[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 182059
TCDAT2

Hurricane Fiona Discussion Number  18
NWS National Hurricane Center Miami FL       AL072022
500 PM AST Sun Sep 18 2022

The eye of Fiona made landfall over extreme southwestern Puerto
Rico around 1920 UTC, and the center of the hurricane is now moving
into the Mona Passage between Puerto Rico and the Dominican
Republic.  Earlier observations from Hurricane Hunter aircraft and
WSR-88D radar velocity data indicate that the maximum winds were
near 75 kt.  Since there has been little change in the organization
of the system since the aircraft missions earlier today, the
intensity is kept at that value for now.  A NOAA Saildrone went
through the eye of Hurricane Fiona earlier today and the data from
that vessel indicated a minimum central pressure of 986 mb.
Another Air Force Hurricane Hunter mission into Fiona is scheduled
for this evening.

The hurricane will be moving through a fairly moist air mass and
over SSTs warmer than 29 deg C for the next few days.  It should be
noted that the SHIPS output shows 15-20 kt of vertical wind shear
over Fiona for the next several days.  However that same guidance
model shows steady strengthening with the system becoming a major
hurricane in about 48 hours.  Based on the bulk of the numerical
guidance, the official intensity forecast is increased slightly from
the previous NHC prediction, and is near or a little below the
model consensus.

Center fixes indicate that Fiona's motion is between
west-northwest and northwest, or about 305/8 kt.  There has been
little change to the track model guidance, which is fairly tightly
clustered albeit with some differences in forward speed.  The
cyclone should move along the western periphery of a subtropical
high pressure area for the next 3-4 days.  Later in the forecast
period, Fiona is expected to accelerate northeastward and
north-northeastward as it encounter the faster high-latitude flow.
The official track forecast has not been changed significantly,
and remains in close agreement with the TVCA dynamical model.

Key Messages:

1.  Hurricane conditions are expected to begin in portions of the
warning area in the Dominican Republic tonight and Monday.  Tropical
storm conditions will reach the Dominican Republic this evening.

2. Heavy rains from Fiona will continue across Puerto Rico through
tonight and occur over the Dominican Republic later today into
Monday. These rainfall amounts will produce catastrophic
life-threatening flash floods and urban flooding across Puerto Rico
and portions of the eastern Dominican Republic, along with mudslides
and landslides in areas of higher terrain.

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


FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 18.2N  67.3W   75 KT  85 MPH
 12H  19/0600Z 18.7N  68.2W   80 KT  90 MPH
 24H  19/1800Z 20.0N  69.2W   85 KT 100 MPH
 36H  20/0600Z 21.4N  70.1W   90 KT 105 MPH
 48H  20/1800Z 22.8N  70.8W  100 KT 115 MPH
 60H  21/0600Z 24.1N  70.9W  105 KT 120 MPH
 72H  21/1800Z 25.7N  70.7W  110 KT 125 MPH
 96H  22/1800Z 30.0N  68.5W  105 KT 120 MPH
120H  23/1800Z 37.5N  61.5W   95 KT 110 MPH

$$
Forecaster Pasch
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