ATL: PHILIPPE - Advisories

[cycloneye]

BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 37A
NWS National Hurricane Center Miami FL AL172023
200 PM AST Mon Oct 02 2023

...PHILIPPE FORECAST TO CAUSE HEAVY RAINS AND FLOODING TO PORTIONS
OF THE LEEWARD ISLANDS LATER TODAY...


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...17.3N 61.0W
ABOUT 55 MI...90 KM ESE OF BARBUDA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES

[cycloneye]

BULLETIN
Tropical Storm Philippe Advisory Number 38
NWS National Hurricane Center Miami FL AL172023
500 PM AST Mon Oct 02 2023

...TROPICAL STORM WARNING ISSUED FOR ANTIGUA...
...PHILIPPE LIKELY TO CAUSE HEAVY RAINS AND SOME FLOODING TO
PORTIONS OF THE LEEWARD ISLANDS OVERNIGHT...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...17.6N 61.5W
ABOUT 20 MI...30 KM E OF BARBUDA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The government of Antigua has issued a Tropical Storm Warning for
Antigua.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Barbuda
* Antigua




Tropical Storm Philippe Discussion Number 38
NWS National Hurricane Center Miami FL AL172023
500 PM AST Mon Oct 02 2023

The center of Philippe remains exposed this afternoon with
some convection firing closer to the center over the last few
hours. Heavy rainfall and thunderstorms remain displaced to the
south and southeast of the center as high northwesterly vertical
wind shear persists. The initial intensity is again held steady at
45 kt for this advisory, consistent with SFMR data from the Air
Force Reserve reconnaissance aircraft mission showing a large area
of 40-45 surface winds mostly on the east and southeast side of the
system earlier this afternoon. Another Air Force Reserve mission is
scheduled for this evening.

The storm continues to move to the northwest (305 degrees) at 6 kt
this afternoon. Philippe refuses to gain much vertical depth as a
tropical cyclone and has been steered more by the lower-level
ridge. Thus, the track forecast is again adjusted westward to
match recent satellite trends and in line with the weaker model
guidance. The cyclone is forecast to pass near Barbuda tonight
before turning north-northwest north of the Leeward Islands.
Around mid-week, Philippe should turn northward due to flow between
a mid-level trough in the southwest Atlantic and the subtropical
ridge. Uncertainty greatly increases after that point, with huge
differences showing up between the GFS- and ECMWF-based guidance.
The differences in model track forecasts are related to whether this
trough captures Philippe's circulation, causing Philippe to move
more to the north-northwest, or whether it is shunted more to the
northeast ahead of the trough. Consistent with model guidance, the
track forecast has shifted farther west from the previous advisory
and is in line with the consensus aids and mean ensemble track
guidance. Further adjustments to the west may be necessary.

Strong northwesterly vertical wind shear is expected to
prevent significant strengthening in the short term. Shear is
forecast to decrease a bit for a short period of time in the next 2
to 3 days and could allow for some strengthening. However, almost
all of the guidance is showing a less conducive environment, and
the NHC forecast reflects this trend, lying on the high end of
model guidance but in line with HCCA. The uncertainty is extremely
large at the end of the forecast period as some models are now
showing an extratropical transition due to the mid-latitude trough,
but a lot depends on how strong Philippe eventually becomes, which
has clearly not been very predictable during this storm's lifetime.


KEY MESSAGES:

1. Tropical storm conditions are expected across Barbuda and
Antigua beginning this evening while Philippe passes near and
north of the area. Interests elsewhere in the northern Leeward
Islands should continue to monitor this system.

2. Heavy rainfall from Philippe could produce isolated to scattered
flash flooding over the northern Leeward Islands, particularly
across Barbuda and Antigua, through Tuesday.


FORECAST POSITIONS AND MAX WINDS

INIT 02/2100Z 17.6N 61.5W 45 KT 50 MPH
12H 03/0600Z 18.2N 62.2W 45 KT 50 MPH
24H 03/1800Z 19.1N 62.6W 45 KT 50 MPH
36H 04/0600Z 20.6N 63.0W 45 KT 50 MPH
48H 04/1800Z 22.2N 63.4W 45 KT 50 MPH
60H 05/0600Z 23.9N 63.8W 50 KT 60 MPH
72H 05/1800Z 26.0N 63.8W 55 KT 65 MPH
96H 06/1800Z 30.6N 62.2W 60 KT 70 MPH
120H 07/1800Z 35.0N 60.0W 65 KT 75 MPH

$$
Forecaster Blake/Stevenson

[cycloneye]

Tropical Storm Philippe Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL172023
600 PM AST Mon Oct 02 2023

...PHILIPPE MAKES LANDFALL IN BARBUDA...

Satellite imagery indicate that the center of Philippe made
landfall on the island of Barbuda around 6 PM AST (2200 UTC).
Maximum sustained winds are near 50 mph (85 km/h).
The latest minimum pressure central pressure is estimated to be 999
mb (29.50 inches).


SUMMARY OF 600 PM AST...2200 UTC...INFORMATION
----------------------------------------------
LOCATION...17.7N 61.8W
ABOUT 40 MI...65 KM N OF ANTIGUA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES

$$
Forecaster Roberts/Pasch

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BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 38A
NWS National Hurricane Center Miami FL AL172023
800 PM AST Mon Oct 02 2023

...HEAVY RAINS AND FLOODING EXPECTED OVER PORTIONS OF THE
LEEWARD ISLANDS OVERNIGHT...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...17.6N 62.0W
ABOUT 80 MI...130 KM ESE OF ST. MARTIN
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES

[cycloneye]

BULLETIN
Tropical Storm Philippe Advisory Number 39
NWS National Hurricane Center Miami FL AL172023
1100 PM AST Mon Oct 02 2023

...HEAVY RAINS AND FLOODING EXPECTED OVER PORTIONS OF THE
LEEWARD ISLANDS TONIGHT AND TUESDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.8N 62.1W
ABOUT 70 MI...110 KM ESE OF ST. MARTIN
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Barbuda
* Antigua


Tropical Storm Philippe Discussion Number 39
NWS National Hurricane Center Miami FL AL172023
1100 PM AST Mon Oct 02 2023

Philippe continues to be under the influence of significant
westerly to northwesterly vertical wind shear. The center, which
is located on the northwestern edge of the main area of deep
convection, recently passed over Barbuda. Most of the stronger
convection is over the southern and southeastern portions of the
circulation, so the Leeward Islands should continue to experience
strong winds and heavy rains even when the center of the storm
begins to move north of those islands. The current intensity is
kept at 45 kt based on SFMR-observed surface winds from an Air Force
Hurricane Hunter aircraft that is still investigating the system.

