ATL: DON - Advisories

[cycloneye]

BULLETIN
Subtropical Storm Don Advisory Number 1
NWS National Hurricane Center Miami FL AL052023
500 AM AST Fri Jul 14 2023

...SUBTROPICAL STORM DON FORMS OVER THE CENTRAL ATLANTIC...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...32.9N 46.8W
ABOUT 1165 MI...1875 KM WSW OF THE AZORES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES



Subtropical Storm Don Discussion Number 1
NWS National Hurricane Center Miami FL AL052023
500 AM AST Fri Jul 14 2023

The area of low pressure that NHC has been monitoring roughly midway
between Bermuda and the Azores has become Subtropical Storm Don.
The storm is assessed as subtropical because it is embedded within
an upper-level trough and has a relatively large radius of maximum
wind. Several hours ago, a well-defined center of circulation
developed and deep convection has remained sufficiently organized,
especially in bands to the east of the center. A pair of partial
ASCAT passes from around 00Z showed peak winds around 45 kt, and
that is the initial intensity set for this advisory.

Don has been moving slowly northward at about 5 kt during the past 6
to 12 hours, and a continued slow northward or north-northwestward
motion is expected during the next couple of days as a building
ridge over the central Atlantic prevents it from accelerating
poleward. That ridge is expected to weaken on Sunday while another
ridge builds to the southeast of Don and a trough amplifies over the
northeastern Atlantic. This pattern change should cause Don to turn
eastward on Sunday and then southeastward early next week. The NHC
track forecast lies near the middle of the guidance envelope, in
best agreement with the various consensus aids.

The storm is likely near its peak intensity already. Dry air is
wrapping in on the south and west sides of the circulation and that
stable air is expected to continue to entrain into the storm during
the next several days. In addition, sea surface temperatures are
expected to decrease along the forecast track during the next 2 or
3 days. Although the environment is not conducive for
strengthening, it is also not hostile enough to cause significant
weakening. Therefore, the NHC official forecast shows a gradual
decay in Don’s strength. The environment looks more conducive by
the end of the period, and some strengthening is possible by then
if the storm survives that long. The NHC intensity forecast
follows the theme of the models, which are tightly clustered.


FORECAST POSITIONS AND MAX WINDS

INIT 14/0900Z 32.9N 46.8W 45 KT 50 MPH
12H 14/1800Z 33.5N 47.0W 45 KT 50 MPH
24H 15/0600Z 34.9N 47.3W 45 KT 50 MPH
36H 15/1800Z 36.4N 47.8W 45 KT 50 MPH
48H 16/0600Z 37.6N 47.8W 40 KT 45 MPH
60H 16/1800Z 38.4N 47.1W 40 KT 45 MPH
72H 17/0600Z 38.5N 44.9W 35 KT 40 MPH
96H 18/0600Z 35.9N 40.7W 35 KT 40 MPH
120H 19/0600Z 33.4N 38.5W 40 KT 45 MPH

$$
Forecaster Cangialosi

[cycloneye]

Subtropical Storm Don Discussion Number 2
NWS National Hurricane Center Miami FL AL052023
1100 AM AST Fri Jul 14 2023

Don's deep convection has been waning in intensity since the
overnight hours, with most of the activity located in broken bands
to the north and east of the center of circulation. The cyclone
remains subtropical, given that it is embedded within a deep-layer
trough and has a relatively large radius of maximum winds. A
just-received ASCAT pass over Don shows a swath of 35-40 kt winds
to the east of the center, so the initial intensity is therefore
lowered to 40 kt.

Don's recent motion has been north-northwestward, or 340/6 kt, with
the cyclone surrounded by a pair of strong mid-level ridges to its
east and north, and a broad trough over the western Atlantic. The
ridge to the east will be the main steering influence, and that
feature is expected to migrate westward across the Atlantic during
the next several days. Don is forecast to move slowly around the
northern side of the ridge, turning northward, eastward, and then
southeastward over the next 5 days. In spite of the somewhat
complicated mid-latitude pattern, the track models are in fairly
good agreement for much of the forecast period. The new NHC track
forecast is nudged northward during the 2- to 4-day part of the
forecast toward the consensus aids but otherwise is very similar to
the forecast from earlier this morning.

Subsiding dry air on the back side of the trough is getting
entrained into Don's circulation, and the storm is over waters of
25-26 degrees Celsius, heading towards waters as cold as 23 degrees
in about 3 days. Although the trough may be able to continue to
supply some baroclinic energy to Don, the cyclone's maximum winds
are likely to gradually diminish over the next few days given the
less favorable thermodynamic environment. There is a chance that
Don could lose enough convective organization and become a
post-tropical cyclone at some point during the next few days.
However, by days 4 and 5, Don will be heading back southward toward
relatively warmer waters, and a new mid-latitude shortwave trough
may provide a boost to the system's organization and strength. As a
result, the NHC intensity forecast shows possible restrengthening at
the end of the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 33.7N 47.3W 40 KT 45 MPH
12H 15/0000Z 34.5N 47.5W 40 KT 45 MPH
24H 15/1200Z 36.0N 47.8W 40 KT 45 MPH
36H 16/0000Z 37.4N 48.1W 35 KT 40 MPH
48H 16/1200Z 38.5N 47.7W 35 KT 40 MPH
60H 17/0000Z 39.0N 46.2W 35 KT 40 MPH
72H 17/1200Z 38.6N 43.9W 35 KT 40 MPH
96H 18/1200Z 35.7N 40.0W 35 KT 40 MPH
120H 19/1200Z 33.7N 38.6W 40 KT 45 MPH

$$
Forecaster Berg

[cycloneye]

Subtropical Storm Don Discussion Number 3
NWS National Hurricane Center Miami FL AL052023
500 PM AST Fri Jul 14 2023

Don is producing two broken bands of convection which are displaced
to the east of the low-level center. The cyclone still leans
heavily on the subtropical side of the spectrum, lacking a central
dense overcast, being associated with an upper-level low, and having
an asymmetric distribution of convection. However, this morning's
ASCAT data did indicate that the radius of maximum winds had
contracted down to 30 n mi, more akin to a tropical cyclone. Based
on the earlier ASCAT data and an Hebert-Poteat classification of
ST2.5 from TAFB, the initial intensity remains 40 kt.

