.1N 37.1W 45 KT 50 MPH
36H 10/0000Z 21.4N 39.0W 50 KT 60 MPH
48H 10/1200Z 22.7N 40.3W 60 KT 70 MPH
60H 11/0000Z 24.3N 41.3W 65 KT 75 MPH
72H 11/1200Z 25.9N 42.0W 70 KT 80 MPH
96H 12/1200Z 28.8N 42.9W 75 KT 85 MPH
120H 13/1200Z 31.8N 43.7W 75 KT 85 MPH

$$
Forecaster Hogsett/Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 6
NWS National Hurricane Center Miami FL AL142023
500 PM AST Fri Sep 08 2023

Margot continues to be a disorganized tropical storm. Over the past
few hours, visible satellite depicts the low-level center has become
exposed with deep convection displaced to the northeast. This deep
convection has continued to persist, however the system has not
become better organized today. An earlier AMSR2 microwave pass
showed that the structure of the system is fairly poor with very
little banding features. Subjective and objective satellite
intensity estimates from SAB/TAFB for this advisory were unchanged
for this cycle. Given the disorganized structure and the satellite
estimates, the initial intensity remains 35 kt for this advisory.

The tropical storm is moving west-northwestward at about 15 kt along
the southern edge of a mid-level ridge. Margot is expected to
continue this general motion for the next day or so. Afterwards a
weakness in the ridge will allow for a turn more northwestward, then
northward by early next week. Overall, models are in fairly good
cross-track agreement in the short term. However beyond day
3, there begins to be some divergence in the model suite, due to
uncertainty in the steering flow. The ECMWF lies on the left side of
the envelope, while the GFS is on the right side. The official
track forecast is similar to the previous advisory, and lies in the
center of the guidance closest to the HCCA and TVCA consensus aids.

The intensity forecast is fairly difficult given the mixed
environmental conditions. Sea surface temperatures are sufficiently
warm along the forecast track, but vertical wind shear is already
impacting the system and is forecast to remain throughout much of
the forecast period. Given the competing factors and current lack of
organization, the intensity guidance shows only gradual
strengthening throughout the forecast period. The official forecast
is similar to the previous, near the intensity consensus aids the
IVCN and HCCA.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 18.8N 34.3W 35 KT 40 MPH
12H 09/0600Z 19.8N 36.3W 40 KT 45 MPH
24H 09/1800Z 21.0N 38.5W 45 KT 50 MPH
36H 10/0600Z 22.2N 40.1W 50 KT 60 MPH
48H 10/1800Z 23.6N 41.0W 55 KT 65 MPH
60H 11/0600Z 25.1N 41.7W 65 KT 75 MPH
72H 11/1800Z 26.9N 42.2W 70 KT 80 MPH
96H 12/1800Z 30.0N 42.6W 75 KT 85 MPH
120H 13/1800Z 33.1N 43.4W 75 KT 85 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 7
NWS National Hurricane Center Miami FL AL142023
1100 PM AST Fri Sep 08 2023

Margot hasn't become any better organized during the last six hours.
Deep convection is limited to the northeast quadrant of the sheared
tropical storm. A pair of ASCAT passes showed winds up to 30 kt in
the eastern half of the cyclone, but did not sample the location
where the maximum winds are likely occuring. Satellite estimates
from TAFB and the ADT were therefore used as the basis for the
intensity for this advisory, which is still 35 kt.

Despite the shear and some dry air around the tropical storm noted
in water vapor imagery, all of the intensity guidance indicates that
Margot will strengthen over the next few days. The NHC forecast
therefore shows slow strengthening throughout the forecast period,
similar to the previous advisory. Most of the models are similar to
the NHC forecast, but both HAFS models are outliers, showing Margot
strengthening to a major hurricane in 3-4 days. This appears
unlikely at least within the next 3 days or so, given the expected
wind shear and the current structure of the tropical storm.
Therefore, the NHC forecast is very close to, but generally just
below the intensity consensus.

