[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200018
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 20 2022

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 1800 UTC surface analysis and satellite imagery through
2230 UTC.

...SPECIAL FEATURES...

Hurricane Fiona is centered near 20.2N 70.1W at 20/0000 UTC or
115 nm SE of Grand Turk Island moving NW at 9 kt. Estimated
minimum central pressure is 974 mb. Maximum sustained wind speed
is 90 kt with gusts to 110 kt. Maximum seas with this system can
reach 27 ft. Steady strengthening is expected during the next
couple of days, and Fiona is forecast to become a major hurricane
on Tuesday. On the forecast track, the center of Fiona will pass
near or to the east of the Turks and Caicos on Tuesday. Swells
generated by Fiona are affecting the Virgin Islands, Puerto Rico,
the northern coast of Hispaniola, the Turks and Caicos Islands,
and the southeastern Bahamas. These swells will continue to spread
westward across the southwestern Atlantic toward the central and
northwestern Bahamas and the east coast of the United States
through midweek. The 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 NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

Shower and thunderstorm activity has increased this evening in
association with a 1014 mb low pressure located over the central
subtropical Atlantic near 30N46W. Some slow development is
possible during the next couple of days, and a tropical depression
could form during that time before environmental conditions
become less conducive later this week. The system should generally
move toward the N or NE. The system has a medium chance of
tropical cyclone development within the next 48 hours.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave extends its axis along 48W, from
15N southward, moving westward 10 to 15 kt. Scattered moderate
convection is from 07N to 11N between 46W-51W.

An Atlantic Ocean tropical wave extends its axis along 58W,
moving westward from 10 to 15 kt. A surface trough extends N of
the wave from 27N54W to 21N57W. Scattered showers are noted along
the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through coastal Africa near 14N17W to a
1011 mb low near 09N28W to 09N36W. The ITCZ continues from 09N36W
to 11N46W, then resumes W of a tropical wave near 11N49W to
11N56W. Scattered moderate convection is noted from 06N to 13N
between 51W and 56W.

GULF OF MEXICO...

Weak surface ridging over the eastern United States extends
southwestward into the Gulf of Mexico, supporting moderate
easterly winds across the central and eastern Gulf. A surface
trough extends across far eastern Gulf along 81W. Recent
altimeter data depicts wave heights of 2-3 ft across most of the
basin, except for 3-4 ft in the eastern Bay of Campeche. The rest
of the Gulf remains under fairly tranquil weather conditions.

For the forecast, high pressure over the southeastern U.S. will
maintain gentle to moderate easterly breezes and slight seas the
next few days.

CARIBBEAN SEA...

Please see the Special Features section above for information on
Hurricane Fiona.

Outside of convection associated with Fiona, scattered showers
and thunderstorms are within 60 nm of the coast of Honduras.
Scattered showers associated with the east Pacific monsoon trough
is noted near the coasts of western Venezuela, Colombia and
eastern Panama, mainly south of 14N between 72W-82W.

Fresh northeast winds are occurring in the Windward Passage
currently. Moderate to fresh winds are noted across the eastern
half of the basin, while light and variable winds prevail across
the western half. An area of winds over 20 kt and wave heights of
8-12 ft associated with Fiona is confined north of 15N between
65W-70W. Wave heights of 2-4 ft over the western Caribbean, while
4-6 ft seas are elsewhere over the eastern Caribbean.

For the forecast, Hurricane Fiona will continue to intensify as
the system moves farther away from the Caribbean through mid-
week. Residual swell over the eastern Caribbean from Fiona will
subside through Tue.

ATLANTIC OCEAN...

Refer to the Special Features section above for details on
Hurricane Fiona and the tropical waves moving across the basin.

A surface trough extends across the Florida Peninsula. Scattered
showers prevail across the peninsula and western Atlantic waters
mainly W of 76W. To the east, low pressure of 1014 mb is
analyzed near 29N49W with scattered showers in its vicinity. See
the section above for more details about the potential of this
low to become a tropical system within the next 48 hours.
Moderate winds around and near the low. An upper-level low
located near 25N46W is supporting scattered showers from 24N-30N
between 45W-52W. Relatively weak high pressure that is anchored
by a 1023 mb high center north of the area near 35N32W remains
elsewhere.

Mostly moderate winds along with wave heights of 4-6 ft are
across most of the Atlantic. The exception is near Hurricane
Fiona. Per an overnight ASCAT pass, fresh to strong winds are
south of 23N between 63W-70W in association with Fiona. Wave
heights of 8 ft and higher are associated with these winds. The
overnight ASCAT data passes revealed large swaths of fresh
northeast to east trade winds from 15N to 30N between 24W-33W and
from 12N to 21N between 33W-45W. An area of fresh north winds is
off the coast of Africa from 18N to 22N between the coast and 22W.

For the forecast west of 55W, Hurricane Fiona will move to 21.2N
70.5W Tue morning, 22.8N 71.1W Tue afternoon, 24.1N 71.3W Wed
morning, 25.7N 71.0W Wed afternoon, 27.6N 70.2W Thu morning, and
29.9N 68.9W Thu afternoon. Fiona will change little in intensity
as it moves north of the area to 37.0N 62.3W Fri afternoon. High
pressure will build in the wake of Fiona.

$$
ERA/AH
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