Don deviated to the left of the previous forecast track during the
past few hours and is estimated to be moving northwestward, or
325/7 kt. Despite that, the track forecast reasoning is unchanged.
An eastern Atlantic mid-level ridge will be the main steering
influence and is expected to migrate westward across the Atlantic
during the next several days. Don is forecast to move around the
northern and eastern side of the ridge, turning northward,
eastward, and then southward over the next 5 days. The new NHC
track forecast has been shifted a bit westward, mainly due to the
recent deviation to the west, and is close to a blend of the TVCA
and FSSE consensus aids.

Subsidence behind the trough is causing dry air to be entrained
into Don's circulation, and the storm is currently over waters of
25-26 degrees Celsius. The forecast track takes Don over waters as
cold as 23 degrees in about 3 days, and simulated satellite imagery
from the GFS and ECMWF suggests that the convective coverage
and pattern could be quite degraded by that time. Still, the
intensity guidance is in relatively good agreement that Don will
only weaken a bit during the next several days, with some possible
restrengthening by the end of the forecast period when the storm
again reaches warmer waters. For continuity's sake, the forecast
continues to show Don maintaining subtropical storm status for the
next 5 days, but it could become post-tropical at any time if the
convection wanes and loses organization.


FORECAST POSITIONS AND MAX WINDS

INIT 14/2100Z 34.1N 48.0W 40 KT 45 MPH
12H 15/0600Z 35.1N 48.3W 40 KT 45 MPH
24H 15/1800Z 36.5N 48.7W 40 KT 45 MPH
36H 16/0600Z 37.8N 48.6W 35 KT 40 MPH
48H 16/1800Z 38.7N 47.7W 35 KT 40 MPH
60H 17/0600Z 38.7N 45.8W 35 KT 40 MPH
72H 17/1800Z 37.9N 43.7W 35 KT 40 MPH
96H 18/1800Z 35.0N 40.7W 35 KT 40 MPH
120H 19/1800Z 33.0N 40.6W 40 KT 45 MPH

$$
Forecaster Berg

[cycloneye]

Subtropical Storm Don Discussion Number 4
NWS National Hurricane Center Miami FL AL052023
1100 PM AST Fri Jul 14 2023

Don continues to display characteristics of a sheared subtropical
storm. Infrared satellite imagery shows remnants of earlier
convective activity are offset to the north and east of the
circulation and a single burst of fresh convection has formed just
east of the exposed low-level center. Subjective satellite estimate
from TAFB still classify Don as a ST2.5, and the initial intensity
remains at 40 kt.

The cyclone has turned northward after a brief wobble westward.
The motion, averaged over 12 hours, is northward at 8 kt. The
track forecast reasoning remains the same. A ridge centered over
the eastern Atlantic will shift westward over the next few days.
Don will move around the periphery of the ridge, continuing
northward, and then turning eastward and southward by the end of the
forecast period. The updated track forecast has moved back east of
the previous prediction, largely due to the initial position, and
is close to the consensus model aids.

Don has just moved over waters cooler than 25 degrees Celsius and
continues to entrain dry mid-level air. Along the forecast track,
sea surface temperatures are forecast to decrease over the next few
days as the cyclone moves northward. Simulated satellite imagery
from global models suggests the convective organization should
degrade during this timeframe, though some models show Don
restrengthening with the southward bringing it over warmer waters.
The official intensity forecast is unchanged from the previous
advisory and maintains Don's subtropical classification through the
forecast period. However, should the storm continue to lose
convective coverage and organization it could become post-tropical
at any time.


FORECAST POSITIONS AND MAX WINDS

INIT 15/0300Z 34.7N 47.2W 40 KT 45 MPH
12H 15/1200Z 35.8N 47.5W 40 KT 45 MPH
24H 16/0000Z 37.1N 47.7W 40 KT 45 MPH
36H 16/1200Z 38.4N 47.2W 35 KT 40 MPH
48H 17/0000Z 38.8N 45.7W 35 KT 40 MPH
60H 17/1200Z 38.7N 43.8W 35 KT 40 MPH
72H 18/0000Z 37.5N 42.0W 35 KT 40 MPH
96H 19/0000Z 34.5N 39.9W 35 KT 40 MPH
120H 20/0000Z 33.4N 39.9W 40 KT 45 MPH

$$
Forecaster Bucci

[cycloneye]

Subtropical Storm Don Discussion Number 5
NWS National Hurricane Center Miami FL AL052023
500 AM AST Sat Jul 15 2023

Don appears to be holding steady in strength. The storm is
producing bands of deep convection mostly on its north side, with
dry air continuing to wrap into the southern half of the
circulation. The latest satellite intensity estimates range from 35
to 45 kt, and based on these data, the initial intensity is held at
40 kt.

Although the storm has been wobbling around, the general motion has
been northward at about 8 kt during the past 12-24 hours, and that
should continue through tonight. On Sunday, a turn to the east is
expected as Don moves in the flow on the north side of a subtropical
ridge over the eastern Atlantic. The storm will likely turn
southeastward beginning late Monday as a trough amplifies over the
northeastern Atlantic and western Europe. However, the steering
currents could collapse during the middle part of next week causing
the storm to stall. Despite the relatively complex steering flow,
the models are in general agreement and have not changed much during
the past several cycles. The NHC track forecast is a little to the
north of the previous one in the short term, but most of the
changes were minor. This track is close to the various consensus
models.

Don is over relatively cool 25 degree C waters and the sea surface
temperatures are expected to decrease another couple of degrees
along the forecast track during the next 2 days or so. These
generally unfavorable oceanic conditions combined with dry air
surrounding the system should cause Don to either hold steady or
lose some strength during the next 2 or 3 days. In fact, it is
possible that Don becomes a post-tropical cyclone at some point
during that time period. However, beyond a few days, the storm is
expected to move back over slightly warmer waters, which could allow
Don to restrengthen if manages to survive that long. The NHC
intensity forecast is the same as the previous one and near the
middle of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 15/0900Z 35.7N 47.8W 40 KT 45 MPH
12H 15/1800Z 36.9N 48.1W 40 KT 45 MPH
24H 16/0600Z 38.2N 48.1W 40 KT 45 MPH
36H 16/1800Z 39.1N 47.0W 35 KT 40 MPH
48H 17/0600Z 39.3N 45.0W 35 KT 40 MPH
60H 17/1800Z 38.7N 43.3W 35 KT 40 MPH
72H 18/0600Z 37.3N 41.7W 35 KT 40 MPH
96H 19/0600Z 34.3N 41.0W 35 KT 40 MPH
120H 20/0600Z 33.2N 41.0W 40 KT 45 MPH

$$
Forecaster Cangialosi

[cycloneye]

Subtropical Storm Don Discussion Number 6
NWS National Hurricane Center Miami FL AL052023
1100 AM AST Sat Jul 15 2023

While the low-level circulation of Don remains robust, any
associated convection is weaker than overnight and farther from the
center. Satellite intensity estimates haven't changed much, so the
initial wind speed will stay at 40 kt, though this feels a little
generous. Unfortunately, the morning scatterometer passes missed
the center.

