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 If nothing appears above but an error message, no current data were found.