[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 130301
TCDAT5

HURRICANE NICOLE DISCUSSION NUMBER  36
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL152016
1100 PM AST WED OCT 12 2016

Nicole's satellite presentation has improved, with a warm, distinct,
30 n mi wide eye surrounded by cloud tops of -70C. The large eye is
also now visible on the Bermuda radar. An Air Force Reserve
Hurricane Hunter aircraft just measured a 700-mb wind of 119 kt
and a peak SFMR wind of 118 kt. Based on these data, the initial
intensity is set to 115 kt for this advisory. The latest
extrapolated minimum pressure from the aircraft is around 950 mb, a
decrease of 20 mb since this morning. The aircraft data also showed
an expansion of the hurricane force wind field in the northwest and
southeast quadrants.

The shear is expected to increase quickly, reaching 25-30 kt by 12 h
and 45-50 kt by 36 hours. This increase in shear and a gradual
decrease in SSTs should result in some weakening in the first 36
to 48 hours, but baroclinic forcing from a mid-latitude shortwave
trough should maintain Nicole as a powerful cyclone through the
forecast period. The amount of tropical characteristics Nicole will
have late in the forecast period remains uncertain, as the cyclone
will not undergo a classical extratropical transition. Post-tropical
status is shown at days 3 through 5, but confidence in this part of
the forecast remains low. The NHC intensity forecast is close to the
latest intensity consensus through 48 hours and is based on global
models after that time.

The initial motion estimate is 020/10, as Nicole is beginning to
recurve into the mid-latitude flow ahead of a broad longwave trough
moving offshore of the U.S. east coast. This synoptic pattern
should result in Nicole accelerating northeastward and then
east-northwestward in the next 24 to 48 hours. After 72 hours, the
trough moves away from Nicole, and leaves the cyclone meandering in
a region of weak steering currents to the south of a high-latitude
ridge, and only a a slow eastward to northeastward drift is expected
at days 4 and 5. The new NHC track forecast is an update of the
previous one through 24 hours, and continues to take the core of
Nicole near or over Bermuda on Thursday. After 24 hours, the new
NHC track has been shifted a bit to the right, and lies to the right
of the multi-model consensus, favoring a blend of the global models
and their ensemble means.

The forecast at days 3 through 5 has been coordinated with the NOAA
Ocean Prediction Center.

Note that while hurricanes often affect Bermuda, a hurricane this
strong is rare. There have only been seven major hurricanes that
have passed within 40 n mi of Bermuda in the Atlantic hurricane
database, which goes back to 1851.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 30.1N  66.4W  115 KT 130 MPH
 12H  13/1200Z 31.6N  65.3W  105 KT 120 MPH
 24H  14/0000Z 33.8N  62.7W   90 KT 105 MPH
 36H  14/1200Z 35.7N  59.0W   80 KT  90 MPH
 48H  15/0000Z 37.3N  55.0W   75 KT  85 MPH
 72H  16/0000Z 38.5N  50.5W   75 KT  85 MPH...POST-TROPICAL
 96H  17/0000Z 38.5N  50.0W   65 KT  75 MPH...POST-TROPICAL
120H  18/0000Z 40.0N  49.0W   65 KT  75 MPH...POST-TROPICAL

$$
Forecaster Brennan
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