In contrast, there is higher confidence in the track forecast. All
models indicate that Margot will continue its current
west-northwestward motion for another day or so, and then turn
north-northwestward to northward after that. The track model spread
increases quickly beyond day 4, at which time confidence in the
forecast is a little lower than normal. The model consensus hasn't
changed much, so only small adjustments were made to the official
track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 19.5N 35.8W 35 KT 40 MPH
12H 09/1200Z 20.4N 37.6W 40 KT 45 MPH
24H 10/0000Z 21.5N 39.5W 45 KT 50 MPH
36H 10/1200Z 22.6N 40.8W 50 KT 60 MPH
48H 11/0000Z 23.9N 41.6W 55 KT 65 MPH
60H 11/1200Z 25.5N 42.0W 60 KT 70 MPH
72H 12/0000Z 27.0N 42.4W 65 KT 75 MPH
96H 13/0000Z 30.0N 43.0W 70 KT 80 MPH
120H 14/0000Z 33.0N 43.5W 75 KT 85 MPH

$$
Forecaster D. Zelinsky

[cycloneye]

Tropical Storm Margot Discussion Number 8
NWS National Hurricane Center Miami FL AL142023
500 AM AST Sat Sep 09 2023

Margot has become better organized this morning. The earlier noted
exposed surface center has become obscured with bursts of deep
convection while the outflow pattern has become more diffluent in
the northeast quadrant of the cyclone. Therefore, the initial
intensity is raised to 40 kt and is based on the TAFB and SAB Dvorak
satellite intensity estimates.

Although some northerly shear and dry mid-level air intruding
from the southwest has slowed the intensification rate, the
intensity guidance indicates that Margot will become a hurricane
next week. In fact, the upper-level pattern becomes more favorable
by mid-period, although the statistical SHIPS intensity guidance
shows modest southerly shear at the time. Therefore, the official
forecast indicates gradual intensification through the entire
forecast period. The NHC intensity forecast favors the reliable
multi-model consensus aids, which is just below the Decay SHIPS
beyond day 3.

Margot is moving west-northwestward at 11 kt around the southwestern
periphery of a subtropical high over the eastern Atlantic. A
west-northwest to northwest motion is forecast through early
Sunday, followed by a turn toward north-northwest to north by late
Sunday with some reduction in forward speed. A slight adjustment
to the right of the previous forecast track was made to hedge
closer to the HFIP HCCA corrected consensus aid and TVCA simple
multi-model guidance.



FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 19.9N 36.9W 40 KT 45 MPH
12H 09/1800Z 20.6N 38.4W 45 KT 50 MPH
24H 10/0600Z 21.7N 39.9W 45 KT 50 MPH
36H 10/1800Z 22.8N 40.6W 55 KT 65 MPH
48H 11/0600Z 24.2N 41.0W 60 KT 70 MPH
60H 11/1800Z 25.7N 41.4W 65 KT 75 MPH
72H 12/0600Z 27.4N 41.5W 70 KT 80 MPH
96H 13/0600Z 31.2N 42.1W 75 KT 85 MPH
120H 14/0600Z 34.5N 43.4W 75 KT 85 MPH

$$
Forecaster Roberts

[cycloneye]

Tropical Storm Margot Discussion Number 9
NWS National Hurricane Center Miami FL AL142023
1100 AM AST Sat Sep 09 2023

Margot is looking a little better organized on satellite imagery
this morning compared to yesterday. A SSMIS microwave pass from
earlier this morning depicted that some banding features are trying
to develop on the northeastern side of the low-level center. The
deep convection also continues to burst near the center of the
system as well, with cold cloud tops. Subjective and objective
satellite intensity estimates from SAB/TAFB remain the same as the
previous cycle. Therefore, the initial intensity remains 40 kt for
this advisory.

Margot is currently within an environment of moderate vertical wind
shear and dry mid-level relative humidities. However, despite the
less than favorable environment the intensity guidance indicates
that Margot will gradually strengthen over the next few days as it
enters a more favorable upper-level wind pattern, and continues
over warm sea surface temperatures. The NHC forecast therefore
shows slow strengthening throughout the forecast period, similar to
the previous advisory, and lies near the HCCA and IVCN consensus
aids.

Margot is moving west-northwestward at 10 kt around the edge of a
subtropical ridge over the eastern Atlantic. This west-northwest
motion will continue during the next day or so, followed by a turn
to the northwest and northward by late in the weekend and early next
week, with a slower forward motion. Models are in fairly good
agreement in the short-term. However, the track model spread
increases in both cross- and along-track spread beyond day 3 to 4,
as there is some uncertainty in the steering flow. The NHC track
forecast lies near the model consensus aids, and only slight
adjustments to the previous forecast were made.


FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 20.5N 38.0W 40 KT 45 MPH
12H 10/0000Z 21.2N 39.3W 45 KT 50 MPH
24H 10/1200Z 22.3N 40.3W 50 KT 60 MPH
36H 11/0000Z 23.6N 40.8W 55 KT 65 MPH
48H 11/1200Z 25.0N 41.4W 60 KT 70 MPH
60H 12/0000Z 26.6N 41.7W 65 KT 75 MPH
72H 12/1200Z 28.4N 41.9W 70 KT 80 MPH
96H 13/1200Z 32.0N 42.4W 75 KT 85 MPH
120H 14/1200Z 34.3N 43.2W 75 KT 85 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 10
NWS National Hurricane Center Miami FL AL142023
500 PM AST Sat Sep 09 2023

Margot's satellite depiction has not improved much throughout the
afternoon. The system is dealing with west-southwesterly wind
shear, and struggling to become better organized. The low-level
center does have intermittent convective bursts that are then
sheared to the northeast. Given the lack of improvement in
satellite, the subjective and objective satellite intensity
estimates from SAB/TAFB remain steady. Therefore, the initial
intensity remains 40 kt for this advisory.

Environmental conditions are currently not very favorable with
moderate vertical wind shear, and dry mid-levels. Despite
the less than favorable environment the intensity guidance indicates
that Margot will gradually strengthen over the next few days as it
enters a more conducive upper-level wind pattern. The NHC forecast
is similar to the previous one, with gradual strengthening
anticipated, and lies near the corrected consensus aids.

Margot is moving northwestward at 8 kt around the edge of a
subtropical ridge over the eastern Atlantic. This northwest motion
will continue during the next day or so, followed by a turn to the
north-northwest and north by late in the weekend and early next
week. Models are in fairly good agreement in the short-term.
However, the track model spread increases in both cross- and
along-track directions beyond day 3. There has been a shift to the
right in the consensus aids, and the NHC has followed suit with a
slight shift to the right in the extended range. However, the NHC
track forecast remains to the left of some of the consensus aids,
and if this trend continues further adjustments to the forecast
track will be needed.


FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 21.0N 38.7W 40 KT 45 MPH
12H 10/0600Z 21.7N 39.7W 45 KT 50 MPH
24H 10/1800Z 23.1N 40.3W 50 KT 60 MPH
36H 11/0600Z 24.6N 40.7W 50 KT 60 MPH
48H 11/1800Z 26.0N 41.0W 55 KT 65 MPH
60H 12/0600Z 27.7N 41.2W 60 KT 70 MPH
72H 12/1800Z 29.7N 41.3W 65 KT 75 MPH
96H 13/1800Z 33.1N 41.8W 70 KT 80 MPH
120H 14/1800Z 34.8N 41.8W 75 KT 85 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 11
NWS National Hurricane Center Miami FL AL142023
1100 PM AST Sat Sep 09 2023

Although Margot has not become significantly better organized since
earlier today, recent scatterometer data indicate that it has
strengthened slightly with maximum winds around 45 kt. The system
continues to experience westerly shear that is at least partially
associated with the upper-level outflow of Hurricane Lee. In spite
of the shear, the center appears to be embedded within the main
area of deep convection. However, the overall cloud pattern
remains elongated from west-southwest to east-northeast and
convective banding features are not well defined at this time.

Center fixes indicate that the cyclone continues moving
northwestward, or at about 315/8 kt. Over the next couple of days,
Margot should turn north-northwestward to northward while passing
through a break in the mid-level subtropical ridge. Later in the
forecast period, the system's forward progress could be blocked by a
ridge building to its northwest. Some of the track guidance models,
notably the GFS, show Margot turning eastward around the end of the
forecast period. The official track forecast has been shifted
somewhat to the right of the previous NHC prediction, but is not as
far east as the new GFS solution. This is between the simple and
corrected dynamical consensus tracks.

The dynamical guidance indicates that the vertical wind shear
over Margot should remain moderate to strong for the next 48 hours
or so. In 3 to 5 days the global models show an upper-level
anticyclone developing over the system, which would favor
intensification, although the mid-level humidities are forecast to
be only marginally conducive by that time. Gradual strengthening is
predicted, at just a slightly faster pace than the previous NHC
forecast, and in good agreement with the latest intensity model
consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 10/0300Z 21.6N 39.1W 45 KT 50 MPH
12H 10/1200Z 22.5N 39.8W 50 KT 60 MPH
24H 11/0000Z 23.9N 40.2W 50 KT 60 MPH
36H 11/1200Z 25.4N 40.6W 55 KT 65 MPH
48H 12/0000Z 27.0N 40.9W 60 KT 70 MPH
60H 12/1200Z 28.8N 41.0W 65 KT 75 MPH
72H 13/0000Z 30.7N 41.1W 70 KT 80 MPH
96H 14/0000Z 34.0N 41.2W 75 KT 85 MPH
120H 15/0000Z 36.0N 40.0W 75 KT 85 MPH

$$
Forecaster Pasch

[cycloneye]