The cyclone has wobbled west-northwestward this evening and the
current motion estimate is 300/6 kt. Over the next few days,
Philippe should move along the western periphery of a mid-level
subtropical high pressure area. Most of the guidance model tracks
have shifted even farther west, with the exception of the GFS
deterministic and ensemble mean forecasts, which appear to be
eastern outliers at this time. Based the new dynamical model
consensus, the official forecast track is, again, shifted farther
west from the previous one. Later in the forecast period, the
spread in the guidance models increases. Notably,the GFS
prediction shows that a mid-tropospheric trough over the
northwestern Atlantic fails to capture the cyclone and take it
northward into Atlantic Canada, but keeps Philippe moving slowly
over the subtropical Atlantic at 5 days and even beyond.

Little change in intensity is likely for the next couple of days
while the storm remains in an environment of strong vertical wind
shear. In 2 to 3 days, the global models suggest that Philippe
could encounter a more favorable upper-tropospheric wind
environment, with more anticyclonic and diffluent upper-level winds
evolving over the system. Therefore, some strengthening is
predicted in the latter half of the forecast period. The official
intensity forecast is near the high end of the model guidance,
however.


KEY MESSAGES:

1. Tropical storm conditions are expected across Barbuda and
Antigua tonight while Philippe passes just north of the area.
Interests elsewhere in the northern Leeward Islands should continue
to monitor this system.

2. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the Leeward and northern Windward
Islands, particularly between Barbuda and Dominica, into early
Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0300Z 17.8N 62.1W 45 KT 50 MPH
12H 03/1200Z 18.4N 62.8W 45 KT 50 MPH
24H 04/0000Z 19.7N 63.4W 45 KT 50 MPH
36H 04/1200Z 21.3N 64.0W 45 KT 50 MPH
48H 05/0000Z 23.0N 64.4W 45 KT 50 MPH
60H 05/1200Z 24.8N 64.7W 50 KT 60 MPH
72H 06/0000Z 26.9N 64.3W 55 KT 65 MPH
96H 07/0000Z 31.6N 62.8W 60 KT 70 MPH
120H 08/0000Z 36.0N 60.0W 60 KT 70 MPH

$$
Forecaster Pasch

[cycloneye]

Tropical Storm Philippe Discussion Number 40
NWS National Hurricane Center Miami FL AL172023
500 AM AST Tue Oct 03 2023

High clouds from a recent convective burst just southeast of
Philippe's center has obscured the low-level center for much of the
night. However, surface observations and microwave imagery indicate
that the center is still located near the northwestern edge of the
large convective mass, and it is passing very near Anguilla in the
northern Leeward Islands. Most of the stronger winds are located
over the southern and southeastern portions of the circulation
where a wind gust to 41 kt was reported on Antigua a few hours ago.
The Leeward Islands are likely to experience strong gusty winds and
heavy rains even as the center moves north of those islands this
morning. The intensity of the cyclone remains 45 kt, based on
earlier SFMR and dropwindsonde data from an Air Force Reserve
reconnaissance aircraft. The next mission into Philippe is
scheduled for later this morning.

Philippe's motion has been wobbling between west-northwest and
northwest at about 7 kt. A more definitive northwestward heading is
expected to begin today as Philippe moves around the western portion
of a mid-level ridge over the central subtropical Atlantic. The
storm's motion should become north-northwestward to northward on
Wednesday and Wednesday night as it moves between the ridge to its
east and trough off the southeastern United States coast. By late in
the forecast period, there is significant bifurcation in the track
guidance with the GFS slowing the system down, while the ECMWF and
UKMET show the cyclone moving quickly northward into Atlantic Canada
ahead of a deep-layer trough. The GFS track appears to be an
eastern outlier at this time. Thus, the NHC track forecast was
shifted westward at days 4 and 5 to be closer to the multi-model
consensus aids. Additional adjustments in the long-range track
forecast may be required in subsequent advisories.

Strong vertical shear is forecast to linger over Philippe during
the next two to three days, and little change in strength is
forecast during that time. The system could encounter a region of
diffluent upper-level winds later in the period which could support
some strengthening. The NHC intensity forecast shows a slightly
lower peak than before as the intensity guidance and global models
generally show less strengthening than before.


KEY MESSAGES:

1. Tropical storm conditions are expected across Barbuda, Antigua,
and Anguilla this morning. Strong gusty winds are also likely
elsewhere in the Leeward Islands today.

2. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the Leeward and northern Windward
Islands, particularly between Barbuda and Dominica, into early
Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 18.5N 62.9W 45 KT 50 MPH
12H 03/1800Z 19.2N 63.4W 45 KT 50 MPH
24H 04/0600Z 20.6N 64.0W 45 KT 50 MPH
36H 04/1800Z 22.1N 64.4W 45 KT 50 MPH
48H 05/0600Z 23.9N 64.7W 45 KT 50 MPH
60H 05/1800Z 26.0N 64.6W 45 KT 50 MPH
72H 06/0600Z 28.3N 64.1W 50 KT 60 MPH
96H 07/0600Z 32.8N 62.3W 55 KT 65 MPH
120H 08/0600Z 38.5N 61.5W 55 KT 65 MPH

$$
Forecaster Brown

[cycloneye]

BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 40A
NWS National Hurricane Center Miami FL AL172023
800 AM AST Tue Oct 03 2023

...FLOODING RAINS CONTINUE OVER PORTIONS OF THE NORTHERN WINDWARD
ISLANDS AND THE LEEWARD ISLANDS...
...TROPICAL STORM WATCH ISSUED FOR THE BRITISH VIRGIN ISLANDS...


