[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 080839
TCDAT5

TROPICAL STORM NICOLE DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152016
500 AM AST SAT OCT 08 2016

Nicole's structure has changed dramatically just within the past
six hours due to about 45 kt of northerly shear.  The deep
convection is now oriented linearly from east to west and is
displaced more than 100 n mi to the south of the exposed low-level
center.  Dvorak Current Intensity numbers have dropped to 3.0 from
TAFB, SAB, and the UW-CIMSS ADT, and Nicole's initial intensity is
lowered to 45 kt.

Deep-layer northerly flow continues to push Nicole southward, and
the initial motion is estimated to be 190/6 kt.  The winds on the
west side of a mid-level low should continue forcing Nicole
generally southward for the next 24-36 hours until these two
systems become collocated with one another.  After 36 hours, Nicole
is expected to be steered back toward the north, ahead of Hurricane
Matthew's remnant mid-level circulation.  There are some
differences among the track models associated with exactly how
the interaction between Nicole and Matthew will play out.  The
notable outlier is the ECMWF model, which swings Nicole
northwestward and then westward around the north side of Matthew
after 48 hours.  In deference to this model, the new NHC track
forecast is a little west and slower than the previous forecast,
and it lies very close to an average of the GFS and ECMWF models.

The vertical shear affecting Nicole is expected to remain high for
several more days, possibly not dropping below 20 kt until after 72
hours.  Still, sea surface temperatures will remain between 29 and
30C, so Nicole may be able to continue producing bursts of deep
convection that will prevent its intensity from decreasing much.
Some restrengthening at the end of the forecast period is possible,
although trends are suggesting that the shear may once again
increase by day 5.  Based on the latest guidance, the official
intensity forecast is lowered by 5 kt for much of the forecast
period.  If the shear wins out, however, then Nicole's intensity
could end up being lower than shown in the forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  08/0900Z 25.9N  65.6W   45 KT  50 MPH
 12H  08/1800Z 25.2N  65.6W   45 KT  50 MPH
 24H  09/0600Z 24.7N  65.6W   40 KT  45 MPH
 36H  09/1800Z 24.8N  65.7W   40 KT  45 MPH
 48H  10/0600Z 25.4N  65.9W   40 KT  45 MPH
 72H  11/0600Z 28.0N  66.5W   40 KT  45 MPH
 96H  12/0600Z 30.0N  67.5W   45 KT  50 MPH
120H  13/0600Z 32.5N  66.0W   50 KT  60 MPH

$$
Forecaster Berg

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