Tropical Storm FIONA Advisory 9月14日

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Tropical Depression Seven Discussion Number   1
NWS National Hurricane Center Miami FL       AL072022
1100 AM AST Wed Sep 14 2022

Visible satellite imagery shows that the circulation associated
with the area of low pressure in the tropical Atlantic has become
better defined.  The associated convection has persisted overnight
and this morning, and although it is confined to the eastern
portion of the circulation it has enough organization to classify
the system as a tropical depression.  The initial intensity is set
at 30 kt, which is a little above the latest TAFB Dvorak
classification of T1.5, but in line with overnight scatterometer
data.

Moderate westerly shear and a dry mid-level atmosphere are expected
to prevent significant intensification, but some modest
strengthening is possible over the next day or two, and the NHC
forecast calls for the depression to become a tropical storm tonight
or Thursday. After the system moves into the eastern Caribbean, the
westerly shear is forecast to increase somewhat and the global
models suggest that the system could struggle to maintain its
closed circulation after that time.  The NHC intensity forecast is
a little above the IVCN intensity forecast, and maintains the
system as a tropical cyclone through the forecast period.  Weakening
is indicated by day 5 when the system is forecast to interact with
Hispaniola.

The depression is moving westward or 280/12 kt.  The cyclone is
forecast to move slightly north of due westward along the south
side of a low to mid-level ridge that is anchored over the central
and western Atlantic.  Although the track guidance is tightly
clustered, there are some differences in forward speed with the
ECMWF much faster than the GFS.  The NHC forecast lies near the
middle of the guidance envelope and is near the TVCA and GFEX
consensus aids to account for the differences in the forward speed.

Key Messages:

1.  The system is expected to move through the Leeward Islands on
Friday or Friday night, bringing heavy rainfall and possible wind
impacts. Interests in the Leeward Islands should monitor the
progress of the depression as tropical storm watches could be
required for some islands later today.

2.  The system could move near or over portions of the Virgin
Islands, Puerto Rico, and Hispaniola this weekend and early next
week, potentially bringing heavy rainfall and some wind impacts to
these areas, and interests there should monitor the progress of the
depression.


FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 16.6N  49.6W   30 KT  35 MPH
 12H  15/0000Z 16.7N  51.5W   35 KT  40 MPH
 24H  15/1200Z 16.8N  53.9W   40 KT  45 MPH
 36H  16/0000Z 16.9N  56.5W   40 KT  45 MPH
 48H  16/1200Z 17.0N  59.3W   40 KT  45 MPH
 60H  17/0000Z 17.1N  62.0W   40 KT  45 MPH
 72H  17/1200Z 17.4N  64.6W   40 KT  45 MPH
 96H  18/1200Z 18.0N  68.5W   40 KT  45 MPH
120H  19/1200Z 19.1N  71.7W   30 KT  35 MPH...INLAND

$$
Forecaster Brown