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Hurricane Fiona Forecast Discussion

WTNT42 KNHC 181453

Hurricane Fiona Discussion Number  17
NWS National Hurricane Center Miami FL       AL072022
1100 AM AST Sun Sep 18 2022

Observations from Air Force and NOAA Hurricane Hunter aircraft
and Doppler velocities from the San Juan WSR-88D radar indicate
that Fiona is strengthening, and is now a hurricane.  The aircraft
and radar data support a current intensity of 70 kt.  Satellite
imagery shows an expanding upper-level outflow pattern over the

Fiona should be moving in an environment of moderate vertical
shear, over warm SSTs, and within a fairly moist air mass for the
next few days.  The only obvious impediments to strengthening
should be the interaction with the land masses of Puerto Rico and
Hispaniola during the next day or so.  The official forecast is
above the previous one, but still a little below the model
consensus.  It appears likely that Fiona will become the first
major hurricane of this Atlantic season in a few days.

Although the movement has still been a little irregular based on
recent aircraft center fixes, a smoothed initial motion is still
west-northwestward, or 285/7 kt.  There has been little change to
the track forecast reasoning.  Over the next few days, the
hurricane should move along the western periphery of a
mid-tropospheric anticyclone.  Thereafter, Fiona is likely to turn
north-northeastward and accelerate later in the forecast period as
it comes under the influence of higher-latitude westerlies.  The
official forecast is just a little bit to the left of, and
slightly slower than, the previous NHC track during the first 12 to
24 hours and very close to it thereafter.  This is very
similar to the latest dynamical model consensus aid, TVCA.

Key Messages:

1.  Hurricane conditions are expected across portions of Puerto Rico
today and in portions of the Dominican Republic tonight and Monday. 
Tropical storm conditions are occurring across the U.S. and British 
Virgin Islands and will reach the Dominican Republic later today 
and tonight.

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 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 possible in the Turks and Caicos Islands and the
southeastern Bahamas by late Monday or early Tuesday.


INIT  18/1500Z 17.3N  66.5W   70 KT  80 MPH
 12H  19/0000Z 17.9N  67.3W   75 KT  85 MPH
 24H  19/1200Z 18.9N  68.4W   75 KT  85 MPH
 36H  20/0000Z 20.3N  69.3W   80 KT  90 MPH
 48H  20/1200Z 21.8N  70.1W   90 KT 105 MPH
 60H  21/0000Z 23.2N  70.6W   95 KT 110 MPH
 72H  21/1200Z 24.6N  70.6W  100 KT 115 MPH
 96H  22/1200Z 28.5N  69.3W  100 KT 115 MPH
120H  23/1200Z 34.8N  64.4W  100 KT 115 MPH

Forecaster Pasch

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