Post-Tropical Cyclone Nigel Forecast Discussion Number 28

By | September 22, 2023

WTNT45 KNHC 220834

Post-Tropical Cyclone Nigel Discussion Number  28
NWS National Hurricane Center Miami FL       AL152023
900 AM GMT Fri Sep 22 2023

Nigel has completed its transition to an extra-tropical cyclone this 
morning. Convection from earlier has waned, and is well displaced 
from the exposed low-level center. Based on a blend of an earlier 
partial ASCAT pass and subjective Dvorak satellite intensity 
estimates, the initial intensity is lowered to 60 kt for this 

The system is encountering very strong vertical wind shear and ocean 
temperatures below 20 degrees Celsius. The system is forecast to 
continue to gradually weaken over the next couple of days. However, 
the system will remain a strong extra-tropical cyclone with an 
expanding wind field. The NHC intensity forecast is similar to the 
previous advisory and lies near the model consensus.

Nigel continues to race northeastward at 32 kt. A northeastward 
motion is forecast to continue the next day or so, as it remains in 
the flow along the southern edge of a deep mid-latitude trough. 
Afterwards, Nigel should rotate around the eastern side of a large 
extratropical cyclone over the North Atlantic, with the two 
extratropical systems merging in about 48 h.  The model guidance 
remains in fairly good agreement, and the NHC forecast lies in the 
center of the guidance envelope.


INIT  22/0900Z 46.3N  32.6W   60 KT  70 MPH...POST-TROPICAL
 12H  22/1800Z 48.8N  27.2W   50 KT  60 MPH...POST-TROP/EXTRATROP
 24H  23/0600Z 53.0N  23.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 36H  23/1800Z 56.4N  23.3W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  24/0600Z...DISSIPATED

Forecaster Kelly

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