SUMMARY OF 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...18.6N 63.5W
ABOUT 40 MI...60 KM NW OF ANGUILLA
ABOUT 55 MI...90 KM E OF ANEGADA BRITISH VIRGIN ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES

[cycloneye]

BULLETIN
Tropical Storm Philippe Advisory Number 41
NWS National Hurricane Center Miami FL AL172023
1100 AM AST Tue Oct 03 2023

...CENTER OF PHILIPPE PASSING JUST NORTHEAST OF THE BRITISH VIRGIN
ISLANDS...
...FLOODING RAINS CONTINUE OVER PORTIONS OF THE LEEWARD ISLANDS...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...18.9N 63.9W
ABOUT 70 MI...115 KM NW OF ANGUILLA
ABOUT 80 MI...130 KM ENE OF ST. THOMAS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The government of Antigua and Barbuda has discontinued the Tropical
Storm Warning for Barbuda.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Anguilla

A Tropical Storm Watch is in effect for...
* British Virgin Islands



Tropical Storm Philippe Discussion Number 41
NWS National Hurricane Center Miami FL AL172023
1100 AM AST Tue Oct 03 2023

Philippe's center has become exposed to the northwest of the deep
convection, and visible satellite images from this morning suggest
that it has lost definition. This is confirmed by the crew from an
ongoing Air Force Reserve Hurricane Hunter aircraft, which
indicated a center uncertainty of 10 n mi. The plane has only
measured a peak 850-mb flight-level wind of 41 kt and SFMR winds of
35-40 kt mainly within the southeastern quadrant over the waters
between the northern Leeward Islands. Dropsonde data also indicate
the pressure has risen to 1004 mb. Based on these data, Philippe's
initial intensity is set at 40 kt.

Philippe has sped up a bit, although it has not yet begun to turn
to right. The current motion is barely northwestward (305 degrees)
at 9 kt, with the center now passing just to the northeast of
Anegada Island in the British Virgin Islands. The track guidance
insists that Philippe will turn toward the north-northwest later
today as it moves around the western periphery of a mid-level high
over the central Atlantic. However, the shallow, sheared structure
of the cyclone may cause it to remain on the western side of the
guidance envelope in the short term, potentially delaying any
northward turn. The guidance is in good agreement that the
northward turn will eventually occur, but then there are significant
speed differences as the storm moves across the western Atlantic.
Primarily due to the storm's resistance to begin turning, the new
NHC track forecast has been shifted about 45-50 n mi to the west of
the previous prediction, but it lies very close to the latest TVCA
and HCCA consensus aids. Except for HWRF and HMON (which turn
Philippe to the east), the rest of the guidance is in more agreement
that the storm may approach Atlantic Canada in about 5 days.

Moderate to strong shear is expected to persist over Philippe for
awhile. Therefore, little change in strength is expected during
the next day or two. The upper-level environment may become a
little more conducive for strengthening when Philippe moves
northward over the western Atlantic, but confidence in that
occurring is still quite low. The NHC intensity forecast continues
to show some modest strengthening and is close to the HCCA
consensus aid. Global models fields, as well as phase-space
diagrams, indicate that Philippe could acquire frontal features as
it is approaching Atlantic Canada, and the NHC forecast therefore
shows it becoming post-tropical by day 5.


KEY MESSAGES:

1. Tropical storm conditions are expected to continue on Anguilla
and are possible on the British Virgin Islands through today.
Strong gusty winds are also likely elsewhere in the Leeward Islands
today.

2. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the northern Leeward Islands and
the British Virgin Islands into early Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 18.9N 63.9W 40 KT 45 MPH
12H 04/0000Z 19.8N 64.4W 40 KT 45 MPH
24H 04/1200Z 21.2N 65.0W 40 KT 45 MPH
36H 05/0000Z 22.9N 65.4W 40 KT 45 MPH
48H 05/1200Z 24.8N 65.6W 45 KT 50 MPH
60H 06/0000Z 27.3N 65.2W 45 KT 50 MPH
72H 06/1200Z 30.1N 64.4W 50 KT 60 MPH
96H 07/1200Z 35.5N 63.3W 55 KT 65 MPH
120H 08/1200Z 41.7N 63.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg

[cycloneye]

Tropical Storm Philippe Discussion Number 42
NWS National Hurricane Center Miami FL AL172023
500 PM AST Tue Oct 03 2023

Philippe has continued to lose organization for much of the day.
Satellite images and aircraft fixes from this morning indicate that
the circulation has become elongated, and the remaining deep
convection has relatively little, if any, organization relative to
the center, which is now located just north of the Virgin Islands.
The initial intensity remains 40 kt based on the earlier SFMR data,
but this could be generous given the overall loss of convective
organization.

The current motion is northwestward, or 310/10 kt. Over the next
couple of days, Philippe is expected to turn northward between a
strong mid-level high over the subtropical Atlantic and a developing
cut-off low east of Florida, with its forward speed increasing in
2-3 days when it becomes positioned between these two features. The
northward motion is expected to continue through the end of the
forecast period as another deep-layer trough moves eastward across
eastern North America. The most notable change in this NHC forecast
is that the guidance has again shifted westward, both due to an
adjustment caused by Philippe's recent motion and a general westward
trend in the track guidance. The official forecast is close to the
TVCA consensus aid, but it's not as far to the west as the latest
ECMWF and HCCA solutions. The risk continues to increase for some
form of Philippe, likely as a post-tropical cyclone, to reach
Atlantic Canada or eastern New England in about 5 days.

