Official Discussion issued by the National Hurricane Center

Joyce (AL102018) DATA RELEASED: 9/14/2018 5:00:00 PM UTC

Copy of official data

Tropical Storm Joyce Discussion Number   9
NWS National Hurricane Center Miami FL       AL102018
500 PM AST Fri Sep 14 2018

Convection associated with Joyce has increased since the last
advisory, with a vigorous band now near the center in the northern
semicircle.  In response, satellite intensity estimates have edged
upward, and the initial intensity is increased to 40 kt as a blend
between the TAFB subjective Dvorak estimates and the CIMSS
satellite consensus.  The cyclone now has good cirrus outflow in
the northern semicircle as an upper-level low seen in water vapor
imagery passes south of the cyclone.

The storm is starting its forecast turn toward the east and the
initial motion is now 125/5.  As Tropical Storm Helene to the
east-northeast of Joyce moves away, Joyce is expected to turn
northeastward with an increase in forward speed during the next
24 h, followed by an eastward turn after 48 h.  The global models
continue to trend faster, and after 48 h there has been a southward
shift compared to the previous guidance.  Therefore, the new
forecast track will be notably faster than the previous track and
the 72 h point will be shifted southward.  The new track is still a
little to the north of the various consensus models.

Southwesterly upper-level winds are still forecast to increase over
the cyclone during the next day or two, and the forecast track takes
Joyce over decreasing sea surface temperatures.  This combination
should lead to a weakening trend, especially after 24 h.  The new
intensity forecast is adjusted upward a little from the previous
one based on the initial intensity, but it still calls for Joyce to
dissipate by 96 h in agreement with most of the global models.  It
is possible that Joyce could strengthen a little more during the
first 12 h while the upper-level low helps keep the stronger shear
away from the storm.


INIT  14/2100Z 31.4N  44.1W   40 KT  45 MPH
12H  15/0600Z 31.6N  43.1W   40 KT  45 MPH
24H  15/1800Z 32.6N  41.1W   40 KT  45 MPH
36H  16/0600Z 33.9N  38.7W   35 KT  40 MPH
48H  16/1800Z 35.0N  35.6W   30 KT  35 MPH
72H  17/1800Z 35.5N  28.5W   30 KT  35 MPH
96H  18/1800Z...DISSIPATED

Forecaster Beven