Atlantic Discussions
Basin Outlook & Discussion
ABNT20 KNHC 212327

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Thu Oct 21 2021

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Tropical cyclone formation is not expected during the next 5 days.

Forecaster Beven


AXNT20 KNHC 212317

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Fri Oct 22 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
2300 UTC.


The axis of a tropical wave is along 41W, south of 17N and it is
moving W at 10-15 kt. Saharan dry air follows the wave axis, as 
a result convection is limited near the wave. 

A tropical wave is along 55W, south of 17N. Scattered moderate 
to isolated strong convection is noted ahead of the wave axis S
of 10N between 55W and 60W. This convective activity is also
affecting parts of Guyana and Suriname. 

Another tropical wave is over the eastern Caribbean along 66W, 
south of 21N and it is moving W at 10-15 kt. This wave is at the
leading edge of a large area of Saharan dry air. Scattered 
showers are near the northern end of the wave axis. The wave is
also helping to induce some convective activity over northern

A second tropical wave is moving westward across the central
Caribbean. Its axis is along 74W extending from the Haiti to N 
Colombia, and it is moving W at 10-15 kt. Scattered moderate to
isolated strong convection is seen over parts of Hispaniola and
northern Colombia. 


The monsoon trough extends across the coast of Senegal from 
14N17W to 10N22W to 03N24W. The ITCZ continues from 03N24W to 
01N35W to 01N50W. Aside from convection noted in the tropical 
waves section above, scattered moderate convection is noted from 
05N to 10N and E of 16W to the W coast of Africa, and near 07N20W.


High pressure of 1025 mb located just E of Bermuda extends a
ridge across Florida into the eastern Gulf of Mexico. A surface
trough is over the NE Gulf while another surface trough is 
analyzed over the Bay of Campeche where some shower activity is 
noted. An area of showers, with embedded thunderstorms is over 
the SE Gulf and the Straits of Florida where moderate to fresh 
easterly winds prevail. Mainly gentle to moderate winds dominate 
the Gulf region with seas in the 3-5 ft range E of 92W, and 1-3 
ft elsewhere. Highest seas of 4-6 ft are in the Straits of 

For the forecast, weak high pressure will generally dominate the
Gulf waters into early next week, although a stalling cold front
will skirt across the NE Gulf this weekend. Moderate to fresh 
easterly winds are expected across the SE Gulf through tonight, 
otherwise gentle to moderate winds will prevail. 


A pair of tropical waves are moving westward across the east and
central Caribbean. Please, the Tropical Waves section for details.
Convection has flare-up over the central and western Caribbean, 
including Cuba, Hispaniola, Jamaica, NE Honduras, northern Nicaragua
and the northern Yucatan Peninsula. A diffluent pattern aloft is
helping to induce this convective activity. A surface trough is 
over the Yucatan peninsula. 

Latest scatterometer data provided observations of fresh to strong
winds E of the Lesser Antilles. Seas are in the 7 to 10 ft range
W of 50W based on altimeter data and buoy 41040. Gentle to moderate
trade winds are generally observed across the Caribbean Sea, with
seas of 3-5 ft S 0f 18N E of 80W, and 1-3 ft elsewhere, except 
3-4 ft in the Yucatan Channel. 

For the forecast, high pressure N of the area will support fresh
to locally strong trades E of the Windward Islands through the 
weekend. During this period, moderate to fresh winds are expected
over the south-central Caribbean, with winds reaching locally 
strong in the Venezuela basin. Gentle to moderate tradewinds will
prevail elsewhere. 


High pressure of 1025 mb located just E of Bermuda dominates the
SW N Atlantic, the Bahamas and Florida. This system extends westward
into the eastern Gulf of Mexico. A dissipating frontal boundary 
stretches from 31N44W to 26N56W, then continues as a surface 
trough to the Turks and Caicos Islands. Some shower and thunderstorm
activity is near the trough axis. Moderate to locally fresh NE 
winds are N of the trough, particularly between 60W and 70W with
seas of 6-7 ft. A 1029 mb Azores High dominates the remainder of
the Atlantic forecast area, and is driving moderate to fresh NE 
to E trades N of the ITCZ. Seas are generally 4 to 6 ft, except
6-9 ft W of the Canary Islands in NW swell.

The Cumbre Vieja volcano, on the island of La Palma in the 
Canary Islands, has been erupting since 19 September 2021. Ash 
emission is on-going. A volcanic ash plume is identifiable on  
satellite imagery moving toward El Hierro Island. Marine and 
aviation interests should monitor this ongoing situation by 
reading the Volcanic Ash Advisory issued by Meteo- France at /la-palma/.

For the forecast west of 65W, high pressure will move east of 
the forecast region tonight, and a weak cold front will move off
the SE U.S. coast Fri night, then stall over northwest portions 
of the area through the weekend. Moderate to locally fresh winds 
tonight will subside by Fri as the high pressure moves away from 
the area.


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