ZCZC HFOTCDCP4 ALL TTAA00 PHFO DDHHMM Hurricane Norman Discussion Number 37 NWS Central Pacific Hurricane Center Honolulu HI EP162018 1100 PM HST Wed Sep 05 2018 Cold convective cloud tops persist within the inner core of Norman, but the eye has started to become cloud-filled as the system begins to feel the effects of increasing wind shear. Subjective Dvorak current intensity estimates ranged from 5.0/90 kt at SAB to 5.5/102 kt out of HFO and JTWC, while CIMSS ADT came in with a higher estimate of 107 kt. Given the steady state nature of the satellite presentation through most of today, the intensity will be held at 105 kt for this advisory. The long-awaited turn toward the northwest is underway, with the initial motion set at west-northwest (295 degrees) at 7 kt. Norman will gradually turn toward the northwest on Thursday as the hurricane heads toward a weakness in the deep ridge centered far to the northeast. The northwestward motion will persist through the weekend as Norman interacts with a mid- to upper-level trough sitting to the northwest. The track forecast is essentially an update of the prior advisory through 48 hours and was nudged slightly west of the prior advisory afterward. The track forecast is nearest to TVCE, FSSE, and HCCA and is down the middle of the guidance envelope, which is tightly clustered through 48 hours then spreads considerably thereafter. None of the reliable guidance suggests direct impacts from Norman on the main Hawaiian Islands. However, as the tropical cyclone will be in our general vicinity for the next couple of days, people should continue to monitor the progress of this system. Although Norman has been maintaining intensity, weakening will commence shortly. As Norman approaches a weakness in the deep ridge, it is encountering increasing southwesterly vertical wind shear that is being produced by the mid- to upper-level trough parked to the northwest. This wind shear will steadily increase through Saturday and remain in place through the next five days. In addition, SSTs will begin to cool late Thursday. The combined effect will be steady weakening, which will likely render Norman a post-tropical remnant low on late Sunday or Monday. The rate of weakening has been accelerated slightly compared to the prior advisory, but the intensity forecast remains on the higher side of a tightly clustered guidance envelope of both the dynamical and statistical models. FORECAST POSITIONS AND MAX WINDS INIT 06/0900Z 20.3N 149.8W 105 KT 120 MPH 12H 06/1800Z 20.9N 150.8W 95 KT 110 MPH 24H 07/0600Z 21.9N 151.8W 85 KT 100 MPH 36H 07/1800Z 22.9N 152.9W 70 KT 80 MPH 48H 08/0600Z 24.0N 154.1W 55 KT 65 MPH 72H 09/0600Z 26.2N 156.6W 35 KT 40 MPH 96H 10/0600Z 28.0N 158.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 11/0600Z 30.0N 161.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Wroe NNNN