Tropical Storm Oscar Forecast Discussion

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WTNT41 KNHC 210837
TCDAT1

Tropical Storm Oscar Discussion Number   9
NWS National Hurricane Center Miami FL       AL162024
500 AM EDT Mon Oct 21 2024

The center of Oscar has continued to move over eastern Cuba
overnight.  Although radar imagery from Guantanamo Bay has shown
a continued degradation of Oscar's inner core, bands of deep
convection with heavy rainfall remain over portions of the island.
A couple of ASCAT passes from earlier in the night showed that
tropical-storm-force winds were occurring along both the southern
and northern coasts of eastern Cuba.  Given the decrease in inner 
core organization over the past several hours, the initial 
wind speed has been lowered perhaps conservatively to 45 kt for 
this advisory.

Radar and surface observations from Guantanamo Bay indicate that
the center is located just north of that location.  The initial 
motion estimate is a somewhat uncertain 270/2 kt.  The storm 
should begin to turn northwestward and northward later today ahead 
of a shortwave trough moving over the northwestern Bahamas.  Some 
of the dynamical model guidance suggests that the center may 
re-form near the northern coast of Cuba later today, rather than 
the low-level center continuously tracking across the mountainous 
terrain of the island.  Regardless of the details of the track over 
eastern Cuba, Oscar is expected to emerge off the northern coast of 
Cuba later today or tonight.  Thereafter, the cyclone should 
accelerate northeastward over portions of the southeastern Bahamas 
and western Atlantic ahead of the aforementioned trough.  In 60-72 
hours, global model guidance indicates that the circulation will 
become elongated and that it will be absorbed by a larger developing 
non-tropical area of low pressure between Bermuda and the 
southeastern U.S. coast by day 3. The track guidance is again 
faster this cycle, and the NHC forecast has been adjusted 
accordingly. 

Additional weakening is expected while Oscar moves over eastern
Cuba today.  Most of the guidance now keeps Oscar a tropical
cyclone after it emerges off the northern coast of Cuba, but
increasing westerly vertical wind shear and dry mid-level air 
should prevent significant restrengthening before it is absorbed by 
a non-tropical area of low pressure. 

The primary hazard associated with Oscar will be heavy rainfall and 
life-threatening flash flooding, particularly over the mountainous 
terrain of eastern Cuba. 


Key Messages:

1. Through midweek, heavy rainfall from Oscar will lead to areas of
significant, life-threatening flash flooding along with mudslides 
across portions of eastern Cuba, especially within the Sierra 
Maestra. In addition, localized flash flooding will be possible 
across the southeastern Bahamas.

2. Tropical storm conditions are expected to continue today across 
portions of eastern Cuba. Tropical storm conditions are also 
expected in portions of the southeastern Bahamas tonight and 
Tuesday. 


FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 20.2N  75.1W   45 KT  50 MPH...INLAND
 12H  21/1800Z 20.6N  75.3W   40 KT  45 MPH...INLAND
 24H  22/0600Z 21.5N  75.0W   40 KT  45 MPH...OVER WATER
 36H  22/1800Z 22.9N  74.0W   40 KT  45 MPH
 48H  23/0600Z 24.5N  72.4W   40 KT  45 MPH
 60H  23/1800Z 26.7N  70.2W   40 KT  45 MPH
 72H  24/0600Z...ABSORBED BY NON-TROPICAL LOW PRESSURE AREA

$$
Forecaster Brown