[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182207
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sun Sep 19 2021

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
2050 UTC.

...SPECIAL FEATURES...

Post-Tropical Cyclone Odette is centered near 39.1N 65.1W at
18/2100 UTC or 260 nm ESE of Nantucket Massachusetts moving ENE
at 16 kt. Estimated minimum central pressure is 1001 mb. Maximum
sustained wind speed is 40 kt with gusts to 50 kt. The convection
is located well east of the given center with scattered moderate
to strong noted from 35N to 41N between 55W and 63W. Odette
is moving toward the east-northeast and this general motion with
an increase in forward speed is expected through Sun. A turn
toward the east and east-southeast with a decrease in forward
speed is expected on Mon and Tue. On the forecast track, the
center of Odette will pass well south of Atlantic Canada tonight
through Mon. Strengthening as a post-tropical cyclone is forecast
during the next day or two. Please read the latest Atlantic
High Seas Forecast issued by the Ocean Prediction Center at
https://www.ocean.weather.gov/ and the latest NHC Public Advisory
at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and
Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml
for more details. Please refer to products from the Canadian
Hurricane Centre for additional information on potential impacts
in Newfoundland at weather.gc.ca/hurricane/

Atlantic Gale Warning: A tropical wave is in the Atlantic Ocean
along 51W/52W from 06N to 22N, while a 1008 mb low pressure area
is along the tropical wave near 15.5N52W, or about 650 nm E-SE of
the northern Leeward Islands, moving west at around 15 kt.
Associated winds are currently 20 to 30 kt, and are forecast to
increase to 35 kt in the next few hours with a gale warning
currently in place. Peak seas are currently 8 to 10 ft. Scattered
moderate to strong convection is noted within 300 nm in the east
semicircle, 180 nm southwest quadrant, and 480 nm in the
northwest quadrant. This low continues to show signs of
organization, however satellite-derived wind data from a few hours
ago indicated that the system does not yet have a well- defined
surface circulation. Only a slight increase in organization of
this system would lead to the formation of a tropical depression
or tropical storm, which is expected to occur later today or
tonight while the low moves toward the west-northwest at about 15
kt. This system is expected to be near the northern Leeward
Islands on Mon and Tue, and interests there should monitor its
progress. Upper-level winds are likely to become less conducive
for development when the system reaches the southwestern Atlantic
by the early to middle part of next week. This low has a high
chance for tropical cyclone formation in the next 48 hours.
Additional information on this system, including gale warnings,
can be found in the High Seas Forecasts issued by the National
Weather Service at:
www.hurricanes.gov/marine and latest NHC Tropical Weather Outlook
at www.hurricanes.gov for more details.

A tropical wave is in the Atlantic Ocean along 26W/27W from 03N to
19N, while a 1008 mb low pressure area is along the tropical wave
near 09N26.5W, over the far eastern Atlantic a few hundred nm
south-southwest of the Cabo Verde Islands, moving west at around
5 kt. Associated winds are currently 20 to 30 kt with peak seas of
8 to 10 ft. Scattered moderate to strong convection is noted from
07N to 11N between 25W and 33W. The low continues to show some
signs of organization, and environmental conditions appear
conducive for further development of this system. A tropical
depression could form over the next couple of days while moving
toward the northwest at 10 to 15 kt to the west of the Cabo Verde
Islands. This system is expected to reach cooler waters and an
area of stronger upper- level winds early next week, which could
limit its development. This low has a medium chance for tropical
cyclone formation in the next 48 hours.
Additional information on this system can be found in the Meteo-
France High Seas Forecast at:
http://weather.gmdss.org/II.html and also refer to the latest NHC
Tropical Weather Outlook at www.hurricanes.gov for more details.

...TROPICAL WAVES...

Refer to the Special Features section above for details on two
tropical waves in the Atlantic Ocean.