Don has wobbled northwestward overnight, at about 8 kt. The storm
should turn northward later today and then eastward by late tomorrow
while it moves around the periphery of a strong subtropical ridge.
The biggest change to the forecast of Don is that the track guidance
has shifted northward in the first few days of the forecast period.
The NHC forecast is shifted in that direction, with little change in
the longer range as Don moves southward around the east side of the
strong ridge.

The storm should remain in a marginal environment during the next
few days with cool SSTs and dry air lurking, causing the system to
keep about the same strength or gradually decay. With the northward
forecast change, taking Don across cooler waters, it is possible
that Don could weaken into a depression or a remnant low in a
couple of days. Some re-intensification is possible at long
range when Don moves over warmer waters, though the uncertainty is
high. No big changes were made to the previous forecast, but it
wouldn't be surprising if downward adjustments were necessary in
the afternoon forecast package.


FORECAST POSITIONS AND MAX WINDS

INIT 15/1500Z 36.5N 48.8W 40 KT 45 MPH
12H 16/0000Z 37.8N 48.9W 35 KT 40 MPH
24H 16/1200Z 39.1N 48.3W 35 KT 40 MPH
36H 17/0000Z 39.5N 46.7W 35 KT 40 MPH
48H 17/1200Z 39.3N 44.6W 35 KT 40 MPH
60H 18/0000Z 38.4N 42.9W 35 KT 40 MPH
72H 18/1200Z 36.8N 41.9W 35 KT 40 MPH
96H 19/1200Z 33.9N 41.5W 35 KT 40 MPH
120H 20/1200Z 33.0N 42.0W 40 KT 45 MPH

$$
Forecaster Blake

[cycloneye]

Subtropical Storm Don Discussion Number 7
NWS National Hurricane Center Miami FL AL052023
500 PM AST Sat Jul 15 2023

Don has a poor appearance on the latest satellite imagery, with only
weak banding noted on the southeastern side of the circulation,
mostly removed from the center, and only moderate convection. With
the overall degradation in the satellite presentation, the current
wind speed is lowered slightly to 35 kt, consistent with the latest
TAFB classification.

The environment near Don is pretty harsh during the next few days,
with waters of 23-24C, dry air aloft, and bouts of shear. While
this should be counteracted by cool upper-level conditions, which
promote deep convection over lower sea-surface temperatures than
typical, most factors suggest some weakening next week. Thus the
latest forecast of Don is decreased from the previous one, leaning
closer to the global model solutions that generally show the system
becoming a depression in a day or so. While there's a chance of
re-strengthening at long range, it is probably just as likely that
the system will degenerate into a remnant low before that point.

Don continues wobbling, but appears to have started its northward
motion at about 8 kt. The storm should turn eastward by late
tomorrow and southward on Tuesday while it moves around the
northern periphery of a strong subtropical ridge. Don will probably
enter a weaker steering flow near midweek, with little net motion
expected for a day or so. Only minor eastward adjustments were
required to the NHC track forecast at long range as much of the
guidance come in close to the previous prediction. For such an
unusual July track, the guidance is in fairly good agreement, and
the NHC track is just west of the model consensus by day 5.


FORECAST POSITIONS AND MAX WINDS

INIT 15/2100Z 37.3N 48.6W 35 KT 40 MPH
12H 16/0600Z 38.3N 48.5W 35 KT 40 MPH
24H 16/1800Z 39.3N 47.3W 30 KT 35 MPH
36H 17/0600Z 39.4N 45.3W 30 KT 35 MPH
48H 17/1800Z 38.6N 43.1W 30 KT 35 MPH
60H 18/0600Z 37.1N 41.5W 30 KT 35 MPH
72H 18/1800Z 35.4N 40.7W 30 KT 35 MPH
96H 19/1800Z 33.2N 41.0W 35 KT 40 MPH
120H 20/1800Z 33.5N 42.0W 35 KT 40 MPH

$$
Forecaster Blake

[cycloneye]

Subtropical Storm Don Discussion Number 8
NWS National Hurricane Center Miami FL AL052023
1100 PM AST Sat Jul 15 2023

Don continues to sporadically produce bursts of convection and cling
to subtropical cyclone status. The storm currently consists of an
exposed low-level center with a limited area of thunderstorms in the
eastern portion of the circulation. The initial intensity remains
at 35 kt based on recent data from a scatterometer overpass
(ASCAT-C).

Atmospheric and oceanic conditions are generally not conducive for
development. Sea surface temperatures are between 23-24 degrees
Celsius along the forecast track for the next few days. Dry
mid-level humidities from subsiding air are also expected to be
quite low. However, isolated convection driven by cool upper-level
temperatures could still continue for the next several days
preventing Don from becoming a post-tropical cyclone. There is also
a chance the storm could slightly re-strengthen in the long-term
forecast when it moves southward. The official forecast is
unchanged from the the previous prediction.

The storm is moving northward at about 9 kt. The reasoning behind
the track forecast has also not changed. A strong subtropical ridge
is expected to steer Don eastward by late tomorrow and southward on
Tuesday. In the 4-5 day forecast period, Don will be in a region
with weak steering currents and likely linger in the same general
area. The updated NHC track forecast is very similar to the last
advisory forecast and the consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT 16/0300Z 38.2N 48.7W 35 KT 40 MPH
12H 16/1200Z 39.1N 48.2W 35 KT 40 MPH
24H 17/0000Z 39.7N 46.6W 30 KT 35 MPH
36H 17/1200Z 39.3N 44.5W 30 KT 35 MPH
48H 18/0000Z 38.2N 42.6W 30 KT 35 MPH
60H 18/1200Z 36.6N 41.4W 30 KT 35 MPH
72H 19/0000Z 35.1N 41.0W 30 KT 35 MPH
96H 20/0000Z 33.5N 41.6W 35 KT 40 MPH
120H 21/0000Z 34.2N 42.8W 35 KT 40 MPH

$$
Forecaster Bucci

[cycloneye]

Subtropical Storm Don Discussion Number 9
NWS National Hurricane Center Miami FL AL052023
500 AM AST Sun Jul 16 2023

Don is barely a subtropical storm. As mentioned in the previous
discussion, the ASCAT-C pass from around 00Z showed peak winds near
35 kt in a small area about 60 n mi east-northeast of the center.
Deep convection is limited to the same region where the strongest
winds were observed. The initial intensity remains 35 kt for this
advisory based on the earlier ASCAT data and a blend of the latest
satellite intensity estimates that range from 25 to 45 kt.

