Official Discussion issued by the National Hurricane Center

Joyce (AL102018) DATA RELEASED: 9/15/2018 5:00:00 AM UTC

Copy of official data

Tropical Storm Joyce Discussion Number  11
NWS National Hurricane Center Miami FL       AL102018
500 AM AST Sat Sep 15 2018

There has not much change with Joyce overnight.  The tropical storm
is producing a fair amount of deep convection to the north and west
of the center, but there are some dry slots on the east side.  A
blend of the latest satellite intensity estimates supports holding
the initial wind speed at 45 kt.  Joyce is currently just east of an
upper-level trough and the flow aloft is quite diffluent near the
cyclone.  This upper-level pattern could allow Joyce to strengthen
slightly today.  However, by tonight, southwesterly flow aloft is
expected to increase over the cyclone.  This increase in shear
combined with decreasing mid-level humidities and cooling SSTs
should lead to a steady weakening trend after 12 hours.  The cyclone
is forecast to dissipate in 3 to 4 days, but some of the models
suggest that this could occur sooner.

The tropical storm is moving eastward at 7 kt.  Joyce is embedded
in the same trough as Helene and it should follow that tropical
cyclone east-northeastward to northeastward at increasing forward
speeds during the next day or two.  Beyond that time, if there
is anything left of Joyce, the system will likely turn back to the
east or east-southeast as it moves within the mid-latitude
westerlies.  The models are in fairly good agreement, and this
forecast lies close to the middle of the guidance envelope.


INIT  15/0900Z 31.9N  42.2W   45 KT  50 MPH
12H  15/1800Z 32.7N  40.6W   50 KT  60 MPH
24H  16/0600Z 33.9N  37.8W   45 KT  50 MPH
36H  16/1800Z 34.6N  34.1W   40 KT  45 MPH
48H  17/0600Z 34.7N  31.0W   35 KT  40 MPH
72H  18/0600Z 33.0N  26.5W   30 KT  35 MPH
96H  19/0600Z...DISSIPATED

Forecaster Cangialosi