The deep-layer trough located near the east coast of the United
States is likely to keep moderate-to-strong westerly or
southwesterly shear over Philippe for much of the forecast period.
As a result, little change in strength is forecast during the next
2-3 days. The GFS and ECMWF are now in good agreement that a
separate baroclinic/non-tropical low will develop just to the west
of Philippe in about 3 days. These two systems are likely to
interact, with Philippe becoming attached to the warm front, and
therefore becoming extratropical, by day 4. It's possible that
Philippe could strengthen slightly due to this baroclinic
interaction, and that scenario is shown in the official forecast.


KEY MESSAGES:

1. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the northern Leeward Islands and
the British Virgin Islands into early Wednesday.

2. Gusty winds are likely to continue across portions of the
northern Leeward Islands and the Virgin Islands through Wednesday.

3. The risk is increasing for tropical storm conditions to occur on
Bermuda later this week. Interests on Bermuda should monitor the
progress of Philippe.


FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 19.6N 64.9W 40 KT 45 MPH
12H 04/0600Z 20.4N 65.4W 40 KT 45 MPH
24H 04/1800Z 22.0N 66.1W 40 KT 45 MPH
36H 05/0600Z 23.8N 66.6W 40 KT 45 MPH
48H 05/1800Z 26.2N 66.6W 40 KT 45 MPH
60H 06/0600Z 29.2N 66.0W 45 KT 50 MPH
72H 06/1800Z 32.2N 65.7W 45 KT 50 MPH
96H 07/1800Z 38.1N 66.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 08/1800Z 45.8N 66.9W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg

[cycloneye]

BULLETIN
Tropical Storm Philippe Advisory Number 43
NWS National Hurricane Center Miami FL AL172023
1100 PM AST Tue Oct 03 2023

...HEAVY RAINS CONTINUE ACROSS PORTIONS OF THE VIRGIN ISLANDS AND
PUERTO RICO...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.1N 65.5W
ABOUT 120 MI...195 KM NNW OF ST. THOMAS
ABOUT 845 MI...1355 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES



Tropical Storm Philippe Discussion Number 43
NWS National Hurricane Center Miami FL AL172023
1100 PM AST Tue Oct 03 2023

Even though the center of Philippe is more than one hundred miles
north of the Virgin Islands, heavy rains on the system's south side
continue to affect portions of the Virgin Islands and Puerto Rico.
The cyclone remains poorly organized with the low-level circulation
appearing diffuse and convection remaining ragged and lacking
organization. The initial intensity is held at 40 kt, which is near
the high end of the satellite intensity estimates.

Philippe is moving northwestward, or 310 degrees, at 10 kt. The
models are in good agreement in showing Philippe turning
north-northwestward to northward on Wednesday when the storm moves
between a mid- to upper-level high over the central Atlantic and a
cut off low off the Florida coast. These features should provide
the steering currents for Philippe through the remainder of the
week, causing a northward motion with some increase in forward
speed. The storm is likely to be near Bermuda on Friday. A larger
trough is expected to move across eastern Canada and the
northeastern U.S. late this week and cut off over the weekend. In
response, Philippe could turn northwestward into northern New
England or Atlantic Canada in 4 to 5 days.

The storm continues to feel the effects of west-northwesterly shear
and dry air entrainment, and its poor structure suggests that
little, if any, intensification is likely in the short term. The
models show some strengthening late this week and early this weekend
when Philippe likely gets some baroclinic support from the nearby
trough. This interaction should also cause Philippe to gain frontal
features and become extratropical in 3 to 4 days before it reaches
northern New England or Atlantic Canada. The NHC intensity forecast
lies near the middle of the guidance envelope.


KEY MESSAGES:

1. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the United States & British Virgin
Islands through Wednesday.

2. Gusty winds are likely to continue across portions of the
northern Leeward Islands and the Virgin Islands through Wednesday.

3. The risk is increasing for tropical storm conditions to occur on
Bermuda late this week. Interests on Bermuda should monitor the
progress of Philippe.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 20.1N 65.5W 40 KT 45 MPH
12H 04/1200Z 21.2N 65.9W 40 KT 45 MPH
24H 05/0000Z 22.8N 66.4W 40 KT 45 MPH
36H 05/1200Z 24.9N 66.7W 40 KT 45 MPH
48H 06/0000Z 27.8N 66.4W 40 KT 45 MPH
60H 06/1200Z 30.7N 66.0W 45 KT 50 MPH
72H 07/0000Z 33.9N 65.9W 50 KT 60 MPH
96H 08/0000Z 40.5N 66.1W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 09/0000Z 49.0N 69.2W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi

[cycloneye]

Tropical Storm Philippe Discussion Number 44
NWS National Hurricane Center Miami FL AL172023
500 AM AST Wed Oct 04 2023

Philippe remains a disorganized tropical storm this morning, yet
continues to produce heavy rainfall over the British and U.S. Virgin
Islands. This activity remains displaced well to the southeast of
the estimated circulation center, and appears to be more associated
with the storm's inflow interacting with a well-defined mid-level
circulation just north of St. Thomas, which is evident from radar in
Puerto Rico. Scatterometer data received just after the last
advisory showed values around 40 kt in this area of convection, and
the initial intensity will be held at 40 kt. This value is on the
higher end of the Dvorak intensity estimates, but does match the
most recent UW-CIMSS SATCON intensity estimate.

The earlier scatterometer data suggested that Philippe had slowed
down some, possibly due to the ongoing convection to its southeast,
but its latest motion appears to have resumed a more northwestward
motion at 325/8 kt. The track guidance remains in agreement about
the storm turning more northward later today, with gradual
acceleration as the mid-level ridge that has been impeding its
poleward progress gradually shifts eastward, and Philippe becomes
steered between a deep-layer low to its west, and the aforementioned
ridge to its east. Compared to the previous cycle, the guidance has
shifted a bit eastward over the first 2-3 days of the forecast
period, and the latest NHC track forecast was shifted a bit further
east early on, but not as far as the consensus aids. After Philippe
passes by Bermuda on Friday, it is forecast to interact with a much
more amplified trough swinging into the northeastern United States
this weekend. This evolution may result in Philippe's track
potentially bending back north-northwest on Saturday, approaching
Atlantic Canada and New England as it phases with the larger trough.
There still remains quite a bit of spread in the track guidance by
96 h due to this interaction.