The storm is currently over cool 24 degree C waters and the sea
surface temperatures along the expected track over the next day or
two are about a degree lower. These unfavorable oceanic conditions
combined with dry air that continues to wrap into the circulation
should cause Don to remain poorly organized. If the storm does
manage to survive beyond 48-72 hours, the water temperatures are
expected to increase a little along the forecast track, which could
cause some increase in thunderstorm activity. Nonetheless,
significant strengthening is not expected due to continued dry air
entrainment and an increase in wind shear. The NHC intensity
forecast is similar to the previous one and shows Don remaining a
weak system through the forecast period. However, even though not
explicitly forecast, it would not be surprising if Don becomes a
remnant low at some point in the next couple of days.

Don is gradually bending to the right and an eastward motion is
expected later today as high pressure builds over the eastern
Atlantic. A turn to the southeast is expected on Monday followed by
a southward motion as the ridge shifts westward and a trough becomes
established over the northeastern Atlantic. Don could stall or loop
around during the middle part of the weak as the steering currents
collapse. The model guidance has not changed much, and the NHC
track forecast generally follows the various consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT 16/0900Z 38.6N 48.4W 35 KT 40 MPH
12H 16/1800Z 39.3N 47.6W 35 KT 40 MPH
24H 17/0600Z 39.4N 45.6W 30 KT 35 MPH
36H 17/1800Z 38.6N 43.5W 30 KT 35 MPH
48H 18/0600Z 37.2N 41.8W 30 KT 35 MPH
60H 18/1800Z 35.8N 41.2W 30 KT 35 MPH
72H 19/0600Z 34.3N 41.3W 30 KT 35 MPH
96H 20/0600Z 32.8N 42.6W 35 KT 40 MPH
120H 21/0600Z 33.6N 44.7W 35 KT 40 MPH

$$
Forecaster Cangialosi

[cycloneye]

Subtropical Depression Don Discussion Number 10
NWS National Hurricane Center Miami FL AL052023
1100 AM AST Sun Jul 16 2023

Satellite images indicate that Don is producing a small area of
convection in the southeastern quadrant, though it is stretch to
call it very organized. Overall, the system is mostly a big swirl
of low- to mid-level clouds with occasional bursts of modest
convection. A 1250 UTC ASCAT-B scatterometer pass showed maximum
winds of about 30 kt, so that will be the initial wind speed.

Don has turned to the east-northeast this morning, and should
gradually execute a large clockwise loop over the central Atlantic
during the next few days, turning southeast, south and southwest.
Model guidance is in good agreement on this course through midweek,
and little change was made to the previous forecast. The long
range forecast is more uncertain, however, with Don potentially
becoming trapped in an area of lighter steering currents before
moving more northward, rather than westward in the loop. The model
spread is enormous by day 5, with about 1000 n mi of distance
between some of the ECMWF ensemble members. The new forecast is
trended westward toward the multi-model ensemble mean, with a
majority suggesting a northwest track at the end of the forecast
period, but that's far from certain.

The environment near Don is expected to be pretty hostile for the
next few days, with any cold air aloft promoting convection being
neutralized by cool waters, dry air surrounding the cyclone, and
some shear. This should result in little intensity change during
the next few days, and Don could also degenerate into a remnant low,
especially tomorrow when conditions could be the most harsh. At
long range, Don might have a chance to re-strengthen since it moves
over warmer waters with more instability, but Don could also be too
weak to take advantage of these factors. Considering the large
track uncertainty, the new forecast is the same as the previous one
at long range, below the model guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 16/1500Z 39.0N 48.1W 30 KT 35 MPH
12H 17/0000Z 39.4N 46.8W 30 KT 35 MPH
24H 17/1200Z 38.9N 44.6W 30 KT 35 MPH
36H 18/0000Z 37.8N 42.5W 30 KT 35 MPH
48H 18/1200Z 36.2N 41.2W 30 KT 35 MPH
60H 19/0000Z 34.7N 41.2W 30 KT 35 MPH
72H 19/1200Z 33.5N 41.8W 30 KT 35 MPH
96H 20/1200Z 33.0N 43.6W 35 KT 40 MPH
120H 21/1200Z 35.0N 47.0W 35 KT 40 MPH

$$

[cycloneye]

Subtropical Depression Don Discussion Number 11
NWS National Hurricane Center Miami FL AL052023
500 PM AST Sun Jul 16 2023

Don is a strange system. Satellite images show that convection has
increased in aerial coverage in the southeastern quadrant of the
cyclone, although it is still not well defined in banding features
or other organizational metrics. The convection is also closer to
the center, and the upper-level low near Don has weakened. In some
ways it has actually gained some tropical characteristics since
yesterday despite remaining over cool waters, but the convective
organization is still shy of a tropical cyclone. Regardless of the
scientific curiosity, there are no signs that the winds have
strengthened, and Don is best classified as a 30-kt subtropical
depression on this advisory.

Don has turned to the east this afternoon and should gradually
execute a large clockwise loop over the central Atlantic during the
next few days, first turning southeast, then south and southwest
through Wednesday. The only change to that part of the forecast was
a slight eastward adjustment at a faster forward speed. There
continues to be a large guidance spread on days 4/5 as Don moves
south of a blocking ridge and eventually turns to the west or
northwest. Interestingly, the regional hurricane models are
generally on the left side of the guidance envelope, and the global
models are on the right side. I just don't trust the regional
guidance in this set-up where the large-scale steering might matter
more than the storm structure (and the regional models struggle in
hybrid situations). Thus, the forecast leans on the eastern side of
the guidance at long range, resulting in little change from the
previous forecast, east of the model consensus.

