[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 100831
TCDAT2

Tropical Storm Ophelia Discussion Number   5
NWS National Hurricane Center Miami FL       AL172017
500 AM AST Tue Oct 10 2017

Although the intensity of Ophelia's deep convection has decreased
during the past several hours, the cloud pattern has improved
and become more symmetric with banding features now better
established around the center.  The initial intensity is held at 45
kt, in agreement with a Dvorak classification from SAB and the
latest satellite consensus estimate from CIMSS at the University of
Wisconsin.

The recent decrease in convection could be associated with some dry
air that has wrapped into the circulation, as seen in total
precipitable water imagery.  The other environmental conditions
appear generally conducive for strengthening with wind shear values
expected to decrease to near 10 kt during the next couple of days
with SSTs remaining marginally warm around 26.5 to 27 deg C.
These conditions combined with an unstable atmosphere should allow
Ophelia to strengthen, and the NHC forecast follows the IVCN and
HCCA consensus models and brings the cyclone to hurricane strength
in 24 to 36 hours.  Although the official forecast shows slight
weakening by the end of the period due to an increase in shear and
cooler waters, the latest guidance suggests that the weakening
could be less than currently forecast.

Satellite fixes indicate that Ophelia has made a turn to the
southeast, as expected.   A continued slow southeast motion is
forecast during the next 36 to 48 hours as mid-level ridging
builds to the north and west of the storm.  After that time, a turn
to the northeast or east-northeast at a progressively faster pace is
expected as a mid- to upper-level trough approaches Ophelia.  The
models are in fairly good agreement, and only minor changes were
made to the previous NHC track forecast.  This prediction lies near
the middle of the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 31.9N  38.8W   45 KT  50 MPH
 12H  10/1800Z 31.7N  38.4W   55 KT  65 MPH
 24H  11/0600Z 30.8N  37.9W   60 KT  70 MPH
 36H  11/1800Z 30.2N  37.4W   70 KT  80 MPH
 48H  12/0600Z 30.0N  36.8W   75 KT  85 MPH
 72H  13/0600Z 31.0N  35.0W   75 KT  85 MPH
 96H  14/0600Z 33.0N  30.5W   75 KT  85 MPH
120H  15/0600Z 35.5N  23.5W   65 KT  75 MPH

$$
Forecaster Cangialosi
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