619 WTPZ45 KNHC 051436 TCDEP5 Hurricane Hector Discussion Number 20 NWS National Hurricane Center Miami FL EP102018 800 AM PDT Sun Aug 05 2018 Hector continues to maintain a 10-15 n mi wide eye surrounded by a ring of -60 to -70 degrees Celsius cloud tops. The eye has become slightly less distinct this morning and recent microwave data suggest that an eyewall replacement cycle could be occurring. A 1111 UTC AMSR2 microwave overpass shows a double eyewall structure with the inner eyewall open to the southwest. The various subjective and objective satellite estimates are between 102-110 kt, and the initial wind speed is kept near the upper-end of these estimates for now. The hurricane is moving westward or 275/10 kt. A westward to west-northwestward motion is expected over the next day or so as Hector is steered by a deep-layer ridge to its north. The ridge is forecast to strengthen north of the Hawaiian Islands by mid-week which should cause the hurricane to move on a general westward track throughout most of the remainder of the forecast period. While all of the dynamical models are in agreement on the overall scenario there is a fairly typical amount of cross-track spread with the ECMWF along the southern edge of the guidance envelope and the HMON and GFS along the northern side. The updated NHC track forecast is close to the latest consensus aids, and little overall change to the previous forecast was required. Hector is forecast to remain over warm SSTs and within a low shear environment for the next couple of days, and it is possible for some fluctuations in intensity to occur as the result of eyewall replacements. By 48 h, the hurricane is predicted to encounter some drier mid-level air which is forecast to cause gradual weakening after that time. The latest NHC intensity forecast is a little above the statistical guidance, closest to the HCCA and FSSE intensity models. While the official forecast track continues to lie south of the Hawaiian Islands, it is too soon to determine what kind of impacts might occur in the state, since track errors can be large at long time ranges. This remains 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 05/1500Z 14.4N 136.9W 110 KT 125 MPH 12H 06/0000Z 14.6N 138.6W 105 KT 120 MPH 24H 06/1200Z 15.1N 141.2W 105 KT 120 MPH 36H 07/0000Z 15.7N 144.1W 100 KT 115 MPH 48H 07/1200Z 16.3N 147.1W 95 KT 110 MPH 72H 08/1200Z 16.8N 153.2W 90 KT 105 MPH 96H 09/1200Z 17.2N 158.8W 90 KT 105 MPH 120H 10/1200Z 17.8N 164.2W 85 KT 100 MPH $$ Forecaster Brown