[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 212044
TCDAT5

Hurricane Nigel Discussion Number  26
NWS National Hurricane Center Miami FL       AL152023
900 PM GMT Thu Sep 21 2023

Nigel's satellite presentation has begun to degrade as increasing
southwesterly vertical wind shear has caused the deep convection to
become displaced to the northeast of the low-level center.  A blend
of the latest Dvorak Current Intensity (CI) numbers and the
objective estimates yields an initial intensity estimate of 70 kt.

A continued increase in vertical wind shear and cooler waters along
the track of Nigel should cause additional weakening.  Nigel is
expected to quickly complete its extratropical transition by 12
hours, and only gradual weakening is forecast after that time.  The
storm has grown in size, and a continue expansion of the 34-kt wind
field is expected during the next couple of days.

Nigel is moving east-northeastward or 060/32 kt.  An east-
northeastward to northeastward motion along the southeastern
side of a strong deep-layer mid-latitude trough is expected during
the next 12 to 24 hours.  After that time, Nigel should rotate
around the eastern side of a large extratropical cyclone over the
North Atlantic.  The dynamical model guidance is tightly clustered,
and the NHC forecast is near a blend of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 43.7N  40.8W   70 KT  80 MPH
 12H  22/0600Z 46.0N  34.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 24H  22/1800Z 49.4N  27.1W   55 KT  65 MPH...POST-TROP/EXTRATROP
 36H  23/0600Z 53.6N  23.1W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  23/1800Z 57.0N  24.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 60H  24/0600Z 57.5N  25.6W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  24/1800Z...DISSIPATED

$$
Forecaster Brown
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