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Tropical Storm Rina Discussion Number   5
NWS National Hurricane Center Miami FL       AL192017
500 AM AST Tue Nov 07 2017

Rina's overall convective cloud pattern has increased is areal
coverage in the eastern semicircle, along with a little more deep
convection having developed near the well-defined low-level center.
In addition, drifting buoy 41506, located about 40 nmi northwest of
the center, reported a pressure of 1011.5 mb at 0600 UTC, and that
datum was used to estimate the central pressure of 1009 mb.
Satellite classifications from TAFB and UW-CIMSS ADT remain at T2.5,
so the intensity is being held at 35 kt for this advisory, which
could be conservative given the lower central pressure.

The initial motion estimate is 005/10 kt. There is no significant
change to the previous forecast track or reasoning. As Rina moves
around the western periphery of a strong deep-layer ridge, the
cyclone should continue to accelerate toward the north today and
then toward the north-northeast on Wednesday. By 48 hours, Rina is
expected to get caught up in the mid-latitude westerlies and
accelerate even more toward the northeast over the cold waters
of the north Atlantic. The NHC track guidance has shifted a little
more to left, so the new official forecast track has also been
nudged in that direction, close to consensus models TVCN and HCCA.

Based on GOES-16 ice physics satellite imagery, the inner-core of
Rina's circulation appears to have tightened up some and has also
become better defined. Some modest strengthening is forecast for
the next 36 h or so due to some baroclinic forcing associated with
an approaching vigorous shortwave trough currently located about 400
nmi to the west. By 48 h, the cyclone will be situated over water
temperatures colder than 20 deg C and within an environment of
increasing deep-layer wind shear. The combination of those two
negative factors are expected is result in Rina becoming an
extratropical cyclone. The NHC intensity forecast is similar to the
HCCA intensity consensus model, and also includes input from the
NOAA Ocean Prediction Center.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 31.4N  49.8W   35 KT  40 MPH
 12H  07/1800Z 33.7N  49.4W   40 KT  45 MPH
 24H  08/0600Z 37.0N  48.8W   45 KT  50 MPH
 36H  08/1800Z 40.4N  47.8W   45 KT  50 MPH
 48H  09/0600Z 44.4N  44.7W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  10/0600Z 53.0N  32.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  11/0600Z...DISSIPATED

$$
Forecaster Stewart

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