[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211759
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Sep 21 2023

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 1200 UTC surface analysis and satellite imagery through
1730 UTC.

...SPECIAL FEATURES...

Hurricane Nigel is centered near 42.2N 45.0W at 21/1500 UTC or
440 nm SE of Cape Race Newfoundland, moving NE at 26 kt.
Estimated minimum central pressure is 977 mb. Maximum sustained
wind speed is 75 kt with gusts to 90 kt. Peak seas are currently 43
ft. Scattered moderate convection is within 270 nm of the center
of Nigel. This general motion to the NE is expected to continue
for the next day or two. Weakening is forecast during the next
couple of days, and Nigel is forecast to become a post-tropical
cyclone tonight or early Friday. Hazards associated with Nigel
will remain well north of the TAFB forecast waters. Please read
the latest HIGH SEAS FORECAST issued by the Ocean Prediction
Center at website under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php. Please
see the latest Nigel NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Potential Tropical Cyclone Sixteen is centered near 28.7N 75.9W
at 21/1500 UTC or 320 nm SE of Charleston South Carolina, moving
N at 8 kt. Estimated minimum central pressure is 1012 mb.
Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Scattered moderate isolated strong convection is from 25N to 31N
between 72W and 75W. This general motion to the north is expected
to continue through early Friday. A north-northwestward to
northward motion is forecast by late Friday and continue into the
weekend. On the forecast track, the center of the cyclone is
expected to approach the coast of North Carolina within the
warning area Friday night and early Saturday. Strengthening is expected
during the next day or two, and the system is forecast to become
a tropical storm as it approaches the coast of North Carolina.
Regardless of whether the system become a tropical storm, the
system is expected to bring tropical-storm conditions to portions
of the southeast and mid-Atlantic coast. 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 Sixteen NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Eastern Tropical Atlantic: A far eastern Atlantic tropical wave
has its axis along 26W from 05N to 22N. It is moving westward at
10-15 kt. Scattered moderate convection is from 12N to 17N between
26W and 31W. Seas are 8-9 ft near the tropical wave. Environmental
conditions are forecast to be conducive for gradual development
of this system, and a tropical depression is likely to form this
weekend or early next week while the system moves generally
westward at 10 to 15 kt across the eastern and central tropical
Atlantic. There is a MEDIUM chance of development through 48
hours. Please see the latest Tropical Weather Outlook at
www.hurricanes.gov for more information.

...TROPICAL WAVES...

A weak central Atlantic tropical wave has its axis along 38W from
04N to 13N. It is moving westward at around 5-10 kt. No
significant convection is noted at this time. The tropical wave
may dissipate or be absorbed by the tropical wave currently along
26W.

A western Atlantic tropical wave has its axis along 55W, from 04N
to 23N, moving westward at 10-15 kt. No significant convection is
occurring with this tropical wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean near 18N16W and
continues to 1011 mb low pressure centered near 14N27W to 09N32W
to 10N53W. Scattered showers are within 180 nm of the monsoon
trough.

GULF OF MEXICO...

Ridging prevails across the basin, as high pressure centered over
the Northeast US presses south-westward. The remnants of a frontal
boundary is decaying across the Florida Keys and far SE Gulf.
Scattered moderate convection is noted across the eastern Gulf
waters, winds and seas may be locally higher in and near the
convection. Light to gentle winds and 1-3 ft seas are noted across
the basin.

For the forecast, high pressure will be in control of the weather
pattern across the Gulf waters allowing for generally gentle to
moderate east to southeast winds and slight seas, except pulsing
to moderate to fresh offshore the western Yucatan Peninsula in the
evenings. Developing low pressure east of Florida will tighten
the pressure gradient over the NE Gulf bringing moderate to
locally fresh NE winds across the NE Gulf tonight into Fri. A
frontal trough associated with the aforementioned low pressure
will move across the southeastern Gulf and the Straits of Florida
tonight into Fri.

CARIBBEAN SEA...

The latest scatterometer data shows fresh winds in the south-
central Caribbean. Elsewhere, trades are gentle to moderate across
most of the basin with seas of 4-6 ft. However, in the NW
Caribbean, winds are light and variable and seas are 2-4 ft.
Scattered showers are noted across the Lesser Antilles.

For the forecast, long period north to northeast swell moving
through the Tropical N Atlantic waters and Caribbean passages will
subside today. Moderate to fresh trade winds in the central
Caribbean will change little through the next few days. Northeast
to east trade winds will pulse to fresh to strong speeds offshore
northern Colombia and northwest Venezuela during the afternoons
and at night into early next week.

ATLANTIC OCEAN...

Please see the SPECIAL FEATURES section and the TROPICAL WAVES
section above.

A decaying stationary front extends from POTENTIAL T.C. SIXTEEN
across the Bahamas to the Florida Keys. A stationary front extends
from POTENTIAL T.C. SIXTEEN north-eastward to 31N73W. Convection
described in SPECIAL FEATURES. Elsewhere across the tropical
Atlantic, 1022 mb high pressure centered near 29N31W guides the
sensible weather. This morning's scatterometer data depicts gentle
to moderate trades across the basin, locally fresh along 20N where
the pressure gradient is maximized. Seas are 4-7 ft in open
waters.

For the forecast W of 55W, PTC Sixteen will move to 30.0N 75.5W
this evening,and will be N of area near 31.7N 75.4W by Fri
morning. In its wake, high pressure ridging will build from E to W
just north of the forecast waters into early next week.

$$
Mahoney
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