Official Discussion issued by the National Hurricane Center

Ernesto (AL052024) DATA RELEASED: 8/18/2024 3:00:00 PM UTC

Copy of official data

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