[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 110237
TCDAT5

TROPICAL STORM NICOLE DISCUSSION NUMBER  28
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152016
1100 PM AST MON OCT 10 2016

The vertical wind shear that has been hampering the development of
Nicole has diminished during the past 6-12 hours.  In response, the
cyclone's convective pattern has become better organized and now is
comprised of a curved band over the eastern semicircle.  Satellite
intensity estimates have not changed significantly since the last
advisory, so the initial intensity remains 50 kt.

The initial motion is now 350/5.  During the next 12-24 hours, a
mid-latitude shortwave trough currently seen in water vapor
imagery north of Nicole is going to move eastward with a shortwave
ridge taking its place north of the tropical cyclone.  This should
cause Nicole to turn northwestward for a time.  After that, the
ridge moves eastward in advance of a second mid-latitude trough
moving eastward from the United States.  This evolution should lead
to Nicole turning northward and then northeastward with an increase
in forward speed as it recurves into the westerlies.  The forward
motion may slow near the 120 hour time as Nicole becomes a large
cut-off extratropical low over the northern Atlantic.  The track
guidance is in good agreement with this scenario, and the new track
forecast is essentially an update of the previous track. The new
forecast has the center of Nicole passing near or over Bermuda
between 48 and 72 hours.

Nicole is forecast to be in a light shear environment over
increasing sea surface temperatures for the next 36-48 hours, and at
the moment none of the low-level cooler air brought southward in the
wake of Post-Tropical Cyclone Matthew is entraining into the
system. However, water vapor imagery shows a lot of dry air just
northwest of the tropical cyclone, and this could slow
intensification in an otherwise favorable environment.  After 48
hours, Nicole is likely to weaken due to increasing shear, although
the dynamical models forecast increasing values of upper-level
divergence that should slow the weakening. Extratropical transition
is expected to occur at about 120 hours. The new intensity forecast
is almost the same as the previous forecast and lies near the upper
edge of the intensity guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  11/0300Z 26.8N  65.5W   50 KT  60 MPH
 12H  11/1200Z 27.4N  66.0W   55 KT  65 MPH
 24H  12/0000Z 28.0N  66.6W   65 KT  75 MPH
 36H  12/1200Z 28.9N  66.8W   70 KT  80 MPH
 48H  13/0000Z 30.5N  66.3W   80 KT  90 MPH
 72H  14/0000Z 34.5N  63.0W   80 KT  90 MPH
 96H  15/0000Z 39.5N  57.0W   75 KT  85 MPH
120H  16/0000Z 42.0N  53.5W   70 KT  80 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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