[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 191459
TCDAT2

Hurricane Fiona Discussion Number  21
NWS National Hurricane Center Miami FL       AL072022
1100 AM AST Mon Sep 19 2022

The center of the hurricane is moving off the northern coast of the
Dominican Republic near eastern Samana Bay.  High-resolution
visible satellite imagery from the GOES-16 mesoscale sector show a
well-organized system, but the eye is currently cloud-filled.  The
current intensity and central pressure, 75 kt and 980 mb, are based
on the assumption of some weakening and filling due to Fiona's
interaction with the land mass of eastern Hispaniola.  An Air Force
Reserve Unit reconnaissance aircraft is scheduled to investigate
the hurricane tonight, assuming that the cyclone will have moved
far enough offshore over the waters of the southwestern Atlantic.

Fiona is moving northwestward, or at about 310/7 kt.  The system is
moving along the southwestern periphery of a mid-level high
pressure area over the subtropical Atlantic.  During the next 2-3
days, the hurricane should gradually turn toward the
north-northwest and north as it rounds the western side of the
high.  Later in the forecast period, a large and strong trough
moving over the northeastern United States should cause Fiona to
accelerate northeastward and north-northeastward.  The official
track forecast remains in agreement with the previous NHC solutions
and is close to both the simple and corrected dynamical model
consensus predictions.

Moderate vertical shear associated with southwesterly upper-level
flow over Fiona is likely to prevail during the next few days.
However, this shear is not expected to be strong enough to offset
the favorable thermodynamics over the southwestern Atlantic.  The
official forecast shows steady strengthening with Fiona becoming
a major hurricane within the next couple of days.  This is in
line with the latest intensity model guidance and also similar to
the previous NHC forecasts.

As the hurricane accelerates deeper into the mid-latitudes and
begins interacting with the strong trough to its west, 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.  Heavy rains from Fiona will continue to produce life-
threatening and catastrophic flooding along with mudslides and
landslides across Puerto Rico through tonight. Life-threatening
flash and urban flooding is likely for eastern portions of the
Dominican Republic through early Tuesday.

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

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  19/1500Z 19.1N  69.2W   75 KT  85 MPH
 12H  20/0000Z 20.1N  69.8W   85 KT 100 MPH
 24H  20/1200Z 21.5N  70.7W   90 KT 105 MPH
 36H  21/0000Z 22.9N  71.2W   95 KT 110 MPH
 48H  21/1200Z 24.2N  71.2W  105 KT 120 MPH
 60H  22/0000Z 26.0N  70.7W  110 KT 125 MPH
 72H  22/1200Z 28.2N  69.9W  110 KT 125 MPH
 96H  23/1200Z 33.3N  65.3W  105 KT 120 MPH
120H  24/1200Z 45.0N  57.5W   80 KT  90 MPH

$$
Forecaster Pasch
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