Don isn't likely to change much in intensity for the next few days,
with a somewhat unfavorable environment persisting. While not
explicitly shown, it could degenerate into a remnant low during the
next few days until it reaches warmer waters. Then, a fair bit of
the guidance brings the system back (as a tropical cyclone) due to
more instability over warmer waters in a lighter shear environment.
The forecast does show Don as a tropical storm in 4 days, but with
water temperatures still below 25C, it isn't expected to be very
strong at long range. The new NHC forecast is close to the previous
one and remains lower than the guidance at the extended time ranges.


FORECAST POSITIONS AND MAX WINDS

INIT 16/2100Z 39.3N 47.0W 30 KT 35 MPH
12H 17/0600Z 39.4N 45.3W 30 KT 35 MPH
24H 17/1800Z 38.5N 42.9W 30 KT 35 MPH
36H 18/0600Z 37.0N 41.1W 30 KT 35 MPH
48H 18/1800Z 35.3N 40.6W 30 KT 35 MPH
60H 19/0600Z 33.8N 40.9W 30 KT 35 MPH
72H 19/1800Z 33.0N 41.5W 30 KT 35 MPH
96H 20/1800Z 33.4N 44.3W 35 KT 40 MPH...TROPICAL CYCLONE
120H 21/1800Z 35.5N 48.0W 35 KT 40 MPH

$$
Forecaster Blake

[cycloneye]

Subtropical Depression Don Discussion Number 12
NWS National Hurricane Center Miami FL AL052023
1100 PM AST Sun Jul 16 2023

Convection has been waxing and waning near Don this evening, with
only a small area of -50 to -60C tops occuring to the east of the
center. Despite the relatively meager convective structure, Don's
appearance now looks more akin to a sheared tropical depression,
since the upper-level low that was over Don at the start of the
weekend has largely dissipated. However, the most recent TAFB Dvorak
classification kept the system subtropical given the limited
convective activity, and so Don will still be classified as a
subtropical cyclone at this time, with maximum sustained winds
of 30 kt for this advisory.

Don continues to move eastward, with the latest motion estimated at
090/9 kt. An anomalously strong low- to mid-level anticyclone is
currently centered south of Don, and this feature is expected to
shift westward and quickly build poleward to the west and northwest
of the cyclone. Eventually this ridge will fold back over to Don's
north towards the end of this week. The net result of this pattern
reconfiguration is Don should begin to execute a clockwise loop over
the Central Atlantic, first turning southeast tomorrow, south and
southwest by Tuesday, and finally turning westward and then
northwestward towards the middle to latter part of the week. The
track guidance this cycle has shifted back eastward, and only modest
track adjustments were needed in the official forecast for the first
three days, followed by an adjustment eastward in days 4-5. However,
given the continued spread in the ensemble track guidance at that
time range, that portion of the forecast remains low confidence.

Don’s short-term future is dependent on its ability to continue
producing enough convective activity to prevent it from becoming a
remnant low. Right now, sea-surface temperatures over the system are
around 23C, about the coldest they will be along its forecast track.
As the system begins to lose latitude over the next several days,
these waters warm to around 25C, while upper-level temperatures
remain sufficently cold to result in increased instability. Both the
regional-hurricane models and global models show Don maintaining or
increasing convective activity near its center as it moves
southward. For these reasons, the latest intensity forecast now
shows the system transitioning to a tropical cyclone a bit earlier,
and also shows some gradual intensification beginning at 48 hours as
the system moves over these warmer waters. A bit more
intensification is shown in the latter part of the forecast, but
still remains under the majority of the guidance in the extended
range given the larger-than-normal uncertainty in the location and
structure of the system at the end of the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 17/0300Z 39.4N 45.8W 30 KT 35 MPH
12H 17/1200Z 39.1N 43.9W 30 KT 35 MPH
24H 18/0000Z 37.9N 41.8W 30 KT 35 MPH
36H 18/1200Z 36.3N 40.7W 30 KT 35 MPH...TROPICAL CYCLONE
48H 19/0000Z 34.6N 40.5W 35 KT 40 MPH
60H 19/1200Z 33.5N 40.9W 35 KT 40 MPH
72H 20/0000Z 33.2N 41.7W 40 KT 45 MPH
96H 21/0000Z 34.2N 44.6W 40 KT 45 MPH
120H 22/0000Z 37.2N 48.1W 40 KT 45 MPH

$$
Forecaster Papin

[cycloneye]

Subtropical Depression Don Discussion Number 13
NWS National Hurricane Center Miami FL AL052023
900 AM GMT Mon Jul 17 2023

Don continues to produce an area of deep convection on its east side
and has generally changed little during the past several hours.
Satellite imagery suggest that the circulation of Don has become
elongated from east to west and confidence is low on its center
position. Since the system has not changed much, the initial
intensity remains 30 kt based on continuity. This estimate is a
little below the latest satellite intensity guidance.

The depression is moving eastward at about 8 kt on the north side of
a subtropical ridge. A turn to the southeast is expected later
today followed by a turn to the south tonight and Tuesday as the
system moves in the flow between the ridge and an amplifying trough
over the northeastern Atlantic. Don is expected to stall during the
middle of the week when the steering currents weaken, but a motion
to the northwest is expected later in the week when the system moves
on the south side of the ridge. Regardless, Don is not expected to
move much during the next several days. This forecast is fairly
similar to the previous one and near the various consensus aids.

Don could gradually gain strength during the next few days while it
moves over slightly warmer waters and remains in low to moderate
wind shear conditions. The models also show the wind field
contracting, suggesting that Don could transition to a tropical
cyclone in the next day or two. The environment is expected to
remain marginally conducive late in the week, which should allow to
Don to maintain its strength. The NHC intensity forecast is the
same as the previous one and below the model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 17/0900Z 39.2N 44.7W 30 KT 35 MPH
12H 17/1800Z 38.6N 42.8W 30 KT 35 MPH
24H 18/0600Z 37.1N 41.0W 30 KT 35 MPH
36H 18/1800Z 35.6N 40.1W 30 KT 35 MPH...TROPICAL CYCLONE
48H 19/0600Z 34.1N 40.3W 35 KT 40 MPH
60H 19/1800Z 33.5N 40.9W 35 KT 40 MPH
72H 20/0600Z 33.5N 41.9W 40 KT 45 MPH
96H 21/0600Z 35.3N 45.3W 40 KT 45 MPH
120H 22/0600Z 38.6N 48.7W 40 KT 45 MPH

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
Tropical Depression Don Advisory Number 14
NWS National Hurricane Center Miami FL AL052023
300 PM GMT Mon Jul 17 2023

...DON IN THE MIDST OF A LARGE TRACK LOOP OVER THE CENTRAL
ATLANTIC...


