841 WTNT45 KNHC 181448 TCDAT5 Tropical Storm Ernesto Discussion Number 28 NWS National Hurricane Center Miami FL AL052024 1100 AM AST Sun Aug 18 2024 After struggling to produce a lot of deep central convection over the past 24 hours, Ernesto resembles more of a typical tropical cyclone this morning, as convection continues to burst and wrap around the center. There have also been hints of a cloud-filled eye feature showing up on visible satellite imagery. However, subjective and objective intensity estimates have not yet responded to the modest improvement in Ernesto's structure on satellite, and the initial intensity will remain just under hurricane intensity at 60 kt this advisory. Ernesto has about a 12-18 h window to intensify back into a hurricane while the shear remains low, and sea-surface temperatures (SSTs) are between 27-28 C before the cyclone reaches the north wall of the Gulf Stream. After Ernesto crosses this feature, the SSTs sharply decrease and shear markedly increases, both which should initiate extratropical transition. This process should be complete in about 48 h with the cyclone opening up into a trough as it is absorbed by another extratropical cyclone beyond 72 h. The NHC intensity forecast is largely an update from the previous cycle, in good agreement with the intensity consensus guidance. The tropical cyclone is beginning to accelerate north-northeastward, estimated at 020/14 kt. There is little change in the forecast track thinking, with a large mid-latitude trough moving into the U.S. East Coast that, in combination with a large subtropical ridge to the southeast, is expected to cause Ernesto to increase in forward speed along with a turn more northeastward over the next couple of days. On this track, Ernesto should make its closest approach to Newfoundland just to the southeast early Tuesday morning, with the bulk of the cyclone's wind field staying offshore of the Canadian Provence. After post-tropical transition, the cyclone is expected to turn east-northeastward until its absorbed by a larger extratropical cyclone. The track guidance this cycle was a bit slower and touch further west early on, but ultimately the latest NHC track forecast ends up very close to the prior one after 24 h. 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 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 could bring wind, wave, and rain impacts to portions of southeastern Newfoundland Monday night 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 18/1500Z 36.1N 62.5W 60 KT 70 MPH 12H 19/0000Z 38.0N 61.5W 65 KT 75 MPH 24H 19/1200Z 41.1N 58.8W 70 KT 80 MPH 36H 20/0000Z 44.6N 53.7W 60 KT 70 MPH 48H 20/1200Z 48.0N 46.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 60H 21/0000Z 50.5N 35.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 21/1200Z 52.1N 23.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 22/1200Z...DISSIPATED $$ Forecaster Papin
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