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Tropical Depression Olivia Discussion Number  53
NWS Central Pacific Hurricane Center Honolulu HI   EP172018
1100 AM HST Thu Sep 13 2018
 
Strong westerly vertical wind shear of more than 30 kt continues to
displace deep convection to the northeast of Olivia's exposed
low-level center. However, this convection has become more vigorous
and closer to the center this morning. Subjective Dvorak current
intensity estimates came in at 2.0 from HFO and 1.5 from JTWC, while
CIMSS ADT is holding the system at 1.5. Given the recent trend in
convection, we will maintain Olivia as a 30 kt tropical depression.

The initial motion is set at west-southwest (240 degrees) at 12 kt.
As the latest burst of convection built toward the the low-level
center, a deceleration and southwesterly turn in the short-term
motion occurred as the weak center was drawn toward the convection.
A more westerly motion is expected to resume later today as the
system is steered by the low-level trade wind flow produced by a
low- to mid-level ridge sitting far to the north. A digging
upper-level trough just north of Olivia will maintain strong
vertical wind shear that should weaken the system. As these features
continue to interact, Olivia is expected to become a post-tropical
remnant low tonight. This shallow system will move west on Friday
then turn toward the west-northwest until dissipation during the
weekend. The track forecast was shifted south from the prior
advisory to account for the recent trend in motion. This track
favors the GFS and CTCI, which lie nearer to the southern end of the
guidance envelope. The intensity forecast closely follows the
statistical guidance of SHIPS and LGEM, which weaken the system
faster than most dynamical guidance.  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 18.7N 163.0W   30 KT  35 MPH
 12H  14/0600Z 18.4N 165.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 24H  14/1800Z 18.5N 167.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  15/0600Z 19.1N 169.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  15/1800Z 20.3N 172.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  16/1800Z...DISSIPATED
 
$$
Forecaster Wroe
 
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