141 WTPZ45 KNHC 052051 TCDEP5 Hurricane Hector Discussion Number 21 NWS National Hurricane Center Miami FL EP102018 200 PM PDT Sun Aug 05 2018 Hector continues to exhibit an impressive satellite presentation. A 1559 UTC SSMIS microwave overpass suggests that Hector likely completed an eyewall replacement since this morning, with the eye becoming better defined. Both conventional satellite imagery and the aforementioned microwave data show little in the way of banding outside of the symmetric CDO, suggesting that Hector has some characteristics of an annular hurricane. Subjective satellite intensity estimates are T6.0/115 kt from TAFB and SAB, and the latest UW/CIMSS objective estimates are up to T6.1 or 117 kt. As result, the initial wind speed is increased to 115 kt, making Hector a category 4 hurricane once again. Hector is forecast to remain within very low vertical wind shear while it traverses SSTs of around 27C during much of the forecast period. However, the hurricane will be moving into an area of drier mid-level air which is likely to induce some weakening later in the forecast period. Given Hector's annular-like structure, the NHC intensity forecast shows a more gradual rate of weakening since annular hurricanes tend to be more stable and weaken more slowly. The NHC intensity forecast is in best agreement with the HFIP corrected consensus model, HCCA. The hurricane continues moving westward or 275/11 kt. There is been no change to the track forecast reasoning. Hector is forecast to move westward to west-northwestward during the next day or so to the south of a deep-layer subtropical ridge. The ridge is expected to strengthen to the north of the Hawaiian Islands by mid-week which is expected to turn the hurricane westward. The models continue to be in good agreement on this general scenario but some cross-track spread remains. The NHC forecast is once again near the middle of the guidance envelope, close to the various consensus models. The NOAA G-IV aircraft will be releasing dropsondes as it circumnavigates Hector during its flight to Hawaii to support forecast operations over the next few days. Data from these dropsondes should be incorporated into this evening's 0000 UTC dynamical models. While the official forecast track continues to lie south of the Hawaiian Islands, only a slight deviation to the north of the forecast track would significantly increase potential impacts on the Hawaiian Islands. It is a good time for everyone in the Hawaiian Islands to ensure they have their hurricane plan in place. For additional information on any potential local impacts from Hector in Hawaii, please refer to products issued by the NWS Weather Forecast Office in Honolulu at: http://www.prh.noaa.gov/hnl FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 14.4N 138.0W 115 KT 130 MPH 12H 06/0600Z 14.7N 139.8W 110 KT 125 MPH 24H 06/1800Z 15.3N 142.4W 105 KT 120 MPH 36H 07/0600Z 15.9N 145.3W 100 KT 115 MPH 48H 07/1800Z 16.4N 148.4W 95 KT 110 MPH 72H 08/1800Z 16.7N 154.5W 90 KT 105 MPH 96H 09/1800Z 17.0N 160.3W 85 KT 100 MPH 120H 10/1800Z 17.7N 166.0W 80 KT 90 MPH $$ Forecaster Brown