03Z及09Z兩報皆評價90節，15Z已減弱到85節，加速北上中。

000
WTNT41 KNHC 301435
TCDAT1

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

升格一級颶風
Hurricane OSCAR
As of 18:00 UTC Oct 28, 2018:
Location: 25.7°N 54.8°W
Maximum Winds: 65 kt  Gusts: N/A
Minimum Central Pressure: 989 mb
Environmental Pressure: 1011 mb
Radius of Circulation: 210 NM
Radius of Maximum Wind: 15 NM

NHC 03Z判定轉暖，上望75節。

ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM

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

NNNN

NHC 命名"OSCAR"，判定為副熱帶風暴，巔峰暫時上望60KT。

000
WTNT41 KNHC 270233
TCDAT1

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

NHC 展望提升至80%。

1. A low pressure system centered nearly 1000 miles east-northeast of
the northern Leeward Islands has changed little in organization
since this morning.  However, the low is expected to move generally
northward over the next couple of days into an area where
environmental conditions are forecast to be conducive for further
development, and a tropical or subtropical storm is likely to form
by early this weekend. After that time, the system is forecast to
turn westward well to the north or northeast of the Lesser Antilles
through early next week.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...90 percent.