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Potential Tropical Cyclone EIGHTEEN


Potential Tropical Cyclone Eighteen Discussion Number   2
NWS National Hurricane Center Miami FL       AL182017
1100 PM EDT Fri Oct 27 2017

Satellite imagery shows that the disturbance over the northwestern
Caribbean Sea is gradually becoming better organized with increasing
convective banding in the western semicircle. However, experimental
shortwave infrared data from GOES-16 appear to show the presence of
multiple low cloud swirls, and it is unclear if the definition of
the center has improved to the point where the system has become a
tropical cyclone.  Thus, the disturbance remains a potential
tropical cyclone at this time.  There are no recent observations of
the winds near the center, so the initial intensity remains 35 kt
based on continuity from the previous advisory.

The initial motion is an uncertain 005/6.  A deep-layer trough and
developing frontal low over the northeastern United States are
expected to cause the disturbance to turn northeastward and
accelerate during the next 24 h, with a fast motion toward the
northeast continuing until the disturbance is absorbed by the
mid-latitude system.  The track guidance is generally in good
agreement with this scenario, although there remains some
cross-track spread due mainly to the uncertain center position.
The new forecast track is similar to the previous track and is in
best agreement with the HFIP Corrected Consensus model.

Environmental conditions appear at least somewhat favorable for
intensification during the next 48 h, with light to moderate shear
and strong upper-level divergence over the system.  After that
time, the system is expected to be absorbed into the aforementioned
mid-latitude system and become a trough rotating around the larger
circulation.  The new intensity forecast is nudged upward slightly
from the previous forecast and now shows a peak intensity of 50 kt
before absorption. However, the forecast lies at the lower edge of
the intensity guidance, and if the system can develop a better-
defined inner core it could strengthen more than currently forecast.


INIT  28/0300Z 18.2N  84.4W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  28/1200Z 20.1N  83.4W   40 KT  45 MPH
 24H  29/0000Z 22.9N  81.1W   45 KT  50 MPH...INLAND
 36H  29/1200Z 26.2N  77.4W   45 KT  50 MPH...OVER WATER
 48H  30/0000Z 30.8N  73.0W   50 KT  60 MPH

Forecaster Beven