已經來到巔峰，快速北上逐漸轉化溫氣。

000
WTNT44 KNHC 080851
TCDAT4

Tropical Storm Rina Discussion Number   9
NWS National Hurricane Center Miami FL       AL192017
500 AM AST Wed Nov 08 2017

Satellite imagery over the past 6 hours indicates that Rina has
taken on a tight comma-cloud appearance, more indicative of a
sub-tropical cyclone than a tropical system. Although an eye-like
feature has recently developed, it appears to be tilted about 20-30
nmi to the north of the low-level center. Dvorak satellite intensity
estimates were ST3.0/45-50 kt from TAFB and T3.5 from SAB. Data
from a late-arriving, partial ASCAT-B scatterometer pass at 0029Z
indicated 46-kt surface winds well east of the center, and the cloud
pattern has improved since that time. Based these data, the
intensity of Rina has been increased to 50 kt.

Rina is moving northward or 010/17 kt. Rina is located just north
of the axis of a deep-layer ridge, which is located to the east of
the cyclone. As a result, a northward to north-northeastward motion
is expected for the next 12-24 h. Thereafter, a shortwave trough
situated to the southwest of Rina should induce acceleration toward
the northeast on Thursday, followed by a more rapid motion of 30-35
kt by Thursday night and Friday as westerly flow on the east side of
a deep-layer trough captures the system. The latest NHC model
guidance has shifted to the west some, but the official forecast
track has only been nudged slightly in that direction due to a
distinct westward bias noted in the model guidance during the past
48 hours.

Although some sight strengthening could occur during the next 6-12
hours, the overall intensity trend is forecast to change little
during the period due to the combination of cold SSTs of less than
20 deg C by 18 h and increasing vertical wind shear of more than 35
kt by 36 hours. By 24 h, Rina should become a post-tropical cyclone
over the cold waters of the far north Atlantic and become
extratropical and merge with a front by 48-72 h.

FORECAST POSITIONS AND MAX WINDS

INIT  08/0900Z 37.1N  48.4W   50 KT  60 MPH
12H  08/1800Z 39.7N  47.7W   50 KT  60 MPH
24H  09/0600Z 43.6N  45.7W   50 KT  60 MPH...POST-TROPICAL
36H  09/1800Z 48.7N  40.6W   50 KT  60 MPH...POST-TROP/EXTRATROP
48H  10/0600Z 53.3N  32.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
72H  11/0600Z...DISSIPATED

$$
Forecaster Stewart

NHC 03Z命名"Rina"，逐漸加速北上。

000
WTNT44 KNHC 070236
TCDAT4

Tropical Storm Rina Discussion Number   4
NWS National Hurricane Center Miami FL       AL192017
1100 PM AST Mon Nov 06 2017

Despite the low-level center being exposed to the west of the deep
convection, a pair of ASCAT-A and ASCAT-B passes between 00Z and
01Z showed an area of 30-35 kt winds east of the cyclone's center.
Based on the ASCAT data, the depression is upgraded to a tropical
storm with the initial intensity set at 35 kt. The rather
disorganized cloud pattern is consistent with the approximately 20
kt of westerly shear analyzed by UW-CIMSS and the SHIPS model. The
environment is only expected to be marginally conducive for
intensification via diabatic processes, with the shear expected to
remain near 20 kt and the SSTs cooling along the forecast track.
After 24 to 36 hours, cooling upper-tropospheric temperatures and
increasing upper-level divergence suggest that Rina will maintain
its intensity as it begins extratropical transition, which should be
complete between by 72 hours. The new NHC intensity forecast is
similar to the previous one and is close to the HWRF and HCCA aids.
The official forecast shows Rina dissipating by 96 hours in
agreement with global model fields.

