Hurricane Ernesto Discussion Number  18
NWS National Hurricane Center Miami FL       AL052024
1100 PM AST Thu Aug 15 2024

Ernesto has been strengthening this evening.  Data from an Air
Force Hurricane Hunter aircraft indicate that the minimum pressure
has fallen to about 968 mb, and a blend of the peak flight-level
and SFMR winds support increasing the initial intensity to 85 kt.
This makes Ernesto a category 2 hurricane on the Saffir-Simpson
Hurricane Wind Scale.  Ernesto has a ragged eye and a large wind
field, with the highest winds occurring in the northeast quadrant.

Ernesto is moving north-northeastward at 12 kt in the flow between
a high pressure system over the central Atlantic and a large-scale
trough off the U.S. east coast.  This general motion is expected to
continue for the next day or two, bringing the hurricane near or
over Bermuda on Saturday.  Around that time, the trough is expected
to lift out, leaving Ernesto in weaker steering currents.  As a
result, a slower and likely more erratic motion to the north or
north-northeast is forecast over the weekend.  Another trough is
expected to approach the cyclone late in the weekend, and that
should cause an accelerated motion to the northeast near or east of
Atlantic Canada early next week.  The NHC track forecast is a touch
to the east and a little slower than the previous one through its
passage near Bermuda to come into better agreement with the latest
consensus aids.

It seems likely that Ernesto will strengthen some more during the
next 12 to 24 hours as it is expected to remain in conducive
environmental conditions of low wind shear, upper-level diffluence,
a relatively moist airmass, and over warm waters during that time.
Thereafter, increasing vertical wind shear and gradually cooler
waters should cause a slow weakening trend.  However, baroclinic
influences could offset some of the weakening, which is why the
official forecast shows little change in strength during the 48- to
72-hour time frame.  Ernesto is forecast to complete extratropical
transition by day 5, when it will likely be embedded within the
mid-latitude westerlies.  The NHC intensity forecast lies near the
high end of the guidance, in best agreement with the HCCA model.


Key Messages:

1. Ernesto is moving toward Bermuda, and it is expected to bring a 
prolonged period of strong winds and storm surge on Bermuda from 
Friday afternoon through Saturday night. A hurricane warning is in 
effect for the island, and preparations to protect life and property 
should be rushed to completion.

2. Rainfall associated with Ernesto is expected to begin to affect
Bermuda overnight and may result in flash flooding Friday through
this weekend.

3. Even though Ernesto is forecast to remain well offshore the U.S.
East Coast, swells generated by the hurricane are expected to affect
the area through the weekend.  Beach goers should be aware of a
significant risk of life-threatening surf and rip currents, and stay
out of the water if advised by lifeguards.  Surf and rip currents
are also possible on the Turks and Caicos, the Bahamas, Bermuda,
and Atlantic Canada during the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 27.1N  68.1W   85 KT 100 MPH
12H  16/1200Z 28.5N  67.1W   95 KT 110 MPH
24H  17/0000Z 30.4N  65.9W   95 KT 110 MPH
36H  17/1200Z 32.1N  65.1W   85 KT 100 MPH
48H  18/0000Z 33.5N  64.8W   80 KT  90 MPH
60H  18/1200Z 35.4N  64.1W   80 KT  90 MPH
72H  19/0000Z 38.2N  62.6W   80 KT  90 MPH
96H  20/0000Z 45.6N  54.6W   70 KT  80 MPH
120H  21/0000Z 51.0N  36.7W   50 KT  60 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi