[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 211455
TCDAT2

Hurricane Fiona Discussion Number  29
NWS National Hurricane Center Miami FL       AL072022
1100 AM EDT Wed Sep 21 2022

Fiona has an impressive presentation on satellite images, with a
well-defined 20-n mi diameter eye embedded within very cold cloud
tops.  The hurricane has a large Central Dense Overcast with
surrounding banding features, especially over the northeastern
quadrant.  Upper-level outflow is well-defined over the northern
and eastern portions of the system.  The current intensity estimate
is kept at 115 kt in agreement with a subjective Dvorak estimate
from SAB.

During the next couple of days, Fiona will continue to traverse
warm ocean waters and remain within a moist air mass.  Therefore
some additional strengthening could occur.  Fluctuations in
intensity are also possible due to eyewall replacements, but these
are difficult to time.  In 60-72 hours, Fiona is expected to
interact with a vigorous mid-latitude trough near the northeastern
United States coast, which should lead to its transition into an
intense extratropical cyclone by 72 hours.

The hurricane continues to move northward, or at about 360/7 kt.
Fiona is likely to move northward to north-northeastward along the
western side of a mid-level subtropical anticyclone during the next
12-24 hours.  After that time, the hurricane is forecast to
gradually accelerate northeastward to north-northeastward along
the eastern side of the above mentioned trough.  The new official
forecast is very similar to the previous NHC prediction and is very
close to both the corrected and simple dynamical model consensus.


Key Messages:

1. Hurricane conditions are possible, and tropical storm conditions
are expected, on Bermuda by late Thursday.

2. Fiona is expected to affect portions of Atlantic Canada as a
powerful hurricane-force cyclone late Friday and Saturday, and could
produce significant impacts from high winds, storm surge, and heavy
rainfall. Interests in these areas should closely monitor the
progress of Fiona and updates to the forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 24.6N  71.7W  115 KT 130 MPH
 12H  22/0000Z 25.8N  71.4W  120 KT 140 MPH
 24H  22/1200Z 28.0N  70.5W  120 KT 140 MPH
 36H  23/0000Z 30.7N  68.9W  115 KT 130 MPH
 48H  23/1200Z 34.4N  65.4W  115 KT 130 MPH
 60H  24/0000Z 39.7N  61.8W  105 KT 120 MPH
 72H  24/1200Z 45.3N  60.6W   85 KT 100 MPH...POST-TROP/EXTRATROP
 96H  25/1200Z 51.5N  60.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  26/1200Z 58.0N  59.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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