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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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