Tropical Storm Margot Discussion Number 12
NWS National Hurricane Center Miami FL AL142023
500 AM AST Sun Sep 10 2023

Westerly shear and a slug of dry air, which was noted in the
MET-10 water vapor imagery, impedes Margot's ability to sustain
deep convection near the surface center while most convection
remains displaced to the northeast. A recent AMSR2 microwave pass
confirmed that the surface center has again become exposed to the
southwest of the convective canopy. The initial intensity is held
at 45 kt and is based on the TAFB and SAB Dvorak satellite
intensity estimates.

The aforementioned moderate shear should continue to undercut the
diffluent southerly flow aloft during the next couple of days.
Afterward, the statistical-dynamic SHIPS guidance indicates that
Margot will slip under a narrow upper-level ridge, favoring
intensification. The only inhibiting factor during the latter part
of the forecast appears to be a less conducive surrounding
thermodynamic environment, which should affect the intensity rate
some. Therefore, only gradual strengthening is forecast and agrees
with intensity consensus models but below the HAFS-B hurricane
model, which predicts Margot as a hurricane on day 4. For now, the
official forecast shows Margot becoming a hurricane in 48 hours in
agreement with the reliable intensity consensus aids, but this
predicted rate of intensification could be generous.

Through the early part of this week, Margot is expected to turn
north-northwestward to northward while entering a growing weakness
in the central Atlantic subtropical ridge. Beyond day 3, Margot
will likely slow its forward motion in response to a building or
blocking high to the northwest. There remains quite a bit of model
spread/uncertainty late in the period, with the two global model
clusters showing Margot either turning eastward or moving toward
the northwest to west. The NHC track forecast conservatively lies
between the HFIP HCCA and simple consensus TVCA, which splits the
two model cluster solutions.



FORECAST POSITIONS AND MAX WINDS

INIT 10/0900Z 22.1N 39.6W 45 KT 50 MPH
12H 10/1800Z 23.1N 40.1W 50 KT 60 MPH
24H 11/0600Z 24.8N 40.5W 55 KT 65 MPH
36H 11/1800Z 26.5N 40.7W 60 KT 70 MPH
48H 12/0600Z 28.2N 40.8W 65 KT 75 MPH
60H 12/1800Z 30.1N 40.9W 70 KT 80 MPH
72H 13/0600Z 32.4N 41.0W 70 KT 80 MPH
96H 14/0600Z 35.0N 41.6W 75 KT 85 MPH
120H 15/0600Z 36.7N 41.9W 75 KT 85 MPH

$$
Forecaster Roberts

[cycloneye]

Tropical Storm Margot Discussion Number 13
NWS National Hurricane Center Miami FL AL142023
1100 AM AST Sun Sep 10 2023

Shear continues to impact Margot's ability to become better
organized. Visible satellite imagery this morning shows that the
low-level center of the system remains on the southwestern edge of
the deep convection. All the deep convection remains sheared to the
northeast. A 1154 UTC scatterometer pass this morning, depicted a
few wind barbs,that were not rain flagged, near 40 kt. Given the
undersampling of this instrument, the intensity is held at 45 kt
for this advisory. This is in agreement with the latest subjective
Dvorak satellite intensity estimate of T3.0 from TAFB.

Margot is currently within an environment of moderate vertical wind
shear, which is inhibiting the organization of the system. Despite
the less than favorable environment, the intensity guidance has
been persistent in Margot gradually strengthening over the next few
days as it enters a more favorable upper-level wind pattern, and
continues over warm sea surface temperatures. The NHC forecast is
for gradual strengthening and has Margot becoming a hurricane in
about two days. This is in agreement with the corrected consensus
HCCA, and IVCN intensity aids.

Margot is expected continue to move north-northwestward to northward
into a weakness in the central Atlantic subtropical ridge. Beyond
day 3, Margot will begin to slow its forward motion as the steering
pattern weakens. Towards the end of the forecast period, there
remains quite a bit of cross-track model spread, and some models
have the system meandering in the central Atlantic. There is higher
than normal uncertainty in this time range. The NHC track forecast
lies between the HFIP HCCA and simple consensus TVCA.

