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Hurricane Olivia Discussion Number  40
NWS Central Pacific Hurricane Center Honolulu HI   EP172018
500 AM HST Mon Sep 10 2018
 
Olivia's eye has been appearing at times this morning. The outflow
pattern remains impressive, so it does not appear to be negatively
impacted by vertical wind shear of around 10 kt. The satellite fix
agencies (JTWC, SAB, and PHFO) provided unanimous subjective Dvorak
current intensity estimates of 4.5/77 kt. The UW-CIMSS ADT estimate
was 4.2/70 kt. Based on all of this information, we are maintaining
the initial intensity at 75 kt for this advisory. Note that an
aircraft flown by the U.S. Air Force Reserves 53rd Weather
Reconnaissance Squadron is scheduled to sample the inner core and
outer wind field of Olivia starting in a few hours. This will
give us a much better idea of the latest intensity of Olivia once
they arrive.
 
Olivia continues to move nearly due west with a current motion of
270/9 kt. This motion is being induced by a deep layer ridge to the
north and northwest of the tropical cyclone. During the next 12
hours or so, the ridge is expected to strengthen and build southward
ahead of Olivia, forcing the tropical cyclone to shift toward a
west-southwest track. This motion is expected to continue through
day 3. The track guidance appears have slightly more spread through
72 hours, especially from 36 to 72 hours. The spread is even greater
during days 4 and 5. The current forecast track is very close to the
previous, except it has been nudged to the right and is slightly
slower during the first 72 hours. Little change has been made in the
day 4 and 5 positions. This closely follows the latest TVCE, FSSE,
GFEX and HCCA guidance. Again, since the is a wider spread in the
track guidance, we want to emphasize the uncertainty in our track
forecast. It is important to NOT focus on the exact forecast track
of Olivia's center across the islands. A slight deviation to the
right or left can bring vastly different weather hazards to any
islands that are directly impacted by this potentially damaging
tropical cyclone.
 
Vertical wind shear remains relatively weak in the vicinity of
Olivia. Water temperatures, as well as ocean heat content values,
are expected to increase along the forecast track. Therefore, Olivia
will likely remain a hurricane through 36 hours. After that,
increasing vertical wind shear is forecast to take its toll on
Olivia, so that it may be a strong tropical storm within 48 hours.
Additional slow weakening is expected to persist during days 3
through 5. The latest forecast is close to the IVCN and CTCI. Note
that based on the latest track and intensity along with the wind
speed probabilities, Tropical Storm Warnings have been issued for
the Big Island of Hawaii and the islands of Maui County.
 
KEY MESSAGES:
 
1.  It is important to not focus on the exact forecast track and
intensity when planning for Olivia. Persons on the main Hawaiian
Islands east of Kauai should continue preparing for the likelihood
of direct impacts from this system today and early Tuesday. Those
impacts could include intense flooding rainfall, damaging winds,
large and dangerous surf, and storm surge.
 
2.  Regardless of the exact track and intensity that Olivia takes
as it approaches the islands, significant effects often extend far
from the center. In particular, the mountainous terrain of Hawaii
can produce localized areas of strongly enhanced winds and
rainfall, even well away from the tropical cyclone center.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/1500Z 21.7N 148.0W   75 KT  85 MPH
 12H  11/0000Z 21.7N 149.3W   75 KT  85 MPH
 24H  11/1200Z 21.4N 151.3W   75 KT  85 MPH
 36H  12/0000Z 21.1N 153.4W   65 KT  75 MPH
 48H  12/1200Z 20.7N 155.7W   60 KT  70 MPH
 72H  13/1200Z 19.9N 160.7W   45 KT  50 MPH
 96H  14/1200Z 20.0N 166.0W   40 KT  45 MPH
120H  15/1200Z 21.0N 171.0W   40 KT  45 MPH
 
$$
Forecaster Houston
 
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