ATL: OSCAR - Advisories

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ATL: OSCAR - Advisories

#1 Postby cycloneye » Fri Oct 26, 2018 9:35 pm

BULLETIN
Subtropical Storm Oscar Advisory Number 1
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Fri Oct 26 2018

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


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...26.7N 45.7W
ABOUT 1255 MI...2020 KM ENE OF THE NORTHERN LEEWARD ISLANDS
ABOUT 1210 MI...1945 KM ESE OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM AST (0300 UTC), the center of Subtropical Storm Oscar was
located near latitude 26.7 North, longitude 45.7 West. The storm is
moving toward the north-northwest near 9 mph (15 km/h). A turn
toward the west and west-southwest at a faster forward speed is
expected on Saturday, with this motion continuing through Sunday
night.

Recent satellite wind data indicate that maximum sustained winds are
near 45 mph (75 km/h) with higher gusts. Gradual strengthening is
forecast during the next couple of days, and Oscar could become a
tropical storm on Sunday.

Winds of 40 mph extend outward up to 105 miles (165 km) mainly to
the east of the center.

The estimated minimum central pressure is 1005 mb (29.68 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Beven





Subtropical Storm Oscar Discussion Number 1
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Fri Oct 26 2018

Satellite imagery and scatterometer data indicate the circulation
of the broad low pressure area over the central Atlantic has become
better defined, with a low-level center developing to the south of
a convective burst. The scatterometer data indicate 35-40 kt winds
about 70-90 n mi from the center, and satellite imagery shows that
the cyclone is entangled with a developing upper-level low. Based
on these factors, advisories are being initiated on the latest in
this year's series of subtropical storms, Oscar.

Due to the recent development of the center, the initial motion is
an uncertain 335/8. The track guidance is in excellent agreement
that Oscar should should turn sharply westward and west-
southwestward during the next 24 h as it pivots around the north
side of the upper-level low, with this general motion continuing
through about 48 h. After that, the cyclone should turn more
westward at a slower forward speed as it approaches a weakness in
the subtropical ridge. A northeastward motion appears likely from
72-120 h due to a mid-latitude trough approaching Oscar from the
west. However, there are significant differences in the forward
speed between the GFS, ECMWF, and UKMET models that make this part
of the forecast low confidence. Overall, the forecast track is
close to the TVCN consensus model, and it splits the difference
between the divergent global models late in the forecast period.

Gradual strengthening is forecast as Oscar remains in the deep-layer
cyclonic flow of the upper-level low during the first 36-48 h.
After that time, the global models suggests the system will have a
chance to develop a tropical cyclone outflow pattern, and based on
this the forecast calls for Oscar to become a tropical cyclone near
the 48 h point. Interaction with the aforementioned mid-latitude
trough may allow some additional intensification before Oscar
encounters stronger shear near the 120 h point. The FV3 model shows
a much weaker Oscar than the other dynamical models, and it is
possible that dry air entrainment may hamper development through
the forecast period. Thus, the intensity forecast is below the
intensity consensus and on the weaker side of the intensity
guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 26.7N 45.7W 40 KT 45 MPH
12H 27/1200Z 27.2N 47.2W 45 KT 50 MPH
24H 28/0000Z 26.6N 50.3W 50 KT 60 MPH
36H 28/1200Z 25.6N 53.2W 50 KT 60 MPH
48H 29/0000Z 25.3N 55.3W 55 KT 65 MPH...TROPICAL CYCLONE
72H 30/0000Z 26.5N 57.5W 60 KT 70 MPH
96H 31/0000Z 30.0N 55.5W 60 KT 70 MPH
120H 01/0000Z 34.0N 50.0W 55 KT 65 MPH

$$
Forecaster Beven


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Re: ATL: OSCAR - Advisories

#2 Postby cycloneye » Sat Oct 27, 2018 5:18 am

Subtropical Storm Oscar Discussion Number 2
NWS National Hurricane Center Miami FL AL162018
500 AM AST Sat Oct 27 2018

Oscar's convective pattern has not changed much since the previous
advisory. The surface center is displaced just to the southeast of
a burst of deep convection, and other convective elements extend
along a broken band over the eastern part of the circulation.
Although satellite classifications have not increased, a drifting
buoy (47546) near Oscar's center recently reported a pressure of
998.8 mb, implying a significant drop in the cyclone's central
pressure from the previous estimate. Based on pressure-wind
relationships, this low pressure would equate to maximum winds
around 45 kt, and that is set as the initial intensity for this
advisory.

Oscar is careening around the northern side of a mid- to
upper-level low, and its initial motion is now west-northwestward,
or 300/10 kt. As the circulation becomes more vertically aligned
in the coming days, the cyclone is forecast to be pushed
westward to west-southwestward by the flow on the back side of a
trough that is dropping southward over the eastern Atlantic. After
48 hours, Oscar is expected to recurve sharply and accelerate toward
the north Atlantic ahead of an approaching mid-latitude trough.
The global models have come into much better agreement on Oscar's
eventual recurvature and acceleration, and confidence in the NHC
track forecast has increased. In fact, the 00Z guidance suite
required a significant increase in Oscar's forecast forward speed
on days 4 and 5, and the new NHC track forecast is much faster than
the previous one at the end of the forecast period, jumping
northward by about 10 degrees of latitude. This new forecast is
close to the TVCN multi-model consensus and HCCA model on day 5,
but it's still not as fast as the 00Z GFS and ECMWF guidance.

Gradually decreasing shear and warmer waters ahead of Oscar should
allow for a steady increase in intensity during the next few days,
and the cyclone is also expected to take on a more tropical
convective pattern in about 36 hours. The intensity models are
showing a little more intensification than before, and the new NHC
intensity forecast has been nudged upward, showing Oscar becoming a
hurricane in 3-4 days. Still, this forecast lies near the lower
bound of the intensity guidance, and additional upward adjustments
may be required in future advisories. Now that most of the models
are showing more acceleration of Oscar toward the north Atlantic
later in the forecast period, there is also more definitive
consensus that Oscar will become an extratropical low by day 5, and
that is now indicated in the official forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 27.3N 47.0W 45 KT 50 MPH
12H 27/1800Z 27.1N 49.1W 45 KT 50 MPH
24H 28/0600Z 26.2N 52.0W 50 KT 60 MPH
36H 28/1800Z 25.7N 54.6W 55 KT 65 MPH...TROPICAL CYCLONE
48H 29/0600Z 25.9N 56.6W 60 KT 70 MPH
72H 30/0600Z 28.4N 57.4W 65 KT 75 MPH
96H 31/0600Z 35.0N 52.0W 70 KT 80 MPH
120H 01/0600Z 45.0N 39.0W 60 KT 70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg
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Re: ATL: OSCAR - Advisories

#3 Postby cycloneye » Sat Oct 27, 2018 9:47 am

BULLETIN
Subtropical Storm Oscar Advisory Number 3
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Sat Oct 27 2018

...OSCAR TURNS TOWARD THE WEST AND CONTINUES TO STRENGTHEN...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.3N 48.4W
ABOUT 1040 MI...1675 KM ESE OF BERMUDA
ABOUT 1125 MI...1810 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES



Subtropical Storm Oscar Discussion Number 3
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Sat Oct 27 2018

Oscar's organization has improved this morning. Although the
subtropical storm is still entangled with an upper-level low,
convection has increased near the center of the cyclone since last
night. The most recent Hebert-Poteat subtropical intensity estimate
from TAFB has increased accordingly to 45-50 kt. Furthermore,
Canadian drifting buoy 47546 recently reported a minimum pressure of
just below 996 mb to the east of Oscar's center, suggesting the
central pressure of the cyclone has decreased since the last
advisory. The initial intensity is therefore increased to 50 kt for
this advisory.

