[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 190856
TCDAT2

Hurricane Fiona Discussion Number  20
NWS National Hurricane Center Miami FL       AL072022
500 AM AST Mon Sep 19 2022

Fiona strengthened before making landfall as an 80-kt hurricane in
the Dominican Republic to the south-southwest of Punta Cana around
0730 UTC this morning. Data from the Air Force Hurricane Hunters
around 0500 UTC indicated a closed eye, with a minimum pressure that
had fallen to 979 mb. Soon thereafter, the eye cleared out in
infrared satellite imagery and the inner core structure improved in
NWS San Juan radar data. The center of Fiona is currently inland
over the eastern Dominican Republic, but radar data indicate that
the outer rainbands of Fiona continue to move northward across
Puerto Rico. The initial intensity is 80 kt for this advisory.

Although the longer-term motion of Fiona is west-northwestward, the
center has been moving more northwestward (310/7 kt) over the past
few hours. This motion should continue as Fiona crosses the eastern
portion of the Dominican Republic this morning and then emerges into
the southwestern Atlantic. After moving away from land, the tightly
clustered track guidance shows Fiona turning north-northwestward and
northward through midweek around the western extent of a subtropical
ridge. Then, an acceleration to the north-northeast is forecast late
this week as Fiona moves within the flow ahead of an amplifying
deep-layer trough that will move off the northeastern U.S. coast.
The NHC track forecast remains very close to the previous one and
lies near the center of the guidance envelope. It is, however, a bit
slower with the recurvature of Fiona later this week, as reflected
in the latest consensus aids.

As the center of Fiona crosses the Dominican Republic, land
interaction may briefly disrupt the organization of the hurricane
and result in some short-term weakening. However, as Fiona moves
away from land, more significant strengthening is expected while it
moves across SSTs greater than 29C within a fairly moist and
unstable environment over the western Atlantic. The latest intensity
guidance unanimously calls for strengthening during the next few
days, and the latest NHC forecast generally falls between the IVCN
and HCCA aids. This brings Fiona up to major hurricane strength by
Wednesday. As the hurricane accelerates deeper into the
mid-latitudes and begins interacting with a deep-layer trough, it is
expected to begin extratropical transition by day 5, although the
process will likely not be completed until after the end of the
forecast period.


Key Messages:

1.  Hurricane conditions are spreading across portions of the
Dominican Republic within the warning area. Tropical storm
conditions will continue on Puerto Rico through this morning and
over portions of the Dominican Republic within the warning area
through tonight.

2. Heavy rains from outer bands of Fiona will continue across Puerto
Rico into this afternoon. The center of Fiona will persist over
eastern Dominican Republic into this afternoon with heavy bands then
lasting through tonight. These rainfall amounts will continue to
produce life-threatening and catastrophic flooding along with
mudslides and landslides across Puerto Rico. Life-threatening flash
and urban flooding is likely for eastern portions of the Dominican
Republic.

3. Fiona is forecast to strengthen after moving away from Puerto
Rico and the Dominican Republic. Hurricane conditions are expected
in the Turks and Caicos on Tuesday, and tropical storm conditions
are expected in the southeastern Bahamas by late Monday or early
Tuesday.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 18.5N  68.6W   80 KT  90 MPH...INLAND
 12H  19/1800Z 19.4N  69.3W   80 KT  90 MPH...NEAR THE COAST
 24H  20/0600Z 20.8N  70.3W   90 KT 105 MPH
 36H  20/1800Z 22.2N  71.0W   95 KT 110 MPH
 48H  21/0600Z 23.6N  71.2W  100 KT 115 MPH
 60H  21/1800Z 25.1N  70.9W  105 KT 120 MPH
 72H  22/0600Z 27.0N  70.2W  110 KT 125 MPH
 96H  23/0600Z 32.5N  66.5W  110 KT 125 MPH
120H  24/0600Z 42.5N  58.5W   95 KT 110 MPH

$$
Forecaster Reinhart
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