A tropical wave is located near the Yucatan Peninsula and far
eastern Bay of Campeche along 91W south of 19N into the eastern
Pacific Ocean, moving west at around 10 kt. No deep convection is
occurring in association with this tropical wave over water,
however showers and thunderstorms are noted over northern
Guatemala and portions of eastern Mexico.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends across the coast the Mauritania at
18N16W through 1008 mb low pressure near 09N26.5W to 05N35W to
06N38W. The ITCZ continues from 06N38W to 12N48W. Other than the
convection described above, scattered moderate and isolated strong
convection is noted from 05N to 08N between 33W and 37W. Scattered
moderate convection is noted within 180 nm south of the monsoon
trough and ITCZ between 30W and 46W.

...GULF OF MEXICO...

A surface trough continues to linger over the north-central and
central Gulf from the coast of Louisiana near 29N90W to 24N95W to
22N97W. Scattered moderate and isolated strong convection is noted
within 240 nm southeast of the trough. Another surface trough is
analyzed from 21N95W to 18N94W in the Bay of Campeche. Otherwise,
a broad ridge extends into the eastern Gulf of Mexico. Gentle to
moderate SE-S return flow is noted south of 25N and east of 93W,
with light and variable winds elsewhere. Seas are in the 2 to 4 ft
range across the central and eastern Gulf, and 3 ft or less across
the western Gulf.

For the forecast, weak high pressure will extend across the
eastern and central Gulf of Mexico through early next week. This
pattern will support continued gentle to moderate winds and mostly
slight seas across the Gulf through the next several days.
Looking ahead, a weak cold front may move into the northwest and
north-central Gulf by mid week.

...CARIBBEAN SEA...

The eastern extension of the east Pacific Ocean monsoon trough
enters the SW Caribbean Sea near the Costa Rica and Panama border
and continues to northern Colombia. Scattered moderate to strong
convection is noted south of 11N. Afternoon and early evening
isolated thunderstorms are noted over portions of Hispaniola,
Jamaica and Cuba, as well as portions of Central America.
Otherwise, the rest of the basin is dominated by generally dry
weather conditions, suppressing the development of showers and
thunderstorms. Moderate to fresh trades are noted north of 10N and
west of 80W, with gentle to moderate trades east of 70W. Seas are
6 to 9 ft in the SW Caribbean, 4 to 6 ft elsewhere west of 70W,
and 3 to 5 ft east of 70W.

For the forecast, the Atlantic ridge will shift westward through
Sun. This will support fresh to strong winds over the south-
central Caribbean and Gulf of Honduras into early Sun. The ridge
will weaken starting Sun night as a tropical wave and area of low
pressure currently across the central Atlantic along 52W move to
the northeast of the Leeward Islands early Mon, then begin to move
more northwest. There is a high chance this low pressure will
form into a tropical cyclone over the next several days.
Regardless of further development, expect increase winds, seas and
thunderstorms north through east of the Leewards early next week.

...ATLANTIC OCEAN...

Refer to the Special Features section above for details on two
disturbances in the tropical Atlantic with a chance of tropical
cyclone formation over the next few days.

Otherwise, a broad 1027 mb subtropical ridge anchored near the
Azores extends southwestward to the Bahamas and Florida. A weak
surface trough is analyzed from 30N51W to 23N54W with scattered
moderate convection noted from 23N to 25N between 52W and 56W.
A few showers and thunderstorms are also noted off the northeast
coast of Florida in association with convection spilling from the
Gulf of Mexico. The rest of the basin enjoys fairly tranquil
weather conditions. Fresh to locally strong NE winds are observed
off the coast of northern Africa and the waters surrounding the
Canary Islands. Moderate to fresh trades are noted north of the
convergence zone and east of 40W, with gentle to moderate winds
elsewhere. Seas in the tropical Atlantic east of 55W are in the 4
to 7 ft range, and 3 to 5 ft west of 55W.

For the forecast west of 55W, weak ridging through the northern
Bahamas will support mostly light breezes and slight seas north of
22N through early next week, and moderate to fresh trade winds
and moderate seas south of 22N through Sun. Meanwhile, an area of
low pressure currently over the central tropical Atlantic along
52W will approach the waters northeast of the Leeward Islands Sun
and Mon then begin to move more northwest over open Atlantic
waters. There is a high chance this low pressure will form into a
tropical cyclone over the next several days. Regardless of further
development, expect increase winds, seas and thunderstorms north
through east of the Leewards Islands and northeast of Puerto Rico
early next week.

$$
Lewitsky
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