Little change has been made to the intensity forecast. The GFS and
many of its associated models (HWRF, DSHP, LGEM) have changed
abruptly and forecast far less intensification than they did just 6
hours ago. However, the CTCI, HMON, and ECMWF-based statistical
guidance still show Oscar reaching hurricane strength within a few
days. Rather than chase a possible short-term trend in the intensity
guidance, the official intensity forecast will stay the course for
now and is a little above the intensity consensus, bringing Oscar to
hurricane strength in around 48 h. After that time, some slight
additional intensification is possible, but Oscar is ultimately
expected to undergo extratropical transition by the end of the
forecast period, which should cause the cyclone to steadily weaken.

Oscar has turned toward the west and the initial motion estimate is
now 270/11 kt. A west-southwestward motion is anticipated later
today as Oscar moves around the back side of an mid- to upper-level
trough over the central Atlantic, followed by a turn toward the west
on the south side of a subtropical ridge to the north. As long as
Oscar intensifies as forecast, it should turn sharply northeastward
early next week ahead of a mid-latitude trough advancing across the
western and central Atlantic, and then accelerate in that direction
while undergoing extratropical transition. The GFS is an outlier,
showing a much weaker and vertically shallow cyclone that does not
fully recurve, but all of the other global models are in generally
good agreement with the scenario listed above. Despite the
inconsistency of the GFS, the model consensus has not changed
significantly since the last advisory, so only minor adjustments
were made to the NHC track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 27.3N 48.4W 50 KT 60 MPH
12H 28/0000Z 26.9N 50.6W 55 KT 65 MPH
24H 28/1200Z 26.2N 53.5W 60 KT 70 MPH...TROPICAL CYCLONE
36H 29/0000Z 25.9N 56.1W 60 KT 70 MPH
48H 29/1200Z 26.5N 57.4W 65 KT 75 MPH
72H 30/1200Z 30.2N 57.0W 70 KT 80 MPH
96H 31/1200Z 37.0N 50.0W 70 KT 80 MPH
120H 01/1200Z 47.0N 38.0W 60 KT 70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Zelinsky
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Re: ATL: OSCAR - Advisories

#4 Postby cycloneye » Sat Oct 27, 2018 3:48 pm

BULLETIN
Subtropical Storm Oscar Advisory Number 4
NWS National Hurricane Center Miami FL AL162018
500 PM AST Sat Oct 27 2018

...OSCAR EXPECTED TO BECOME A TROPICAL STORM TONIGHT...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...26.9N 50.7W
ABOUT 925 MI...1485 KM ESE OF BERMUDA
ABOUT 990 MI...1595 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...W OR 265 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES




Subtropical Storm Oscar Discussion Number 4
NWS National Hurricane Center Miami FL AL162018
500 PM AST Sat Oct 27 2018

Oscar is still located beneath an upper-level low, however it its
convective structure is now more reminiscent of a tropical cyclone.
Deep convection is primarily occuring in a small burst just south
of the center of Oscar, however this convective activity appears to
be displaced by light northerly shear associated with the upper-low.
Earlier AMSU sounding data indicated that the cyclone has developed
a weak but vertically deep warm core which also indicates that Oscar
is nearly a tropical cyclone, if it isn't one already. Oscar is
moving quickly westward away from the upper-low, and will likely
become a tropical storm later tonight if its current structural
trends continue.

The initial intensity is held at 50 kt, based primarily on the
latest Hebert-Poteat subtropical intensity estimate from TAFB. The
intensity guidance has bounced back, and the most of the intensity
guidance is higher than it was six hours ago. While little change
was made to the NHC intensity forecast, it now lies very near the
intensity consensus at all forecast hours. Gradual intensification
is still expected and Oscar is forecast to approach hurricane
strength by Monday. Slight additional intensification is possible
through the middle of next week, until extratropical transition
occurs by 120 h.

Oscar moved very quickly westward this afternoon, but a more
representative motion estimate is 265/15 kt. The latest runs of the
typically reliable global models are in better agreement than they
were this morning. Oscar is forecast to move west-southwestward or
westward for the next day or two on the south side of a mid-level
ridge to the north. The cyclone is then expected to recurve and
accelerate northeastward ahead of a substantial mid-latitude trough
moving across the western and central Atlantic by the middle of next
week. The official track forecast has been adjusted westward to
bring it closer to the latest track consensus, especially for the
first 72 h of the forecast. By day 5, the official forecast is quite
similar to the previous advisory, but with a slightly slower forward
speed for Oscar.

FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 26.9N 50.7W 50 KT 60 MPH
12H 28/0600Z 26.1N 53.0W 50 KT 60 MPH...TROPICAL CYCLONE
24H 28/1800Z 25.7N 55.8W 55 KT 65 MPH
36H 29/0600Z 25.6N 57.9W 55 KT 65 MPH
48H 29/1800Z 26.4N 59.1W 60 KT 70 MPH
72H 30/1800Z 30.6N 57.5W 70 KT 80 MPH
96H 31/1800Z 38.5N 50.0W 70 KT 80 MPH
120H 01/1800Z 46.5N 38.0W 60 KT 70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Zelinsky
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Re: ATL: OSCAR - Advisories

#5 Postby cycloneye » Sat Oct 27, 2018 9:38 pm

BULLETIN
Tropical Storm Oscar Advisory Number 5
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Sat Oct 27 2018

...OSCAR STRENGTHENS AS IT TRANSITIONS TO A TROPICAL STORM...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.7N 51.4W
ABOUT 930 MI...1495 KM ESE OF BERMUDA
ABOUT 910 MI...1465 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WSW OR 240 DEGREES AT 20 MPH...31 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES



Tropical Storm Oscar Discussion Number 5
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Sat Oct 27 2018

Satellite imagery shows that convection associated with Oscar has
become better organized, with increased banding around the low-
level center. In addition, recent scatterometer data indicate that
the system now has a relatively small wind field with a radius of
maximum winds of about 25 n mi. Although the cyclone is still
tangled up with the upper-level low to the point where it has not
yet developed the anticyclonic outflow of a tropical cyclone, the
convection and the wind field now justify calling the system a
tropical storm. The initial intensity has been raised to 55 kt
based on the scatterometer data, and it is possible this is a little
conservative.

The initial motion is a somewhat uncertain 240/17, as the
short-term motion has been more toward the southwest or south. For
the next several hours, Oscar should continue to pivot around the
upper-level low to its east. Thereafter, it should turn more
westward with a decrease in forward speed on the south side of a
large ridge over the North Atlantic. After about 36 h, a large
deep-layer trough moving eastward across the western Atlantic
should cause Oscar to turn northwestward and northward, followed by
recurvature into the westerlies and acceleration. The track
guidance is generally in good agreement with this scenario,
although by 120 h there is some spread in both the direction and
forward speed after recurvature. The new forecast track is near
the various consensus models, and the early part of it is shifted a
little to the south of the previous forecast due to the current
location and motion.

The global models suggest that the core of Oscar should mostly avoid
nearby strong upper-level winds through 24-36 h, and then encounter
strong upper-level divergence associated with the deep-layer trough.
While the environment is not ideal for a tropical cyclone,
conditions appear favorable for additional intensification, and the
intensity forecast now calls for Oscar to reach hurricane strength
in about 24 h. Interaction with the trough after 72 h should start
extratropical transition, which should be complete between 96-120 h.


FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 25.7N 51.4W 55 KT 65 MPH
12H 28/1200Z 25.2N 54.1W 60 KT 70 MPH
24H 29/0000Z 25.1N 56.5W 65 KT 75 MPH
36H 29/1200Z 25.8N 58.2W 70 KT 80 MPH
48H 30/0000Z 27.2N 58.6W 75 KT 85 MPH
72H 31/0000Z 32.5N 55.5W 75 KT 85 MPH
96H 01/0000Z 41.0N 47.0W 70 KT 80 MPH
120H 02/0000Z 48.5N 32.0W 60 KT 70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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Re: ATL: OSCAR - Advisories

#6 Postby cycloneye » Sun Oct 28, 2018 5:05 am

BULLETIN
Tropical Storm Oscar Advisory Number 6
NWS National Hurricane Center Miami FL AL162018
500 AM AST Sun Oct 28 2018

...OSCAR EXPECTED TO BECOME A HURRICANE LATER TODAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...25.0N 52.6W
ABOUT 895 MI...1440 KM ESE OF BERMUDA
ABOUT 820 MI...1320 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...SW OR 235 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES



Tropical Storm Oscar Discussion Number 6
NWS National Hurricane Center Miami FL AL162018
500 AM AST Sun Oct 28 2018

Deep convection near the center of Oscar has diminished somewhat
over the past several hours. However, there are tightly curved
cloud bands very near the center indicating a well-organized
cyclone. Given that the central convection has not increased, the
current intensity estimate is held at 55 kt which is a little above
the latest subjective and objective Dvorak estimates but close to
the value indicated by the previous scatterometer data. Oscar
should remain in a moderate vertical shear environment, and over
26-27 deg C SSTs, for the next couple of days which would allow for
some strengthening. The official forecast is close to the latest
intensity model consensus and calls for the system to become a
hurricane soon. Near or just beyond 96 hours, the shear is forecast
to increase substantially and Oscar should begin to make the
transition to an extratropical cyclone.

The storm has been moving southwestward, or 235/13 kt, on the
southeastern side of a northeast to southwest-oriented mid-level
ridge. The ridge is likely to build to the north of Oscar within
12 to 24 hours, resulting in a turn toward the west. The cyclone
should then turn toward the northwest and north as the ridge shifts
eastward and a trough moves off the eastern U.S. coast. In the
latter half of the forecast period, the system should accelerate
north-northeastward to northeastward in the flow ahead of the
trough. The official track forecast is close to the latest
dynamical model consensus, and similar to the previous NHC track.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 25.0N 52.6W 55 KT 65 MPH
12H 28/1800Z 25.0N 54.5W 65 KT 75 MPH
24H 29/0600Z 25.5N 56.7W 70 KT 80 MPH
36H 29/1800Z 26.4N 58.0W 75 KT 85 MPH
48H 30/0600Z 27.9N 58.0W 75 KT 85 MPH
72H 31/0600Z 34.6N 53.6W 75 KT 85 MPH
96H 01/0600Z 42.5N 44.5W 60 KT 70 MPH
120H 02/0600Z 50.0N 28.5W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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Re: ATL: OSCAR - Advisories

#7 Postby cycloneye » Sun Oct 28, 2018 9:51 am

BULLETIN
Tropical Storm Oscar Advisory Number 7
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Sun Oct 28 2018

...OSCAR POISED TO STRENGTHEN OVER THE CENTRAL ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.5N 53.8W
ABOUT 815 MI...1310 KM ESE OF BERMUDA
ABOUT 780 MI...1255 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...991 MB...29.27 INCHES



Tropical Storm Oscar Discussion Number 7
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Sun Oct 28 2018

Deep convection has redeveloped near the center of Oscar since early
this morning and its low-level center is no longer exposed.
Satellite intensity estimates have not changed since last night and
the estimated intensity of 60 kt is above the various techniques.
The initial intensity estimate is based primarily on the latest
available ASCAT data from last night around 0100 UTC that showed
maximum winds of 55-60 kt. Given the recent increase in convection
observed near the center of Oscar, it seems unlikely that the winds
have decreased since that time. It is worth noting that the small
inner-core of Oscar increases the uncertainty of the intensity
estimate, and could make the cyclone susceptible to short term
intensity fluctuations that are nearly impossible to forecast or
precisely detect.

Virtually no change has been made to the intensity forecast. The
tropical storm is moving over sufficiently warm water to support
intensification and it is located within a light to moderate shear
environment. All the intensity models forecast at least some
strengthening, and Oscar is expected to become a hurricane later
today or tonight, with some additional strengthening possible
through Wednesday. Extratropical transition is forecast to begin
soon thereafter, which will likely result in a decrease in the
maximum winds, even as the extent of tropical-storm-force winds
rapidly increases. This process is expected to be complete by 120 h.
The new NHC intensity forecast is very close to the intensity
consensus IVCN at all forecast hours.

Oscar turned abruptly westward earlier this morning, and the initial
motion estimate is now 270/10 kt. The tropical cyclone is forecast
to continue moving generally westward for another 12 to 24 h on the
south side of a mid-layer ridge over the northern central Atlantic.
Oscar should then turn toward the north between the ridge and a
mid-latitude trough approaching from the west. By Wednesday, the
cyclone is expected to accelerate north-northeastward or
northeastward as it becomes embedded in deep-layer southwesterly
flow ahead of the aforementioned trough. All of the global models
agree on this general scenario, though there are differences
regarding the exact timing that Oscar will begin its recurvature
and how quickly it will accelerate across the northern Atlantic.
That said, the track consensus aids have changed very little, and no
significant changes were made to the previous track forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 25.5N 53.8W 60 KT 70 MPH
12H 29/0000Z 25.6N 55.8W 65 KT 75 MPH
24H 29/1200Z 26.2N 57.8W 65 KT 75 MPH
36H 30/0000Z 27.3N 58.4W 70 KT 80 MPH
48H 30/1200Z 29.3N 57.8W 75 KT 85 MPH
72H 31/1200Z 37.1N 51.3W 80 KT 90 MPH
96H 01/1200Z 45.5N 40.0W 65 KT 75 MPH
120H 02/1200Z 53.0N 22.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Zelinsky
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Re: ATL: OSCAR - Advisories

#8 Postby cycloneye » Sun Oct 28, 2018 3:57 pm

BULLETIN
Hurricane Oscar Advisory Number 8
NWS National Hurricane Center Miami FL AL162018
500 PM AST Sun Oct 28 2018

...OSCAR BECOMES A HURRICANE OVER THE SUBTROPICAL ATLANTIC...
...THE EIGHTH HURRICANE OF THE 2018 ATLANTIC HURRICANE SEASON...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...25.7N 55.5W
ABOUT 725 MI...1165 KM SE OF BERMUDA
ABOUT 710 MI...1145 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...989 MB...29.21 INCHES





Hurricane Oscar Discussion Number 8
NWS National Hurricane Center Miami FL AL162018
500 PM AST Sun Oct 28 2018

Visible and infrared satellite imagery indicate that Oscar's
convective pattern has continued to improve overall today, with a
small eye having developed and been briefly evident between
1700-1800Z. Satellite intensity estimates range from T4.0/65 kt
(TAFB and SAB) to T4.4/75 kt (UW-CIMSS ADT). The initial intensity
has been increased to 65 kt, which is just below the UW-CIMSS
SATCON consensus estimate of 68 kt.

