498 WTPZ41 KNHC 020853 TCDEP1 Hurricane Norman Discussion Number 21 NWS National Hurricane Center Miami FL EP162018 200 AM PDT Sun Sep 02 2018 Norman's structure has continued to slowly improve this morning. A ragged, but fairly clear, eye has been apparent in shortwave and longwave IR imagery for the past several hours, and cloud tops around the eye have generally cooled. The initial intensity has been held at 90 kt, in agreement with the latest Dvorak fixes from TAFB and SAB. However, the most recent objective intensity estimates from the UW-CIMSS ADT are slightly higher, suggesting this estimate could be conservative. Given that Norman appears to be on the upswing, the forecast now allows for some slight re-strengthening over the next 12 h while the hurricane remains over warm waters and the shear is expected to be light. Beyond that time, however, there has been no significant change to the intensity forecast reasoning or the guidance. The cyclone is still expected to gradually weaken as it encounters a marginal environment consisting of cool SSTs, fairly dry air, and by the end of the forecast period, increasing shear. At 24 h and beyond, the NHC forecast is very close to the intensity consensus, and has not been substantially changed from the previous advisory. Norman is beginning to accelerate and the initial motion estimate is 290/11. A strong deep-layer subtropical ridge to the north should keep Norman moving generally westward to west-northwestward through most of the forecast period, with a notable increase in speed for the next day or two. All of the models agree on this general scenario, however there is still some north-south spread in the guidance, with the GFS and ECMWF on opposite sides of the guidance envelope. Like the previous forecast, the official track forecast generally splits these models and lies near the middle of the guidance envelope and the consensus aids, FSSE and HCCA. FORECAST POSITIONS AND MAX WINDS INIT 02/0900Z 17.1N 127.5W 90 KT 105 MPH 12H 02/1800Z 17.7N 129.8W 95 KT 110 MPH 24H 03/0600Z 18.6N 133.0W 90 KT 105 MPH 36H 03/1800Z 19.4N 136.3W 85 KT 100 MPH 48H 04/0600Z 20.1N 139.7W 80 KT 90 MPH 72H 05/0600Z 20.8N 144.6W 70 KT 80 MPH 96H 06/0600Z 21.5N 149.0W 65 KT 75 MPH 120H 07/0600Z 23.0N 152.0W 60 KT 70 MPH $$ Forecaster Zelinsky