[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 220834
TCDAT5

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
advisory.

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.


FORECAST POSITIONS AND MAX WINDS

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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