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Hurricane Hector Discussion Number  42
NWS Central Pacific Hurricane Center Honolulu HI   EP102018
1100 AM HST Fri Aug 10 2018
 
The satellite presentation of Hector showed some signs of
improvement this morning. The hurricane has become more symmetric
with a better defined area of cold cloud tops within the western
portion of the core. Dvorak current intensity numbers remained
6.0/115 kt from HFO, SAB and JTWC, while CIMSS ADT yielded 122 kt.
Given the improvement in the satellite appearance, the initial
intensity will be nudged up to 120 kt.
 
The initial motion of Hector continues to be west-northwest (285
degrees) at 14 kt. A low to mid level ridge far to the north will
cause Hector to move toward the west-northwest today, and as this
ridge is weakened slightly, Hector will make a turn toward the
northwest tonight and Saturday. This general motion toward the
northwest will continue into early next week. Only small changes
were made to the forecast track through 72 hours, with a slight
delay in the turn to the northwest to be more in line with the GFS
and TVCN. On days four and five, the forecast was adjusted to the
left to better capture a slowing of the forward motion and turn
toward the west-northwest that is predicted by all guidance.
 
The window for Hector to maintain intensity will be closing soon, as
the system is expected to start a weakening trend later today or
tonight. Hector currently lies under a weakening ridge aloft, which
is providing outflow in all but the western quadrant, and nearby
SSTs are around 28C.  While little change is expected in SST through
tomorrow, Hector will advance toward an upper level trough sitting
just east of the International Date Line, leading to a steady
increase in southwesterly vertical wind shear. This, along with a
decrease in SSTs by Sunday, is expected to produce a slow weakening
trend that will persist through at least Monday. The intensity
forecast is close to a tightly clustered guidance envelope through
72 hours. On days four and five, the guidance spread increases,
likely due to differences in the affects of relaxing vertical wind
shear. The forecast weakening trend was slowed at that time to be
closer to IVCN and the statistical guidance.
 
Based on the latest track, portions of the Northwestern Hawaiian
Islands west of Maro Reef may require a Tropical Storm or Hurricane
Watch later today or tonight. Note that there is no threat to any of
the main Hawaiian Islands from Kauai to the Big Island.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/2100Z 18.0N 167.2W  120 KT 140 MPH
 12H  11/0600Z 18.8N 168.8W  115 KT 130 MPH
 24H  11/1800Z 20.2N 170.8W  105 KT 120 MPH
 36H  12/0600Z 21.9N 172.7W   95 KT 110 MPH
 48H  12/1800Z 23.8N 174.9W   85 KT 100 MPH
 72H  13/1800Z 27.1N 179.9W   70 KT  80 MPH
 96H  14/1800Z 29.6N 175.1E   60 KT  70 MPH
120H  15/1800Z 32.0N 170.5E   50 KT  60 MPH
 
$$
Forecaster Wroe
 
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