Oscar is moving westward or 270/14 kt. The compact hurricane is
expected to move around the southwestern and western periphery of a
deep-layer ridge for the next 36 hours or so, resulting in a
westward motion overnight, followed by a turn toward the
west-northwest and northwest on Monday, with a slow motion toward
the north expected by early Tuesday. By late Tuesday and continuing
into Friday, Oscar is forecast to turn northeastward and accelerate
ahead of an eastward-moving deep-layer trough that currently lies
just east of the U.S. east coast. This large synoptic-scale feature
is expected to keep Oscar away from the United States, the Bahamas,
and Bermuda. The only fly-in-the-ointment concerning the track
forecast occurs on day 5 when a strong shortwave trough is forecast
to dig southward down the west side of Oscar, possibly capturing the
small cyclone over the north Atlantic and forcing it southward
instead of allowing the small hurricane to recurve deeper into the
high-latitude westerlies. All of the global and regional models are
now indicating this interaction, with the only difference being
whether Oscar remains a separate tropical system or merges with the
shortwave trough. For now, the new official forecast follows the
trend of the previous advisory and shows Oscar remaining a separate
entity, but slowing down considerably as an extratropical cyclone on
days 4 and 5, which is similar to that depicted by the consensus
models HCCA and TVCN.

Oscar is forecast to remain within an environment of mid- to
upper-level temperatures that are colder than average by 2-3 deg C
due to the cyclone still being embedded within the original parent
larger-scale upper-level low/trough. The combination of the below-
average environmental temperatures overlying relatively warm SSTs of
26.5 deg C will result in strong instability, which will aid the
generation of deep convection, especially overnight. Add in Oscar's
small radius of maximum winds (RMW) of 10-15 nmi, and conditions
appear to be conducive for continued strengthening. The shear
directly over the inner-core region is fairly low as noted by
anticyclonic cirrus outflow now apparent in visible and water vapor
imagery, a condition that also favors continued strengthening for
the next 48 hours or so. The HWRF, HMON, and Navy COAMPS-TC models
bring Oscar to major hurricane strength by 48 hours, which isn't out
of the realm of possibilities based on the small RMW and expected
low vertical wind shear. However, the official intensity forecast
remains on the conservative side due to expected occasional
intrusions of very dry mid-level air, which could briefly interrupt
the intensification process. By 72 hours and beyond, increasing
southwesterly shear ahead of the aforementioned deep-layer trough is
expected to induce a weakening trend, which will be enhanced by
Oscar moving over sub-23 deg C SSTs shortly thereafter. The cold
SSTs are expected to aid the transition to a strong extratropical
cyclone. The new intensity forecast is similar to the previous
advisory, except to push forward the timing of peak intensity to 48
hours, and it is a little below the HCCA and IVCN intensity
consensus models due to the aforementioned dry air issues.

FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 25.7N 55.5W 65 KT 75 MPH
12H 29/0600Z 26.1N 57.1W 70 KT 80 MPH
24H 29/1800Z 26.9N 58.4W 75 KT 85 MPH
36H 30/0600Z 28.2N 58.5W 80 KT 90 MPH
48H 30/1800Z 30.7N 57.0W 85 KT 100 MPH
72H 31/1800Z 38.0N 50.2W 80 KT 90 MPH
96H 01/1800Z 45.0N 39.0W 65 KT 75 MPH...POST-TROP/EXTRATROP
120H 02/1800Z 45.0N 30.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Stewart
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Re: ATL: OSCAR - Advisories

#9 Postby cycloneye » Sun Oct 28, 2018 9:47 pm

BULLETIN
Hurricane Oscar Advisory Number 9
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Sun Oct 28 2018

...OSCAR MOVING QUICKLY WESTWARD WITH LITTLE CHANGE IN STRENGTH...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.6N 57.0W
ABOUT 660 MI...1060 KM SE OF BERMUDA
ABOUT 645 MI...1035 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...989 MB...29.21 INCHES




Hurricane Oscar Discussion Number 9
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Sun Oct 28 2018

Satellite imagery indicates that the structure of Oscar has changed
little over the past several hours. Microwave imagery has shown a
ring or eye feature which is at least partly encircled by deep
convection, and an eye has made occasional appearances in infrared
imagery. Satellite intensity estimates have changed little, so the
initial intensity remains 65 kt. One change from the previous
advisory is that recent scatterometer data show that Oscar has
smaller 34-kt wind radii than previously thought, so the initial
and forecast wind radii have been modified.

The initial motion remains 270/14. Oscar is approaching the
western end of a large low- to mid-level ridge over the central
Atlantic, and thus it should turn northwestward with a decrease in
forward speed during the next 24 h or so. From 24-72 h, the
hurricane should recurve into the mid-latitude westerlies on the
east side of a deep-layer trough moving eastward through the western
and central Atlantic. The models are in good agreement on the
forecast track through 72 h, then show significant differences based
on whether Oscar merges with a new cut-off low pressure area over
the central Atlantic or remains a separate system in the westerlies.
The latest GFS has joined the UKMET in showing Oscar racing
northeastward into the northeastern Atlantic by 120 h as a separate
system. In contrast, the HWRF and the FV3 models show a sharp turn
toward the south as the new low captures Oscar. The ECMWF is
between these extremes in showing a more gradual turn toward the
east well to the east of the HWRF/FV3 and well to the southwest of
the GFS/UKMET. The new forecast track is a little west of the
previous track in the early part of the forecast based on the
current position and motion. Later in the forecast period, it has
been shifted a little to the east in best agreement with the ECMWF.

Oscar is forecast to remain in a moist and unstable environment for
the next 36-48 h, and the trough approaching from the west is
likely to create a divergent outflow pattern. Based on this, the
intensity forecast now shows a faster rate of strengthening than
the previous advisory. After reaching its peak intensity in 36-48
h, it appears likely that the extratropical transition will occur
near the 72 h point before the winds drop below hurricane force.
After transition, Oscar is expected to gradually decay. It should
be noted that if the FV3 scenario verifies, Oscar may maintain
tropical cyclone status beyond 72 h.


FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 25.6N 57.0W 65 KT 75 MPH
12H 29/1200Z 25.9N 58.3W 70 KT 80 MPH
24H 30/0000Z 27.1N 59.0W 80 KT 90 MPH
36H 30/1200Z 29.1N 58.3W 85 KT 100 MPH
48H 31/0000Z 32.0N 56.0W 85 KT 100 MPH
72H 01/0000Z 39.0N 48.5W 75 KT 85 MPH...POST-TROP/EXTRATROP
96H 02/0000Z 44.0N 38.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
120H 03/0000Z 45.0N 29.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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Re: ATL: OSCAR - Advisories

#10 Postby cycloneye » Mon Oct 29, 2018 4:59 am

BULLETIN
Hurricane Oscar Advisory Number 10
NWS National Hurricane Center Miami FL AL162018
500 AM AST Mon Oct 29 2018

...OSCAR A LITTLE STRONGER AND LIKELY TO STRENGTHEN FURTHER...
...NO THREAT TO LAND AREAS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...25.7N 57.8W
ABOUT 620 MI...1000 KM SE OF BERMUDA
ABOUT 620 MI...995 KM NNE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES



Hurricane Oscar Discussion Number 10
NWS National Hurricane Center Miami FL AL162018
500 AM AST Mon Oct 29 2018

The cloud pattern of Oscar has continued to become better
organized, with a growing CDO and convective banding features
are better defined, especially over the southern semicircle of
the hurricane. Upper-level outflow is gradually becoming better
established to the south. Although the most recent Dvorak Current
Intensity estimates from TAFB and SAB are at 65 kt, given that the
eye is becoming better defined, the advisory intensity is set at 70
kt. Oscar is currently under some northerly to north-northwesterly
shear, but the shear is expected to diminish somewhat later today.
Also, the tropical cyclone is expected to move through a modestly
moist air mass for the next day or two. Therefore, additional
strengthening is forecast through 36 hours in agreement with the
latest intensity model consensus. Around 48 hours into the forecast
period, the shear begins to increase significantly, with notably
cooler SSTs. This should lead to the onset of a steady weakening
trend. By about 72 hours, the global models indicate that Oscar
will become embedded in a frontal zone, so the official forecast
shows the system becoming an extratropical cyclone at that time.

