[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 120236
TCDAT5

HURRICANE NICOLE DISCUSSION NUMBER  32
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152016
1100 PM AST TUE OCT 11 2016

Nicole's cloud pattern was quite impressive after the release of the
previous advisory, with a distinct eye surrounded by a ring of cloud
tops of around -70C.  However, by 00Z the eye was no longer apparent
in geostationary imagery, and the Dvorak classifications from TAFB
and SAB were T4.5/77 kt.  The eye has reappeared recently, but the
convective tops are a bit more ragged.  The initial intensity is set
to 80 kt, between the subjective Dvorak estimates and the latest
UW-CIMSS ADT of around 90 kt.

Environmental conditions appear conducive for some additional
strengthening in the next 24 hours or so, with the cyclone over
28-29C waters and the shear 15 kt or less.  The NHC intensity
forecast is similar to the previous one during this time and is
above the consensus. The SHIPS model shows southwesterly shear
increasing to 45-50 kt by 48 hours, which should result in some
weakening. Nicole will interact with an upper-level trough in 3-4
days, but global model fields and the FSU phase space diagrams
suggest that Nicole won't complete extratropical transition when it
is left behind by the progressive trough by day 5. Therefore,
the NHC forecast shows Nicole as post-tropical at days 4 and 5, but
baroclinic forcing is expected to keep cyclone near hurricane
intensity through the end of the forecast period.

Nicole has moved little during the past few hours, as the cyclone is
caught in a region of weak steering currents.  In fact, a slow
looping motion has been noted since the previous advisory, and the
best estimate of the initial motion is a westward drift at around 2
kt. The synoptic reasoning has not changed, as Nicole is expected to
gradually recurve into the mid-latitude westerlies in the next 48
hours and then turn east-northeastward ahead of an upper-level
trough moving off the U.S. east coast. By the end of the period, the
trough leaves Nicole behind to the south of a ridge centered over
the Davis Strait, which should result in a slow southeastward drift
at day 5. The NHC track has been shifted a little to the right of
the previous one and is a little slower during the first 36-48
hours, bringing Nicole near or over Bermuda. Late in the period, a
larger rightward shift was made to the NHC track. The new official
forecast remains near the middle of the guidance envelope and is
close to the latest multi-model consensus aid TVCN.

FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 27.3N  66.6W   80 KT  90 MPH
 12H  12/1200Z 28.2N  66.9W   85 KT 100 MPH
 24H  13/0000Z 29.6N  66.8W   90 KT 105 MPH
 36H  13/1200Z 31.5N  65.7W   90 KT 105 MPH
 48H  14/0000Z 33.9N  63.3W   85 KT 100 MPH
 72H  15/0000Z 38.5N  56.5W   80 KT  90 MPH
 96H  16/0000Z 40.5N  52.0W   70 KT  80 MPH...POST-TROPICAL
120H  17/0000Z 40.0N  51.5W   65 KT  75 MPH...POST-TROPICAL

$$
Forecaster Brennan
This weather bulletin was brought to you by:
www.nashvilleweather.net