The exposed low-level center and ASCAT passes result in high
confidence in the initial position, and Rina has begun to move
more steadily, with an initial motion estimate of 010/06. Rina
should continue to accelerate northward and north-northeastward
during the next 36 to 48 hours between a mid-level ridge to the east
and an upper-level trough to the west. After 48 hours, Rina is
forecast to accelerate further as it enters the mid-latitude
westerlies. The track model guidance has shifted left this cycle,
and the along-track spread is quite large by 72 hours, with the GFS
more than 500 n mi northeast of the ECMWF at that time. The new NHC
track forecast has been adjusted westward and a bit slower, and lies
close to a blend of the GFS and ECMWF solutions to the east of the
TVCA multi-model consensus. Confidence in the details of the track
forecast is lower than usual given the large model spread.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 30.4N  49.9W   35 KT  40 MPH
12H  07/1200Z 32.4N  49.6W   40 KT  45 MPH
24H  08/0000Z 35.4N  49.0W   45 KT  50 MPH
36H  08/1200Z 39.0N  48.0W   45 KT  50 MPH
48H  09/0000Z 42.3N  46.2W   45 KT  50 MPH
72H  10/0000Z 51.0N  36.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
96H  11/0000Z...DISSIPATED

$$
Forecaster Brennan

NHC 09Z升格19L，逐漸北上。

000
WTNT44 KNHC 060849
TCDAT4

Tropical Depression Nineteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL192017
500 AM AST Mon Nov 06 2017

GOES-16 night-time visible and infrared satellite imagery indicate
that convection associated with the well-defined low pressure
system located over the central Atlantic Ocean has increased and
become better organized during the past several hours. Satellite
intensity estimates were T1.5/25 kt from both TAFB and SAB at
0600Z.  Since that time, however, a burst of deep convection has
developed over the previously partially exposed low-level
circulation center, which had been located near the northwestern
edge of the large convective cloud mass. Given that the center is
now located farther into the deep convection, NHC objective
intensity estimates have increased to more than 30 kt. As a result,
advisories have been initiated on the nineteenth tropical depression
of the 2017 Atlantic hurricane season.

The initial motion estimate is 095/05 kt. The center of the cyclone
has been moving slowly eastward within the larger cyclonic gyre for
the past 12-18 hours, most likely due to the deep convection being
sheared toward the east.  However, the latest NHC model guidance
indicates that the recent eastward motion should be short-lived
since the larger gyre is forecast to begin moving northward within
the next 6 h or so. As the wind field contracts over the next 24
hours, the motion of the cyclone should stabilize and become less
erratic as deep-layer southerly steering flow becomes established
on the west side of a large-scale subtropical ridge. By 48 h and
beyond, southwesterly flow ahead of mid-latitude trough is forecast
to accelerate the system toward the northeast through 96 h. By
120 h, the cyclone should have merged with a frontal system or have
dissipated over the cold waters of the far north Atlantic. The
official track forecast lies close to a blend of the TVCN, TVCX,
and GFEX consensus track models.

The cyclone is currently embedded within a low-shear environment in
the col region between a weakening upper-level low located to the
southeast and a trough to the northwest. The vertical wind shear is
forecast by the GFS and ECMWF models to remain relatively low for
the next 36 h or so, which should allow for some modest
strengthening to occur despite sea-surface temperatures only being
around 25-26 deg C. Temperatures of 2-3 deg C colder-than-normal
in the mid- and upper-levels of the troposphere, however, should
act to offset the cooler SSTs, providing sufficient instability to
allow for deep convection to continue to develop. Model soundings
and the FSU Cyclone Phase-Space diagram indicate that extratropical
transition should begin shortly after 48 h when the cyclone reaches
about 40N latitude and moves over much cooler water. The NHC
intensity closely follows the HCCA and IVCN consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  06/0900Z 28.9N  50.2W   30 KT  35 MPH
12H  06/1800Z 30.0N  49.9W   35 KT  40 MPH
24H  07/0600Z 32.0N  49.6W   40 KT  45 MPH
36H  07/1800Z 35.4N  49.4W   45 KT  50 MPH
48H  08/0600Z 39.4N  48.2W   45 KT  50 MPH
72H  09/0600Z 49.0N  38.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
96H  10/0600Z 59.0N  15.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  11/0600Z...DISSIPATED

$$
Forecaster Stewart

NHC 00Z展望提升至70%

1. Shower and thunderstorm activity associated with a well-defined low
pressure system located about 850 miles east-southeast of Bermuda
continues to become better organized.  Conditions are currently
favorable for additional development, and a tropical or subtropical
depression could form during the next day or two as the system moves
north-northeastward through the open Atlantic.  Conditions are
expected to become less conducive for development in the middle part
of next week, when the system is expected to reach colder water and
merge with a cold front.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.