Oscar has slowed its forward motion and is now moving at about
270/11 kt. A mid-level high to the north of the cyclone is
expected to quickly shift eastward, while a mid-latitude trough
approaches Oscar from the west in a day or so. This evolution of
the steering flow should cause Oscar to turn northward to
north-northeastward in 24-48 hours. Later in the forecast period,
Oscar is likely to move quickly northeastward on the eastern side
of the trough. There has been some inconsistencies in the track
model guidance around 5 days over the last few forecast cycles,
with the model consensus, TVCN, shifting significantly southward and
then northward. The official forecast track is somewhat to the
left of the previous one near the end of the period, to reflect the
latest consensus prediction.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 25.7N 57.8W 70 KT 80 MPH
12H 29/1800Z 26.1N 58.7W 75 KT 85 MPH
24H 30/0600Z 27.7N 58.7W 80 KT 90 MPH
36H 30/1800Z 30.0N 57.5W 85 KT 100 MPH
48H 31/0600Z 33.0N 54.7W 85 KT 100 MPH
72H 01/0600Z 41.5N 46.5W 70 KT 80 MPH...POST-TROP/EXTRATROP
96H 02/0600Z 46.0N 35.5W 60 KT 70 MPH...POST-TROP/EXTRATROP
120H 03/0600Z 48.0N 26.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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Re: ATL: OSCAR - Advisories

#11 Postby cycloneye » Mon Oct 29, 2018 9:39 am

BULLETIN
Hurricane Oscar Advisory Number 11
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Mon Oct 29 2018

...OSCAR CONTINUES TO STRENGTHEN OVER THE OPEN ATLANTIC...
...NO THREAT TO ANY LAND AREAS...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.8N 58.4W
ABOUT 590 MI...955 KM SE OF BERMUDA
ABOUT 605 MI...975 KM NNE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES



Hurricane Oscar Discussion Number 11
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Mon Oct 29 2018

Oscar's convective cloud pattern has continued to improve since the
previous advisory, with a small, cloud-filled eye now apparent in
visible satellite imagery and also in a recent SSMI/S microwave
pass. In addition, cirrus outflow has been expanding in all
quadrants, especially in the eastern semicircle. The initial
intensity of 75 kt is based on a Dvorak satellite intensity estimate
of T4.5/77 kt from TAFB, a Data-T-number of T4.5/77 kt from SAB, and
an NHC objective intensity estimate of T4.4/75 kt. It is also worth
noting that bursts of lightning activity in the eastern eyewall have
been occurring since around 1100 UTC.

The initial motion estimate is now 285/06 kt. Oscar has slowed its
forward motion significantly and has made the advertised turn toward
the west-northwest. A motion toward the northwest is expected by
late afternoon today as the hurricane rounds the southwestern
periphery of a deep-layer ridge. A turns toward the north and then
toward the north-northeast are forecast on Tuesday as Oscar moves
north of the ridge axis ahead of an eastward-moving deep-layer
trough currently approaching Bermuda. The trough is expected to
continue advancing eastward over the next couple of days,
accelerating Oscar toward the northeast at forward speeds near 25 kt
on Wednesday through Friday. Although a strong shortwave trough is
still forecast to dig southward to the west of Oscar on Wednesday,
none of the model guidance shows the hurricane being captured any
longer, and instead keep the cyclone as a separate entity that
accelerates northeastward into the mid-latitude westerlies as a
strong extratropical cyclone. The official track forecast is similar
to the previous advisory, and lies close to an average of the
corrected-consensus models HCCA and FSSE and the simple consensus
models TVCA and TVCX.

Deep-layer (850-200 mb) shear calculations by the SHIPS model and
UW-CIMSS are at least 25 kt from the northwest, which clearly is not
negatively affecting the improving cirrus outflow. This is likely
due to the large 1000-km domain that the SHIPS model uses to compute
vertical wind shear. Furthermore, most of the cloud top temperatures
within the outflow layer appear to be mostly below the 200-mb level,
and closer to the 250-mb level. The large shear values are resulting
in much less intensification forecast by the SHIPS and LGEM
statistical-dynamical intensity models. As a result, the official
intensity forecast leans more toward the HCCA and FSSE models, which
are weighing more heavily the stronger intensity forecasts provided
by the HWRF, HMON, and Navy COAMPS-TC models, which have Oscar
strengthening to just below major hurricane status in 24-36 hours.
By 48 hours and beyond, sharply decreasing SSTs along with
increasing southwesterly shear ahead of a deep-layer trough are
expected to cause Oscar to gradually weaken and transition to a
strong extratropical low in 60-72 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 29/1500Z 25.8N 58.4W 75 KT 85 MPH
12H 30/0000Z 26.8N 58.7W 85 KT 100 MPH
24H 30/1200Z 28.7N 58.0W 90 KT 105 MPH
36H 31/0000Z 31.4N 56.1W 90 KT 105 MPH
48H 31/1200Z 35.0N 52.6W 80 KT 90 MPH
72H 01/1200Z 43.0N 43.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
96H 02/1200Z 50.0N 30.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
120H 03/1200Z 55.0N 15.0W 55 KT 65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Stewart
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Re: ATL: OSCAR - Advisories

#12 Postby cycloneye » Mon Oct 29, 2018 3:41 pm

BULLETIN
Hurricane Oscar Advisory Number 12
NWS National Hurricane Center Miami FL AL162018
500 PM AST Mon Oct 29 2018

...OSCAR TURNS NORTHWARD...
...EXPECTED TO PRODUCE HIGH SURF ALONG BERMUDA BEACHES THROUGH
WEDNESDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...26.5N 58.5W
ABOUT 550 MI...885 KM SE OF BERMUDA
ABOUT 645 MI...1035 KM NNE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...978 MB...28.88 INCHES



Hurricane Oscar Discussion Number 12
NWS National Hurricane Center Miami FL AL162018
500 PM AST Mon Oct 29 2018

The overall cloud pattern of Oscar is somewhat asymmetrical, and
convective banding is limited to the eastern semicircle of the
cyclone. However, recent visible and microwave imagery indicate
that tight eyewall of the hurricane is still very well defined,
despite the 20 kt or more of westerly shear analyzed in SHIPS and
UW-CIMSS diagnostics. It appears that the shear is not having much
of an affect on Oscar's inner-core, and in fact the small eye of the
hurricane has become better defined over the past 6 hours. Recent
objective and subjective intensity estimates support an intensity of
75-80 kt, and given the small radius of maximum winds (RMW) of
Oscar, it seems more appropriate to round up, yielding an estimated
intensity of 80 kt.

All of the dynamical intensity guidance calls for additional
intensification in the short term. Persistent lightning inside the
hurricane's RMW during the past several hours also supports the
notion of additional strengthening, as this signal has been
associated with intensifying hurricanes in the past. By 24 h and
beyond, Oscar will likely level off in intensity and then begin to
weaken while it moves over much cooler SSTs and begins extratropical
transition. Although this process will likely result in a rapid
expansion of Oscar's tropical-storm-force wind field, it should also
cause the maximum winds associated with the cyclone to steadily
decrease through the end of the week. The NHC intensity forecast is
similar to the previous advisory, and generally follows IVCN
through the forecast period.

