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Hurricane Hector Discussion Number  38
NWS Central Pacific Hurricane Center Honolulu HI   EP102018
1100 AM HST Thu Aug 09 2018

Hurricane Hector has continued westward, 275/14 kt, well south of
the main Hawaiian Islands and has maintained a well-defined eye over
the past several hours. In the satellite imagery the system is a
bit asymmetric with the upper level outflow better in the
northeastern semicircle and slightly restricted on the southwestern
side. Subjective Dvorak intensity estimates came in at 5.5/102 kt
from PHFO, SAB, and JTWC. CIMSS ADT was 5.7/107 kt at 1800 UTC.
Based on a blend of these values, the current intensity for this
package is held at 105 kt.

Hector has been moving westward to the south of a solid mid-level
ridge. The ridge is forecast to weaken as a low pressure system cuts
off near the Dateline over the next couple of days. This should
result in a gradual turn toward the west-northwest over the next
day or so, followed by a more northwestward track. The latest
objective aids are in good agreement with this scenario but are a
bit north of the previous package. Thus, the forecast has been
adjusted north accordingly and is close to the dynamical model
consensus. 

In the near term, there do not appear to be any environmental
factors that will result in significant intensity changes. The SSTs
along the track are expected to be in the 27C to 28C range and
vertical shear should remain weak over the next couple of days.
SHIPS guidance indicates that shear should increase after 48 hours.
Beyond day 3, the adjustment of the track forecast north of the
previous track takes Hector across the SST gradient into cooler
waters. Thus, the intensity forecast shows a little more aggressive
weakening than the previous forecast with Hector weakening to a
tropical storm on day 5. This trend is consistent with ICON. Note
that HWRF and HMON have been the best intensity aids so far and
show a more aggressive weakening than the official forecast,
especially after 48 hours.

A Tropical Storm Watch remains in effect for Johnston Island. If the
expected turn toward the west-northwest does not occur, tropical
storm conditions are possible there starting late Friday. Elsewhere,
interests in the Northwestern Hawaiian Islands, including Midway and
Kure Atolls and the Papahanaumokuakea Marine National Monument west
of Laysan Island should monitor the progress of Hector. This does
not include the main Hawaiian Islands.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/2100Z 16.9N 161.5W  105 KT 120 MPH
 12H  10/0600Z 17.2N 163.6W  105 KT 120 MPH
 24H  10/1800Z 17.9N 166.2W  105 KT 120 MPH
 36H  11/0600Z 18.9N 168.6W  105 KT 120 MPH
 48H  11/1800Z 20.3N 170.7W   95 KT 110 MPH
 72H  12/1800Z 23.8N 175.0W   85 KT 100 MPH
 96H  13/1800Z 27.0N 179.5E   65 KT  75 MPH
120H  14/1800Z 31.0N 174.5E   55 KT  65 MPH
 
$$
Forecaster Kodama
 
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