[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 260604
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
204 AM 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
0545 UTC.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 28W from
05N to 20N, moving westward at 15 kt. Scattered moderate
convection is within 30 nm of line from 12N28W to 11N34W, and
within 30 nm of line from 06N26W to 05N28W to 04N32W. Isolated
showers are elsewhere from 10N to 13N between 27W and 30W.

Another eastern Atlantic tropical wave has its axis along 38W/39W
from 04N to 20N, moving westward at 10-15 kt. Broken to overcast
multilayer clouds along with scattered moderate isolated strong
convection are noted where the wave axis crosses the monsoon
trough, and to the south of the monsoon trough. The scattered
moderate isolated strong convection is occurring from 05N to 07N
between 35W and 37W. Scattered moderate isolated strong convection
is within 30 nm of line from 11N34W to 11N38W, and within 30 nm of
line from 11N39W to 11N44W. Scattered showers and isolated
thunderstorms are seen along the monsoon trough within 120 nm east
of the wave.

A central Atlantic tropical wave has its axis along 55W from 03N
to 19N, moving westward at 15 kt. Isolated showers and thunderstorms
are within 60 nm either side of the wave south of 08N.

A central Caribbean Sea tropical wave has its axis along 72W south
of 19N to well inland S America, moving westward at 10-15 kt.
Rather dry and stable conditions surround this wave. Isolated
showers moving quickly westward are possible near this wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from coast of Senegal near
14N17W, to 10N23W, 09N30W, 08N36W, and 07N39W. The ITCZ continues
from 07N39W to 05N45W and 05N50W. Aside from convection associated
with the tropical waves, increasing scattered moderate isolated
strong convection is south of the trough axis within 30 nm of a
line from 06N12W to 07N20W to 07N26W, and also within 60 nm of
08N145W.

...DISCUSSION...

GULF OF MEXICO...

A narrow NE-to-SW oriented upper-level trough extends from 32N81W
near the South Carolina/ Georgia border, across NE Florida, to
28N83W in the NE corner of the Gulf of Mexico, to 23N88W in the
Gulf of Mexico. An inverted mid/upper-level trough progressing
westward at 15-20 kt is along a position from near 30N85W to
25N87W and to near 23N88.5W. A surface trough is analyzed from
29N84W to 24N85W. Latest radar and satellite imagery show
scattered showers and thunderstorms covering over much of the
waters east of 88W. Isolated showers and thunderstorms are noted
between 88W and 96W. Weak high pressure exists over the area.

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. A surge of moderate to fresh NE to
E winds will accompany this trough. High pressure will continue
across the remainder of the area, supporting a gentle to moderate
wind flow.

CARIBBEAN SEA...

An upper-level trough extends from an upper low near 22N62W
southwestward to near 20N64W, then becomes a shear axis to
another upper-level low at 15N71W. Lack of deep level moisture
over the eastern and central Caribbean is only allowing for
isolated showers to persist there in the easterly flow. A rather
weak upper-level low is over the far southwestern Caribbean near
12N77W. Scattered showers and thunderstorms are seen south of 14N
and west of 77W. A very moist and unstable atmospheric environment
present over the remainder of the western Caribbean is conducive
for sustaining scattered shower and thunderstorm activity as well
as for additional ones to form there into the upcoming week.
Scattered showers and thunderstorms over and near the Windward
Passage will continue through at least tonight under, with support
from upper-level disturbances that are rotating in a cyclonic
fashion around an upper-level low centered between the central
Bahamas and Cuba.

Fresh to strong winds and building seas to 10 ft will prevail in
the south-central Caribbean Sea through Wed. The tropical wave
along 72W will move across the rest of the central Caribbean
through Mon evening, and across the western Caribbean Tue through
Wed night. Another tropical wave is forecast to approach the
Lesser Antilles on Tue and Tue night, and enter the eastern
Caribbean on Wed. This wave is forecast to be accompanied by
scattered to numerous showers and thunderstorms, some of which may
produce gusty winds and rough seas.

ATLANTIC OCEAN...

An upper-level cyclonic circulation center is identified on water
vapor imagery to be between the central and Cuba near 23N77W,
moving westward. A second cyclonic circulation center is near
28N67W. A surface trough, clearly noted in scatterometer pass from
last night, is analyzed from near 27N70W to just north of Haiti
at 20N72W. Gentle to moderate winds are being produced by the
gradient associated with this trough. Instability provided by
these features on an already very moist and unstable atmosphere is
allowing for scattered showers and thunderstorms to continue over
the waters west of 65W, with the most concentrated activity
present from 24N to 27N between 69W and 73W. Scattered showers
and isolated thunderstorms are seen from 24N to 26N between 68W
and 71W due to an upper-level disturbance moving westward around
the southwestern periphery of an upper-level ridge that extends
from an upper anticyclone that is near 31N60W. Isolated showers
are elsewhere west of 70W. The surface trough is forecast to move
across western half of the area through Mon.

An upper-level trough extends from an upper-level cyclonic
circulation center near 33N18W to another upper-level cyclonic
circulation near 30N46W. The trough continues to a third cyclonic
upper-level circulation center near 22N62W and southwestward from
there to near 20N64W. A surface trough is along a position from
31N43W to 29N50W. Scattered showers and thunderstorms are seen
from 29N to 31N between 42W and 49W. Isolated showers, moving
quickly westward, are elsewhere between 42W and 70W.

Winds will pulse to fresh to strong during the evening and
nighttime hours between the southeastern Bahamas and Hispaniola
through the middle of next week. A surface ridge will dominate the
rest of the forecast area, supporting a gentle to moderate
anticyclonic flow.

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

$$
Aguirre
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