Hurricane Nigel Discussion Number  17
NWS National Hurricane Center Miami FL       AL152023
1100 AM AST Tue Sep 19 2023

Nigel continues to exhibit a large eye about 50 n mi across on
satellite images this morning.  The surrounding deep convection has
intensified somewhat over the southern and western portions of the
circulation, and the overall cloud pattern is fairly symmetrical.
The current intensity estimate is increased to 80 kt in agreement
with the latest objective estimates from UW-CIMSS.  A NOAA
Hurricane Hunter aircraft will investigate the hurricane shortly
and should provide a more accurate estimate of Nigel's intensity.

There is still about one more day for the hurricane to intensify
while it remains over SSTs near 28 deg C with weak vertical wind
shear.  Therefore, the official forecast shows some short-term
strengthening and this is generally above the model guidance.  In
48 to 72 hours, the dynamical model guidance shows a large increase
in shear which, along with cooler waters, should result in
weakening.  By 72 hours, the global model forecast indicates that
Nigel will become a frontal low over the northern Atlantic and this
is shown in the official forecast.

As noted earlier, the track forecast for Nigel appears to be
straightforward.  The system is currently moving northwestward
along the western periphery of a mid-level anticyclone.  In 12
to 24 hours, Nigel should turn northward while it moves around
the high.  Afterwards, the system is likely to accelerate
northeastward to the southeast and south of a strong mid-level
trough.  In 3-5 days, Nigel is expected to rotate around the eastern
side of a large extratropical low over the North Atlantic. The NHC
track forecast is close to the model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 30.5N  54.3W   80 KT  90 MPH
12H  20/0000Z 32.3N  54.7W   90 KT 105 MPH
24H  20/1200Z 35.0N  54.2W   90 KT 105 MPH
36H  21/0000Z 38.0N  51.4W   85 KT 100 MPH
48H  21/1200Z 41.0N  46.2W   75 KT  85 MPH
60H  22/0000Z 43.8N  39.0W   65 KT  75 MPH
72H  22/1200Z 46.5N  31.3W   55 KT  65 MPH...POST-TROP/EXTRATROP
96H  23/1200Z 54.0N  20.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  24/1200Z 59.0N  21.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch