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Subtropical Storm Nicole Forecast Discussion


833 
WTNT42 KNHC 071458
TCDAT2

Subtropical Storm Nicole Discussion Number   2
NWS National Hurricane Center Miami FL       AL172022
1100 AM AST Mon Nov 07 2022

The structure of Nicole this morning remains distinctly subtropical, 
as the low-level circulation remains tangled up with an elongated 
upper-level low. The wind-field also remains quite broad, with data 
from the NOAA-P3 Hurricane Hunters this morning showing the highest 
winds remaining displaced well away from the center. The initial 
intensity is being held at 40 kt for this advisory which is 
supported by the subtropical classification of ST2.5/35-40 kt from 
TAFB, the earlier scatterometer data, and recent SFMR winds from the 
NOAA-P3 aircraft in the 40-kt range. 

Nicole might be starting to take a northwestward turn this morning, 
with the estimated motion at 320/8 kt. A continued northwestward 
motion is expected through the day, though there might be some 
wobbles more north or west here and there as the low-level 
circulation continues to interact with the decaying upper-level low. 
After 24 hours, an anomalously strong mid-level ridge is expected to 
amplify over the southeastern U.S. which is expected to steer Nicole 
and result in the system turning westward or even west-southwestward 
on Tuesday night into Wednesday. This ridging will then re-position 
itself to the northeast of Nicole by Thursday and Friday which is 
expected to allow the cyclone to begin gaining latitude after it 
moves across the Florida Peninsula, though how quickly this occurs 
is a source of track uncertainty in this time frame. Finally a broad 
mid-latitude trough is forecast to eject out of the Rockies into the 
Great Lakes region, further eroding the ridge and allowing Nicole to 
recurve by the end of the forecast period. The track guidance is 
fairly tightly clustered for the first 60 hours of the forecast, 
though it has taken a noticeable shift southward this cycle, and the 
NHC track forecast was shifted a bit southward due to this 
adjustment, but still is a bit north of the HFIP Corrected Consensus 
Approach (HCCA). 

Intensity wise, Nicole may take some time to consolidate given its 
large radius of maximum winds and currently meager central 
convection due to nearby dry air related to the nearby upper-level 
low. This feature should gradually decay and warm 27-28 C 
sea-surface temperatures should enable more organized convection to 
develop while the system remains in a low vertical wind shear 
environment. Nicole is forecast to transition to a tropical storm 
sometime in the 24-36 hour period as this convection helps to 
contract the radius of maximum wind, with further intensification 
expected thereafter. The intensity guidance was a bit higher this 
cycle, and the latest forecast now takes Nicole to a 65-kt hurricane 
in 60 hours, which is close to the latest HCCA, HMON, and SHIPS 
guidance. After Nicole moves inland, weakening is anticipated, and 
the region that Nicole is forecast to emerge off in the northern 
Gulf of Mexico has cooler SSTs that likely would not support robust 
reintensification. Regardless on the ultimate intensity of Nicole, 
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 much 
of the upcoming week.

Key Messages:

1. Hurricane conditions are possible across portions of the 
northwestern Bahamas and southeast to east-central Florida 
beginning Wednesday, where a Hurricane Watch has been issued.  
Tropical storm conditions are possible in the Tropical Storm Watch 
areas in Florida and Georgia beginning Wednesday.

2. A dangerous storm surge is possible across portions of the 
northwestern Bahamas, much of the east coast of Florida and portions 
of coastal Georgia.  A Storm Surge Watch has been issued for most of 
the east coast of Florida and portions of coastal Georgia.

3. 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, and outside of the cone, and affect much of the Florida 
peninsula and portions of the southeast U.S.

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


FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 26.2N  69.4W   40 KT  45 MPH...SUBTROPICAL STORM
 12H  08/0000Z 27.0N  70.5W   40 KT  45 MPH...SUBTROPICAL STORM
 24H  08/1200Z 27.7N  71.9W   45 KT  50 MPH...SUBTROPICAL STORM
 36H  09/0000Z 27.6N  74.1W   55 KT  65 MPH...TROPICAL STORM
 48H  09/1200Z 26.9N  76.5W   60 KT  70 MPH
 60H  10/0000Z 26.6N  78.7W   65 KT  75 MPH
 72H  10/1200Z 27.3N  81.2W   50 KT  60 MPH
 96H  11/1200Z 29.4N  83.9W   45 KT  50 MPH
120H  12/1200Z 33.3N  79.0W   45 KT  50 MPH...INLAND

$$
Forecaster Papin/Brown




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