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Tropical Storm Olivia Discussion Number  43
NWS Central Pacific Hurricane Center Honolulu HI   EP172018
1100 PM HST Mon Sep 10 2018
 
Hurricane Hunters from the 53rd Weather Reconnaissance Squadron are 
again penetrating Olivia's core this evening, and found the low-
level center further east than anticipated. Some conflicting data 
exists as to the current intensity, as the central pressure has 
risen, but winds in the northwest quadrant were stronger than 
earlier today. A blend of the data supports maintaining the initial 
intensity at 60 kt for this advisory.

The initial motion estimate for this advisory is 280/8 kt, with 
Olivia still being steered by a mid-level ridge centered to the 
distant northeast. Track guidance continues to indicate that a mid-
level ridge building to the northwest of Olivia will induce a
motion toward the west and west-southwest, with this expected to
begin on Tuesday. At 72 hours and beyond, an upper level low is
expected to develop between the ridge and Olivia, imparting a
west-northwest motion on the tropical cyclone. The updated track
forecast is shifted just slightly to the south of the previous,
mostly after day 2, so the track forecast near the islands has
changed little. Notable along-track differences between the GFS and
ECMWF/HWRF exist, with the ECMWF/HWRF continuing to bring Olivia
over the islands about 6-12 hours faster. The official forecast is
on the north side of the guidance envelope, is close to the
multi-model consensus TVCE, with the short-term forward speed a
blend of the GFS and ECMWF/HWRF. 

Shear is expected to increase over the next 24 to 48 hours while 
SSTs increase to greater than 28C. The shear is expected to induce 
slow but steady weakening, and the updated intensity forecast is
close to the previous and closely follows the multi-model intensity
consensus IVCN. 

KEY MESSAGES: 

1. Resist the temptation to make comparisons between Lane and
Olivia. Although Lane was a stronger tropical cyclone near the
islands, it did not bring direct core impacts to the state. In some
areas, Olivia could bring significantly worse impacts than those
brought by Lane. Those impacts could include intense flooding
rainfall, damaging winds, and large and dangerous surf.

2. It is important to not focus on the exact forecast track 
and intensity when planning for Olivia. Regardless of the track 
that Olivia takes as it approaches the islands, significant impacts 
can be expected away from the center. In particular, the
mountainous terrain of Hawaii can produce localized areas of
strongly enhanced wind gusts and rainfall.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/0900Z 22.0N 150.1W   60 KT  70 MPH
 12H  11/1800Z 21.7N 151.9W   55 KT  65 MPH
 24H  12/0600Z 21.4N 154.1W   50 KT  60 MPH
 36H  12/1800Z 20.9N 156.3W   45 KT  50 MPH
 48H  13/0600Z 20.3N 158.5W   45 KT  50 MPH
 72H  14/0600Z 19.7N 163.1W   40 KT  45 MPH
 96H  15/0600Z 20.5N 168.0W   35 KT  40 MPH
120H  16/0600Z 22.0N 172.5W   30 KT  35 MPH
 
$$
Forecaster Birchard
 
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