SUMMARY OF 300 PM GMT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...38.6N 42.9W
ABOUT 860 MI...1385 KM W OF THE AZORES
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...ESE OR 120 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1011 MB...29.86 INCHES


Tropical Depression Don Discussion Number 14
NWS National Hurricane Center Miami FL AL052023
300 PM GMT Mon Jul 17 2023

Satellite images indicate that Don continues to produce a cluster of
deep convection, displaced east of the center due to shear. Despite
the cool waters, this deep convection has persisted overnight, and
the cloud pattern most resembles a sheared tropical cyclone,
although the circulation remains elongated. This structure is
confirmed by the latest TAFB Dvorak estimate, which gave a tropical
classification for the first time at 12 UTC. Thus, Don is changed to
a tropical cyclone on this advisory, although it is still a 30-kt
depression on the basis of a recent scatterometer pass at 1229 UTC
that showed a small area of winds around 30 kt.

Don is moving east-southeastward at about 12 kt, with a better
estimate of motion available due to the aforementioned scatterometer
pass. The depression is about a quarter of the way through making a
large anticyclonic loop over the central Atlantic, forced by a
blocking ridge to its north. The new forecast is shifted to the
east during the next few days as guidance has trended faster with a
more vertically intact cyclone structure noted. In the long range,
the blocking ridge shifts eastward, allowing Don to turn
northwestward and cross over its own path in about 5 days. While
the ECMWF still remains east of most of the other guidance, the
model consensus is close to the previous forecast, so the new track
forecast is about the same as the last prediction.

The depression is expected to move over warmer waters by midweek,
though some increase in shear could reduce the chances for
significant restrengthening (and the waters are only 25 degrees C
or so). Still, basically all of the models now bring this to a
tropical storm within a few days, and the new forecast continues to
follow suit. At long range, the SSTs start to decrease again, and
the system is forecast to cross its own path, resulting in less
instability due to a presumed cool wake from the storm. I've
elected to raise the forecast 5 kt in about 4 days, but it is still
below most of the guidance, as the environment just doesn't seem
that conducive for a significant increase in winds.


FORECAST POSITIONS AND MAX WINDS

INIT 17/1500Z 38.6N 42.9W 30 KT 35 MPH
12H 18/0000Z 37.7N 41.1W 30 KT 35 MPH
24H 18/1200Z 36.0N 39.8W 30 KT 35 MPH
36H 19/0000Z 34.5N 39.3W 30 KT 35 MPH
48H 19/1200Z 33.8N 39.8W 35 KT 40 MPH
60H 20/0000Z 33.4N 40.8W 35 KT 40 MPH
72H 20/1200Z 33.7N 42.0W 40 KT 45 MPH
96H 21/1200Z 35.8N 45.5W 45 KT 50 MPH
120H 22/1200Z 39.5N 49.0W 40 KT 45 MPH

$$
Forecaster Blake

[cycloneye]

Tropical Depression Don Discussion Number 15
NWS National Hurricane Center Miami FL AL052023
900 PM GMT Mon Jul 17 2023

GOES-16 visible imagery shows that Don is comprised of multiple
low-level swirls rotating around the larger circulation, which is
better defined than you might think at the surface based on earlier
scatterometer data. Overall, the system is not well organized due
to persistent shear, dry air and marginal instability, with only a
distant burst of convection well east of the center. There has been
no change with the latest satellite classifications, so the initial
wind speed remains 30 kt.

The environment around Don is forecast to become more conducive for
gradual intensification in a couple of days when the cyclone moves
over warmer waters with light-to-moderate shear, tempered by plenty
of mid-level dry air. Surprisingly, many of the recent regional
hurricane models show a hurricane forming over 24-25C waters in
several days time, which is hard to believe given the seemingly
marginal large-scale conditions. Additionally, Don will have to
cross its own cool wake in 4-5 days, which isn't well accounted for
in the models yet. The new forecast is bumped up at day 5 but
remains below the model consensus.

Don has turned southeastward at about 12 kt, in the process of
undergoing a large anticyclonic loop over the central Atlantic due
to a blocking ridge to its north. The depression should begin to
gain latitude again late on Wednesday as the blocking ridge slides
eastward, and eventually Don should turn northwestward by the end of
the forecast period. The biggest question remains how sharp of a
turn will occur late this week, with the ECMWF suite insisting on a
faster northward motion by the weekend, well east of the other
guidance. An examination of those fields suggests that it doesn't
vertically redevelop Don as much as the rest of the guidance,
resulting in the cyclone not responding to the upper-level
southeasterly flow, and instead turning more quickly northward.
Since the new intensity forecast remains on the lower side of the
guidance envelope, the new NHC track forecast will also stay east of
the model consensus, not too different from the last prediction.



FORECAST POSITIONS AND MAX WINDS

INIT 17/2100Z 38.1N 41.6W 30 KT 35 MPH
12H 18/0600Z 37.1N 40.2W 30 KT 35 MPH
24H 18/1800Z 35.4N 39.4W 30 KT 35 MPH
36H 19/0600Z 34.3N 39.5W 30 KT 35 MPH
48H 19/1800Z 33.6N 40.5W 35 KT 40 MPH
60H 20/0600Z 33.8N 41.5W 35 KT 40 MPH
72H 20/1800Z 34.4N 43.0W 40 KT 45 MPH
96H 21/1800Z 36.7N 46.8W 45 KT 50 MPH
120H 22/1800Z 40.5N 50.0W 45 KT 50 MPH

$$
Forecaster Blake

[cycloneye]

BULLETIN
Tropical Storm Don Advisory Number 16
NWS National Hurricane Center Miami FL AL052023
300 AM GMT Tue Jul 18 2023

...SATELLITE WIND DATA INDICATES DON HAS BECOME A TROPICAL STORM...


