Tropical Prediction Center's Tropical Weather Discussion


North America - Central America - Gulf of Mexico - Caribbean - Atlantic Ocean

Data from the Plymouth State Weather Center

AXNT20 KNHC 162353

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
753 PM EDT Mon Jul 16 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 
2315 UTC.


SW Caribbean Sea gale warning: The synoptic pattern set-up with 
strong high pressure situated over the central Atlantic interacting
with broad low pressure over the SW Caribbean Seas and over 
northern S America will allow for the ongoing strong to near gale
force NE to E strong winds near the coast of Colombia from 11N to
13N between 73W and 75W to again reach minimal gale force Tue 
night and Wed night over the same area along with seas in the 
range of about 9-12 ft. Please read the High Seas Forecast, under
the AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details.


A tropical wave is over W Africa along 12W from 04N-15N, moving W
at 15 kt. A well defined 700 mb trough is noted together with an
inverted-V convection signature. Widely scattered moderate
convection is from 07N-15N between 08W-18W. 

An eastern Atlantic tropical wave axis stretches from near 21N40W
to 06N42W, moving westward at 15-20 kt. The wave is depicted on 
GOES-16 RGB imagery as having a rather broad inverted-V shape 
envelope of broken to overcast of mainly stratocumulus clouds 
covering over an area from 09N-23N between 30W-50W. Scattered 
moderate convection is behind the wave along and within 60 nm 
either side of the ITCZ between 35W-40W. Scattered showers and 
isolated thunderstorms are ahead of the wave from 06N-09N between 
the wave and 44W. The GOES-16 RGB images along with visible images
of the far eastern Atlantic are depicting yet another massive 
plume of Saharan dry air and associated dust following in behind 
the wave from 09N-27N east of 36W to well inland Africa, where 
even more intense Saharan dust is being captured by the GOES-16 
imagery behind and around another tropical wave. Visibilities 
within these areas of dust are expected to be sharply reduced.

An eastern Caribbean Sea tropical wave is tilted NE to SW with its 
axis reaching from E Hispaniola to the coast of Venezuela at 
10N71W, moving westward at about 20 kt. This wave continues to be
impinged upon by Saharan dust as observed in GOES-16 satellite 
imagery. Scattered moderate convection is inland over most of
Hispaniola. This wave will move across the rest of the eastern 
Caribbean Sea through by early Tue, then across the central 
Caribbean Sea through Wed night and the western Caribbean Seas Thu
through Fri before moving inland Central America and the Yucatan 
Peninsula Fri night. The Saharan dust in its wake will filter 
across the eastern Caribbean and much of the central Caribbean 
through Wed.

A western Caribbean Sea tropical wave has its axis along 87W S of
20N, moving westward at 10-15 kt. Scattered moderate isolated 
strong convection is over the Yucatan Peninsula and Central 
America from Guatemala to Panama. This wave will move west of the
area and into the eastern Pacific late Tue.

The monsoon trough extends from W Africa near 15N17W to 08N30W.
The ITCZ continues to 08N30W to 08N40W to South America near
06N53W. Widely scattered moderate convection is is from 05N-09N
between 20W-48W. 


A 1019 mb high centered over the central gulf waters near 27N92W,
and is the main feature that is influencing the synoptic pattern 
across the basin. Its associated gradient is allowing for 
generally light to moderate anticyclonic flow to exist over the 
gulf waters. Current NWS mosaic radar shows scattered moderate to
isolated strong convection over the northern gulf north of 28N 
and E of 92W. Similar convection is over the Florida Peninsula. 
This activity is expected to remain active through at least the 
next couple of days as upper-level disturbances move from E to W 
around the eastern periphery of an upper-level anticyclone 
centered over western Texas. Isolated showers and thunderstorms 
moving westward are present over much of the eastern gulf waters 
as well as over the eastern half of the central gulf. This 
activity should continue through tonight and into Tue. Expect high
pressure to prevail across the northern waters through Thu. A 
surface trough will move westward off the Yucatan Peninsula each 
evening through Thu, enhancing nocturnal winds over the eastern 
section of the SW Gulf.


Please read the Special Features section for details about
pulsing gale force winds near the coast of Colombia. Aside from 
the tropical waves mentioned above, an upper level low is noted 
on water vapor imagery just to the south of the Yucatan Channel.
A rather dry and stable environment is only for isolated showers 
moving quickly with the trade wind flow to occur across much of 
the basin. Mainly fresh E winds will continue over the central 
Caribbean Sea through Thu, with the exception of strong NE-E winds
in the SW and S central sections of the Caribbean outside the 
near gale to minimal gale force wind area described above.


A weak surface trough extends from near 32N78W southwestward to
just east of NE Florida. Scattered showers and isolated
thunderstorms are seen north of 28N between 72W and 79W. Another
surface trough extends from near 32N60W to 29N67W and
northwestward to near 32N76W. Scattered moderate isolated strong 
convection is along and within 90-120 nm SE of this trough 
between 60W-64W while isolated showers and thunderstorms are along
and within 60 nm SE of the trough between 64W-75W. This trough 
will slowly weaken through Tue as the supporting upper trough 
lifts to the NE away from it. High pressure will build in the wake
of the trough. A large area of Saharan Air Layer (SAL) dust
that is currently over the central Atlantic from 08N-24N and 
between 45W-60W will continue to translate westward through the 
rest of the week. A weaker area of dust is visible from the SE 
Bahamas to 60W and from 09N-27N, also translating in westward 

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