Oscar's eye has wobbled during the past several hours, but the
hurricane appears to have already begun its expected turn toward the
north. The hurricane is essentially on-track, and no major changes
were required to the NHC track forecast. A large mid-latitude
trough to the west will likely cause Oscar to accelerate
north-northeastward or northeastward beginning by late Tuesday, and
then rapidly move across the northern central Atlantic in that
direction. The global models are in reasonably good agreement on
the speed and heading of Oscar through day 5, which is somewhat
unusual for a recurving cyclone. The new official track forecast is
based on a blend of the simple and corrected multi-model consensus
aids, and confidence in the track forecast is fairly high.

Although Oscar is not expected to directly affect any land areas,
large swells from Oscar will affect Bermuda through Wednesday.
Please consult products from your local weather office as these
conditions could cause life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 29/2100Z 26.5N 58.5W 80 KT 90 MPH
12H 30/0600Z 27.8N 58.4W 90 KT 105 MPH
24H 30/1800Z 29.9N 57.2W 90 KT 105 MPH
36H 31/0600Z 33.0N 54.3W 85 KT 100 MPH
48H 31/1800Z 37.3N 50.3W 80 KT 90 MPH
72H 01/1800Z 46.7N 40.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 02/1800Z 54.0N 25.0W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 03/1800Z 60.0N 12.0W 50 KT 60 MPH...POST-TROP/EXTRATROP

$$
Forecaster Zelinsky
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Re: ATL: OSCAR - Advisories

#13 Postby cycloneye » Mon Oct 29, 2018 9:42 pm

BULLETIN
Hurricane Oscar Advisory Number 13
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Mon Oct 29 2018

...OSCAR STRENGTHENS WHILE MOVING NORTHWARD OVER THE CENTRAL
ATLANTIC...
...EXPECTED TO PRODUCE HIGH SURF ALONG BERMUDA BEACHES THROUGH
WEDNESDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.4N 58.3W
ABOUT 515 MI...830 KM SE OF BERMUDA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...970 MB...28.65 INCHES



Hurricane Oscar Discussion Number 13
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Mon Oct 29 2018

The satellite presentation of Oscar continued to improved after
the release of the previous advisory, with the small eye becoming
a little more distinct around 0000 UTC, but it has again become
cloud filled within the past hour or so. Recent microwave imagery
continues to depict a tiny eye with a solid ring of deep convection
surrounding it, but there is little outer banding over the
southwestern portion of the circulation likely due to shear and
dry air. Objective satellite intensity estimates which may be
having trouble discerning the small eye are around 80 kt, while
subjective T-numbers range from T5.0 from SAB to T5.5 from TAFB.
As a result, the initial intensity has been increased to 90 kt
for this advisory.

Although the NHC intensity forecast does not explicitly show
additional strengthening, Oscar has another 12 hours or so over
SSTs of 26-26.5 deg C in which some slight intensification could
occur. After that time, increasing southwesterly shear and cooler
waters along the forecast track should cause the hurricane to weaken
gradually as extratropical transition begins. Oscar is forecast to
complete extratropical transition in about 48 hours, and remain a
powerful post-tropical cyclone over the north Atlantic for much of
the forecast period. The global models indicate that Oscar's wind
field will quickly expand during its transition to a post-tropical
cyclone, and this is reflected in the NHC wind radii forecast.

The hurricane has been moving slightly east of due north or 010/8
kt. Oscar is forecast to begin to accelerate north-northeastward or
northeastward ahead of a deep-layer trough that will be moving over
the western Atlantic on Tuesday. The hurricane should be well
embedded within the deep-layer southwesterly flow ahead of the
trough by Tuesday night or Wednesday, and the cyclone is expected to
move rapidly northeastward across the north-central and northeastern
Atlantic later this week. There has been little change to the
guidance envelope, and the new NHC track forecast is essentially
an update of the previous advisory. The official forecast again
lies near the various consensus aids and is near the middle of the
tightly clustered model guidance.

Although Oscar is not expected to directly affect any land areas,
large swells from Oscar will affect Bermuda through Wednesday.
Please consult products from your local weather office as these
conditions could cause life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 27.4N 58.3W 90 KT 105 MPH
12H 30/1200Z 28.8N 57.7W 90 KT 105 MPH
24H 31/0000Z 31.5N 55.6W 85 KT 100 MPH
36H 31/1200Z 35.3N 52.1W 80 KT 90 MPH
48H 01/0000Z 40.1N 47.8W 70 KT 80 MPH...POST-TROP/EXTRATROP
72H 02/0000Z 49.1N 36.4W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 03/0000Z 56.2N 22.0W 55 KT 65 MPH...POST-TROP/EXTRATROP
120H 04/0000Z 62.5N 9.5W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown
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Re: ATL: OSCAR - Advisories

#14 Postby cycloneye » Tue Oct 30, 2018 4:42 am

BULLETIN
Hurricane Oscar Advisory Number 14
NWS National Hurricane Center Miami FL AL162018
500 AM AST Tue Oct 30 2018

...OSCAR MOVING FASTER TOWARD THE NORTH...
...EXPECTED TO PRODUCE HIGH SURF ALONG BERMUDA BEACHES THROUGH
WEDNESDAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...28.6N 58.2W
ABOUT 470 MI...755 KM ESE OF BERMUDA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...970 MB...28.65 INCHES




Hurricane Oscar Discussion Number 14
NWS National Hurricane Center Miami FL AL162018
500 AM AST Tue Oct 30 2018

Oscar's eye is less distinct on infrared satellite imagery than it
was several hours ago. Conventional and microwave imagery suggest
that the center is tilted a bit to the northeast with height, and
there continues to be some erosion of convection over the
southwestern quadrant of the hurricane. This is indicative of some
southwesterly shear over the system, and Oscar does not appear
likely to strengthen further. The current intensity is held at 90
kt based on a blend of Dvorak Current Intensity numbers from TAFB
and SAB. Model guidance indicates that the shear will not increase
further until tonight, so the intensity is held steady for the next
12 hours. After that time, south-southwesterly shear if forecast to
increase and become quite high in 36-48 hours. Around that time,
global models show Oscar interacting with a frontal zone, and
causing significant warm and cold air advection around the center,
indicating the transition to a vigorous extratropical cyclone.
Not surprisingly, the global guidance also shows a substantial
increase in the size of the system during and after the
extratropical transformation, and this is reflected in the NHC wind
radii forecasts.

Oscar is beginning to move faster, just to the east of due north, or
around 010/11 kt. There is little change to the track forecast
reasoning from the previous advisory. Over the next couple of days,
Oscar should continue to accelerate, toward the north-northeast,
in the flow on the southeast side of a mid-latitude trough that has
just moved off the United States east coast. Later in the period,
post-tropical Oscar should become more embedded within the trough
and in the mid-latitude westerlies, and move northeastward over the
northeastern Atlantic. The official track forecast is similar to
the previous one and is a blend of the simple and corrected
dynamical model consensus predictions.

