Hurricane Ernesto Discussion Number  23
NWS National Hurricane Center Miami FL       AL052024
500 AM AST Sat Aug 17 2024

Satellite and surface observations indicate that the center of 
Ernesto made landfall on the western side of Bermuda at about 430 AM 
AST, with the National Museum of Bermuda recently reporting light 
winds and a central pressure of 972 mb.  The system overall has 
become less organized as drier air has infiltrated much of the 
circulation's southern semicircle.  Earlier aircraft reconnaissance 
data supported 75-80 kt as an initial intensity, and with the 
degradation in the satellite imagery, 75 kt is chosen as the current 
intensity (and operational landfall intensity).  The Air Force 
Hurricane Hunters should be out again in a few hours to sample the 
cyclone.

While the current moderate shear is forecast to weaken today, it 
will take some time for the vortex to recover from the dry air as 
it moves across warm waters north of Bermuda.  Thus little change in
intensity is anticipated in the short term, and re-strengthening
could begin tomorrow.  This should be a fairly short-lived window,
however, since Ernesto will be crossing the north wall of the Gulf
Stream on Monday while moving into a strong wind shear environment.
Therefore, steady weakening is forecast for the work week, and
Ernesto is expected to complete extratropical transition near or
just east of Newfoundland. The NHC intensity forecast is largely
an update of the previous one, a bit lower in the short-term to
account for recent guidance.

Ernesto has turned more to the north-northeast overnight and slowed
down to about 8 kt.  The motion should creep in that direction today
as the hurricane is stuck in an area of lighter steering currents,
waiting for the next trough to move off the U.S. East coast.  This
slow motion and Ernesto's large size will cause a long duration of
impacts through tonight on Bermuda.  The trough should force the
cyclone to accelerate northeastward later in the weekend and early
next week, taking Ernesto near Newfoundland Monday night.  The
guidance is again slower than the previous cycle, so the NHC track
forecast is trended in that direction. Global model fields depict
that Ernesto should open into a trough, or become absorbed in a
larger polar low by 120 h over the northern Atlantic ocean, thus the
NHC forecast now shows the system dissipated at that time.

Key Messages:

1. Ernesto is expected to bring periods of strong winds, storm
surge and battering waves on Bermuda through tonight.  A hurricane
warning is in effect for the island, and residents there should
listen to orders from local officials.

2. Heavy rainfall from Ernesto will continue to impact Bermuda
through tonight and will likely result in considerable life-
threatening flash flooding, especially in low-lying areas on the
island.

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 Bahamas, Bermuda, and Atlantic Canada
during the next few days.

4. Interests in Atlantic Canada should monitor the progress of
Ernesto.


FORECAST POSITIONS AND MAX WINDS

INIT  17/0900Z 32.3N  64.8W   75 KT  85 MPH
12H  17/1800Z 33.3N  64.4W   70 KT  80 MPH
24H  18/0600Z 34.6N  63.9W   70 KT  80 MPH
36H  18/1800Z 36.6N  62.9W   75 KT  85 MPH
48H  19/0600Z 39.8N  61.2W   80 KT  90 MPH
60H  19/1800Z 43.5N  57.5W   70 KT  80 MPH
72H  20/0600Z 47.0N  51.5W   60 KT  70 MPH...POST-TROPICAL
96H  21/0600Z 51.5N  32.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  22/0600Z...DISSIPATED

$$
Forecaster Blake