[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 222042
TCDAT2

Hurricane Fiona Discussion Number  34
NWS National Hurricane Center Miami FL       AL072022
500 PM AST Thu Sep 22 2022

The satellite presentation of Fiona has recovered somewhat since
this morning with the eye becoming a little better defined, and
a ring of convection with cloud tops of -65 to-70 degrees
surrounding the center.  There is a fairly large spread in the
subjective and objective satellite estimates, which range from
102 kt to 124 kt.  The initial wind speed remains near the mid
point of estimates at 115 kt, which was supported by the earlier
aircraft reconnaissance data. The next reconnaissance flight is
scheduled into the hurricane this evening.

The hurricane continues to accelerate north-northeastward with an
initial motion estimate of 025/17 kt.  The track forecast
reasoning has not changed from the previous advisory.  Fiona is
forecast to continue to accelerate north-northeastward tonight,
with the hurricane making its closest approach to Bermuda overnight
or early tomorrow.  On Friday, a vigorous mid-latitude trough that
is forecast to move off the coast of the northeastern United States
should cause Fiona to turn northward toward Atlantic Canada.  The
dynamic models are in good agreement that the cyclone will pass
over portions of eastern Nova Scotia by Saturday morning, and then
move more slowly northward over the Gulf of St. Lawrence and
portions of Newfoundland and Labrador over the weekend.  The track
guidance remains tightly clustered, and the official forecast lies
near the center of the model envelope.

Fiona is expected to remain in a low shear environment and over warm
water for the next 12-24 hours.  Therefore, little change in
intensity is expected during that time.  After 24 hours, the system
will interact with the aforementioned trough, and Fiona is forecast
to transition into a powerful post-tropical cyclone with
hurricane-force winds Friday night.  Gradual weakening is predicted
later in the weekend while the system moves northward over
Newfoundland and Labrador.

The cyclone is forecast to grow in size as it approaches Atlantic
Canada, and earlier ASCAT data showed that the tropical-storm-force
winds have already expanded over the eastern portion of the storm.
The initial and forecast wind radii have been adjusted accordingly.


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 are in effect 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  22/2100Z 30.4N  69.5W  115 KT 130 MPH
 12H  23/0600Z 32.8N  67.3W  110 KT 125 MPH
 24H  23/1800Z 37.8N  63.1W  110 KT 125 MPH
 36H  24/0600Z 43.8N  61.3W   95 KT 110 MPH...POST-TROP/EXTRATROP
 48H  24/1800Z 47.3N  60.9W   75 KT  85 MPH...POST-TROP/EXTRATROP
 60H  25/0600Z 50.4N  59.4W   55 KT  65 MPH...POST-TROP/EXTRATROP
 72H  25/1800Z 53.9N  58.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  26/1800Z 60.9N  58.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  27/1800Z 64.3N  57.2W   30 KT  35 MPH...POST-TROP/EXTRATROP

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