SUMMARY OF 300 AM GMT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...37.4N 40.4W
ABOUT 735 MI...1180 KM W OF THE AZORES
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...SE OR 140 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES




Tropical Storm Don Discussion Number 16
NWS National Hurricane Center Miami FL AL052023
300 AM GMT Tue Jul 18 2023

The convective structure of Don this evening has improved somewhat,
with a decent area of -55 to -65C cold cloud tops centered a bit to
the northeast of the low-level center. The center is also perhaps a
bit better defined than earlier, with the ongoing convective
activity possibly helping to tighten the center up. While subjective
Dvorak classifications have not increased much this evening, an
ASCAT-C pass at 2302 UTC caught the eastern portion of the
circulation, with several believable wind vectors of up to 35 kt.
Thus, Don is being upgraded to a tropical storm this advisory with
sustained winds of 35 kt.

Don continues to move southeastward at 125/11 kt. This motion is
expected to continue curving clockwise over the next several days as
the cyclone remains steered by a building mid-level ridge that is
forecast to shift southwestward to northwestward relative to Don.
Eventually this ridge will fold over the storm, allowing Don to
begin gaining latitude again in 48-60 h. Overall, the track guidance
this cycle has shifted a bit to the east and the NHC track has been
shifted a little in that direction, though still remains much
further west than the ECMWF model. There continues to be a large
spread in guidance solutions by the end of the forecast period, and
the current forecast remains low-confidence in that time frame.

Even though Don is a bit stronger currently, the overall forecast
environment is not all that conducive for much intensification in
the short-term. Sea-surface temperatures under the cyclone are
around 24C currently, and are only forecast to warm perhaps another
degree C over the next 36-48 h. However, model-derived soundings
from the GFS and HAFS models suggest that tropospheric instability
does increase as environmental temperatures subtly cool in the
mid-levels. The simulated IR imagery from these models around that
time shows better organization of convective activity around a
smaller core, and if this structure were to verify, some gradual
intensification is possible. The latest NHC intensity forecast shows
a bit more intensification than before, mostly related to the
initial intensity, but still caps the system off as a 45-kt tropical
storm by the end of the forecast period, which remains a bit under
the model consensus. The latter part of the forecast is likely
dependent on the Don's ultimate track. A further left track, like
the GFS and HAFS-A/B, may take the cyclone over warmer SSTs, and
result in a stronger storm. However, a more rightward track like
the ECMWF would take Don over its cold wake and likely would limit
additional intensification.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 37.4N 40.4W 35 KT 40 MPH
12H 18/1200Z 36.3N 39.3W 35 KT 40 MPH
24H 19/0000Z 34.9N 39.0W 35 KT 40 MPH
36H 19/1200Z 34.1N 39.3W 35 KT 40 MPH
48H 20/0000Z 33.8N 40.4W 40 KT 45 MPH
60H 20/1200Z 34.2N 41.6W 40 KT 45 MPH
72H 21/0000Z 35.0N 43.2W 45 KT 50 MPH
96H 22/0000Z 37.4N 46.8W 45 KT 50 MPH
120H 23/0000Z 41.3N 49.2W 45 KT 50 MPH

$$
Forecaster Papin

[cycloneye]

Tropical Storm Don Discussion Number 17
NWS National Hurricane Center Miami FL AL052023
900 AM GMT Tue Jul 18 2023

Convection associated with Don has decreased somewhat in coverage
and organization over the past several hours, with patches of
convection now occurring near the center over the northern
semicircle. Various subjective and objective satellite intensity
estimates are in the 30-40 kt range, and these have changed little
since the previous advisory. Based on that, the initial intensity
remains 35 kt.

The initial motion is now 145/10 kt. The cyclone's motion is
expected to continue curving clockwise over the next several days as
it is steered by a building mid-level ridge that is forecast to
shift southwestward to northwestward relative to Don. Eventually
this ridge will move to the northeast and east of Don, allowing the
storm to turn northwestward and eventually northward. One change
in the guidance since the previous forecast is that it now shows a
little more westward motion after 36 h than previously, and the new
track forecast during this time is nudged a little farther to the
west, There continues to be a significant spread in guidance
solutions by the end of the forecast period, and the current
forecast remains low-confidence in that time frame.

Don is currently over sea surface temperatures of about 24C and in
an area of relatively dry mid-level air. The sea surface
temperatures along the forecast track increase to 25C during the
next 72 h, and the cyclone could encounter a more moist air mass
during that time. Based on this and the intensity guidance, the new
intensity forecast shows modest intensification during the next 72
h. The forecast peak intensity of 45 kt is a compromise between the
weaker SHIPS/LGEM models and the stronger HWRF/HMON/HAFS models.
Overall, the new intensity forecast lies near the intensity
consensus and has only minor adjustments since the previous
forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 36.3N 39.6W 35 KT 40 MPH
12H 18/1800Z 35.2N 39.0W 35 KT 40 MPH
24H 19/0600Z 34.2N 39.1W 35 KT 40 MPH
36H 19/1800Z 33.8N 39.8W 40 KT 45 MPH
48H 20/0600Z 33.7N 41.0W 40 KT 45 MPH
60H 20/1800Z 34.3N 42.3W 45 KT 50 MPH
72H 21/0600Z 35.2N 44.1W 45 KT 50 MPH
96H 22/0600Z 38.0N 48.0W 45 KT 50 MPH
120H 23/0600Z 42.0N 49.0W 45 KT 50 MPH

$$
Forecaster Beven

[cycloneye]

Tropical Storm Don Discussion Number 18
NWS National Hurricane Center Miami FL AL052023
300 PM GMT Tue Jul 18 2023

Don has struggled to produce deep convection today, despite the
storm moving over warmer waters, with only a few moderate bands on
the eastern side of the circulation. A scatterometer pass near
1200 UTC showed maximum winds just above 30 kt, and it seems like
the system is vacillating between 30 and 35 kt as an initial wind
speed, based primarily on convective trends. I don't really want
to be chasing every burst of convection, so the conservative thing
is to wait a little longer before downgrading it to a depression.

The system should not change much in intensity over the next day or
so while it encounters a slightly more conducive (but still
marginal) environment. It also wouldn't be a surprise if Don became
a depression again in the short-term. Modest intensification is
forecast later this week while the system encounters warmer SSTs,
higher mid-level moisture, and the shear remains light or moderate.
The new forecast is similar to the previous one, below the model
consensus given the overall mediocre environment for strengthening.

