ZCZC HFOTCDCP4 ALL TTAA00 PHFO DDHHMM Hurricane Norman Discussion Number 33...COR NWS Central Pacific Hurricane Center Honolulu HI EP162018 1100 PM HST Tue Sep 04 2018 Norman's large distinct eye surrounded by cold cloud tops have persisted for several hours now. In addition, the overall outflow pattern is indicative of a stronger tropical cyclone compared with 12 hours ago. An AMSU microwave pass from 0635z, which was provided by FNMOC/NRL, also confirmed that the eyewall is closed in all quadrants. As a result, all of the satellite fix agencies (SAB, JTWC, and PHFO) provided subjective Dvorak current intensity estimates of 4.5/77 kt. In addition, the latest UW-CIMSS estimate was 4.8/85 kt. Based on the vastly improved appearance of Norman, and a blend of these intensity estimates, we have increased the intensity to 80 kt for this advisory. Norman continues to move westward, or 270 deg, at 10 kt. It is being steered by a deep subtropical ridge located to the north and northeast. The NOAA Gulfstream IV aircraft completed a mission to sample the environment around Norman earlier this afternoon. Their primary target was this ridge and the weakness that is developing west of the ridge. As a result, most of the track forecast guidance had these data available for initialization of the models at 0000z. The latest model guidance shows little spread through the next 36 hours, which likely is a result of the strength of the ridge. However, starting around 48 to 72 hours, the spread increases. this is likely due to the way the different models forecast the weakening of the western flank of the ridge due to an upper-level trough digging down into the region north of Hawaii. This weakening of the ridge is expected to cause Norman to slow its forward motion and gradually turn toward the west-northwest on Wednesday. This will likely be followed by a turn toward the northwest from Wednesday night into this weekend. The latest forecast track has been nudged slightly left of the previous forecast, and remains near the middle of the guidance envelope through the next 2 days. Even though the guidance spread increases during days 3 through 5, all of the models support the general northwestward motion persisting. The official forecast is also very close to the TVCE, HCCA and GFEX consensus model guidance. Norman is expected to remain a hurricane for the next couple of days. The latest CIRA ocean heat content (OHC) analysis appears to support additional intensification during the next 12 hours or so. In addition, vertical wind shear is around 10 kt based on the latest UW-CIMSS estimate. By late Wednesday night, all guidance is in good agreement that Norman will start to weaken under the effects of increasing southwesterly vertical wind shear, cooler SSTs, and drier environmental conditions. This weakening will likely persist through day 5, when Norman is forecast to become a remnant low. The intensity forecast follows similar trends of the prior advisory, and favors the latest ICON. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 19.6N 146.6W 80 KT 90 MPH 12H 05/1800Z 19.8N 147.9W 85 KT 100 MPH 24H 06/0600Z 20.4N 149.4W 85 KT 100 MPH 36H 06/1800Z 21.3N 150.5W 75 KT 85 MPH 48H 07/0600Z 22.5N 151.4W 70 KT 80 MPH 72H 08/0600Z 25.2N 153.4W 50 KT 60 MPH 96H 09/0600Z 27.5N 155.0W 30 KT 35 MPH 120H 10/0600Z 29.5N 156.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Houston NNNN
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