National Hurricane Center Discussion

	( WTPZ45 )
 

114 
WTPA41 PHFO 131458
TCDCP1
 
Tropical Storm Hector Discussion Number  53
NWS Central Pacific Hurricane Center Honolulu HI   EP102018
500 AM HST Mon Aug 13 2018
 
The core of Hector has been nearly devoid of deep convection since
late Sunday afternoon. The most recent estimate of vertical wind
shear from SHIPS is about 16 knots from the southwest. A few
thunderstorms have recently developed in the northwest semicircle
far from the exposed low-level circulation center (LLCC). However,
this does not appear to be enough to revive Hector in the near
future. The latest subjective Dvorak intensity estimates are
T3.0/45 knots from PHFO, SAB, and JTWC. The UW-CIMSS ADT estimate
is T2.0/30 knots. Based on all of this guidance, we are lowering
the initial intensity to 45 knots, which may be generous, for this
advisory.
 
Since we can easily monitor the movement of the exposed LLCC in
satellite imagery, the initial motion is set at 290/15 knots. The
track forecast has been adjusted only slightly from the previous
one. Again, the latest model guidance remains tightly clustered
through 72 hours, with the spread in the forecast tracks increasing
on Days 4 and 5. Hector is expected to continue on a west-northwest
track along the eastern periphery of a retrograding upper-level low
located west of the International Date Line near Longitude 171E. As
this low aloft continues to move west, an upper level ridge is
forecast to build north of the Hector. This will likely steer the
tropical storm toward the west-northwest during the next 48 hours. A
gradual turn toward the northwest is expected around 72 hours,
followed by a turn toward the north on days 4 and 5, as Hector
rounds the western end of the ridge. The latest forecast track
remains very close to the consensus guidance. Note that since the
system is sheared, the forecast track is also close to the TABS
through 48 hours. 
 
The latest intensity forecast is adjusted downward due to the
continued relatively rapid weakening of Hector. The forecast
guidance shows the shear may relax within 12 to 24 hours, but the
system will likely be weaker by this time. In addition, it 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. Most of the intensity
guidance levels off during the 36 through 48 hour time frame, while
the SHIPS guidance and GFS indicate some unrealistic strengthening.
The main weakening trend is during days 3 through 5. In addition,
Hector is forecast to transition to an extratropical system in about
96 hours.
 
Note that large breaking waves will likely persist this morning
along portions of the Northwestern Hawaiian Islands, especially
in the vicinity of Kure Atoll and Midway Atoll, due to south and
southeast swells generated by Hector.

This will be the final advisory from the Central Pacific Hurricane
Center on this system. The next bulletin will be issued by RSMC
Tokyo Japan. For U.S. interests, see Department of Defense warnings
issued by the Joint Typhoon Warning Center in Honolulu, Hawaii.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 25.3N 179.8E   45 KT  50 MPH
 12H  14/0000Z 26.2N 177.4E   40 KT  45 MPH
 24H  14/1200Z 27.4N 174.2E   40 KT  45 MPH
 36H  15/0000Z 28.5N 171.1E   35 KT  40 MPH
 48H  15/1200Z 29.9N 168.1E   35 KT  40 MPH
 72H  16/1200Z 33.0N 164.0E   30 KT  35 MPH
 96H  17/1200Z 37.5N 163.5E   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  18/1200Z 43.5N 166.5E   25 KT  30 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Houston
 

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