Tropical Storm Sean Forecast Discussion Number 10

By | October 13, 2023

WTNT44 KNHC 130833

Tropical Storm Sean Discussion Number  10
NWS National Hurricane Center Miami FL       AL192023
500 AM AST Fri Oct 13 2023

Moderate westerly deep-layer shear continues over Sean this morning, 
and most of the associated deep convection is displaced to the east 
of Sean's center. Although the low-level circulation remains at 
least partially exposed in proxy-visible satellite images, new 
bursts of deep convection have recently developed closer to the 
center of Sean. It remains to be seen whether this activity will be 
persistent enough to support any additional strengthening. The 
latest objective and subjective satellite intensity estimates range 
from 30-45 kt, and a blend of these data support keeping the initial 
intensity at 40 kt.

Sean is moving west-northwestward (285 degrees) at 11 kt. The 
general track forecast reasoning has not changed. Sean should move 
west-northwestward to northwestward over the next few days while 
being steered by a weak subtropical ridge over the eastern and 
central Atlantic. There are no significant changes noted in the 
latest track guidance. The updated NHC forecast lies slightly to the 
left of the previous prediction, primarily the result of a more 
west-northwestward initial motion based on recent center fixes.

The various global and regional models suggest Sean is likely near 
or at its peak intensity. Although the shear could weaken some 
during the next couple of days, the convective structure of Sean is 
unlikely to improve much while the storm gains latitude and moves 
into a drier, more stable environment. The NHC forecast continues to 
show gradual weakening during the next few days, in good agreement 
with the latest multi-model consensus aids. The global models show 
an even faster rate of weakening, as the system becomes devoid of 
organized convection by early next week in both GFS and ECMWF 
model-simulated satellite imagery. Sean is still forecast to open 
into a trough and dissipate between 72-96 h.


INIT  13/0900Z 14.3N  40.5W   40 KT  45 MPH
 12H  13/1800Z 15.1N  41.6W   40 KT  45 MPH
 24H  14/0600Z 16.4N  42.9W   35 KT  40 MPH
 36H  14/1800Z 17.6N  44.2W   35 KT  40 MPH
 48H  15/0600Z 18.4N  45.3W   30 KT  35 MPH
 60H  15/1800Z 19.2N  46.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  16/0600Z 19.7N  47.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  17/0600Z...DISSIPATED

Forecaster Reinhart

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