FORECAST POSITIONS AND MAX WINDS

INIT 10/1500Z 23.0N 40.0W 45 KT 50 MPH
12H 11/0000Z 24.1N 40.3W 50 KT 60 MPH
24H 11/1200Z 25.8N 40.6W 55 KT 65 MPH
36H 12/0000Z 27.5N 40.6W 60 KT 70 MPH
48H 12/1200Z 29.5N 40.7W 65 KT 75 MPH
60H 13/0000Z 31.6N 40.9W 70 KT 80 MPH
72H 13/1200Z 33.3N 41.3W 70 KT 80 MPH
96H 14/1200Z 35.6N 41.6W 75 KT 85 MPH
120H 15/1200Z 36.9N 41.7W 70 KT 80 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 14
NWS National Hurricane Center Miami FL AL142023
500 PM AST Sun Sep 10 2023

Margot has become better organized this afternoon. Visible and
infrared satellite imagery indicate that the low-level center has
tucked up under the deep convection. A recent SSMI/S microwave pass
depicts that there is well-defined curved banding around the center.
Deep convection continues to burst near the center. Subjective and
objective Dvorak satellite estimates from TAFB and SAB are T/3.5 and
T/3.0, respectively. Given the improved structure, this advisory
will lean towards the higher end of these estimates and the initial
intensity is raised to 55 kt.

Margot is still within an environment of moderate southwesterly wind
shear. The vertical wind shear is forecast to persist, but
strengthening is forecast over the coming days as the system is
entering a more favorable upper-level divergent wind pattern. Margot
will continue to traverse warm sea surface temperatures throughout
the forecast period, around 28 degrees Celsius. The NHC forecast is
slightly higher in the short term, with Margot forecast to become a
hurricane on Monday. The NHC intensity forecast lies near the HCCA
and IVCN consensus intensity aids.

Margot is moving northward at around 8 kt. A northward motion is
expected to continue into a weakness in the central Atlantic
subtropical ridge. In about 2 to 3 days, Margot's forward motion is
forecast to slow down as the steering flow weakens. Towards the end
of the forecast period, there remains considerably large
cross-track model spread. The NHC track forecast lies between the
consensus aids, with the system meandering over the central
Atlantic.


FORECAST POSITIONS AND MAX WINDS

INIT 10/2100Z 23.9N 40.1W 55 KT 65 MPH
12H 11/0600Z 25.1N 40.2W 60 KT 70 MPH
24H 11/1800Z 26.8N 40.4W 65 KT 75 MPH
36H 12/0600Z 28.7N 40.4W 70 KT 80 MPH
48H 12/1800Z 30.8N 40.5W 75 KT 85 MPH
60H 13/0600Z 32.9N 40.9W 75 KT 85 MPH
72H 13/1800Z 34.3N 41.4W 75 KT 85 MPH
96H 14/1800Z 36.3N 41.3W 75 KT 85 MPH
120H 15/1800Z 37.2N 41.2W 70 KT 80 MPH

$$
Forecaster Kelly

[cycloneye]

Tropical Storm Margot Discussion Number 15
NWS National Hurricane Center Miami FL AL142023
1100 PM AST Sun Sep 10 2023

Margot has been exhibiting a figure six cloud pattern on satellite
imagery, with a dry slot wrapping around the eastern portion of the
circulation. Central convection has not increased recently, and the
system has become essentially co-located with an upper-level trough.
The combination of Margot and the trough appears to have created an
upper-level outflow channel over the northeast quadrant, but outflow
is limited elsewhere. Subjective Dvorak classifications are T3.5
from both TAFB and SAB, corresponding to a current intensity of 55
kt. Objective intensity estimates from UW-CIMSS are mostly a little
lower, and there is no change to the current maximum winds for this
advisory.

The storm continues to move on a northward heading with a motion
estimate of 360/7 kt. Margot should move generally northward
through a weakness in the mid-level subtropical ridge for the next
48 to 72 hours with a gradual decrease in forward speed. In 3 to 5
days, a blocking high develops to the north of the tropical cyclone.
This should result in a slow and possibly erratic motion late in
the forecast period. The official forecast track, which is similar
to the one from the previous advisory, is rather close to the latest
dynamical model consensus, TVCA, objective aid.

Global model predictions indicate that, over the next couple of
days, the upper-level trough will shift south and southwest of
Margot with anticyclonic upper-tropospheric flow developing over the
system. This should be conducive for some strengthening, and the
official forecast shows Margot becoming a hurricane soon and then
intensifying a little more over the next 48 hours. This is in good
agreement with the LGEM and consensus intensity models.


