Hurricane Oscar Forecast Discussion

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WTNT41 KNHC 202046
TCDAT1

Hurricane Oscar Discussion Number   7
NWS National Hurricane Center Miami FL       AL162024
500 PM EDT Sun Oct 20 2024

Oscar is very close to making landfall this afternoon along the 
northern coast of eastern Cuba. Since the final observations from 
the morning Air Force Reconnaissance mission, the hurricane's 
structure on satellite imagery and radar out of Guantanamo Bay has 
not changed appreciably, with rotating cold convective bands noted 
on 1 minute GOES-16 imagery, and the eyewall on radar coming and 
going, occasionally open on the western side. Subjective and 
objective intensity estimates have not changed much from when the 
plane was in the hurricane this morning, so the initial intensity 
will remain at 70 kt this advisory. 

Oscar has continued a west-southwestward motion, but is slowing down 
as it nears the Cuban coast, estimated now at 250/5 kt. The 
strongest mid-level ridging is now oriented to the northwest of 
Oscar and is helping to steer the small hurricane west-southwestward 
into Cuba. However, by tomorrow a digging shortwave trough on the 
eastern side of a broader trough across the western Atlantic should 
further erode the steering flow north of Oscar, with much of the 
track guidance showing the system executing a slow but sharp turn 
northward on Monday, ultimately causing the tropical cyclone to 
emerge back out over open waters in 24-36 h. How fast Oscar then 
accelerates to the northeast could be related to how vertically deep 
the circulation is by the early part of this week, with the GFS 
showing a shallow Oscar drifting slowly over the central Bahamas, 
while the ECMWF keeps a stronger Oscar accelerating northeastward. 
The NHC track forecast is a little faster than the previous 
advisory, slightly favoring the ECMWF forecast solution over the GFS 
given its better performance with this small tropical cyclone, and 
lies not far off the TVCA and HCCA consensus aids. 

The small inner core of Oscar is likely to be severely disrupted by 
the higher terrain of eastern Cuba after it makes landfall, and 
weakening after it moves ashore will likely be quick. Some of the 
guidance, especially the GFS, suggests that Oscar could weaken more 
than shown here in the latest NHC intensity forecast. Once Oscar 
re-emerges over the Atlantic Ocean, the forecast environment is not 
very favorable for reintensification, with westerly shear increasing 
above 30 kt in 36 h and plenty of very dry air waiting to be 
imported into the cyclone's core. The NHC forecast does not show any 
intensification after it emerges back offshore, and most of the 
guidance shows the small cyclone being absorbed by the much larger 
baroclinic trough sometime this week, though the timing varies among 
the global and hurricane-regional model guidance.

Key Messages:

1. A Hurricane Warning is in effect for a portion of the northern 
coast of eastern Cuba where Oscar is expected to make landfall 
shortly. 

2. Oscar is expected to produce a dangerous storm surge on portions 
of the north shore of eastern Cuba this afternoon and evening.

3. Through midweek, heavy rainfall from Oscar will lead to areas of 
significant, potentially 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.


FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 20.5N  74.3W   70 KT  80 MPH
 12H  21/0600Z 20.4N  75.0W   55 KT  65 MPH...INLAND
 24H  21/1800Z 20.6N  75.4W   40 KT  45 MPH...INLAND
 36H  22/0600Z 21.6N  75.5W   40 KT  45 MPH...OVER WATER
 48H  22/1800Z 22.7N  75.0W   40 KT  45 MPH
 60H  23/0600Z 23.7N  73.9W   40 KT  45 MPH
 72H  23/1800Z 25.2N  72.0W   35 KT  40 MPH
 96H  24/1800Z...DISSIPATED

$$
Forecaster Papin