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Subtropical Storm Nicole Forecast Discussion


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WTNT42 KNHC 072057
TCDAT2

Subtropical Storm Nicole Discussion Number   3
NWS National Hurricane Center Miami FL       AL172022
400 PM EST Mon Nov 07 2022

Nicole's structure has changed little today. There is some limited
convective activity near the center with a large band of showers and
thunderstorms extending well north and east over the southwestern
Atlantic.  An Air Force Reserve reconnaissance aircraft that has
been investigating the system this afternoon and has found
flight-level and SFMR winds supporting tropical storm strength about
80 n mi northwest of the center, but earlier scatterometer data
indicated that the strongest winds are likely occurring in the band
well removed from the center.  The aircraft reported that the
pressure is down to around 1000 mb.  The initial intensity is
maintained at 40 kt and is based on a blend of the aircraft and
earlier satellite wind data.

Nicole is moving northwestward or 310/8 kt.  A northwestward
motion is expected to continue overnight as the storm moves around
the northeastern portion of a decaying upper-level low. On Tuesday,
Nicole is forecast to turn westward or west-southwestward as a
strong mid-level ridge amplifies over the eastern United States.
This motion should bring the center of Nicole near or over the
northwestern Bahamas on Wednesday.  After that time, the ridge is
forecast to shift eastward, which should allow Nicole to turn
west-northwestward or northwestward as it approaches and then moves
over the Florida Peninsula. Later in the period, a large
mid-latitude trough moving into the central United States is
expected to cause Nicole to recurve northeastward. The track
guidance is in good agreement during the first few days of the
forecast period, and the confidence in this portion of the track
forecast is relatively high.  The new NHC track foreast is similar
to the previous advisory through 72 hours, but shows a track
slightly farther inland along the southeast U.S. coast on day 4.
There is increasing along-track spread after 72 hours, with the
GFS and UKMET slower than the latest ECMWF. The NHC forecast is
near the multi-model consensus aids at those times.

Nicole's sprawling structure and nearby dry mid-level air suggest
that it will take some time for the cyclone to begin strengthening.
Warm ocean temperatures that Nicole will be traversing should
allow for a gradual increase in convection near the center, and
this combined with low vertical wind shear, is expected to result in
gradual moistening of the environment around Nicole.  Most of the
dynamical models indicate that Nicole will be able to develop a
smaller inner core and transition into a tropical cyclone in 24
to 36 hours, and once that occurs, a faster rate of intensification
is anticipated. The latest NHC intensity prediction is similar to
the previous advisory and calls for the system to be at or near
hurricane strength when it passes near or over the northwest
Bahamas and reaches the east coast of Florida. The official wind
speed forecast is closest to the HFIP corrected consensus, and
near the most recent dynamical hurricane models.  Regardless of
Nicole's exact intensity, the storm's large size due to an enhanced
pressure gradient north of the storm will likely cause significant
wind, storm surge, and rainfall impacts over a large portion of the
northwestern Bahamas, Florida, and the southeastern coast of the
United States during the next few days.

Key Messages:

1.  Hurricane conditions and a dangerous storm surge are expected in
portions of the northwestern Bahamas beginning Tuesday night, where
a Hurricane Warning has been issued.

2.  Hurricane conditions are possible across portions of the coast
of southeast and east-central Florida beginning late Wednesday,
where a Hurricane Watch is in effect.  Tropical storm conditions
are possible in the Tropical Storm Watch areas in Florida and
Georgia beginning by early Wednesday.

3. A dangerous storm surge is possible across much of the east coast
of Florida and portions of coastal Georgia.  The storm surge will be
accompanied by large and damaging waves.

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
U.S.

5. Nicole will produce heavy rainfall by Wednesday night and
Thursday across the Florida Peninsula. Flash and urban flooding will
be possible along with river rises on portions of the St. Johns
River.


FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 26.6N  70.6W   40 KT  45 MPH...SUBTROPICAL STORM
 12H  08/0600Z 27.3N  71.5W   40 KT  45 MPH...SUBTROPICAL STORM
 24H  08/1800Z 27.6N  73.2W   45 KT  50 MPH...SUBTROPICAL STORM
 36H  09/0600Z 27.0N  75.5W   55 KT  65 MPH...TROPICAL CYCLONE
 48H  09/1800Z 26.7N  77.6W   60 KT  70 MPH
 60H  10/0600Z 27.0N  80.0W   65 KT  75 MPH
 72H  10/1800Z 28.0N  82.3W   40 KT  45 MPH...INLAND
 96H  11/1800Z 31.2N  82.6W   40 KT  45 MPH...INLAND
120H  12/1800Z 37.5N  73.8W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown



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