FORECAST POSITIONS AND MAX WINDS

INIT 11/0300Z 24.6N 39.9W 55 KT 65 MPH
12H 11/1200Z 26.0N 40.0W 60 KT 70 MPH
24H 12/0000Z 27.8N 40.0W 65 KT 75 MPH
36H 12/1200Z 29.8N 40.1W 70 KT 80 MPH
48H 13/0000Z 31.8N 40.5W 75 KT 85 MPH
60H 13/1200Z 33.6N 41.2W 75 KT 85 MPH
72H 14/0000Z 34.8N 41.6W 75 KT 85 MPH
96H 15/0000Z 36.6N 41.0W 75 KT 85 MPH
120H 16/0000Z 37.5N 40.8W 65 KT 75 MPH

$$
Forecaster Pasch

[cycloneye]

Tropical Storm Margot Discussion Number 16
NWS National Hurricane Center Miami FL AL142023
900 AM GMT Mon Sep 11 2023

This morning's satellite presentation consists of an isolated area
of deep convection near Margot's surface center and a curved band
displaced about 160 mi to the northeast beneath upper-level
southerly diffluent flow. This distinctive cloud pattern is a
result of very dry mid-tropospheric air intruding from the
southwest and wrapping around and into the northeast sector of the
cyclone. The Dvorak satellite intensity estimates from TAFB and
SAB haven't changed since last night, and the initial intensity is
held at 55 kt for this advisory.

The latest GFS and ECMWF sounding analyses show modest northwesterly
shear undercutting the diffluent southerly flow aloft while drying
and stabilizing the mid-level portion of the atmosphere. In fact,
the statistical-dynamic SHIPS indicates 40 to 50% relative humidity
in the surrounding environment. The deterministic and SHIPS models
still indicate, however, that the upper-level trough providing these
inhibiting conditions will lift northeastward soon, allowing
anticyclonic upper-tropospheric flow to develop over Margot. As a
result, the cyclone should strengthen, and the NHC intensity
forecast follows suit and indicates the cyclone becoming a hurricane
in less than 24 hours while intensifying further through mid-week.
Weakening is predicted beyond day 3 as the thermodynamic environment
in the mid-latitudes of the central Atlantic becomes even less
favorable. The official intensity forecast follows the HFIP HCCA
corrected consensus intensity model through 48 hours, then is based
on a blend of the HCCA, Decay SHIPS, and the IVCN intensity aids.

Margot's initial motion during the past 12 hours has been north, or
360/7 kt. A mid-tropospheric subtropical ridge extending from west
Africa to the eastern subtropical Atlantic should steer the cyclone
in a generally northward trajectory through an amplified weakness
over the central Atlantic over the next 72 hours. Through the
remaining period, Margot is expected to slow in forward speed, and
possibly meander, in response to high pressure building to the
north of the cyclone over the central north Atlantic. The NHC
forecast track is adjusted slightly to the right beyond 48 hours,
and lies between the previous forecast and the TVCA simple average
multi-model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 25.3N 40.0W 55 KT 65 MPH
12H 11/1800Z 26.6N 39.9W 60 KT 70 MPH
24H 12/0600Z 28.6N 39.8W 70 KT 80 MPH
36H 12/1800Z 30.8N 40.1W 75 KT 85 MPH
48H 13/0600Z 32.7N 40.8W 75 KT 85 MPH
60H 13/1800Z 34.0N 41.7W 75 KT 85 MPH
72H 14/0600Z 35.0N 42.0W 75 KT 85 MPH
96H 15/0600Z 36.7N 41.0W 70 KT 80 MPH
120H 16/0600Z 37.1N 40.9W 60 KT 70 MPH

$$
Forecaster Roberts

[cycloneye]

Tropical Storm Margot Discussion Number 17
NWS National Hurricane Center Miami FL AL142023
Issued by the NWS Weather Prediction Center College Park MD
300 PM GMT Mon Sep 11 2023

Satellite images indicate that Margot is strengthening. A ragged
eye has emerged from the central dense overcast pattern, although
it is open on the east side. Additionally, overnight microwave
data showed the eye pattern on numerous passes, suggesting this is
a real eye feature. With the improvement in the satellite
presentation, the initial wind speed is set to 60 kt, closest to
the D-MINT intensity estimate from UW-CIMSS, but below recent
Dvorak DT estimates of 65 kt.