The intensity forecast remains murky. Right now, the low-level
circulation of Philippe remains diffuse, and even though vertical
wind shear could potentially slacken some over the next 24 hours,
the cyclone appears to be in no state to intensify in the
short-term. Thereafter, Philippe may have an opportunity to take
advantage of some synoptic mid-latitude dynamics associated with the
initial upper-level trough positioned to the west of its
circulation. Thus, some gradual intensification is shown between
36-60 h. With that said, some of the model guidance (like the most
recent GFS run) shows Philippe instead being absorbed into this
non-tropical feature, though that solution is not shown at this
time. Regardless, increasing baroclinicity should also begin to
initiate extratropical transition after 48 hours, which is forecast
to be fully complete sometime in the 72-96 h forecast time frame.
The latest NHC intensity forecast remains near the middle of the
guidance envelope, and is also close to the HFIP Corrected
Consensus Approach (HCCA).

KEY MESSAGES:

1. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the United States & British Virgin
Islands through today.

2. Gusty winds are likely to continue across portions of the
northern Leeward Islands and the Virgin Islands through early today.

3. The risk is increasing for tropical storm conditions to occur on
Bermuda late this week. Interests on Bermuda should monitor the
progress of Philippe, and Tropical Storm Watches could become
required for the island later today.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 20.5N 65.5W 40 KT 45 MPH
12H 04/1800Z 21.4N 65.8W 40 KT 45 MPH
24H 05/0600Z 23.3N 66.0W 40 KT 45 MPH
36H 05/1800Z 26.0N 66.0W 45 KT 50 MPH
48H 06/0600Z 29.0N 65.5W 45 KT 50 MPH
60H 06/1800Z 32.0N 65.0W 50 KT 60 MPH
72H 07/0600Z 35.3N 65.1W 50 KT 60 MPH
96H 08/0600Z 43.1N 66.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 09/0600Z 51.5N 72.0W 30 KT 35 MPH...POST-TROP/EXTRATROP

$$
Forecaster Papin

[cycloneye]

Tropical Storm Philippe Discussion Number 45
NWS National Hurricane Center Miami FL AL172023
1100 AM AST Wed Oct 04 2023

Visible satellite images this morning indicate that Philippe's
low-level circulation remains elongated, and the center is still
located on the northwestern edge of an area of deep convection.
This convective activity continues to produce heavy rains over the
U.S. and British Virgin Islands, as well as northeastern Puerto
Rico. The initial intensity remains 40 kt based on a blend of the
latest subjective and objective satellite estimates, with sustained
tropical-storm-force winds limited to the eastern semicircle.

Philippe has turned toward the north-northwest with an initial
motion of 335/6 kt. The flow between a strong mid-tropospheric
high over the central Atlantic and a deep-layer trough just off the
east coast of Florida is expected to steer Philippe northward, and
at a faster forward speed, beginning tonight and continuing for the
next few days. The track guidance is in good agreement on this
general scenario, although there is some east-to-west spread among
the models related to how Philippe interacts with a non-tropical
low that is forecast to develop to its west in about 2-3 days.
After day 3, a deeper trough is forecast to swing across eastern
North America, and much of the guidance suggests that Philippe
might bend back to the left a bit and approach Atlantic Canada or
eastern Maine in 3-4 days. Overall, the NHC track forecast is near
the middle of the guidance envelope, close to the TVCX and HCCA
consensus aids, and is also nearly identical to the previous
prediction.

Overall, moderate-to-strong vertical shear is expected to persist
over Philippe during the next few days, and very little change in
intensity is forecast during that time. Once Philippe begins to
interact with the developing low pressure to its west and the
associated upper-level trough, baroclinic influences could support
some strengthening. This strengthening is shown by most of the
intensity models, including the GFS and ECMWF global models, and
the official forecast therefore shows a peak intensity of 50 kt at
60 and 72 hours. Model-based phase-space diagrams, simulated
satellite imagery, and SHIPS diagnostics all suggest that Philippe
will become attached to a front between days 3 and 4 to the north
of Bermuda, and the official forecast therefore shows a completion
of extratropical transition by Sunday morning.


KEY MESSAGES:

1. Heavy rainfall from Philippe is expected to produce scattered
flash flooding across portions of the U.S. and British Virgin
Islands through today. Heavy rainfall from Philippe will begin to
affect Bermuda on Thursday.

2. Tropical storm conditions are possible on Bermuda beginning
Friday morning, and a Tropical Storm Watch is now in effect for the
island.

3. Philippe is likely to move over portions of Atlantic Canada and
eastern New England, likely as a post-tropical cyclone, this
weekend. Regardless of Philippe's intensity or structure,
interests in those areas should monitor the storm's progress and be
prepared for the possibility of strong winds and heavy rainfall.


FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 21.2N 65.7W 40 KT 45 MPH
12H 05/0000Z 22.3N 66.0W 40 KT 45 MPH
24H 05/1200Z 24.7N 66.2W 40 KT 45 MPH
36H 06/0000Z 27.6N 65.9W 45 KT 50 MPH
48H 06/1200Z 30.8N 65.3W 45 KT 50 MPH
60H 07/0000Z 34.2N 65.1W 50 KT 60 MPH
72H 07/1200Z 37.8N 65.3W 50 KT 60 MPH
96H 08/1200Z 46.8N 67.8W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 09/1200Z 52.9N 71.9W 25 KT 30 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg

[cycloneye]

BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 45A
NWS National Hurricane Center Miami FL AL172023
200 PM AST Wed Oct 04 2023

...AIR FORCE RESERVE HURRICANE HUNTERS INVESTIGATING PHILIPPE...


