Tropical Storm Ernesto Discussion Number 7
NWS National Hurricane Center Miami FL AL052018
500 PM AST Thu Aug 16 2018
Visible and infrared satellite imagery shows that convective
banding has increased closer to the center of Ernesto today. The
system has also lost much of its outer cloud bands and is no longer
co-located with an upper-level low. On this basis, Ernesto is now
being classified as a tropical storm. The initial intensity remains
40 kt, which is based on recent satellite estimates and the earlier
ASCAT data. Although the cyclone is forecast to move over cooler
waters and become post-tropical very soon, the global models deepen
the system somewhat due to baroclinic processes. In addition, the
expected increase in the cyclone's forward speed is likely to result
in an increase in the wind speed. The new NHC intensity forecast
calls for slight strengthening over the next 12-24 hours, with
little overall change in intensity thereafter. The system is still
predicted to merge with a frontal zone as it approaches Ireland and
the United Kingdom late Saturday or Saturday night.
Ernesto continues to accelerate northeastward and is now moving
045/16 kt. The cyclone should accelerate further while moving
northeastward to east-northeastward within the mid-latitude
westerlies over the next day or two. The dynamical model guidance
remains tightly clustered and little change was made to the
previous NHC track forecast.
Subtropical Storm Ernesto Discussion Number 2...Corrected
NWS National Hurricane Center Miami FL AL052018
1100 AM AST Wed Aug 15 2018
Convection associated with the subtropical cyclone became better
organized after the release of the previous advisory, but
cloud tops have warmed recently with the convection becoming
somewhat fragmented. An Hebert-Poteat subtropical classification of
T2.5 from TAFB suggests that they system is producing gale-force
winds, and recent scatterometer data that passed over the far
eastern portion of the circulation revealed 30-kt winds. Since the
instrument missed the radius of maximum winds, it is assumed that
stronger winds exist over the eastern portion of the circulation,
and the initial intensity is increased to 35 kt, making the system
a subtropical storm.
Ernesto has about 24 hours over marginally warm SSTs and in a low-
shear environment in which to strengthen. After that time, the
cyclone will be moving over much colder water which should cause it
to become post-tropical within 48 hours. The post-tropical cyclone
is forecast to merge with a frontal zone associated with a larger
extratropical cyclone over the North Atlantic in 3 to 4 days.
The cyclone is moving northward at about 6 kt. A mid-level trough
that is moving off the east coast of the United States should cause
Ernesto to turn north-northeastward later today, and the cyclone is
forecast to accelerate northeastward by late Thursday as it becomes
embedded within the mid-latitude westerlies. The dynamical model
guidance continues to be in good agreement, and the new NHC track
forecast remains in the middle of the guidance envelope.
1. A non-tropical low pressure system located about 700 miles south
of Cape Race, Newfoundland, is producing a large area of cloudiness
and disorganized thunderstorms mainly to the east of the center.
Environmental conditions are forecast to become a somewhat more
conducive for some subtropical or tropical development by Wednesday.
The system is forecast to move northeastward over the colder waters
of the North Atlantic by late Thursday or Friday, which should limit
any additional development.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...40 percent.
組圖打開中，請稍候......