Margot is moving northward at about 9 kt, and that general motion
should continue for the next few days, with a north-northwest bend
expected by midweek as ridging builds to the east of the storm. A
large mid-latitude ridge is forecast to block Margot's path after
that time, causing the cyclone to basically stall by the weekend.
Guidance is in very good agreement for the first few days, then the
uncertainty grows in unsteady steering currents beneath the ridge,
with aids fanning out in all directions. The new forecast is
similar to the previous one, showing little motion at days 4-5 as a
compromise between the various divergent model solutions.

The storm has a chance to strengthen further over the next couple
of days while it moves over relatively warm waters up to 28 deg C
and in lessening shear. In a few days, an increase in shear and
dry-air entrainment should gradually weaken Margot. This is an
interesting forecast because the dynamical model guidance is well
below the statistical guidance, despite a seemingly conducive
environment for intensification. The new NHC forecast leans
closer to the statistical models, adjusted a bit higher than the
last NHC intensity prediction, similar to the Florida State
Superensemble and NOAA corrected-consensus models.



FORECAST POSITIONS AND MAX WINDS

INIT 11/1500Z 26.1N 40.0W 60 KT 70 MPH
12H 12/0000Z 27.6N 40.0W 65 KT 75 MPH
24H 12/1200Z 29.8N 40.0W 75 KT 85 MPH
36H 13/0000Z 31.9N 40.5W 80 KT 90 MPH
48H 13/1200Z 33.6N 41.4W 80 KT 90 MPH
60H 14/0000Z 34.7N 41.9W 75 KT 85 MPH
72H 14/1200Z 35.8N 41.8W 70 KT 80 MPH
96H 15/1200Z 37.1N 40.9W 65 KT 75 MPH
120H 16/1200Z 37.0N 41.0W 55 KT 65 MPH

$$
Forecaster Blake/Taylor

[cycloneye]

Hurricane Margot Discussion Number 18
NWS National Hurricane Center Miami FL AL142023
Issued by the NWS Weather Prediction Center College Park MD
900 PM GMT Mon Sep 11 2023

Satellite images this afternoon indicate that Margot continues to
strengthen with a more defined eye present while recent microwave
data shows improvement in the overall eye pattern. The latest TAFB
Dvorak intensity estimate of 65 kt, combined with the improved
satellite structure provides enough support to set the initial wind
speed at 65 kt this forecast cycle, making Margot the fifth
hurricane of the Atlantic season.

Margot is moving northward at about 10 kt. This motion is expected
to continue for the next couple of days before a slowing trend
occurs as Margot bends to the north-northwest due to a building
ridge to the east of the hurricane. Further slowing in the storm's
motion is expected by this weekend as a large mid-latitude ridge
blocks its path, effectively stalling the system. Beyond that time,
there continues to be uncertainty in the track with the various
model guidance showing a wide spread of possible solutions. The new
forecast lies near the previous NHC track, shifted a bit to the
west at long range.

The environment will continue to become more conducive for further
strengthening over the next 36 to 48 hours, with a gradual decrease
in vertical shear expected while Margot remains over relatively warm
waters of around 28 deg C. Beyond 72 hours, increasing shear and
drier air working into the system is likely to weaken Margot some.
The new forecast shows an increase in intensity through 48 hours
based on the expected favorable environment and higher statistical
guidance, leaning toward the Florida State Superensemble and NOAA
corrected-consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 27.0N 39.8W 65 KT 75 MPH
12H 12/0600Z 28.5N 39.8W 75 KT 85 MPH
24H 12/1800Z 30.7N 40.0W 80 KT 90 MPH
36H 13/0600Z 32.6N 40.7W 85 KT 100 MPH
48H 13/1800Z 34.1N 41.5W 85 KT 100 MPH
60H 14/0600Z 35.2N 41.6W 80 KT 90 MPH
72H 14/1800Z 36.0N 41.4W 75 KT 85 MPH
96H 15/1800Z 37.1N 40.8W 65 KT 75 MPH
120H 16/1800Z 37.0N 41.5W 55 KT 65 MPH

$$
Forecaster Taylor/Blake

[cycloneye]

Hurricane Margot Discussion Number 19
NWS National Hurricane Center Miami FL AL142023
300 AM GMT Tue Sep 12 2023

Margot has continued to become better organized over the past
several hours. The eye is becoming a little more distinct, and
inner-core convection has intensified somewhat, with cooling cloud
tops. Convective banding features are evident, particularly over
the southeastern portion of the circulation. Upper-level outflow
is well defined over the northern semicircle of the system. The
current intensity estimate is now 70 kt which is a blend of
subjective Dvorak classification estimates from TAFB and SAB.

