070 WTNT45 KNHC 190844 TCDAT5 Hurricane Ernesto Discussion Number 31 NWS National Hurricane Center Miami FL AL052024 500 AM AST Mon Aug 19 2024 Satellite imagery shows that Ernesto's eye is irregularly-shaped, with fairly cold convective cloud tops over the northern portion of the circulation. The southwestern part of the high cloud canopy is beginning to become slightly blunted, which suggests some southwesterly shear is beginning to affect the system. The various objective intensity estimates from UW-CIMSS indicate that, a couple of hours ago, the hurricane strengthened a little more, but recently the overall cloud pattern appears to have become a little less organized. This suggests that Ernesto has stopped strengthening, and the current intensity estimate is set at 75 kt which is in general agreement with subjective Dvorak T-numbers. Center fixes indicate a gradual increase in forward speed overnight and the initial motion estimate is 030/18 kt. Ernesto is expected to accelerate northeastward in the flow ahead of a large deep-layer trough near the U.S. east coast for the next 24 hours or so. This motion should bring the center of the cyclone near southeastern Newfoundland tonight or early Tuesday. Based on the NHC forecast, most of the stronger winds in the system's circulation are expected to stay offshore of Newfoundland. Thereafter, a faster east-northeastward motion over the North Atlantic is forecast while the cyclone becomes fully embedded within the mid-latitude westerlies. In 2-3 days, Ernesto is likely to open up into a trough while merging with a large extratropical low to the south of Iceland. The official track forecast follows the latest dynamical model consensus and is just slightly to the north of the previous NHC prediction. Ernesto will be traversing significantly cooler waters later today and will be impacted by increasing west-southwesterly vertical wind shear during the next day or two. Therefore, a weakening trend should begin by tonight or earlier. The official intensity forecast is quite similar to the latest Decay-SHIPS numerical guidance. Simulated satellite imagery from the global models suggest that the system will become post-tropical within the next day or so. Key Messages: 1. Even though Ernesto is forecast to remain well offshore of the U.S. East Coast, swells generated by the hurricane will continue to affect the area through the early part of this week. Beach goers should be aware that there is a significant risk of life-threatening surf and rip currents, and should stay out of the water if advised by lifeguards. Surf and rip currents are also possible on the Bahamas, Bermuda, and Atlantic Canada during the next few days. 2. Ernesto will likely bring some wind, wave, and rain impacts to portions of southeastern Newfoundland tonight into Tuesday morning. Breaking waves could bring the possibility of coastal flooding, particularly along southwest-facing shorelines from Bunin east to Avalon regions. For additional impact specific information, please see statements issued by the Canadian Hurricane Centre. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 40.2N 60.5W 75 KT 85 MPH 12H 19/1800Z 42.7N 57.3W 75 KT 85 MPH 24H 20/0600Z 46.3N 51.0W 65 KT 75 MPH...POST-TROPICAL 36H 20/1800Z 49.0N 41.8W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 21/0600Z 50.8N 30.8W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 21/1800Z 53.0N 19.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 22/0600Z...DISSIPATED $$ Forecaster Pasch