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Tropical Storm Otis Discussion Number   5
NWS National Hurricane Center Miami FL       EP182023
1000 AM CDT Mon Oct 23 2023
 
Otis has been relatively steady in strength this morning. Satellite 
images indicate that deep convection has been pulsing during the 
past several hours.  The low-level center remains on the east side 
of the thunderstorm activity due to easterly wind shear. The 
satellite intensity estimates have not changed much, therefore, the 
initial intensity is held at 40 kt.

Otis is moving slowly north-northwestward at 5 kt in the flow 
between a mid- to upper-level trough to its northwest and a ridge to 
its east.  There continues to be significant disagreement among the 
models with the ECMWF showing Otis moving inland in about 48 hours 
while the GFS, HWRF, and HAFS models keep the system offshore during 
the next several days.  A closer inspection of the guidance suggests 
that the differences in these solutions are related to the vertical 
depth and convective organization of Otis in the short term, which 
affects its forward speed.  Since it appears that the ECMWF model 
has the best handle on the short term convective trends, the NHC 
track forecast continues to favor that solution overall.  This 
prediction is a little to the left of the previous one, mostly based 
on the initial position/motion.

Although Otis is expected to remain in a moderate wind shear 
environment, abundant moisture and warm SSTs should support gradual 
strengthening as long as Otis remains offshore.  The NHC intensity 
forecast is a little higher than the previous one, following the 
IVCN and HCCA consensus aids.  Rapid weakening is expected after 
Otis moves inland due to the rugged terrain in southern and 
southwestern Mexico.
 
Key Messages:
 
1. Heavy rains from Otis will begin to impact areas of southwest
Mexico early this week.  This rainfall will produce flash and urban
flooding, along with mudslides in areas of higher terrain.
 
2. Tropical storm conditions are possible by Tuesday night along
portions of the southern coast of Mexico, where a Tropical Storm
Watch is in effect.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/1500Z 12.0N  97.5W   40 KT  45 MPH
 12H  24/0000Z 12.6N  97.7W   45 KT  50 MPH
 24H  24/1200Z 13.6N  98.0W   45 KT  50 MPH
 36H  25/0000Z 14.6N  98.5W   50 KT  60 MPH
 48H  25/1200Z 15.4N  99.0W   55 KT  65 MPH
 60H  26/0000Z 16.2N  99.5W   55 KT  65 MPH
 72H  26/1200Z 17.5N 100.5W   35 KT  40 MPH...INLAND
 96H  27/1200Z...DISSIPATED
 
$$
Forecaster Cangialosi/Delgado
 
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