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...22.0N 65.8W
ABOUT 255 MI...410 KM NNW OF ST. THOMAS
ABOUT 715 MI...1150 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

[cycloneye]

Tropical Storm Philippe Discussion Number 46
NWS National Hurricane Center Miami FL AL172023
500 PM AST Wed Oct 04 2023

Philippe still has an elongated circulation with discrete clusters
of deep convection extending well to the east and south of the
center. Aircraft and satellite-derived wind data suggest that the
maximum winds have decreased a bit, and Philippe is barely a
tropical storm. An Air Force Reserve Hurricane Hunter aircraft
only measured peak 850-mb flight-level winds of 39 kt, and although
SFMR winds were reported between 35-40 kt, a comparison with ASCAT
data and a visual assessment from the flight crew indicate that
these data were at least 10 kt too high. The consensus of all
available data suggest that 35 kt is a more representative value
for the initial intensity.

The latest fixes indicate that Philippe has turned northward with
an initial motion of 350/10 kt. A northward motion with an
increase in forward speed is expected through the next 3 days while
Philippe moves between a deep-layer trough just east of Florida and
the subtropical ridge over the central Atlantic. After day 3, a
larger trough is forecast to move across eastern North America and
become negatively tilted, which is expected to cause Philippe to
bend to the north-northwest when it reaches Atlantic Canada or
eastern New England over the weekend. The track models (at
least the ones that carry Philippe for the entire forecast period)
remain in good agreement on this scenario, and the NHC track
forecast is close to the HCCA consensus aid.

The forecast for Philippe's intensity and structure remains complex.
The 12Z GFS still shows a separate non-tropical low developing over
the western Atlantic, with Philippe becoming absorbed by the warm
front to the east of the low in 2-3 days. However, that appears to
be an outlier scenario at this time since the ECMWF, UKMET, and
Canadian models keep Philippe as a distinct and dominant low. Even
if it doesn't become absorbed, Philippe is likely to become
frontal by day 3, and the NHC forecast now shows the system as
extratropical by Saturday afternoon. Little change in strength is
likely during the next couple of days, but Philippe could strengthen
a little due to baroclinic influences while it goes through
extratropical transition. The NHC intensity forecast is below the
intensity consensus aids for the first 48 hours, but then is between
IVCN and the ECMWF after that time.


KEY MESSAGES:

1. Tropical storm conditions are expected on Bermuda beginning
early Friday morning, and a Tropical Storm Warning is now in effect.
Heavy rainfall will begin to affect the island on Thursday.

2. Philippe is likely to move over portions of Atlantic Canada and
eastern New England, likely as a post-tropical cyclone, this
weekend. Regardless of Philippe's intensity or structure, interests
in those areas should monitor the storm's progress and be prepared
for the possibility of strong winds and heavy rainfall.


FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 22.6N 65.9W 35 KT 40 MPH
12H 05/0600Z 24.0N 66.1W 35 KT 40 MPH
24H 05/1800Z 26.6N 66.0W 35 KT 40 MPH
36H 06/0600Z 29.8N 65.7W 40 KT 45 MPH
48H 06/1800Z 33.3N 65.3W 45 KT 50 MPH
60H 07/0600Z 36.9N 65.4W 50 KT 60 MPH
72H 07/1800Z 40.9N 65.9W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 08/1800Z 50.5N 69.5W 40 KT 45 MPH...POST-TROP/EXTRATROP
120H 09/1800Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

Tropical Storm Philippe Discussion Number 47
NWS National Hurricane Center Miami FL AL172023
1100 PM AST Wed Oct 04 2023

Philippe has generally changed little during the past several hours.
The storm still resembles an elongated trough in satellite images
with a north-south oriented area of deep convection extending a
couple of hundred north and several hundred miles south of the
center. Areas of heavy rain continue to linger near Puerto Rico and
the Virgin Islands. Since the system appears to be steady in
strength, the initial intensity is held at 35 kt based on the
earlier aicraft data. This wind speed estimate is also in line with
the latest satellite intensity estimates.

The storm is moving northward at 11 kt in the flow between a ridge
over the central Atlantic and a mid- to upper-level low off the
Florida coast. This northward motion with an increase in forward
speed is expected during the next few days, taking the center
of the system across Bermuda in 36-48 hours. Philippe will likely
turn northwestward into Maine and Atlantic Canada this weekend when
another trough cuts off over the northeastern U.S. The NHC track
forecast is similar to the previous one and near the middle of the
guidance envelope.

Nearly all of the models show slow strengthening during the next 2
or 3 days, which seems to be due to baroclinic influences from the
trough/low currently east of Florida. The mid- to upper-level
trough/low will likely merge with Philippe in 48-60 hours, which
should cause the system to develop frontal features and become
extratropical after it passes Bermuda. The post-tropical cyclone
is expected to weaken once it moves inland over Maine and Atlantic
Canada. The NHC intensity forecast also lies near the middle of
the guidance envelope.


KEY MESSAGES:

1. Tropical storm conditions are expected on Bermuda beginning
Thursday night, and a Tropical Storm Warning is in effect. Heavy
rainfall will begin to affect the island on Thursday.

