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Hurricane Hector Discussion Number  46
NWS Central Pacific Hurricane Center Honolulu HI   EP102018
1100 AM HST Sat Aug 11 2018
 
Satellite loop shows Hector is feeling the effects of southerly
vertical shear, with the outflow pattern becoming quite asymmetric
outside the immediate eyewall. After briefly clouding over, a
rather murky eye has re-emerged within the past hour or so.
Subjective Dvorak current intensity estimates range from 5.0/90 kt
(PHFO,SAB), to 5.5/102 kt (JTWC). ADT from UW-CIMSS is 98 kt. Based
on a blend of these numbers, the initial intensity for this
advisory is set at 95 kt.
 
The initial motion for Hector is set at 310/12 kt. This represents
the beginning of this system's turn to the northwest which was
expected by the end of the day. The steering environment is
characterized by a mid-level ridge to the northeast of Hector and a
mid- to upper-level low to the northwest. As the ridge remains
stationary and the low becomes better developed, we expect an
increase in forward speed as well as a continued northwest motion.
By Monday, the ridge will build to the north of Hector, inducing a
slight turn toward the west that will persist until the end of the
forecast period, at which time Hector is expected to make a turn
back toward the northwest. Given the slightly early turn to the
northwest this morning, the updated track was nudged slightly to the
right through 24 hours, then nudged slightly to the left after 48
hours to stay within the guidance envelope.
 
Southerly shear is expected to increase into the 25 to 30 kt range
through 24 hours, according to SHIPS, prompting us to maintain the
fairly rapid weakening trend through that time. After that, shear
is forecast to decrease, but SSTs are forecast to steadily decrease
as well. SHIPS wants to keep Hector at hurricane strength through
120 hours, while HWRF briefly weakens Hector to tropical storm
strengh at 36 hours. In contrast, global models want to
significantly weaken Hector almost to dissipation by 120 hours. The
official forecast lies between these two, describing a fairly rapid
weakening of this system through 24 hours, followed by more gradual
weakening afterwards.
 
Given the close approach to the Northwestern Hawaiian Islands Hector
is forecast to make on Sunday and Monday, a Tropical Storm Watch
remains posted for the area from Lisianski Island to Pearl and
Hermes Atoll. Interests on Midway and Kure Atolls should continue to
monitor the progress of Hector.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/2100Z 20.1N 170.9W   95 KT 110 MPH
 12H  12/0600Z 21.2N 172.3W   85 KT 100 MPH
 24H  12/1800Z 22.9N 174.7W   75 KT  85 MPH
 36H  13/0600Z 24.2N 177.4W   70 KT  80 MPH
 48H  13/1800Z 25.2N 179.6E   65 KT  75 MPH
 72H  14/1800Z 27.2N 173.7E   60 KT  70 MPH
 96H  15/1800Z 29.4N 167.6E   55 KT  65 MPH
120H  16/1800Z 33.8N 162.8E   50 KT  60 MPH
 
$$
Forecaster Powell
 
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