WTPA45 PHFO 131459
Tropical Depression Olivia Discussion Number 52
NWS Central Pacific Hurricane Center Honolulu HI EP172018
500 AM HST Thu Sep 13 2018
Olivia continues to move rapidly toward the west-southwest away
from the main Hawaiian Islands this morning. Southwesterly vertical
wind shear of over 30 kt remains in the vicinity of Olivia.
Scattered thunderstorms continue to develop far northeast,
southeast, and south of the low-level circulation center (LLCC), but
the core of the system remains completely devoid of deep convection.
An ASCAT pass over Olivia's outer circulation at 0810Z showed a
swath of 30 kt winds. The latest subjective Dvorak current
intensity estimate was 1.5/25 kt from PHFO and JTWC. The UW-CIMSS
ADT was also 1.5/25 kt. We will keep the initial intensity 30 kt for
this advisory based on the earlier scatterometer data. Olivia is
expected to remain a tropical depression into tonight. However, we
continue to indicate it will become a post-tropical remnant low
starting late tonight or on Friday. This intensity forecast is close
to the IVCN guidance.
The initial motion for this advisory is 255/16 kt. The LLCC is being
steered by the low-level trade wind flow. A general west-southwest
motion with a slight decrease in forward speed is forecast through
this morning. Olivia will likely turn toward the west later today,
and then the west-northwest tonight and Friday as the system
increasingly interacts with the upper-level low responsible for the
wind shear. The latest track forecast has been adjusted to the left
during the first 24 hours, which takes into account the faster
initial motion. This track forecast remains close to the previous
forecast for the 36 through 72 hour time period. This forecast track
closely follows the TVCE and HCCA, and remains near the middle of
the guidance envelope.
Lingering moisture from Olivia continues to cause heavy rainfall
across portions of the main Hawaiian Islands this morning. These
wet conditions will likely persist through tonight. Since many
areas are already saturated, any additional heavy rainfall could
produce life-threatening flash flooding.
FORECAST POSITIONS AND MAX WINDS
INIT 13/1500Z 19.5N 162.2W 30 KT 35 MPH
12H 14/0000Z 19.1N 164.2W 30 KT 35 MPH
24H 14/1200Z 19.4N 167.0W 30 KT 35 MPH
36H 15/0000Z 20.0N 169.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 15/1200Z 21.0N 171.7W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 16/1200Z 23.0N 176.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
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