Official Discussion issued by the National Hurricane Center

Ernesto (AL052024) DATA RELEASED: 8/19/2024 9:00:00 AM UTC

Copy of official data

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