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Hurricane Hector Discussion Number  50
NWS Central Pacific Hurricane Center Honolulu HI   EP102018
1100 AM HST Sun Aug 12 2018
 
Hector continues to weaken this morning due to south-southwesterly
shear of around 16 kt over the system as analyzed by the latest
UW-CIMSS shear analysis. The low level circulation center in
visible satellite imagery appears to be on the south side of the
deepest convection.  The latest subjective Dvorak intensity
estimates were 4.0 (65 knots) from PHFO and SAB, and 3.5 (55 knots)
from JTWC. The satellite presentation clearly shows that weakening
is ongoing, but given the persistent deep convection near the low
level circulation center and necessary spin down time needed 
as these systems weaken, will only lower the initial intensity to
65 knots with this advisory. The initial motion is set at 300/15
knots.
 
The latest model guidance remains tightly clustered through 72
hours, with the spread in the track guidance increasing
considerably at 96 and 120 hours. Hector is expected to continue
on a west-northwest track today on the eastern periphery of an upper
level low to the west of the International Date Line. The system is
expected to make a turn to a more westerly direction tonight,
and continue on this course through Wednesday as an upper level
ridge builds north of the system. A turn toward the northwest and
eventually north is then expected Wednesday night through Friday as
Hector rounds the southwest periphery of the upper level ridge. The
new official forecast track is very close to the consensus guidance
as well as the track from the previous advisory. 
 
The intensity forecast calls for slow weakening of Hector over
the next 12 to 24 hours as the system will remain in southwesterly
shear of around 15 kt. The shear is forecast to decrease beyond 24
hours, but the system will likely have weakened by this time and
will be moving over cooler sea surface temperatures. The intensity
guidance is in fairly good agreement through 36 hours, so confidence
during this portion of the forecast is fairly good. There is quite a
bit of spread in the intensity guidance beyond 36 hours however,
with the HWRF and CTCI models continuing to show Hector
re-intensifying a bit during the 48 through 72 hour time frame.
This seems really aggressive given the state the hurricane is in at
the moment and with the continued weakening forecast. As a result,
the official intensity forecast calls for slow weakening through
Monday morning, with Hector becoming a Tropical Storm later today or
tonight. Beyond 24 hours the forecast intensity has been held
steady through 48 hours, with slow weakening expected at the end of
the forecast period as Hector transitions over to an extratropical
system.
 
Probabilities for tropical storm force winds reaching the
Northwestern Hawaiian Islands have decreased since the previous
advisory. A Tropical Storm Watch remains in effect for Kure Atoll
and Midway Atoll and waters between Midway Atoll and Pearl and
Hermes Atoll. The Tropical Storm Watch has been discontinued for
the area from Lisianski Island to Pearl and Hermes Atoll. If Hector
continues to weaken as expected, and the forecast track to the
west-northwest continues, the Tropical Storm Watches currently in
effect may be canceled later today or tonight.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/2100Z 23.7N 175.7W   65 KT  75 MPH
 12H  13/0600Z 24.8N 177.9W   55 KT  65 MPH
 24H  13/1800Z 26.2N 179.0E   50 KT  60 MPH
 36H  14/0600Z 27.0N 175.9E   50 KT  60 MPH
 48H  14/1800Z 28.1N 172.8E   50 KT  60 MPH
 72H  15/1800Z 30.4N 166.5E   45 KT  50 MPH
 96H  16/1800Z 33.7N 162.7E   40 KT  45 MPH
120H  17/1800Z 38.0N 161.9E   35 KT  40 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Burke
 
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