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Tropical Storm Joyce Discussion Number  10
NWS National Hurricane Center Miami FL       AL102018
1100 PM AST Fri Sep 14 2018

Joyce continues to look better organized on GOES-16 satellite
imagery and the convective canopy has expanded. However, recent
microwave data reveals that the cyclone is still tilted to the
northeast due to nearly strong southwesterly wind shear. The most
recent TAFB and SAB Dvorak classifications support raising the
initial intensity to 45 kt. Despite the shear, most of the intensity
guidance shows very slight strengthening over the next 12 to 24
hours, and the NHC intensity forecast is a little higher than the
previous advisory at most forecast times. Persistent shear and
decreasing SSTs along the forecast track should cause Joyce to
weaken beyond that time, likely dissipating entirely shortly after
72 h.  A few models, most notably the HWRF and UKMET, persist the
cyclone a little beyond that, but only as a remnant low.

The storm has turned east as expected, and the initial motion is now
090/5 kt. As the larger Helene begins to accelerate away, a
mid-latitude trough over the central Atlantic should cause Joyce to
turn northeastward and speed up. A turn back toward the east, or
possibly even east-southeast is possible by the end of the forecast
period as Joyce weakens and follows the northern periphery of a
subtropical high over eastern Atlantic.  Very little change has been
made to the track forecast through 48 h, but it has been adjusted to
the south at 72 h, following the latest consensus guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 31.6N  43.6W   45 KT  50 MPH
 12H  15/1200Z 32.2N  42.1W   50 KT  60 MPH
 24H  16/0000Z 33.2N  39.8W   50 KT  60 MPH
 36H  16/1200Z 34.4N  37.1W   45 KT  50 MPH
 48H  17/0000Z 35.1N  33.6W   40 KT  45 MPH
 72H  18/0000Z 34.0N  28.4W   35 KT  40 MPH
 96H  19/0000Z...DISSIPATED

$$
Forecaster Zelinsky

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