Hurricane Nigel Forecast Discussion Number 15

Mon, Sep 18th 2023, 10:42 PM

Issued at 1100 PM AST Mon Sep 18 2023

WTNT45 KNHC 190242

Hurricane Nigel Discussion Number 15
NWS National Hurricane Center Miami FL

1100 PM AST Mon Sep 18 2023

Nigel has become a little better organized this evening, with a
ragged eye becoming more apparent in infrared satellite imagery. An
earlier SSMIS microwave overpass revealed a fairly well-defined
low-level inner-core structure, but the eye was open to the
northwest. Subjective Dvorak intensity estimates from TAFB and SAB
were a consensus T4.5 (77 kt), and the various objective estimates
were in the 70-80 kt range at 0000 UTC. Based on a blend of these
intensity estimates, the initial wind speed is set at 75 kt for
this advisory.

Although Nigel's strengthening appears to have been disrupted by
dry air entrainment today, the hurricane has about another 24-36
hours within low shear conditions and over warm SSTs in which
to strengthen. The NHC intensity forecast calls for additional
strengthening during that time, but the peak intensity has been
lowered slightly. After 36-48 hours, increasing southwesterly
vertical wind shear and cooler SSTS along the track of Nigel are
expected to cause gradual weakening. The NHC wind speed forecast
is in best agreement with the HFIP corrected-consensus aid, which
is at the higher end of the guidance in the short term. The global
models indicate that extratropical transition is likely to begin by
72 hours, and that process should be complete by day 4.

Nigel continues to move northwestward (310 degrees) at about 10 kt.
The hurricane should continue on that general heading and speed
through midday Tuesday, but as it nears the western extent of the
ridge, Nigel is predicted to turn northwestward and northward
shortly thereafter. By 48 hours, an approaching mid- to upper-level
trough is forecast to cause Nigel to accelerate northeastward over
the central and northeastern Atlantic through the remainder of the
forecast period. The track guidance remains tightly clustered, with
the primary differences being how much Nigel accelerates
northeastward later in the period. The NHC track forecast is a
blend of the typically reliable GFS and ECMWF models, nd is close
to the various consensus aids.


INIT 19/0300Z 28.6N 52.7W

75 KT 85 MPH
12H 19/1200Z 29.9N 53.8W

85 KT 100 MPH
24H 20/0000Z 32.1N 54.5W

90 KT 105 MPH
36H 20/1200Z 34.7N 54.1W

90 KT 105 MPH
48H 21/0000Z 37.6N 51.6W

85 KT 100 MPH
60H 21/1200Z 40.5N 46.6W

80 KT 90 MPH
72H 22/0000Z 43.4N 39.5W

70 KT 80 MPH
96H 23/0000Z 50.0N 24.7W

120H 24/0000Z 57.0N 17.4W


Forecaster Brown

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