Large swells from Oscar will affect Bermuda through Wednesday.
Please consult products from your local weather office as these
conditions could cause life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 28.6N 58.2W 90 KT 105 MPH
12H 30/1800Z 30.6N 57.1W 90 KT 105 MPH
24H 31/0600Z 34.0N 54.3W 85 KT 100 MPH
36H 31/1800Z 38.5N 50.5W 80 KT 90 MPH
48H 01/0600Z 43.5N 46.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 02/0600Z 50.5N 35.5W 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 03/0600Z 57.5N 21.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 04/0600Z 63.0N 9.0W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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Re: ATL: OSCAR - Advisories

#15 Postby cycloneye » Tue Oct 30, 2018 9:54 am

BULLETIN
Hurricane Oscar Advisory Number 15
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Tue Oct 30 2018

...OSCAR TURNS NORTH-NORTHEASTWARD...
...HIGH SURF EXPECTED ALONG BERMUDA BEACHES THROUGH WEDNESDAY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...29.7N 57.7W
ABOUT 455 MI...735 KM ESE OF BERMUDA
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...NNE OR 20 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...972 MB...28.71 INCHES



Hurricane Oscar Discussion Number 15
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Tue Oct 30 2018

Cloud-top temperatures have warmed a bit overall, and the convective
pattern is becoming more asymmetric as dry air is infiltrating the
southern and eastern part of Oscar's circulation. However, the
hurricane is still producing plenty of inner-core convection and
some lightning strikes. Dvorak Current Intensity numbers from TAFB
and SAB still support maximum winds of 90-100 kt, but objective
numbers are much lower (65-75 kt), so Oscar's initial intensity is
lowered slightly to 85 kt.

Increasing shear and stronger upper-level divergence will likely
offset each other in the short term, causing Oscar to maintain its
intensity or only slightly weaken during the next 24 hours.
However, a cold front is quickly approaching Oscar from the
northwest, and their interaction is expected to cause Oscar to
complete extratropical transition and become fully embedded within
the frontal zone in about 36 hours. Oscar's winds should gradually
diminish after it becomes extratropical, but the NHC official
forecast remains above the various consensus aids from 36 hours and
beyond and lies closest to the GFS and ECMWF global models, which
should have a good handle on the cyclone's structure during the
post-tropical phase.

Oscar continues to accelerate and has turned north-northeastward,
or 020/12 kt, while entering the flow between a large high over the
eastern/central Atlantic and a mid-latitude trough now moving over
the western Atlantic. Oscar is expected to become embedded within
the trough by 36 hours (the completion of extratropical transition),
with the entire system becoming a cut-off low north of the jet
stream by days 4 and 5. The track models are in fairly good
agreement on Oscar's future path, but there are speed differences
by the end of the forecast period. Of particular note, the ECMWF
is much faster than the other models, showing a more progressive
pattern on day 5. The NHC track forecast lies close to the
previous official forecast to maintain continuity, but it is still
faster than the GFS, HWRF, and the TVCN multi-model consensus at
day 5.

Large swells from Oscar will affect Bermuda through Wednesday.
Please consult products from your local weather office as these
conditions could cause life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 29.7N 57.7W 85 KT 100 MPH
12H 31/0000Z 31.8N 56.1W 80 KT 90 MPH
24H 31/1200Z 35.6N 52.6W 80 KT 90 MPH
36H 01/0000Z 40.6N 48.7W 75 KT 85 MPH...POST-TROP/EXTRATROP
48H 01/1200Z 45.1N 44.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
72H 02/1200Z 52.6N 31.8W 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 03/1200Z 59.0N 18.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 04/1200Z 63.5N 6.5W 45 KT 50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg
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Re: ATL: OSCAR - Advisories

#16 Postby cycloneye » Tue Oct 30, 2018 3:40 pm

BULLETIN
Hurricane Oscar Advisory Number 16
NWS National Hurricane Center Miami FL AL162018
500 PM AST Tue Oct 30 2018

...OSCAR ACCELERATING OVER THE CENTRAL ATLANTIC...
...HIGH SURF EXPECTED ALONG BERMUDA BEACHES THROUGH WEDNESDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...31.3N 56.6W
ABOUT 485 MI...780 KM E OF BERMUDA
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NNE OR 25 DEGREES AT 20 MPH...31 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES


Hurricane Oscar Discussion Number 16
NWS National Hurricane Center Miami FL AL162018
500 PM AST Tue Oct 30 2018

Recent microwave imagery indicates that Oscar continues to maintain
a small inner-core, however, it is tilted somewhat southwest to
northeast with height due to increasing southwesterly wind shear.
Cloud tops have continued to warm over the past few hours, and
objective and subjective intensity estimates have decreased since
this morning. The initial intensity has been lowered to 75 kt,
based primarily on a blend of Final-T and Current Intensity
estimates from TAFB and SAB.

The hurricane is moving over 24 deg C waters and a cold front
associated with a large mid-latitude trough is quickly approaching
from the west. This combination should soon kick off the
extratropical transition (ET) process, and the most recent runs of
the GFS, ECMWF, and UKMET indicate that Oscar will become fully
extratropical within 36 h, if not sooner. Very gradual weakening is
still expected during the next day or so while ET occurs, however,
all of the dynamical models forecast that Oscar will be at or very
near hurricane-strength when it becomes post-tropical. The maximum
winds of the cyclone will likely slowly decrease thereafter, but
Oscar will likely have a very large wind field and gale-force winds
are possible over a large portion of the far north Atlantic. By
day 5, the post-tropical low is forecast to merge with another
mid-latitude low pressure system over the far northeastern Atlantic.

As expected, the hurricane is accelerating north-northeastward, with
an initial motion estimate of 025/17 kt. Further acceleration is
likely over the next 36 hours, and the global models are in
remarkably good agreement on the track of the cyclone through that
time. A turn toward the northeast is expected thereafter, and
while there are still speed differences between the various global
model solutions, the NHC forecast remains near the fairly steady
multi-model consensus at all forecast hours. Almost no change was
made to the official track forecast, which is merely an update of
the previous advisory.

Although Oscar is forecast to move farther from Bermuda overnight,
large swells from the hurricane are expected to affect portions of
the island's coast through Wednesday. Please consult products from
your local weather office as these conditions could cause
life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 31.3N 56.6W 75 KT 85 MPH
12H 31/0600Z 33.8N 54.5W 70 KT 80 MPH
24H 31/1800Z 38.3N 50.9W 65 KT 75 MPH
36H 01/0600Z 43.0N 46.8W 65 KT 75 MPH...POST-TROP/EXTRATROP
48H 01/1800Z 46.7N 42.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 02/1800Z 54.0N 28.5W 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 03/1800Z 59.0N 15.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 04/1800Z...DISSIPATED

$$
Forecaster Zelinsky
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Re: ATL: OSCAR - Advisories

#17 Postby cycloneye » Tue Oct 30, 2018 9:42 pm

BULLETIN
Hurricane Oscar Advisory Number 17
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Tue Oct 30 2018

...OSCAR CONTINUES ACCELERATING OVER THE CENTRAL ATLANTIC...
...HIGH SURF EXPECTED ALONG BERMUDA BEACHES THROUGH WEDNESDAY...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...32.8N 55.2W
ABOUT 560 MI...900 KM E OF BERMUDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NE OR 35 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES



Hurricane Oscar Discussion Number 17
NWS National Hurricane Center Miami FL AL162018
1100 PM AST Tue Oct 30 2018

While conventional satellite imagery continues to show an area of
deep convection over the center of Oscar, recent microwave data
suggest that the inner core has become fragmented and that the
circulation is tilted from southwest to northeast. The overall
cloud pattern has also expanded northward as Oscar begins to
interact with a frontal zone that is approaching the system from
the northwest. A blend of the latest Dvorak T- and Current
Intensity (CI) numbers yields an initial wind speed of 70 kt for
this advisory. Oscar will be moving over decreasing SSTs and into
an area of higher vertical wind shear tonight and Wednesday which
is likely to cause some additional weakening during that time. The
hurricane should complete its extratropical transition in about 24
hours, and the dynamical models indicate that the post-tropical
cyclone is likely to maintain 60-65 kt winds for at least another
couple of days. Some weakening is expected by 96 hours before the
system merges with another low pressure area over the far
northeastern Atlantic.

Oscar has turned northeastward and continues to accelerate. An
additional increase in forward speed is anticipated during the next
day or two, as the cyclone becomes embedded within deep-layer
southwesterly flow ahead of a mid-latitude trough. Late in the
period, the post-tropical low is forecast to slow down over the
northeastern Atlantic. The track guidance remains in good
agreement, except for some forward speed differences late in the
period. The NHC track forecast is once again close to the various
consensus aids and very similar to the previous advisory.

Large swells from Oscar are expected to continue to affect portions
of the coast of Bermuda through Wednesday. Please consult products
from your local weather office as these conditions could cause
life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 31/0300Z 32.8N 55.2W 70 KT 80 MPH
12H 31/1200Z 35.6N 52.6W 65 KT 75 MPH
24H 01/0000Z 40.2N 48.9W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 01/1200Z 44.3N 44.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
48H 02/0000Z 48.2N 38.7W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 03/0000Z 55.2N 24.3W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 04/0000Z 61.0N 12.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 05/0000Z...MERGED WITH LARGER EXTRATROPICAL LOW

$$
Forecaster Brown
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Re: ATL: OSCAR - Advisories

#18 Postby cycloneye » Wed Oct 31, 2018 5:00 am

Hurricane Oscar Discussion Number 18
NWS National Hurricane Center Miami FL AL162018
500 AM AST Wed Oct 31 2018

Oscar continues to become less tropical-looking in appearance.
Central convection is now minimal, and the overall cloud pattern is
quite asymmetric, with the main area of dense overcast over the
western portion of the circulation, stretching northward over an
approaching frontal boundary. The current intensity estimate is 65
kt in accord with the latest Dvorak Current Intensity numbers from
TAFB and SAB. Oscar is expected to merge with the nearby front in
12-18 hours, by which time the global models depict considerable
cold and warm advection around the center. This indicates that
Oscar will become an extratropical cyclone tonight, but energy from
baroclinic processes will likely maintain the system near hurricane
strength for the next couple of days. Only gradual weakening is
expected thereafter and post-tropical Oscar will likely be a strong
cyclone for the next 4 days or so. Post-tropical Oscar is forecast
to merge with another extratropical cyclone at high latitudes over
the weekend. The official intensity forecast is close to the
latest GFS prediction, which should be appropriate for a
mid-latitude system.

Oscar is moving quickly toward the northeast, or 035/19 kt. The
hurricane is being steered by the flow on the eastern side of a
trough that is passing through Atlantic Canada. In a day or so,
post-tropical Oscar should become embedded within the trough and
move rapidly northeastward in the mid-latitude westerlies over the
north-central and northeastern Atlantic. The track guidance is in
fairly good agreement, aside from some speed differences in the
latter part of the forecast period. The official forecast is close
to the latest dynamical model consensus, and is similar to the
previous NHC track.

Large swells from Oscar are expected to continue to affect portions
of the coast of Bermuda through today. Please consult products
from your local weather office, as these conditions could cause
life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 31/0900Z 34.1N 53.6W 65 KT 75 MPH
12H 31/1800Z 37.6N 50.9W 65 KT 75 MPH
24H 01/0600Z 42.2N 47.1W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 01/1800Z 46.0N 42.2W 65 KT 75 MPH...POST-TROP/EXTRATROP
48H 02/0600Z 49.7N 36.4W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 03/0600Z 56.0N 23.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
96H 04/0600Z 61.5N 10.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 05/0600Z...MERGED WITH LARGER EXTRATROPICAL LOW

$$
Forecaster Pasch
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Re: ATL: OSCAR - Advisories

#19 Postby cycloneye » Wed Oct 31, 2018 9:36 am

Hurricane Oscar Discussion Number 19
NWS National Hurricane Center Miami FL AL162018
1100 AM AST Wed Oct 31 2018

Oscar is quickly transforming into an extratropical low. Although
there is still a little bit of deep convection just north of the
center, a more prominent cloud shield extends northward from the
western part of the circulation. In addition, GOES-16 derived
products show Oscar's center nearly embedded within a frontal zone
and cold air advection occurring on the back side of the system.
The maximum winds are a bit uncertain, but for now they are held at
65 kt based on the Dvorak Current Intensity number from TAFB and
the latest microwave estimates, which range from 60-70 kt.

Oscar is expected to complete extratropical transition later today
when it becomes fully attached to the frontal boundary. Baroclinic
energy is likely to keep the cyclone's intensity relatively steady
for the next 48 hours or so, although it should be noted that the
GFS shows some intensification later today as a sting jet develops
to the west of the center. After 48 hours, the post-tropical
cyclone is expected to gradually lose strength, and the NHC
intensity forecast continues to most closely follow the GFS model,
which is at the high end of the guidance envelope. Despite this
weakening, Oscar's wind field is expected to grow substantially,
affecting a large portion of the north Atlantic Ocean over the next
several days.

A northeastward acceleration continues with an initial motion of
035/25 kt. Further acceleration toward the north Atlantic is
expected during the next 48 hours while Oscar becomes more fully
embedded within the mid-latitude flow. The new NHC track forecast
was shifted slightly northward and westward from the previous
forecast to trend closer to the latest consensus aids, but
otherwise the track forecast reasoning remains unchanged.

Large swells from Oscar are expected to continue to affect portions
of the coast of Bermuda through today. Please consult products
from your local weather office, as these conditions could cause
life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 36.6N 51.6W 65 KT 75 MPH
12H 01/0000Z 40.2N 48.7W 65 KT 75 MPH...POST-TROP/EXTRATROP
24H 01/1200Z 44.5N 44.3W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 02/0000Z 48.4N 38.7W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 02/1200Z 52.1N 32.4W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 03/1200Z 57.8N 18.6W 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 04/1200Z 64.0N 5.5W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 05/1200Z...DISSIPATED

$$
Forecaster Berg
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Re: ATL: OSCAR - Advisories

#20 Postby cycloneye » Wed Oct 31, 2018 3:40 pm

Post-Tropical Cyclone Oscar Discussion Number 20
NWS National Hurricane Center Miami FL AL162018
500 PM AST Wed Oct 31 2018

Satellite imagery and scatterometer data indicate that Oscar has
become a hurricane-force extratropical low, as the central
convection has all but dissipated and frontal-band-type cloud
features have become better defined. The scatterometer data show
hurricane-force winds about 70 n mi south of the center, and that
the overall wind field has expanded considerably since the previous
overpass. The cyclone is expected to maintain an intensity of 60-65
kt for the next 48 h, then gradually weaken as the baroclinic energy
wanes, with dissipation occurring between 96-120 h over the far
northeastern Atlantic.

The initial motion is now 030/30 kt. Oscar is now well embedded in
the mid-latitude westerlies, and for the next 3-4 days it should
move generally northeastward with a gradual decrease in forward
speed.

Much of the current forecast, especially the intensity and the
size, is based on input from the NOAA Ocean Prediction Center.

This is the last advisory on Oscar from the National Hurricane
Center. Additional information on this system can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web
at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 39.3N 49.6W 65 KT 75 MPH...POST-TROP/EXTRATROP
12H 01/0600Z 42.6N 46.6W 65 KT 75 MPH...POST-TROP/EXTRATROP
24H 01/1800Z 46.8N 41.4W 65 KT 75 MPH...POST-TROP/EXTRATROP
36H 02/0600Z 50.7N 35.1W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 02/1800Z 54.2N 28.4W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 03/1800Z 59.5N 15.0W 55 KT 65 MPH...POST-TROP/EXTRATROP
96H 04/1800Z 67.0N 2.0W 45 KT 50 MPH...POST-TROP/EXTRATROP
120H 05/1800Z...DISSIPATED

$$
Forecaster Beven
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