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Hurricane Dorian Discussion Number  55
NWS National Hurricane Center Miami FL       AL052019
1100 PM EDT Fri Sep 06 2019
 
During the past couple of hours Dorian's eye has become no longer
apparent in conventional satellite imagery. Microwave data shows an
eye-like feature just to the south of the convection, and also
indicates that the hurricane is becoming asymmetric. The lack of
symmetry is the first indication or hint that Dorian is slowly
beginning to acquire some extratropical characteristics. The rain
shield is now placed to the northwest of the center, and the wind
field is expanding in the southern semicircle.  Dvorak numbers are
either steady or have decreased slightly, and consequently the
initial intensity is kept at 80 kt in this advisory.
 
The hurricane is rapidly reaching cooler waters and guidance shows
an area of significantly strong shear along the forecast path
of Dorian. Given these conditions, the NHC forecast calls for
gradual weakening, but Dorian is still expected to make landfall in
Nova Scotia with hurricane intensity late Saturday. Dorian is
forecast to complete its transition to extratropical once it crosses
Nova Scotia.
 
The hurricane is racing northeastward or 045 degrees at 22 kt. Since
Dorian is already embedded within a fast southwesterly flow ahead of
a mid-latitude trough, the current northeast heading should
continue until dissipation occurs in about 3 days, if not sooner.
The track guidance is in remarkably good agreement, and the NHC
forecast is in the middle of the guidance envelope, increasing the
confidence in the track forecast.
 
Key Messages:
 
1. Regardless of whether it is a hurricane or a post-tropical
cyclone, Dorian is expected to have a significant impact in portions
of eastern Canada. Dangerous storm surge impacts are likely in
portions of the Gulf of St. Lawrence, southwestern Newfoundland and
eastern Nova Scotia this weekend. Hurricane-force winds are also
likely in Nova Scotia, Prince Edward Island and possibly
Newfoundland Saturday and Sunday. Refer to information from the
Canadian Hurricane Centre for more information on these hazards.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0300Z 38.3N  70.2W   80 KT  90 MPH
 12H  07/1200Z 40.8N  66.9W   75 KT  85 MPH
 24H  08/0000Z 45.0N  63.0W   70 KT  80 MPH...INLAND
 36H  08/1200Z 49.0N  59.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 48H  09/0000Z 52.0N  55.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  10/0000Z 56.0N  41.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  11/0000Z...DISSIPATED
 
$$
Forecaster Avila
 
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