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Tropical Storm Joyce Discussion Number  13
NWS National Hurricane Center Miami FL       AL102018
500 PM AST Sat Sep 15 2018

The circulation of Joyce is elongated this afternoon, with the
center partially exposed.  It has been interesting to watch deep
convection firing in the northeastern quadrant, kicking off new
small swirls that rotate around the mean circulation.  A blend of
the Dvorak estimates from TAFB/SAB supports keeping the wind speed
40 kt on this advisory.

There is no change to the intensity forecast reasoning.  The
environment is predicted to be nearly steady-state around Joyce
through Sunday, with strong shear being offset by waters near 27C.
Thereafter, as the hostile shear continues, the mid-level air should
become drier near the center, and SSTs cool off below 26C.  These
conditions should cause Joyce to slowly weaken early next week, and
dissipate in 3 days or so.  This forecast is basically the same as
the previous one, but it isn't out of the realm of possibility the
cyclone could open up into a trough before that time.

Joyce continues to accelerate, now moving east-northeastward at
about 15 kt.  The storm remains embedded within the same trough as
Tropical Storm Helene, and Joyce should move east-northeastward
during the next day or so.  Beyond that time, as Joyce becomes a
shallow cyclone, it is forecast to turn southeastward due to
low-level flow around the eastern side of a building ridge over the
central Atlantic Ocean.  The track forecast is simply an update to
the previous one, and continues to be on the southern side of the
guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 33.1N  39.6W   40 KT  45 MPH
 12H  16/0600Z 34.1N  37.2W   40 KT  45 MPH
 24H  16/1800Z 34.8N  33.8W   40 KT  45 MPH
 36H  17/0600Z 34.8N  30.5W   35 KT  40 MPH
 48H  17/1800Z 34.0N  28.0W   30 KT  35 MPH
 72H  18/1800Z 31.5N  26.5W   25 KT  30 MPH
 96H  19/1800Z...DISSIPATED

$$
Forecaster Blake

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