[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

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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