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.