[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Sun Aug 26 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 0000 UTC surface analysis and satellite imagery through
2345 UTC.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave partially crosses the W
African coast with its axis along 16W/17W from 04N to 20N, moving
westward at 10-15 kt. The wave is embedded within the broad
monsoonal trough region of W Africa. Moisture and convection
within this region has continues to increased during the past
couple of days as observed on GOES-16 imagery. The latest imagery
shows scattered moderate to strong convective clusters just east
of thew wave axis along and just inland the coast of Africa from
09N to 12N. Broken to overcast multilayer clouds with embedded
scattered moderate convection are seen within 240 nm west and 120
nm east of the wave axis from 05N to 10N.

A central Atlantic tropical wave has its axis along 45/46W from
03N to 20N, moving westward at 15 kt. This wave is surrounded
by a rather stable and dry environment. Only isolated showers are
possible within 120 nm on either side of the wave.

A western Caribbean Sea tropical wave has its axis along 78W
south of 20N, moving westward at 10-15 kt. This wave is moving
into an area of pre- existing upper level cyclonic wind flow. The
northern portion of the wave is helping to trigger off scattered
moderate convection over eastern Cuba, while at the same time
an upper-level low moves westward across central Cuba. Isolated
showers are possible within 120 nm on either side of the wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal sections of
Guinea-Bissau near 12N17W to 10N24W to 10N34W and to 09N445. No
ITCZ was discernible. Aside from convective activity associated
with the far eastern Atlantic tropical wave, scattered moderate
isolated strong convection is within 240 nm south of the trough
axis between 23W and 28W. Scattered moderate convection is within
180 nm south and 120 nm north of the trough axis between 34W and
38W. Similar activity is within 60 nm south of the trough axis
between 29W and 32W.

...DISCUSSION...

GULF OF MEXICO...

An upper level trough extends from the coastal waters of Georgia
and South Carolina, across NE Florida, to an upper-level low at
24N92W. At the surface, a westward moving trough extends from
28N88W to 22N88W. Upper-level cyclonic wind flow covers nearly the
entire Gulf of Mexico east of 94W eastward. A second upper-level
low is noted at the coast of Mexico near 20N97W. With these
features in play along with a very moist and unstable atmosphere
in place, abundant scattered shower and thunderstorm activity will
continue over much of the basin through the next couple of days.

A surface trough will develop during the evening hours in the
Yucatan Peninsula, before pushing offshore into the SW corner of
the Gulf of Mexico each night. This trough, in combination with
daytime heating and ample instability in place, has triggered off
scattered moderate isolated strong convection over much of the
Yucatan Peninsula. The activity is expected to diminish late
tonight. A surge of moderate to fresh NE to E winds will
accompany this trough. A weak surface ridge will remain
over the rest of basin, with its associated gradient supporting
a gentle to moderate wind flow regime.

CARIBBEAN SEA...

An upper level trough extends from a 21N63W Atlantic Ocean cyclonic
circulation center, through the Mona Passage, to 16N72W just off
the coast of Hispaniola, and eventually to 15N77W to the south of
Jamaica. Isolated moderate rainshowers are from 14N northward
from 80W eastward. Isolated to widely scattered showers are on the
Atlantic Ocean side of Cuba between the SE Bahamas and 80W. An
upper-level low moving westward is evident over central Cuba near
22N78W. Scattered moderate convection covers just about the entire
island of Cuba.

A shear axis extends from the upper-level low over Cuba to 19N83W
and to near 17.5N86W. Plenty of atmospheric instability exists
across the western Caribbean. This is resulting scattered showers
and thunderstorms to exist west of 80W, including the Gulf of
Honduras. In addition, the eastern segment of the eastern Pacific
monsoon trough stretches eastward into the far southwestern
Caribbean to the northwestern coast of Colombia. Scattered showers
and thunderstorms are seen along and near this trough axis south
of 11N and west of 75W.

Fresh to strong winds, and building seas to 10 feet, will continue
in the south central Caribbean Sea through Wed. A stronger
tropical wave will approach the waters E of the Lesser Antilles on
Tuesday, bringing fresh easterly winds and sea heights about 8
feet. The wave will enter the eastern Caribbean early on
Wed, increasing the likelihood of scattered showers and isolated
thunderstorms over much of the Lesser Antilles.

ATLANTIC OCEAN...

The southernmost point of a surface trough is 31N81W along the
coast of SE Georgia. An upper level trough extends from NE Florida
to a central Gulf of Mexico cyclonic circulation center. Widely
scattered moderate to isolated strong rainshowers are to the NW of
the line that passes through 32N71W to 28N80W along the eastern
coast of Florida.

An upper level trough extends from 32N68W, to an upper-level
low near 28N70W and to a second upper-level low over central
Cuba. Isolated to widely scattered moderate rainshowers are
elsewhere from 20N northward 66W and 80W.

An upper level trough is at the western edge of the Canary
Islands, from a 35N16W cyclonic circulation center to 24N21W. A
second upper level trough extends from an upper-level low near
32N43W to 28N50W and to a second upper-level low near 21N63W. The
trough continues toward the southern coast of Hispaniola. A
surface trough extends from a 1022 mb low pressure center that is
near 31N50W southwestward to near 29N52W. Isolated showers and
thunderstorms are elsewhere to the NW of the line that passes
through 32N38W to 24N50W to 18N62W.

A central Bahamas surface trough is forecast to move across the
area through Mon. Gentle to moderate winds will be associated
with this trough. The wind speeds will pulse to fresh to strong at
night just north of Hispaniola through Tue. A weak surface ridge
will remain over the remainder of these waters, with its
associated gradient supporting gentle to moderate E to SE wind
flow.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Aguirre
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