000 WTNT45 KNHC 180855 CCA TCDAT5 Tropical Storm Ernesto Discussion Number 27...Corrected NWS National Hurricane Center Miami FL AL052024 500 AM AST Sun Aug 18 2024 Corrected text of second key message. Ernesto's cloud pattern hasn't changed much overnight, and lacks a well-defined eye feature. Deep convection has been trying to wrap around the eastern portion of the circulation, giving the system a fairly symmetric overall appearance. The current intensity estimate is held at 60 kt which is in good agreement with the latest objective, AID, estimates from UW-CIMSS. Subjective Dvorak satellite estimates are somewhat lower. Unfortunately the most recent scatterometer overpasses missed most of the circulation. The tropical cyclone continues on a rather slow north-northeastward heading, with an initial motion estimate of 025/8 kt. The steering flow on the east side of a large mid-tropospheric trough approaching the U.S. east coast should cause an increase in forward speed during the next day or so along with a turn toward the northeast. In 2-3 days, Ernesto is likely to turn toward the east-northeast with additional acceleration as it becomes embedded in the mid-latitude westerlies over the north Atlantic. The track guidance models remain in good agreement, and little changes to the previous NHC track forecast were required. Ernesto is still over warm waters, and should remain over SSTs of at least 27 deg C for the next 24 hours or so. Also, vertical wind shear is forecast to remain low today with upper-level divergence diagnosed over the area by the SHIPS model diagnostics. These environmental factors favor a short period of restrengthening today, and this reflected in the official forecast. In 36-48 hours, the cyclone will encounter much cooler waters and this should cause weakening. Simulated IR satellite imagery from the global models show an increasingly asymmetric cloud structure by the time the system passes near Newfoundland, and the official forecast indicates post-tropical transition by 48 hours. Ernesto is predicted to open up and become a large trough over the northeastern Atlantic by 96 hours. Key Messages: 1. Even though Ernesto is forecast to remain well offshore of the U.S. East Coast, swells generated by the hurricane are expected to affect the area through early next 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 could bring wind and wave impacts to portions of southeastern Newfoundland late Monday and Monday night. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 34.6N 63.0W 60 KT 70 MPH 12H 18/1800Z 36.4N 62.2W 65 KT 75 MPH 24H 19/0600Z 39.4N 60.4W 70 KT 80 MPH 36H 19/1800Z 42.9N 56.5W 65 KT 75 MPH 48H 20/0600Z 46.4N 50.3W 55 KT 65 MPH...POST-TROPICAL 60H 20/1800Z 49.0N 41.4W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 21/0600Z 51.0N 31.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 22/0600Z...DISSIPATED $$ Forecaster Pasch
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