[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161200
TWDAT

Tropical Weather Discussion...UPDATED
NWS National Hurricane Center Miami FL
1205 UTC Fri Sep 16 2022

Updated to include information from the 1200 UTC Intermediate
Advisory for Tropical Storm Fiona

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...SPECIAL FEATURES...

Tropical Storm Fiona is centered near 15.8N 58.8W at 16/1200 UTC
or 150 nm E of Guadeloupe moving W at 13 kt. Estimated minimum
central pressure is 1004 mb. Maximum sustained wind speed is 45 kt
with gusts to 55 kt. Wave heights are currently peaking at 20 to
22 ft near and northeast of the center. The radii of wave heights
12 ft or greater extends outward up to from the center of Fiona to
270 nm in the NE quadrant and 240 nm in the NW quadrant. Fiona
remains a sheared tropical cyclone as noted by the its fully
exposed center to the west of a large area of numerous moderate to
isolated strong convection noted from 13N to 17N between 51W-58W
as noted in satellite imagery. Fiona is forecast to maintain a
westward motion with a gradual decrease in forward speed expected
through Sat night or early on Sun, followed by a turn toward the
west-northwest later on Sunday. On the forecast track, the center
of Fiona is expected to move across the Leeward Islands tonight
and early Sat, and move near or just south of the Virgin Islands
and Puerto Rico late Sat into Sun. Tropical storm conditions are
expected across portions of the northern Leeward Islands within
the warning area beginning this evening. Tropical storm conditions
are possible within the watch area across the Virgin Islands on
Saturday and in Puerto Rico late Sat or Sat night. Heavy rains
from Fiona will reach the Leeward Islands this afternoon,
spreading to the British and U.S. Virgin Islands and Puerto Rico
Saturday into Sun morning, and reaching eastern Hispaniola Sunday.
This rainfall may produce considerable flood impacts including
flash and urban flooding, along with mudslides in areas of higher
terrain particularly southern Puerto Rico and eastern Dominican
Republic. Swells generated by Fiona are beginning to affect the
Leeward Islands and will spread westward to the Virgin Islands and
Puerto Rico on today through Sat. These swells could cause life-
threatening surf and rip current conditions. Please consult
products from your local weather office.

Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest
T.S. Fiona NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 24W from
02N to 15N moving westward at 15 kt. Scattered moderate to
isolated convection is ahead of the wave from 06N to 14N between
the wave and 29W.

A central Atlantic tropical wave has its axis along 39W from 05N
to 20N moving westward at 15 kt. Scattered showers and isolated
thunderstorms are within 180 nm either side of the wave from 16N
to 20N. Some slow development of this system is possible late
this weekend and early next week while it moves northwestward to
northward over the central subtropical Atlantic. The current
outlook assigns a low probability of tropical cyclone formation
through both 48 hours and 5 days.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Mauritania near
17N16W southwestward to 12N24W to 13N30W and northwest to 15N38W.
Associated convection in the area is described in the tropical
wave section above.

GULF OF MEXICO...

A weakening stationary boundary extends from near Crystal River,
Florida to 28N86W, while a surface trough is analyzed from the
Florida southwest coast to just north of the northeast tip of the
Yucatan Peninsula. These features are supporting scattered
moderate convection within about 120 nm of the Florida coast.
Similar convection is also noted along a trough in the southern
Bay of Campeche. Outside of convective activity, generally gentle
to moderate east winds are across the majority of the basin per
latest ASCAT data passes. Wave heights remain relatively low, in
the 1-3 ft range.

For the forecast, the weakening stationary front will dissipate
today as high pressure builds over the southeastern U.S. into the
weekend. This will maintain gentle to moderate easterly breezes
and slight seas through early next week. The surface trough will
continue to support convection over the southeastern Gulf into
Sat.

CARIBBEAN SEA...

Tropical Storm Fiona is forecast to impact the northeast Caribbean.
Please refer to the Special Features Section for more details.

The gradient between subtropical high pressure and lower pressure
over the southern Caribbean is supporting moderate to fresh
easterly flow across the majority of the basin. Wave heights are
4-6 ft in the eastern and central basin and 3-5 ft in the
northwestern Caribbean.

For the forecast, Tropical Storm Fiona near 15.8N 58.8W 1004 mb
at 8 AM EDT moving W at 13 kt. Maximum sustained winds 45 kt
gusts 55 kt. Fiona will maintain intensity as it moves to near
15.9N 60.0W this afternoon, to near 16.3N 62.5W late tonight, then
begin to gradually strengthen as it moves to near 16.7N 64.6W Sat
afternoon with maximum sustained winds 55 kt gusts 65 kt, move to
near 17.0N 66.3W late Sat night, to near 17.3N 67.8W Sun
afternoon with maximum sustained winds 60 kt gusts 75 kt and to
near 18.1N 69.2W late Sun night. Fiona will change little in
intensity as it reaches near 20.0N 71.0W late Mon night and to
near 22.0N 72.5W late Tue night. Relatively weak high pressure
will build behind Fiona.

ATLANTIC OCEAN...

Tropical Storm Fiona is the main feature impacting portions of
the Atlantic. Please refer to the Special Features Section for
more details.

A cold front is over the western Atlantic extending from weak low
pressure of 1015 mb near 32N74W southwestward to 29N80W, where it
transitions to a weakening stationary front to inland central
Florida and to the eastern Gulf of Mexico. Behind the front,
winds are moderate northeast winds are present along with wave
heights of 4-6 ft seas. Ahead of the front, winds are gentle to
moderate, southeast in direction, along with wave heights of 2-4
ft. Riding associate to high pressure of 1021 near 29N60W dominates
the central Atlantic. The related gradient is allowing for light
to gentle winds and wave heights of 3-5 ft due to a north swell.
A surface trough extends from near 31N41W to 28N47W. No convection
is occurring with this feature. A tighter pressure gradient in
the eastern Atlantic between high pressure of 1201 mb near 31N27W
and lower pressure to its southeast and south in the vicinity of
the monsoon trough is supporting moderate to fresh northeast winds
and 6-8 ft wave heights.

For the forecast west of 55W, Tropical Storm Fiona is near 15.7N
58.8W 1004 mb at 8 AM EDT moving W at 13 kt. Maximum sustained
winds 45 kt gusts 55 kt. Fiona will maintain intensity as it
moves to near 15.9N 60.0W this afternoon, to near 16.3N 62.5W late
tonight, then begin to gradually strengthen as it moves to near
16.7N 64.6W Sat afternoon with maximum sustained winds 55 kt gusts
65 kt, move to near 17.0N 66.3W late Sat night, to near 17.3N
67.8W Sun afternoon with maximum sustained winds 60 kt gusts 75 kt
and to near 18.1N 69.2W late Sun night. Fiona will change little
in intensity as it reaches near 20.0N 71.0W late Mon night and to
near 22.0N 72.5W late Tue night. A cold front extends from weak
low pressure of 1015 mb near 32N74W southwestward to 29N80W, where
it transitions to a weakening stationary front to inland central
Florida. The cold front will shift eastward through the weekend as
the stationary boundary gradually weakens. Moderate to northeast
winds north of the frontal boundary will continue through the most
of the weekend. Scattered showers and thunderstorms are expected
near the frontal boundary.

$$
Aguirre/Mahoney
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