ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Tropical Storm Greg Discussion Number 2 NWS National Hurricane Center Miami FL EP082023 1100 PM HST Sun Aug 13 2023 After the release of the previous advisory a burst of deep convection developed closer to the center of the cyclone. However, easterly shear has caused the area of convection to propagate westward away from the center, leaving it exposed. Recently arriving ASCAT overpasses show that the depression has strengthened into a tropical storm. Both ASCAT-B and ASCAT-C revealed peak winds of 34-35 kt to the north-northwest of the center. Greg is moving westward or 275 degrees at 11 kt. A narrow mid-level ridge to the north of the cyclone should continue to steer it westward to west-northwestward during the next 2 to 3 days. After that time, the tropical storm is forecast to gradually weaken and come under the influence of the low-level trade wind flow. That should cause the cyclone to turn westward or west-southwestward late in the period. The track model envelope shifted southward this cycle so the NHC forecast was adjusted accordingly. The new forecast track is near the HFIP corrected consensus aid, but it is not as far south as the typically reliable GFS and ECMWF models. The tropical storm is located over SSTs of around 28 degrees Celsius, but within an area of light to moderate easterly shear. These conditions are expected to allow for some modest strengthening during the next couple of days. After that time, slightly cool waters, the continuation of easterly shear, and a drier mid-level air mass are likely to cause gradual weakening. Much of the intensity guidance predict a lower peak intensity this cycle, and the official forecast has been adjusted slightly downward. It should be noted that the ECMWF and GFS show the system degenerating into a trough of low pressure by day 5. This scenario is certainly possible, but not reflected in the latest official forecast. The depression will cross into the central Pacific basin by 1200 UTC today. Therefore, the next advisory on this system will be issued by the Central Pacific Hurricane Center at 1500 UTC or 500 AM HST. Information about this system will continue to be available on the web at hurricanes.gov FORECAST POSITIONS AND MAX WINDS INIT 14/0900Z 11.3N 139.8W 35 KT 40 MPH 12H 14/1800Z 11.4N 141.5W 40 KT 45 MPH 24H 15/0600Z 11.5N 143.9W 45 KT 50 MPH 36H 15/1800Z 11.7N 146.2W 45 KT 50 MPH 48H 16/0600Z 12.1N 148.6W 45 KT 50 MPH 60H 16/1800Z 12.5N 151.1W 45 KT 50 MPH 72H 17/0600Z 12.8N 153.6W 40 KT 45 MPH 96H 18/0600Z 12.7N 158.7W 35 KT 40 MPH 120H 19/0600Z 12.1N 163.9W 30 KT 35 MPH $$ Forecaster Brown NNNN