AXNT20 KNHC 212353
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
753 PM EDT Thu Jun 21 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 1800 UTC surface analysis and satellite imagery through
The axis of a tropical wave is near 26W from 03N-12N, moving W at
20 kt. Abundant cloudiness surrounds the wave's axis but
convection is limited.
The axis of a tropical wave is near 35W from 3N-11N, moving W at
20 kt. Scattered showers are noted from 05N to 08N between 30W and
The axis of a tropical wave is near 44W from 3N-11N, moving W at
about 15 knots. Scattered moderate convection is noted from 03N to
08N between 40W and 47W.
The axis of a tropical wave is near 62W from 6N-17N, moving W at
about 10 knots. Scattered moderate convection associated to this
wave is affecting much of the Windward Islands.
The axis of a tropical wave is near 73W from northern Colombia to
western Hispaniola. Moisture associated to this tropical wave is
supporting scattered showers and isolated thunderstorms across
The monsoon trough passes through the coastal sections of Guinea
near 10N13W to 05.5N30W. The ITCZ continues from 05.5N30W to
05N34W to 05N43W to 05N52W. Outside of the convection associated
with the tropical waves, isolated moderate convection is from 04N
to 08N between 55W and 58W.
GULF OF MEXICO...
A 1009 mb low pressure centered along the Texas/NE Mexico border
near 26.5N99W continues to produce a large area of showers with
embedded tstms over the western Gulf coast and NE Mexico,
particularly over the states of Nuevo Leon and Tamaulipas, where
heavy rain has been reported. This slow moving system will
continue to generate rounds of rainfall across the western Gulf
coast from Texas to western Louisiana today. Flooding of low lying
and poor drainage areas will be possible. Winds and seas in the
NW Gulf will diminish further today as the low weakens.
A broad ridge will persist over the eastern Gulf, and support
light winds and seas less than 3 ft east of 88W through the
A surface trough will develop in the Yucatan Peninsula each
afternoon, then move westward across the SW Gulf during the
overnight hours, accompanied by fresh to occasionally strong east
to southeast winds.
A tropical wave is moving across the central Caribbean. Another
tropical wave is moving into the eastern Caribbean. See Tropical
Waves section for details. Expect increasing showers and isolated
thunderstorms in association with the passage of these tropical
High pressure N of area is forecast to strengthen over the next
couple of days while moving westward. As a result, the trade
winds over the south-central Caribbean will strengthen and expand
in areal coverage across the basin through early next week. Winds
could reach near gale force along the coast of Colombia by Sun
night. Fresh to strong winds will affect the Gulf of Honduras
each night beginning tonight through Mon night.
An upper-level trough extends from a cyclonic circulation located
over the western Atlantic near 27N67W to another cyclonic
circulation over the NW Caribbean and the Yucatan Peninsula. A
diffluent pattern aloft between this trough and an anticyclonic
circulation over the south-central Caribbean is helping to support
scattered showers and tstms across the Caribbean waters from 15N-
20N between the tropical wave along 73W and 85W. As of 2100 UTC,
a trough, surface reflection of the upper-level low is analyzed
over the NW Caribbean, and extends from 20N86W to the Gulf of
Honduras. Abundant tropical moisture will persist across the NW
Caribbean and the Yucatan Peninsula on Fri.
An upper-level trough extends from a cyclonic circulation centered
near 27N67W to eastern Cuba. Scattered showers and tstms are
noted on the SE semicircle of the low affecting mainly the waters
from 21N to 27N between 60W and 70W.
High pressure of 1029 mb centered near 33N34W extends a ridge
westward across the forecast area. Fresh trades are noted along
the southern periphery of the ridge, but mainly between 40W-70W.
This high pressure will slowly shift westward through Sat night,
then remain nearly stationary near 30N55W through Tue. The
tightening pressure gradient that results over the central
Atlantic will support fresh to strong trade winds and seas of 8-10
ft E of the Lesser Antilles to about 45W by early Sat morning.
These marine conditions will persist on Sun.
The Saharan Air Layer (SAL) from CIMSS and visible satellite
imagery indicate the presence of African dust between the west
coast of Africa and the Lesser Antilles, more concentrated E of
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