Recent center fixes show a slight rightward wobble in the track but
the longer-term motion estimate is generally northward or 010/10 kt.
Margot is expected to move northward to north-northwestward between
two subtropical high pressure areas over the next few days. Later
in the forecast period, a blocking mid-level high pressure system
develops to the north of the tropical cyclone. This will cause
Margot to move rather slowly and perhaps erratically over the
subtropical Atlantic in the 4-5 day time frame. The official track
forecast is fairly close to the previous NHC prediction and
generally follows the multi-model TVCN consensus solution.

Global models indicate that the upper-level tropospheric flow over
Margot should be conducive for some more strengthening during the
next 36 hours or so, with diffluent anticyclonic winds aloft over
the system. The official intensity forecast is about the same as
the previous one and remains close to the model consensus. The
statistical-dynamical guidance DSHIPS suggests that the hurricane
could become a little stronger than shown here. Later in the
period, increasing shear and cooler ocean waters will likely cause
a weakening trend.


FORECAST POSITIONS AND MAX WINDS

INIT 12/0300Z 28.0N 39.6W 70 KT 80 MPH
12H 12/1200Z 29.7N 39.8W 75 KT 85 MPH
24H 13/0000Z 31.8N 40.2W 80 KT 90 MPH
36H 13/1200Z 33.4N 41.2W 85 KT 100 MPH
48H 14/0000Z 34.6N 41.9W 85 KT 100 MPH
60H 14/1200Z 35.6N 41.9W 80 KT 90 MPH
72H 15/0000Z 36.5N 41.4W 75 KT 85 MPH
96H 16/0000Z 37.3N 41.4W 65 KT 75 MPH
120H 17/0000Z 38.5N 42.0W 55 KT 65 MPH

$$
Forecaster Pasch

[cycloneye]

Hurricane Margot Discussion Number 20
NWS National Hurricane Center Miami FL AL142023
900 AM GMT Tue Sep 12 2023

Margot's eye became obscured in infrared satellite imagery a couple
of hours ago, but the hurricane still has a well-defined Central
Dense Overcast surrounded by convective banding features. A dry
slot has become entrained into the eastern part of the circulation,
between the CDO and the outermost banding. Based on consensus
Dvorak estimates of T4.5 from TAFB and SAB, the initial intensity
is raised to 75 kt.

Margot is moving northward (360/11 kt) along the western periphery
of a mid-level ridge emanating out of western Africa, and this
steering mechanism should keep the hurricane on a general
northward or north-northwestward trajectory for the next few
days. A blocking ridge is forecast to form in 2-3 days over the
north Atlantic, which is likely to cause Margot to slow down during
the middle to latter part of the forecast period. However, the
ridge may be relatively progressive, and by day 5 many of the track
models show the storm picking up some speed again once the ridge
gets out of the way. The most notable change in the NHC track
forecast is that it's faster than the previous prediction on days 4
and 5 to better align with the latest guidance.

The hurricane is currently within a strongly diffluent environment
to the east of an upper-level trough, but the environment is
forecast to evolve to an anticyclone aloft and low shear within the
next 12 hours. Continued strengthening is therefore likely, but
any intensification trend could be halted soon after 24 hours when
the hurricane slows down and potentially upwells cooler waters.
The NHC intensity forecast is above the intensity consensus during
the first day or two and is closest to the statistical-dynamical
guidance. Weakening is likely to occur after 48 hours due to
cooler waters and an increase in deep-layer shear.


FORECAST POSITIONS AND MAX WINDS

INIT 12/0900Z 29.3N 39.5W 75 KT 85 MPH
12H 12/1800Z 30.9N 39.9W 80 KT 90 MPH
24H 13/0600Z 32.7N 40.8W 85 KT 100 MPH
36H 13/1800Z 34.0N 41.7W 85 KT 100 MPH
48H 14/0600Z 35.0N 42.1W 85 KT 100 MPH
60H 14/1800Z 36.0N 41.9W 80 KT 90 MPH
72H 15/0600Z 36.9N 41.6W 75 KT 85 MPH
96H 16/0600Z 38.2N 42.6W 60 KT 70 MPH
120H 17/0600Z 40.4N 43.4W 50 KT 60 MPH

$$
Forecaster Berg