2. Philippe is likely to move over portions of Atlantic Canada and
eastern New England, likely as a post-tropical cyclone, this
weekend. Regardless of Philippe's intensity or structure, interests
in those areas should monitor the storm's progress and be prepared
for the possibility of strong winds and heavy rainfall.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0300Z 23.8N 66.1W 35 KT 40 MPH
12H 05/1200Z 25.4N 66.3W 35 KT 40 MPH
24H 06/0000Z 28.4N 66.0W 40 KT 45 MPH
36H 06/1200Z 31.9N 65.9W 40 KT 45 MPH
48H 07/0000Z 35.3N 66.4W 45 KT 50 MPH
60H 07/1200Z 39.0N 66.7W 50 KT 60 MPH
72H 08/0000Z 43.3N 67.1W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 09/0000Z 51.6N 73.2W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 10/0000Z...DISSIPATED

$$
Forecaster Cangialosi

[cycloneye]

Tropical Storm Philippe Discussion Number 48
NWS National Hurricane Center Miami FL AL172023
500 AM AST Thu Oct 05 2023

Philippe's low-level structure continues to be quite broad and
diffuse this morning. This structure has made finding the center
position quite a challenge. An earlier 0513 UTC GMI microwave pass
confirmed this broad structure, though it did hint at a tighter
mesoscale feature tucked under the convection to the southeast of
the broader low-level rotation seen on 1-minute GOES-16 imagery. The
initial intensity remains 35 kt this advisory, in agreement with the
TAFB subjective Dvorak estimate, in addition to an earlier received
saildrone observation that had sustained tropical-storm-force winds
well to the southeast of the broad circulation center.

Because the center is difficult to pinpoint, the initial motion is
also uncertain, estimated due north at 360/12 kt. The storm's
current motion is a result of it being steered between a mid-level
ridge positioned to its east, and a mid- to upper-level low
positioned to its west. This pattern should persist, leading to
Philippe gradually accelerating towards Bermuda over the next 24-36
h. Interestingly, the guidance has quite a bit of spread this cycle
in the short-term, likely related to how the current broad and
diffuse circulation interacts with the trough to its west, with the
HAFS-A/B runs notably pivoting Philippe further west early on than
the remainder of the guidance. The NHC track forecast ops to favor
the simple consensus aids, though it is worth noting the HFIP
Corrected Consensus Approach (HCCA) is farther west due to the
influence of these HAFS tracks. I guess it is not all that
surprising to see Philippe throw one additional curve ball in the
track forecast given the extreme difficulty the track forecast for
this system has proven to be over the last couple of weeks. After
48 hours, the guidance actually comes back into better agreement,
showing a gradual bend north-northwest and northwest when Philippe,
now a post-tropical cyclone, reaches the coast of Atlantic Canada
or New England this weekend.

The intensity forecast presents its own challenges. Assuming that
Philippe remains a distinct entity relative to the developing
non-tropical low to its west, the storm could intensify while it
interacts with this upper-level trough to its west. However, its
unclear if this will prove to be a favorable trough interaction, or
if this trough will ultimately just absorb the tropical cyclone
without much increase in the winds. Regardless, after Philippe
passes north of Bermuda, increasing baroclinicity will hasten its
transition to an extratropical cyclone. However, FSU phase-space
diagrams suggest the system could undergo a warm-seclusion-type
transition, resulting in further deepening even after the system
becomes extratropical. The post-tropical cyclone is then expected to
weaken once it moves inland over Maine and/or Atlantic Canada. The
NHC intensity forecast continues to lie near the middle of the
guidance envelope.


KEY MESSAGES:

1. Tropical storm conditions are expected on Bermuda beginning
tonight, where a Tropical Storm Warning remains in effect. Heavy
rainfall will also begin to affect the island later today, which
could produce flash-flooding.

2. Philippe is likely to move over portions of Atlantic Canada and
eastern New England, likely as a post-tropical cyclone by this
weekend. Regardless of Philippe's intensity or structure, interests
in those areas should monitor the storm's progress and be prepared
for the possibility of strong winds and heavy rainfall.


FORECAST POSITIONS AND MAX WINDS

INIT 05/0900Z 24.8N 65.9W 35 KT 40 MPH
12H 05/1800Z 26.7N 66.0W 35 KT 40 MPH
24H 06/0600Z 30.0N 66.0W 40 KT 45 MPH
36H 06/1800Z 33.3N 66.0W 45 KT 50 MPH
48H 07/0600Z 36.7N 66.2W 50 KT 60 MPH
60H 07/1800Z 40.2N 66.7W 50 KT 60 MPH...POST-TROP/EXTRATROP
72H 08/0600Z 45.2N 67.8W 45 KT 50 MPH...POST-TROP/INLAND
96H 09/0600Z 50.5N 76.0W 30 KT 35 MPH...POST-TROP/INLAND
120H 10/0600Z...DISSIPATED

$$
Forecaster Papin

[cycloneye]

BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 48A
NWS National Hurricane Center Miami FL AL172023
800 AM AST Thu Oct 05 2023

...AIR FORCE RESERVE HURRICANE HUNTERS FIND PHILIPPE A LITTLE
STRONGER BUT STILL IN A STATE OF DISORGANIZATION...


SUMMARY OF 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...24.9N 66.3W
ABOUT 455 MI...735 KM N OF ST. THOMAS
ABOUT 520 MI...835 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

[cycloneye]

Tropical Storm Philippe Discussion Number 49
NWS National Hurricane Center Miami FL AL172023
1100 AM AST Thu Oct 05 2023

Philippe's low-level circulation remains broad this morning with
most of the associated deep convection located within the eastern
semicircle. Despite the continued disorganized structure, an Air
Force Reserve Hurricane Hunter mission this morning measured peak
850-mb flight-level winds of 56 kt and SFMR surface winds of 40-45
kt. Based on these data, Philippe's initial intensity is raised to
45 kt.

The latest fixes suggest that Philippe is moving just west of due
north (355 degrees) at 10 kt. This northward motion, with an
increase in forward speed, is expected to continue through Saturday
while Philippe moves over the western Atlantic between a deep-layer
trough east of Florida and a mid-level high over the central
Atlantic. A north-northwestward turn is likely to occur as the
cyclone is approaching Atlantic Canada or eastern New England, due
to a larger trough approaching from the west. Since Philippe may
interact with a baroclinic zone and a developing non-tropical low
to its west in another day or two, the nuances of the track
forecast still need to be worked out, but nearly all of the track
guidance agrees on the forecast scenario described above. The NHC
forecast is close to the HCCA consensus aid and brings the center
to the coast of Nova Scotia, New Brunswick, or eastern Maine
between 60 and 72 hours. The center should then be absorbed by a
broad area of low pressure to its west over Quebec some time on
Sunday.

