[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 151459
TCDAT5

HURRICANE NICOLE DISCUSSION NUMBER  46
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152016
1100 AM AST SAT OCT 15 2016

Nicole has intensified since the last advisory, likely due to
baroclinic influences from a nearby upper-level trough.
Just-received ASCAT-B data shows 70-75 kt winds to the southwest of
the center, and a drifting buoy south of the center reported a
pressure 966.6 mb at 1000 UTC, suggesting a falling
central pressure.  Based on these data, the intensity is increased
to 75 kt.  It should be noted that the cloud pattern has some
characteristics of a subtropical cyclone due to the cyclone's
interaction with the upper-level trough.

The GFS and the ECMWF continue to forecast organized central
convection for the next 48 hours or so, indicating that Nicole is
likely to maintain tropical cyclone characteristics despite cooler
air entraining into the circulation. After that time, the cyclone
should move over sea surface temperatures of 16 deg C or less that
should cause the central convection to dissipate. Based on this, the
intensity forecast calls for Nicole to become post-tropical by 72
hours and then fully extratropical by 96 hours. The new intensity
forecast is adjusted upward for the first 12 hours based on the
current intensity, and after that it is an update of the previous
forecast.  Overall, the forecast lies near the upper end of the
intensity guidance.

Nicole appears to be slowing its forward motion, and the motion
estimate is now 075/11.  A slow easterly motion is expected during
the next 36 hours or so while the cyclone is an area of weaker flow
in the mid-latitude westerlies.  After that time, a large
mid-latitude trough moving into eastern Canada should steer the
cyclone north-northeastward with an increase in forward speed.  The
new forecast track is again similar to the previous track and lies
near the various consensus models.

Guidance from the NOAA Ocean Prediction Center was used for the
forecast wind radii.

Swells from Nicole will affect Bermuda and portions of the U.S. east
coast and Atlantic Canada during the next couple of days.  By early
next week, wave models suggest that long-period swell from Nicole
will radiate outward and affect much of the North Atlantic basin.


FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 39.0N  50.3W   75 KT  85 MPH
 12H  16/0000Z 39.3N  48.4W   75 KT  85 MPH
 24H  16/1200Z 39.4N  47.0W   70 KT  80 MPH
 36H  17/0000Z 39.8N  45.8W   65 KT  75 MPH
 48H  17/1200Z 41.1N  44.3W   65 KT  75 MPH
 72H  18/1200Z 47.5N  39.5W   65 KT  75 MPH...POST-TROPICAL
 96H  19/1200Z 56.5N  35.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
120H  20/1200Z 64.5N  32.0W   50 KT  60 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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