Don has turned south-southeastward at about 8 kt. The storm is
about halfway through making a large anticyclonic loop over the
central Atlantic, bending around a blocking ridge in the
mid-latitudes. Don should move more slowly southward overnight and
Wednesday as it sits beneath the ridge, then gradually accelerate
northwestward and northward as it moves around the ridge. The track
guidance is coming into better agreement on this course,
conveniently converging somewhat on the last NHC track forecast, so
no significant changes were required.



FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 35.6N 39.3W 35 KT 40 MPH
12H 19/0000Z 34.6N 39.0W 35 KT 40 MPH
24H 19/1200Z 33.9N 39.4W 35 KT 40 MPH
36H 20/0000Z 33.7N 40.5W 40 KT 45 MPH
48H 20/1200Z 34.0N 41.7W 40 KT 45 MPH
60H 21/0000Z 34.7N 43.3W 45 KT 50 MPH
72H 21/1200Z 35.7N 45.1W 45 KT 50 MPH
96H 22/1200Z 39.0N 49.3W 45 KT 50 MPH
120H 23/1200Z 44.0N 49.5W 45 KT 50 MPH

$$
Forecaster Blake

[cycloneye]

Tropical Storm Don Discussion Number 19
NWS National Hurricane Center Miami FL AL052023
900 PM GMT Tue Jul 18 2023

Deep convection has re-developed on the eastern side of Don this
afternoon, though most of the circulation is pretty skeletal. The
initial wind speed remains 35 kt, close to the latest TAFB
satellite classification, and hopefully the evening scatterometer
passes will hit the storm for the next advisory to get a more
precise estimate of the winds.

The environment near Don gets slightly more conducive for
strengthening during the next day or two with warmer SSTs, higher
mid-level moisture, and light or moderate shear. Gradual
intensification is shown through Thursday, similar to the last
forecast and near or below the model consensus. At long range, the
storm should pass over its own cool wake, and the environment
becomes less conducive overall. The model guidance is lower on this
cycle for late week, closer to the previous NHC wind speed
prediction. Thus, little change in strength is shown at days 3-4,
and Don should lose its deep convection around day 5 when it moves
north of the Gulf Stream.

Don has slowed and turned southward, now at around 6 kt. The storm
should move southwestward on Wednesday and west-northwestward on
Thursday due to steering from a blocking ridge in the north-central
Atlantic. As the ridge slides eastward, Don is likely to head
northward by Saturday and accelerate north-northeastward on Sunday.
The model spread has increased on this cycle, but there's still a
tendency for the weaker model solutions to be east of the model
consensus. Since the NHC intensity prediction remains on the low
side of the guidance, it is reasonable for the track forecast to
remain east of the model consensus, resulting in little net change
to the NHC track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 18/2100Z 34.9N 39.2W 35 KT 40 MPH
12H 19/0600Z 34.1N 39.2W 35 KT 40 MPH
24H 19/1800Z 33.7N 40.0W 35 KT 40 MPH
36H 20/0600Z 33.8N 41.2W 40 KT 45 MPH
48H 20/1800Z 34.3N 42.6W 40 KT 45 MPH
60H 21/0600Z 35.2N 44.4W 45 KT 50 MPH
72H 21/1800Z 36.5N 46.3W 45 KT 50 MPH
96H 22/1800Z 40.5N 49.5W 45 KT 50 MPH
120H 23/1800Z 46.0N 47.5W 40 KT 45 MPH...POST-TROPICAL

$$
Forecaster Blake

[cycloneye]

Tropical Storm Don Discussion Number 20
NWS National Hurricane Center Miami FL AL052023
300 AM GMT Wed Jul 19 2023

Don's convective structure continues to sputter along this evening,
with only a small area of cold cloud tops below -50C centered just
to the east of the low-level center. However, there has been some
modest improvement of the low-level structure on microwave imagery,
with some curved bands on storm's east side. The latest subjective
and objective Dvorak classifications remain around 35 kt, and that
will remain the intensity for this advisory.

While the ongoing convection is relatively meager, it is currently
occuring within Don's radius of maximum wind. High-resolution
guidance (HAFS-A and HWRF) does show this convection persisting near
the center, possibly helping to develop a smaller wind core over the
next several days. Don is also expected to continue moving over
gradually warmer waters to near 26 C in 24-36 hours as the
mid-levels moisten and shear remains under 15 kt. Thus, some gradual
intensification continues to be shown over the next couple of days,
peaking the system at 45 kt in about 48 h. After that time, Don's
intensity is likely to be influenced by its future track,
with a more westward motion taking Don toward warmer waters.
However, the current NHC forecast track takes Don closer to the
cold wake it generated over the weekend. In fact, the latest SHIPS
guidance shows SSTs decreasing again after 48 h, and thus little
additional intensification is shown after that time, which remains
a bit under the consensus aids. By days 4-5, Don should be moving
beyond the north wall of the Gulf Steam, likely losing its
remaining convection and becoming post-tropical.

Don appears to be slowing its forward motion tonight, with the
latest estimated motion at 190/3 kt. This slowdown is likely in
preparation for the system to turn southwestward and westward over
the next 24-36 h as an amplified subtropical ridge grows poleward
over Don. This ridge is then expected to continue sliding eastward
and merge with another subtropical ridge just offshore of
northwestern Africa, which should provide an avenue for Don to
escape northward and then northeastward by the end of the forecast
period. There was not a lot of changes with the track guidance this
cycle, as the weaker ECMWF remains on the eastern side of the
guidance, while the stronger HAFS and GFS remain on the western
side. The NHC track forecast is quite similar to the prior
one, favoring a slightly more eastward track given that Don is
forecast to be on the weaker end of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 34.3N 39.0W 35 KT 40 MPH
12H 19/1200Z 33.8N 39.3W 35 KT 40 MPH
24H 20/0000Z 33.5N 40.5W 40 KT 45 MPH
36H 20/1200Z 33.8N 41.7W 40 KT 45 MPH
48H 21/0000Z 34.6N 43.5W 45 KT 50 MPH
60H 21/1200Z 35.6N 45.6W 45 KT 50 MPH
72H 22/0000Z 37.3N 47.7W 45 KT 50 MPH
96H 23/0000Z 42.1N 49.6W 45 KT 50 MPH
120H 24/0000Z 47.2N 44.6W 35 KT 40 MPH...POST-TROPICAL

$$
Forecaster Papin