[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 220857
TCDAT2

Hurricane Fiona Discussion Number  32
NWS National Hurricane Center Miami FL       AL072022
500 AM EDT Thu Sep 22 2022

Fiona is showing signs of slow decay in satellite imagery, with the
eye gradually becoming cloud filled and the eyewall convection
becoming more ragged.  However, this has not yet led to a
significant decrease in the satellite intensity estimates, which
range from 100-130 kt.  The initial intensity is held at 115 kt
pending the arrival of the next Air Force Reserve Hurricane Hunter
aircraft, but this could be a little generous.

The hurricane has turned north-northeastward during the past several
hours with the initial motion now 025/11 kt.  Fiona is expected to
accelerate in a generally north-northeasterly direction for the next
24 h or so as it is steered along the southern edge of the
mid-latitude westerlies.  This motion should take the center
northwest of Bermuda in 24-30 h.  After that time, an even faster
motion is forecast as the hurricane interacts with a powerful
deep-layer trough moving into the Atlantic from the northeastern
United States. This interaction should steer the cyclone toward
Atlantic Canada later Friday and Friday night.  After 48 h, a
northward motion at a decreasing forward speed is expected, with the
center moving near or over, eastern Nova Scotia, the Gulf of St.
Lawrence, and portions of Newfoundland and Labrador into the
Labrador Sea by days 4 and 5.  The track guidance remains very
tightly clustered, and the new NHC track forecast is again mainly an
update of the previous prediction.

Little change, or perhaps a slow decrease in intensity is expected
during the next 24 h or so while Fiona remains over warm waters of
29-30 degrees Celsius and in a generally low-shear environment.
After that, interaction with the aforementioned mid-latitude trough
should begin the process of extratropical transition, which should
complete between 48-60 h as the center of Fiona approaches Nova
Scotia.  The extratropical low is forecast to continue producing
hurricane-force winds as it crosses Nova Scotia and moves into the
Gulf of St. Lawrence through 60 h, and it is expected to continue
producing gale-force winds as it moves across Newfoundland and
Labrador until near the end of the forecast period.  There is little
change in the intensity guidance from the previous advisory, and
there are only minor changes in the intensity forecast.

The wind radii were modified based on a combination of
scatterometer and synthetic aperture radar data.


Key Messages:

1. Hurricane conditions are expected on Bermuda tonight through
Friday morning, and a Hurricane Warning has been issued for the
island.

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.  Interests in these
areas should closely monitor the progress of Fiona and updates to
the forecast.

3. Large swells generated by Fiona are expected to cause dangerous
and possibly life-threatening surf and rip current conditions along
the east coast of the United States, the Bahamas, Bermuda, and
Atlantic Canada during the next few days.  Please consult products
from your local weather office.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 27.4N  70.6W  115 KT 130 MPH
 12H  22/1800Z 29.3N  69.7W  115 KT 130 MPH
 24H  23/0600Z 32.5N  66.9W  110 KT 125 MPH
 36H  23/1800Z 37.4N  63.3W  105 KT 120 MPH
 48H  24/0600Z 43.0N  61.3W   95 KT 110 MPH
 60H  24/1800Z 46.7N  60.9W   75 KT  85 MPH...POST-TROP/EXTRATROP
 72H  25/0600Z 49.7N  60.4W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  26/0600Z 57.0N  58.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  27/0600Z 62.5N  58.0W   30 KT  35 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
This weather bulletin was brought to you by:
www.nashvilleweather.net