Little change in intensity is expected during the next day or two,
particularly since model guidance suggests that the shear over
Philippe could strengthen further. Despite the shear, some
additional strengthening is possible in about 48 hours when
Philippe could receive an injection of baroclinic energy from the
trough located east of Florida. That process should also
kick-start extratropical transition, and the NHC forecast shows the
transition complete by 60 hours (late Saturday) when Philippe is
located offshore of Nova Scotia. Weakening is forecast once
Philippe moves inland, and it's likely that the strongest winds from
the system will continue to occur on the eastern side of the
circulation, primarily over parts of Atlantic Canada.


KEY MESSAGES:

1. Tropical storm conditions are expected on Bermuda beginning
early Friday morning, and a Tropical Storm Warning remains in
effect. Heavy rainfall will also begin to affect the island today,
which could produce flash-flooding.

2. Philippe is expected to move over portions of Atlantic Canada and
eastern New England as a post-tropical cyclone this weekend.
Regardless of Philippe's intensity or structure, interests in those
areas should be prepared for the possibility of strong winds and
heavy rainfall and monitor statements from their local weather
office.


FORECAST POSITIONS AND MAX WINDS

INIT 05/1500Z 25.6N 66.3W 45 KT 50 MPH
12H 06/0000Z 27.7N 66.4W 45 KT 50 MPH
24H 06/1200Z 30.9N 66.3W 45 KT 50 MPH
36H 07/0000Z 34.2N 66.6W 50 KT 60 MPH
48H 07/1200Z 37.6N 66.6W 50 KT 60 MPH
60H 08/0000Z 41.8N 66.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
72H 08/1200Z 47.4N 68.0W 40 KT 45 MPH...POST-TROP/INLAND
96H 09/1200Z...DISSIPATED

$$
Forecaster Berg

[cycloneye]

BULLETIN
Tropical Storm Philippe Intermediate Advisory Number 49A
NWS National Hurricane Center Miami FL AL172023
200 PM AST Thu Oct 05 2023

...PHILIPPE CONTINUES NORTHWARD...
...HEAVY RAINS APPROACHING BERMUDA FROM THE SOUTH...


SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...26.2N 66.3W
ABOUT 430 MI...695 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES

[cycloneye]

Tropical Storm Philippe Discussion Number 50
NWS National Hurricane Center Miami FL AL172023
500 PM AST Thu Oct 05 2023

Philippe's convective structure is gradually evolving as it begins
to run into an old frontal zone to its north. A band of rain is
developing over the northern part of the circulation along the
old front and is beginning to move over Bermuda, while other deep
convection extends east and southeast of the center. The initial
intensity is held at 45 kt based on this morning's aircraft
reconnaissance data. Another mission is scheduled into Philippe
this evening.

The current motion is a little faster toward the north, or 360/12
kt. The track forecast reasoning has not changed. Philippe should
continue accelerating northward over the western Atlantic during
the next 60 hours while moving between a mid-level high over the
central Atlantic and a deep-layer trough off the southeastern U.S.
coast. On this track, the center will approach the coasts of Nova
Scotia, New Brunswick, and eastern Maine Saturday night. After
that time, Philippe is expected to turn north-northwestward ahead
of an approaching mid-latitude trough, and it is forecast to become
absorbed by another area of low pressure over eastern Quebec late
Sunday. The NHC track forecast generally lies close to the TVCA
and HCCA consensus aids during the entire forecast period.

Diagnoses from the SHIPS model suggest that southwesterly shear
will increase to 30 kt or more over the next 12-24 hours. Because
of that, no intensification is anticipated in the short term.
Extratropical transition is likely to begin on Friday as Philippe
moves into and tightens the thickness gradient to its north, and
that process could cause the storm to strengthen a little due to
baroclinic influences. This scenario is supported by the GFS and
ECMWF global models, as well as LGEM, IVCN, and HCCA consensus aids.
Extratropical transition is forecast to be complete by 48 hours
(Saturday afternoon) as Philippe becomes fully frontal, but the
intensity is unlikely to change much before the center reaches land.
Weakening is forecast once Philippe moves inland, and it's likely
that the strongest winds from the system will occur on the eastern
side of the circulation, primarily over parts of Atlantic Canada.

Based on the forecast for Philippe to become post-tropical by
Saturday, and after coordination with National Weather Service
offices in New England and the Canadian Hurricane Centre, the
current plan is for hazards in New England and Atlantic Canada to
be handled via local non-tropical statements and not issue tropical
watches or warnings. We will continually assess this plan if the
forecast evolves and tropical watches or warnings become warranted.


KEY MESSAGES:

1. Tropical storm conditions are expected on Bermuda beginning
early Friday morning, and a Tropical Storm Warning remains in
effect. Heavy rainfall is expected to affect the island today into
early Friday. This could produce flash flooding.

2. Philippe is expected to move over portions of Atlantic Canada and
New England as a post-tropical cyclone this weekend. Regardless of
Philippe's intensity or structure, interests in those areas should
be prepared for the possibility of strong winds and heavy rainfall
and monitor statements from their local weather office. The
rainfall could produce isolated to scattered instances of urban and
flash flooding.


FORECAST POSITIONS AND MAX WINDS

INIT 05/2100Z 27.0N 66.2W 45 KT 50 MPH
12H 06/0600Z 29.2N 65.8W 45 KT 50 MPH
24H 06/1800Z 32.5N 65.7W 45 KT 50 MPH
36H 07/0600Z 35.5N 66.1W 50 KT 60 MPH
48H 07/1800Z 39.0N 66.2W 50 KT 60 MPH...POST-TROP/EXTRATROP
60H 08/0600Z 43.8N 66.7W 50 KT 60 MPH...POST-TROP/EXTRATROP
72H 08/1800Z 48.6N 71.4W 40 KT 45 MPH...POST-TROP/INLAND
96H 09/1800Z...DISSIPATED

$$
Forecaster Berg