Tropical Storm Sean Forecast Discussion Number 8

By | October 12, 2023

WTNT44 KNHC 122033

Tropical Storm Sean Discussion Number   8
NWS National Hurricane Center Miami FL       AL192023
500 PM AST Thu Oct 12 2023

Sean remains fairly disorganized on satellite imagery this 
afternoon. The low-level center is still exposed, however there has 
been a recent burst of convection closer to the center. Subjective 
Dvorak intensity estimates have increased since the previous cycle, 
with final-T numbers of T2.5/T2.0 from TAFB and SAB, respectively. 
These estimates are in fairly good agreement with the scatterometer 
data from earlier. Therefore, the initial intensity for this 
advisory is held at 35 kt.

The tropical storm is moving at a slightly faster northwestward 
motion at 310/10 kt, gaining a little more latitude since this 
morning. A weak ridge to the northeast of the system will continue 
to steer Sean northwestward to west-northwestward throughout the 
forecast period. Model guidance remains in fairly good agreement 
with this scenario. There was a slight shift to the right in the 
short-term center positions to account for the slightly faster 
northwestward motion.  Otherwise, the track forecast is similar to 
the previous and lies near the consensus aids.

Westerly vertical wind shear is expected to persist over the system 
for the next day or so, before decreasing along Sean's forecast 
track.  However, the system will be moving into an area with drier 
mid-level RH values, a more stable environment, and a less favorable 
upper-level wind pattern. Simulated satellite imagery from the GFS 
and ECMWF models suggest that Sean could struggle to produce 
organized convection in the coming days. While small intensity 
fluctuations are possible, the NHC intensity forecast remains near 
the HCCA and IVCN consensus aids, keeping Sean a tropical storm for 
the next day or so, then weakening it back into a depression. 
Afterwards, the system is forecast to degenerate into a 
post-tropical remnant low as it becomes devoid of convection, and 
dissipate into a trough by day 4. Although, some global models 
depict that these transitions could occur even sooner than forecast.


INIT  12/2100Z 13.8N  38.2W   35 KT  40 MPH
 12H  13/0600Z 14.5N  39.5W   35 KT  40 MPH
 24H  13/1800Z 15.5N  41.2W   35 KT  40 MPH
 36H  14/0600Z 16.8N  42.6W   30 KT  35 MPH
 48H  14/1800Z 18.0N  43.8W   30 KT  35 MPH
 60H  15/0600Z 19.0N  44.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  15/1800Z 19.9N  45.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  16/1800Z...DISSIPATED

Forecaster Kelly

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