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Atlantic Tropical Weather Discussion



743 
AXNT20 KNHC 272330
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Thu Oct 28 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 
2315 UTC.

...SPECIAL FEATURES...

Gulf of Mexico Gale Warning: Strong to gale force winds will 
follow a strong cold front that as of 21Z extends from
southwestern Louisiana to 26N95W and to inland northeastern 
Mexico. The front will quickly move across the basin through Thu 
night. A Gale Warning is in effect for post-frontal gale-force 
winds of 30-40 kt for the north-central and NE Gulf waters 
beginning late tonight into early Thu and continuing through Fri 
morning. Prior to that time, strong to near-gale force northwest 
winds will follow in behind the front along with seas to 9 ft. 
Seas will build to near 20 ft in the wake of the front over the 
northern Gulf. Mariners are urged to exercise caution as a 
rather robust squall line denoted by scattered moderate to 
strong convection is racing out ahead of the front. This 
activity is occurring north of 27N between 90W-92W and from 26N 
to 27N between 92W-94W. Some of this activity may be reaching 
severe limits. It is capable of producing strong gusty winds, 
heavy rain and reduced visibility. Please, see the latest NWS 
High Seas Forecast issued by the National Hurricane Center at 
website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for 
further details.

...TROPICAL WAVES...

The axis of an eastern Atlantic tropical wave extends from 20N31W
to 14N34W and to 04N33W. It is moving westward at about 10-15 kt.
Isolated showers and thunderstorms are east of the wave to 30W 
from 10N to 13N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends off the southern coast of Senegal
near 14N17W to 08N30W and to 06N40W. The ITCZ axis extends from 
07N40W to 07N50W and to the northeast Venezuelan coast near 
08N59W. Scattered moderate convection is within 300 nm south of 
the trough between 20W-29W, within 120 nm north of the trough 
between 20W-25W and within 120 nm south of the trough between
36W-38W. 

GULF OF MEXICO...

A Gale Warning related to a western Gulf cold front is presently 
in effect for the north-central and NE Gulf areas. Please see the 
Special Features section for more information on this marine 
event.

As stated earlier, as of 2100 UTC a strong cold front extends 
from southwestern Louisiana to 26N95W and to inland northeastern 
Mexico. A potent squall line extends from south-central Louisiana
to 28N93W and to 26N95W. Both buoy and oil platform observations 
reveal that fresh to strong southerly winds are present over the 
NW Gulf as well as over the western part of the central Gulf. A 
recent observation from ship with caller ID "KAWM" near 27N91W 
indicates 30 kt winds. Strong wind gusts, heavy rain and reduced 
visibility can be expected as the squall line races eastward 
across the northern Gulf waters through late Thu. Oil platform 
station "KGHB" located near 28N92W recently reported northwest
35 kt winds as convection with the squall line passed over it.
Elsewhere, a warm front extends from southeastern Louisiana to 
27N86W, where it transitions to a stationary front to Fort Myers, 
Florida. Aside from convection with the aforementioned squall 
line, isolated showers are near the stationary front between 84W- 
86W and east of the warm front to 88W north of 29N. The remainder 
of the Gulf is under fairly tranquil weather conditions. Outside 
of the winds being influenced by the strong cold front and squall 
line over the NW Gulf, light to gentle southerly winds are east of
86W, while moderate to fresh southerly winds are west of 86W. 
Seas of 3-6 ft are west of 90W and 1-3 ft are east of 90W.

For the forecast, the previously mentioned strong cold front will
quickly move across the rest of the basin through Thu night 
preceded by a squall line that is accompanied by scattered strong 
to possibly severe scattered showers and thunderstorms. Fresh to 
strong S winds will continue ahead of the front, with strong to 
gale force winds expected over the north-central and NE Gulf from
starting late tonight into Thu and continuing through early Fri.

CARIBBEAN SEA...

The interaction of a weak surface trough in the central Caribbean
Sea and a weak 1010 mb low pressure along the eastern segment of 
the eastern Pacific monsoon trough is resulting in an area of 
showers and isolated thunderstorms from the northwestern coast of
Colombia to 12N and between 76W and 81W. The rest of the basin is
under the influence of a dry air mass as inferred from the
subsidence as depicted in water vapor imagery. This is allowing 
for fairly tranquil weather conditions to exist. Latest ASCAT data
indicates mainly fresh trades south of 15N and east of 78W. Fresh
trades are also over a portion of the Gulf of Honduras per latest
ASCAT data, while gentle to moderate trades are present elsewhere
over the basin. Seas are generally in the 2-4 ft range, except 
for slighter higher seas of 4-6 ft north of 15N and east of 80W.

For the forecast, a weak ridge over the northern Caribbean Sea 
will support mainly fresh trades across the south-central 
Caribbean, including the Gulf of Venezuela through early Thu. 
Gentle to moderate southeast to south winds will continue over 
the northwestern Caribbean through Thu night ahead of a cold 
front that is forecast to reach western Cuba and the northwestern
Caribbean. The front will extend from western Cuba to the Gulf of
Honduras by midday Fri, and from central Cuba to the northeastern
part of Honduras on Sat, then stall on Sun from eastern Cuba to 
near Cabo Gracias a Dios, Nicaragua while dissipating.

ATLANTIC OCEAN...

A cold front extends from the strong extratropical cyclone located
off New England to near 31N65W and southwestward to 27N72W, where
it becomes a stationary front to across the northwestern Bahamas 
and to South Florida. A pre-frontal trough extends from near 
31N62W to just north of the southeastern Bahamas. Scattered 
moderate to isolated strong convection is within 120 nm east 
of the trough north of 27N, while scattered moderate convection 
is within 30 nm of the cold front. Isolated showers and 
thunderstorms are along the stationary front. Afternoon ASCAT
data passes reveal fresh to strong cyclonic winds north of 25N 
and between 57W and 75W. Seas of 8-10 ft due to a northwest to 
north swell mixed with a southeast to south swell are occurring 
north of 27N and between 57W-77W.

Farther east, a weak trough is analyzed from 31N43W to 24N47W.s 
are found in the central Atlantic, but no significant convection 
is associated with this feature. The central and eastern tropical 
Atlantic are dominated by broad high pressure anchored by two 1021
mb high pressure centers: one between the Azores and Madeira 
Islands and the other one near 31N32W. This area of broad high 
pressure is supporting fairly tranquil weather over this part of 
the area. The associated gradient between the high pressure and 
lower pressures to the south is allowing for moderate to locally 
fresh trades to exist south of about 16N and east of about 60W. 
Seas in the range of 4-7 ft are elsewhere over the basin.

The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. High volcanic
ash concentration is in the vicinity of the volcano. Light 
volcanic ash concentration is elsewhere. Volcanic ash is drifting
southwestward. Marine and aviation interests should monitor this 
ongoing situation by reading the Volcanic Ash Advisory issued by 
Meteo- France, at http://vaac.meteo.fr/volcanoes/la- palma/.

For the forecast west of 65W, the cold front will stall tonight.
The entire frontal boundary will gradually dissipating into Thu
North of 25N and east of 75W, fresh to strong west winds follow 
this boundary, along with seas of 8-10 ft. The next cold front 
from will move across the northwestern forecast waters Thu night 
through Fri night, then stall from near 31N68W to eastern Cuba 
over the weekend. Fresh to strong winds and building seas are 
expected on either side of this front.

$$
Aguirre