[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 221451
TCDAT2

Hurricane Fiona Discussion Number  33
NWS National Hurricane Center Miami FL       AL072022
1100 AM EDT Thu Sep 22 2022

The satellite presentation of the hurricane is not quite as
impressive as yesterday.  The large eye has become cloud filled and
the surrounding cloud top temperatures are not quite as cold. An Air
Force Reserve reconnaissance aircraft has very recently reported a
peak 700-mb flight-level wind of 126 kt in the southeastern eyewall.
The peak SFMR winds have been 107 kt and latest minimum central
pressure is around 936 mb.  These data support maintaining the
initial intensity of 115 kt. A NOAA Saildrone located about 45 n mi
east of the center has recently reported sustained winds of 67 kt
and a significant wave height of 50 ft.

The hurricane is beginning to accelerate north-northeastward with an
initial motion estimate of 025/13 kt. Additional acceleration is
expected while Fiona moves north-northeastward along the southern
edge of the mid-latitude westerlies through tonight. On Friday, a
vigorous mid-latitude trough moving off the coast of the
northeastern U.S. is expected to steer Fiona northward toward
Atlantic Canada.  The storm is forecast to pass over portions of
eastern Nova Scotia by Saturday morning, and a slower northward or
north-northeastward motion over the Gulf of St. Lawrence and
portions of Newfoundland and Labrador is expected after that time.
The track guidance remains in very good agreement, and the new
official forecast is once again essentially an update of the
previous one.

Only a slight decrease in intensity is predicted over the next 12-24
hours while Fiona remains over warm waters and in a low-shear
environment. By 36 hours, interaction with the aforementioned trough
will begin extratropical transition, and this process is forecast to
be complete by 48 hours when the system is near Nova Scotia.  The
global model guidance indicates that the post-tropical cyclone will
continue to produce hurricane-force winds when it reaches Nova
Scotia.  The NHC intensity forecast is similar to the previous
advisory and closely follows the global model guidance during the
post-tropical phase.

Based on the latest forecast the Canadian Hurricane Centre has
issued Hurricane and Tropical Storm Watches for much of Atlantic
Canada.


Key Messages:

1. Hurricane conditions are expected on Bermuda tonight through
Friday morning.

2. Fiona is expected to affect portions of Atlantic Canada as a
powerful hurricane-force cyclone late Friday and Saturday, and
significant impacts from high winds, storm surge, and heavy rainfall
are becoming increasingly likely. Hurricane and Tropical Storm
Watches have been issued for much of Atlantic Canada.

3. Large swells generated by Fiona are expected to cause
life-threatening surf and rip current conditions along much of the
east coast of the United States, the Bahamas, Bermuda, and Atlantic
Canada during the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 28.6N  70.2W  115 KT 130 MPH
 12H  23/0000Z 30.7N  68.8W  110 KT 125 MPH
 24H  23/1200Z 34.6N  65.2W  110 KT 125 MPH
 36H  24/0000Z 40.6N  61.8W  105 KT 120 MPH
 48H  24/1200Z 45.5N  61.2W   80 KT  90 MPH...POST-TROP/EXTRATROP
 60H  25/0000Z 48.1N  60.2W   65 KT  75 MPH...POST-TROP/EXTRATROP
 72H  25/1200Z 51.8N  59.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  26/1200Z 58.9N  58.6W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  27/1200Z 64.2N  57.8W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brown
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