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Hurricane Oscar Discussion Number  19
NWS National Hurricane Center Miami FL       AL162018
1100 AM AST Wed Oct 31 2018

Oscar is quickly transforming into an extratropical low.  Although
there is still a little bit of deep convection just north of the
center, a more prominent cloud shield extends northward from the
western part of the circulation.  In addition, GOES-16 derived
products show Oscar's center nearly embedded within a frontal zone
and cold air advection occurring on the back side of the system.
The maximum winds are a bit uncertain, but for now they are held at
65 kt based on the Dvorak Current Intensity number from TAFB and
the latest microwave estimates, which range from 60-70 kt.

Oscar is expected to complete extratropical transition later today
when it becomes fully attached to the frontal boundary.  Baroclinic
energy is likely to keep the cyclone's intensity relatively steady
for the next 48 hours or so, although it should be noted that the
GFS shows some intensification later today as a sting jet develops
to the west of the center.  After 48 hours, the post-tropical
cyclone is expected to gradually lose strength, and the NHC
intensity forecast continues to most closely follow the GFS model,
which is at the high end of the guidance envelope.  Despite this
weakening, Oscar's wind field is expected to grow substantially,
affecting a large portion of the north Atlantic Ocean over the next
several days.

A northeastward acceleration continues with an initial motion of
035/25 kt.  Further acceleration toward the north Atlantic is
expected during the next 48 hours while Oscar becomes more fully
embedded within the mid-latitude flow.  The new NHC track forecast
was shifted slightly northward and westward from the previous
forecast to trend closer to the latest consensus aids, but
otherwise the track forecast reasoning remains unchanged.

Large swells from Oscar are expected to continue to affect portions
of the coast of Bermuda through today.  Please consult products
from your local weather office, as these conditions could cause
life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  31/1500Z 36.6N  51.6W   65 KT  75 MPH
 12H  01/0000Z 40.2N  48.7W   65 KT  75 MPH...POST-TROP/EXTRATROP
 24H  01/1200Z 44.5N  44.3W   65 KT  75 MPH...POST-TROP/EXTRATROP
 36H  02/0000Z 48.4N  38.7W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  02/1200Z 52.1N  32.4W   60 KT  70 MPH...POST-TROP/EXTRATROP
 72H  03/1200Z 57.8N  18.6W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  04/1200Z 64.0N   5.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  05/1200Z...DISSIPATED

$$
Forecaster Berg

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