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Atlantic Tropical Weather Discussion

AXNT20 KNHC 151205

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Mon Oct 15 2018

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through 
1115 UTC.


A broad area of low pressure, called a Central American Gyre, is 
centered over the southwestern Caribbean Sea. Scattered moderate 
to isolated strong convection is noted from 12N to 16N between 
78W and 82W. There is a medium probability that a tropical cyclone
may develop within this broad circulation as the system moves 
westward toawards Central America. Regardless of tropical cyclone
development, this gyre will bring abundant moisture which will 
produce heavy rainfall across portions Central America for the 
next several days, including areas which have already seen heavy 
rainfall earlier this month. This heavy rainfall will bring the 
potential for flash flooding and mudslides over areas of 
mountainous terrain. Refer to your local meteorological service 
for specific information on this potentially dangerous weather 

A cold front will enter the far NW and W central Gulf of Mexico 
by Tue morning. Ahead of the front, numerous showers and 
thunderstorms are expected over the far NW and W central Gulf 
beginning late this morning and increasing this afternoon. This 
front will slowly shift southward over the western Gulf through 
Wed night. Fresh to strong northerly winds behind the front will 
increase to minimal gale force in the W central and SW Gulf behind
the front Tue night through Thu night. Winds will diminish below 
gale force by Fri. Due to the combination of the front with the 
Central American Gyre mentioned above, expect enhanced shower and 
thunderstorm activity over the southwestern Gulf of Mexico by Wed.


A low amplitude tropical wave extends its axis along 46W from 
01N-12N, moving west at 15-20 kt. A 700 mb trough is shown by 
model analyses with this wave. TPW imagery indicates abundant 
moisture in its environment. Scattered moderate to strong 
convection is occurring from 02N-14N between 42W-49W.

A tropical wave extends its axis along 53W from 08N-21N, moving 
west at 10-15 kt. A 700 mb trough is depicted by model analyses 
with the wave, and there is a local maximum in TPW. A recent ASCAT
pass shows that the tropical wave is well- defined at the surface
with 25-30 kt winds from 16N-18N within 60 nm of the wave axis. 
Scattered moderate to strong convection is noted from 11N-18N 
between 49W-52W. It is likely that the tropical wave along 46W 
will be merging with this wave over the next 24 hours. Expect 
plenty of convective activity near and in between both waves. 
Moisture associated with these waves is likely to enhance showers 
and thunderstorms over the Lesser Antilles Tuesday into Wednesday,
and this activity will spread to the eastern Caribbean Sea during
the middle of the week.

A tropical wave extends its axis along 64W from 08N-21N moving 
west at 10 kt. Scattered moderate convection is over Puerto Rico.
Scattered showers are noted over the northern Leeward Islands and
Virgin Islands. This wave is expected to continue weakening into 
Tuesday as it moves toward the central Caribbean.


The monsoon trough enters the eastern Atlantic from the coast of
Africa near 12N17W to 08N21W to 06N30W. The ITCZ extends from 
06N30W to 07N43W. Scattered moderate convection is S of the
monsoon trough from 01N-07N between 14W-24W. 


See Special Features section above for discussion of an expected 
gale behind a cold front in the western Gulf Tue night into Thu.

An upper-level anticyclone over central Mexico extends an upper-
level ridge over the western and north-central Gulf of Mexico. A 
surface ridge prevails across the northeastern and north-central 
Gulf. Isolated moderate convection is over the north central Gulf
from 26N-28N between 88W-90W. Scattered moderate convection is
along the coast of NE Mexico from 22N-26N between 97W-98W.


Two tropical waves will affect the Lesser Antilles over the next 
few days. See the Tropical Waves section for more details. Also 
see the Special Features section for information relating to the 
Central American Gyre.

A mid to upper level trough extends from 23N66W to the Mona
Passage. Elsewhere, scattered showers are within 60 nm of the 
northwest coast of Venezuela and the northeast coast of Colombia.


See above about the tropical waves in the tropical Atlantic. 

A cold front extends across the west Atlantic from 32N59W to 
30N66W, where it becomes a stationary front. The stationary front 
extends from that point to 28N74W, where it becomes a dissipating
stationary front. The dissipating stationary front extends from 
that point to near 27N79W. Isolated showers are along and within
60 nm SE of the front.

A 1024 mb high is centered near 30N47W, leading to relatively 
quiet weather elsewhere.

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