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Hurricane Fiona Discussion Number  25
NWS National Hurricane Center Miami FL       AL072022
1100 AM EDT Tue Sep 20 2022

Fiona has not changed much in organization on satellite images over 
the past several hours, with the eye obscured on visible satellite 
imagery.  Upper-level outflow is still somewhat restricted over the 
western semicircle of the system.  A recent SSMIS microwave image 
suggested that the hurricane may be undergoing an eyewall 
replacement.  Observations from Air Force and NOAA Hurricane Hunter 
aircraft indicate that the central pressure has not changed much 
from earlier this morning.  Flight-level and SFMR-observed surface 
winds from the aircraft do not support an intensity higher than 100 
kt, so the intensity is held at that value for this advisory.  This 
is also in agreement with Dvorak satellite estimates from TAFB and 
SAB, and recent NOAA Synthetic Aperture Radar data.

Numerical guidance indicates that Fiona will continue to be 
influenced by moderate west-southwesterly shear during the next 
couple of days.  However the models also indicate that the 
thermodynamic environment will be conducive for intensification 
over the next 48 hours, as Fiona passes through a moist air mass 
and over warm SSTs of 28-29 deg.  The official intensity forecast 
continues to call for Fiona becoming a category 4 hurricane, in 
agreement with the corrected consensus model guidance, HCCA.  
Beyond 72 hours, the hurricane is expected to interact with a 
vigorous mid-latitude trough moving into the Atlantic from the 
northeastern United States.  This should start the process of 
extratropical transition by 96 hours, with the transition complete 
by the end of the forecast period.  Fiona is expected to remain a 
deep and strong cyclone after extratropical transition.
 
Fiona continues to move north-northwestward, at about 330/8 kt.  
The track guidance has changed very little from the previous 
advisory.  Over the next couple of days, the hurricane should 
continue to move around the western periphery of a mid-level high 
pressure system centered to its east.  in 48-96 hours, Fiona is 
expected to move north-northeastward to northeastward with 
increasing forward speed along the southeast side of a strong 
mid-tropospheric trough.  The official track forecast is similar to 
the previous NHC prediction and in close agreement with the HCCA 
guidance. 
 
 
Key Messages:
 
1.  Heavy rainfall and localized life-threatening flash flooding 
should continue over portions of the Dominican Republic today. 
Heavy rains should continue to impact the Turks and Caicos through 
this afternoon with continued life-threatening flooding. Localized 
additional flash and urban flooding is possible in Puerto Rico.
 
2. Hurricane conditions are affecting portions of the Turks and 
Caicos islands, while tropical storm conditions should affect 
portions of the southeastern Bahamas during the next few hours.
 
3. Interests in Bermuda should continue to monitor the progress of
Fiona.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/1500Z 22.0N  71.4W  100 KT 115 MPH
 12H  21/0000Z 23.0N  71.7W  105 KT 120 MPH
 24H  21/1200Z 24.4N  71.8W  110 KT 125 MPH
 36H  22/0000Z 26.1N  71.2W  115 KT 130 MPH
 48H  22/1200Z 28.3N  70.2W  120 KT 140 MPH
 60H  23/0000Z 31.1N  68.4W  115 KT 130 MPH
 72H  23/1200Z 34.7N  65.2W  110 KT 125 MPH
 96H  24/1200Z 45.0N  60.0W   85 KT 100 MPH
120H  25/1200Z 52.0N  59.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Pasch
 
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