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Hurricane Fiona Forecast Discussion


424 
WTNT42 KNHC 200853
TCDAT2

Hurricane Fiona Discussion Number  24
NWS National Hurricane Center Miami FL       AL072022
500 AM EDT Tue Sep 20 2022

A few hours ago, an Air Force Reserve Hurricane Hunter aircraft 
reported that the central pressure of Fiona had dropped to 967 mb, 
and that the 700-mb flight-level winds were near 95 kt.  In 
addition, the aircraft also reported surface winds estimates from 
the SFMR of 100-105 kt.  The various satellite intensity estimates 
are in the 100-115 kt range, and based on these data the initial 
intensity was increased to 100 kt.  This makes Fiona the first major 
hurricane of the 2022 Atlantic hurricane season.  It should be noted 
that since the aircraft left the storm, the eye has become less 
distinct in satellite imagery.  NOAA and Air Force Reserve Hurricane 
Hunter aircraft are scheduled to investigate Fiona before 12Z to 
see how much, if any, additional strengthening has occurred.

While Fiona has strengthened, satellite imagery continues to show 
restricted outflow in the western semicircle, likely due to 
continued southwesterly vertical wind shear.  While some shear 
should continue through 72 h, it appears it will not be strong 
enough to prevent additional intensification, and Fiona is likely to 
become a category 4 hurricane during this time.  After 72 h, the 
hurricane will interact with a powerful mid-latitude trough moving 
into the Atlantic from the eastern United States.  This should start 
the process of extratropical transition by 96 h, with the transition 
complete by the end of the forecast period.  Fiona is expected to 
remain intense through much of the transition, with the GFS, ECMWF, 
and UKMET forecasting 85-95 kt winds and unusually low central 
pressures at 96 h.

Fiona has moved northwestward during the past several hours, but a 
longer-term motion is north-northwestward or 330/9 kt.  There is no 
change in the track forecast philosophy, as during the next 
48-60 h the hurricane should gradually turn north while moving 
around the western periphery of a mid-level ridge. After that,
Fiona is forecast to turn north-northeastward and accelerate as it 
interacts with the aforementioned strong mid-latitude trough, with 
a northward motion expected after the cyclone completes 
extratropical transition.  The track guidance, while remaining 
tightly clustered, has shifted a little westward during the first 
72 h, and this part of the new forecast track is nudged a little 
westward as well.  

Key Messages:

1. Outer bands from Fiona will continue to produce heavy rain over 
mostly coastal and eastern sections of the Dominican Republic and in 
local portions of southern Puerto Rico over the next 24 hours as 
Fiona moves north-northwest over the southwest Atlantic Ocean. Heavy 
rainfall and localized life-threatening flash flooding will continue 
over portions of the Dominican Republic today. Heavy rains around 
the center of Fiona will impact the Turks and Caicos through this 
afternoon with continued life-threatening flooding. Localized 
additional flash and urban flooding is possible in the southern 
portion of Puerto Rico.

2. Hurricane conditions are spreading over the Turks and Caicos 
islands, while tropical storm conditions should spread over 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  20/0900Z 21.3N  70.9W  100 KT 115 MPH
 12H  20/1800Z 22.3N  71.4W  110 KT 125 MPH
 24H  21/0600Z 23.6N  71.7W  115 KT 130 MPH
 36H  21/1800Z 25.1N  71.5W  120 KT 140 MPH
 48H  22/0600Z 27.1N  70.7W  120 KT 140 MPH
 60H  22/1800Z 29.6N  69.4W  120 KT 140 MPH
 72H  23/0600Z 32.6N  66.8W  115 KT 130 MPH
 96H  24/0600Z 42.5N  60.0W   90 KT 105 MPH
120H  25/0600Z 50.5N  59.5W   55 KT  65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven




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