ZCZC HFOTCDCP1 ALL TTAA00 PHFO DDHHMM Hurricane Hector Discussion Number 25 NWS Central Pacific Hurricane Center Honolulu HI EP102018 500 AM HST Mon Aug 06 2018 The satellite presentation of Hurricane Hector has improved overnight, with a well defined 10 to 15 nautical mile wide eye surrounded by a large ring of -70 to -80 Celsius cloud tops. The latest subjective Dvorak current intensity estimates from SAB and JTWC came in at 6.5 (127 knots), while PHFO came in at 6.0 (115 knots). The latest estimate using the Advanced Dvorak technique from UW-CIMSS yielded 6.8 (135 knots). Given that Hector's satellite presentation has improved since the previous advisory, we have elected to raise the initial intensity to 125 knots which correlates well with a blend of the available intensity estimates. Hector has continued to track westward at about the same speed as the previous advisory, so the initial motion remains 280/13 knots. The latest model guidance remains tightly clustered and brings Hector just north of due west over the next 36 to 48 hours due to a weakness in the subtropical ridge to the northeast of the Hawaiian Islands. Beyond 48 hours, the subtropical ridge is forecast to build to the north of the Hawaiian Island chain, and this should steer Hector due westward from 48 to 96 hours, before bending back to the west-northwest beyond 96 hours as a digging upper level trough between 170W and the International Date Line begins to erode the western portion of the subtropical ridge. The new official forecast track is very close to the model consensus and nearly identical to the previous official track forecast. Hector will remain in a favorable low shear environment through the forecast period, but there are some factors that should lead to gradual weakening over the next few days. The hurricane will be traveling over marginal sea surface temperatures around 27C through Wednesday, before the SSTs increase slightly to around 28C to the south of the Hawaiian Islands Wednesday night through Friday. Additionally and likely more importantly, very dry mid-level air will begin to surround the storm beginning later today or tonight, and this is expected to lead to a slow and gradual weakening of the system through Wednesday night. The intensity of Hector is then expected to level off Wednesday night through Friday as it encounters the higher SSTs, with some indication from the HWRF that re-intensification could occur. The intensity forecast has been adjusted slightly higher than the previous forecast due to both the statistical and dynamical models trending higher and coming into somewhat better agreement. Given the recent better performance of the dynamical guidance in comparison to the statistical guidance, more weight was placed on the dynamical models when preparing the intensity forecast for this advisory package as well. A couple reconnaissance missions are scheduled to be flown today between 18Z and 00Z, one by the Air Force Reserve 53rd Weather Reconnaissance Squadron which will provide additional important data to assist in future track and intensity forecasts. The other will be a NOAA G4 mission which will sample the environment around Hector, providing valuable data for ingestion into the models. While the official forecast track continues to lie to the south of the Hawaiian islands, only a slight deviation to the north of the forecast track would significantly increase potential impacts to the state of Hawaii. Now is a good time for everyone in the Hawaiian Islands to ensure that they have their hurricane plan in place. For additional information on any potential impacts from Hector in Hawaii, please refer to products issued by the NWS Weather Forecast Office here in Honolulu at: http://www.prh.noaa.gov/hnl . FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 15.0N 141.9W 125 KT 145 MPH 12H 07/0000Z 15.4N 144.0W 120 KT 140 MPH 24H 07/1200Z 15.9N 146.9W 115 KT 130 MPH 36H 08/0000Z 16.2N 149.9W 110 KT 125 MPH 48H 08/1200Z 16.5N 153.0W 105 KT 120 MPH 72H 09/1200Z 16.6N 159.3W 95 KT 110 MPH 96H 10/1200Z 17.0N 165.4W 90 KT 105 MPH 120H 11/1200Z 17.7N 170.6W 90 KT 105 MPH $$ Forecaster Jelsema NNNN