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Tropical Depression Joyce Discussion Number  18
NWS National Hurricane Center Miami FL       AL102018
1100 PM AST Sun Sep 16 2018

Joyce is managing to maintain tropical cyclone status despite very
strong westerly vertical wind shear.  The system still displays cold
cloud tops, but only within the northeast quadrant and at least
100 nm from the center.  The shear is being induced primarily by
50-kt 200 mb winds.  Usually such strong vertical shear would
completely decapitate a tropical cyclone.  However, systems in
higher latitudes and moving in the same direction as the shear
vector tend to be somewhat more resilient to the detrimental
effects of the shear.  Nonetheless, it is anticipated that Joyce
will soon succumb to the combination of high shear, cool waters,
and dry mid-levels, and become a remnant low within 48 hours, if not
sooner.  The official intensity forecast shows a gradual weakening,
nearly the same as the previous advisory and based upon a blend of
the LGEM statistical scheme and the HWRF/HMON dynamical models.

Joyce is moving toward the east at a quick 18-kt clip.  The system
has not been picked up by the mid-latitude westerlies and is
expected to be advected around the lower tropospheric Bermuda-Azores
high. Joyce should slow its forward speed and turn toward the
southeast (on Monday), the south (on Tuesday), and finally the
southwest (on Wednesday) before dissipating in about four days.  The
track forecast is based upon the tightly clustered TVCN multi-model
consensus and is slightly farther east because of the quicker
eastward initial motion than previously observed.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 34.0N  30.3W   30 KT  35 MPH
 12H  17/1200Z 33.7N  27.9W   30 KT  35 MPH
 24H  18/0000Z 32.8N  26.5W   30 KT  35 MPH
 36H  18/1200Z 31.7N  26.3W   25 KT  30 MPH
 48H  19/0000Z 30.5N  27.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  20/0000Z 28.9N  29.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  21/0000Z...DISSIPATED

$$
Forecaster Landsea

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