[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 190255
TCDAT2

Hurricane Fiona Discussion Number  19
NWS National Hurricane Center Miami FL       AL072022
1100 PM AST Sun Sep 18 2022

Radar imagery and recent fixes from an Air Force Reserve Hurricane
Hunter aircraft show that Fiona has jogged westward over the Mona
Passage, in between Puerto Rico and the Dominican Republic this
evening.  Radar, microwave imagery, and observations from the
aircraft indicate that the eye has become smaller, with the radius
of maximum winds decreasing to 10-15 n mi. There has been some
warming of the clouds tops in the band just outside the CDO, but the
conventional satellite presentation has not changed much since late
this afternoon.  The aircraft has measured a peak 700-mb flight-
level wind of 75 kt, and SFMR winds of around 70 kt. A dropwindsonde
in the northwestern eyewall measured a mean wind of 89 kt in the
lowest 150 m of the profile, which supports the 75 kt initial
intensity. The aircraft just reported a minimum pressure of 982 mb
on it latest pass through the center just a short time ago.

As mentioned above, Fiona has been moving more westward this
evening, but the longer-term motion estimate is 300/9 kt. With this
westward jog, the center is likely to make landfall in the eastern
portion of the Dominican Republic overnight, and the early portion
of the track forecast has been adjusted accordingly.  The dynamical
model guidance insists that a northwestward motion should begin
soon, and the models are in good agreement that Fiona will move
around the western periphery of a subtropical ridge over the next
several days.  Later in the forecast period, Fiona is forecast to
accelerate northeastward, and north-northeastward ahead of a trough
that is expected to move across the northeastern United States by
the end of the week. The official forecast is near the center of
the guidance envelope, but is slightly slower than the previous
forecast at days 4 and 5 to be closer to the latest consensus aids.

Fiona could strengthen slightly within the next few hours before it
reaches the coast of the Dominican Republic overnight.  After that
time, some weakening could occur while the center remains near
eastern Hispaniola.   Once Fiona moves over the Atlantic waters
north of the Dominican Republic, the hurricane will be over warm
water and in fairly moist environment.  Although there is likely to
be some moderate shear over the hurricane, nearly all of the
intensity models suggest the cyclone will strengthen, and the
official forecast again calls for Fiona to become a major hurricane
in a couple of days.  The NHC intensity forecast is close to the
IVCN intensity aid, and is similar to the previous wind speed
forecast.

Based on Fiona's latest forecast track, the government of the
Bahamas has issued a Hurricane Warning for the Turks and Caicos
Islands.

Key Messages:

1.  Hurricane conditions are expected to begin in portions of the
warning area in the Dominican Republic within the next few hours.
Tropical storm conditions will continue to spread over portions of
the Dominican Republic within the warning area through Monday.

2. Heavy rains from Fiona will continue across Puerto Rico overnight
tonight and spread over the Dominican Republic through Monday.
These rains will continue to produce life-threatening and
catastrophic flash 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.  Hurricane conditions
are expected in portions of the Turks and Caicos Islands on Tuesday,
and tropical storm conditions are expected in the southeastern
Bahamas by late Monday or early Tuesday.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0300Z 18.0N  68.1W   75 KT  85 MPH
 12H  19/1200Z 19.0N  69.1W   80 KT  90 MPH
 24H  20/0000Z 20.4N  70.0W   90 KT 105 MPH
 36H  20/1200Z 21.9N  70.8W   95 KT 110 MPH
 48H  21/0000Z 23.3N  71.1W  100 KT 115 MPH
 60H  21/1200Z 24.7N  71.1W  105 KT 120 MPH
 72H  22/0000Z 26.4N  70.5W  110 KT 125 MPH
 96H  23/0000Z 31.2N  67.4W  110 KT 125 MPH
120H  24/0000Z 40.3N  59.8W   95 KT 110 MPH

$$
Forecaster Brown
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