[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 081455
TCDAT2

Tropical Storm Nicole Discussion Number   6
NWS National Hurricane Center Miami FL       AL172022
1000 AM EST Tue Nov 08 2022

Deep convection has developed and persisted near the center of
Nicole this morning and while there are still some characteristics
of a subtropical cyclone, the smaller radius of maximum winds and
improving inner-core convection suggest it has made the transition
to a tropical cyclone.  A NOAA reconnaissance aircraft has reported
that the pressure has fallen to around 992 mb, and has found
700-mb flight-level winds of 54 kt and believable SFMR winds of
40-42 kt. Based on those data, the initial intensity was raised to
45 kt at 1200 UTC, and is kept there for this advisory.

The anticipated westward turn appears to have occurred, and the
initial motion estimate is 280/8 kt. A strong deep-layer ridge
over the southeastern United States is expected to steer the storm
westward to west-southwestward during the next 24 to 36 hours.
This motion will bring the center of Nicole near the northwest
Bahamas on Wednesday.  After that time, the ridge is forecast to
shift eastward allowing Nicole to turn west-northwestward to
northwestward, as it approaches the east coast of Florida.
By 72 hours, Nicole is forecast to recurve over the southeastern
United States ahead of a mid-latitude trough.  Although there is
good agreement on this overall scenario, there is some increased
spread in the track guidance on exactly when Nicole makes the
west-northwestward turn near the east coast of Florida.  The
typically reliable GFS and ECMWF models are along the southern side
of the guidance envelope, while the regional hurricane models (HWRF
and HMON) are on the northern side.  Since the storm is likely near
the apex of its most northern point, it is worth noting the the
model trackers are noticeable north of the raw model fields.  In
fact, the GFS tracker is about 45-50 n mi north of its raw fields.
The NHC track is very close to the previous forecast, which is
along the southern side of dynamical model trackers and is closest
to the GFS ensemble mean. Until the guidance stabilizes, it is
prudent not to make any significant changes.

Nicole will be traversing relatively warm SSTs of 27-28 degrees
Celsius and upper-level conditions that are expected to allow for
steady strengthening during the approach to the northwestern
Bahamas and the east coast of Florida.  The NHC forecast calls for
Nicole to become a hurricane when it is near the northwest Bahamas
and remain a hurricane when it reaches Florida.  The NHC
intensity forecast is close to the various intensity consensus
aids.  Weakening is expected after Nicole moves inland over Florida
and while it accelerates northeastward over the southeastern United
States.  Although the system could still produce
tropical-storm-force winds over the adjacent offshore waters.
Nicole should be extratropical by late Friday, and most of the
global models show the circulation dissipating between days 4 and 5.


Key Messages:

1. Hurricane conditions and a dangerous storm surge are expected in
portions of the northwestern Bahamas on Wednesday, where a Hurricane
Warning is in effect.

2.  Hurricane conditions are expected across portions of the coast
of southeast and east-central Florida beginning late Wednesday or
Wednesday night, where a Hurricane Warning has been issued.
Tropical storm conditions are expected in the Tropical Storm Warning
areas in Florida and Georgia beginning early Wednesday.

3. A dangerous storm surge is expected along much of the east coast
of Florida and portions of coastal Georgia where a Storm Surge
Warning is in effect.  The storm surge will be accompanied by large
and damaging waves.  Residents in the warning area should listen to
advice given by local officials.

4. Do not focus on the exact track of Nicole since it is expected to
be a large storm with hazards extending well to the north of the
center, outside of the forecast cone. These hazards are likely to
affect much of the Florida peninsula and portions of the southeast
United States.

5. Nicole will produce heavy rainfall Wednesday and Thursday across
the Florida Peninsula. Flash and urban flooding will be likely with
possible river rises on the St. Johns River. Flash, urban and small
stream flooding will be possible in Southeast Georgia and portions
of South Carolina Thursday into Thursday night.


FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 27.8N  72.7W   45 KT  50 MPH
 12H  09/0000Z 27.3N  74.1W   50 KT  60 MPH
 24H  09/1200Z 26.8N  76.0W   60 KT  70 MPH
 36H  10/0000Z 27.0N  78.3W   65 KT  75 MPH
 48H  10/1200Z 28.1N  80.9W   60 KT  70 MPH...INLAND
 60H  11/0000Z 30.0N  83.1W   40 KT  45 MPH...INLAND
 72H  11/1200Z 32.7N  82.5W   35 KT  40 MPH...INLAND
 96H  12/1200Z 41.7N  73.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  13/1200Z...DISSIPATED

$$
Forecaster Brown
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