Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 212353

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
753 PM EDT Mon Aug 21 2017

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.

A tropical wave extends from 21N84W to 10N85W moving W-NW at 
15-20 kt. The remnant circulation of Harvey continues to be 
analyzed as a 1008 mb low pressure along the wave axis near 
17N84.5W with scattered to numerous showers and thunderstorms 
occuring from 16N-23N between 80W-89W. The convective activity has
increased today, but the system still lacks a well-defined center
of circulation, and surface pressures are not falling at this 
time. Some development of this disturbance is still possible 
before it reaches the coast of Belize or the Yucatan Peninsula 
early Tuesday. Regardless of development, locally heavy rainfall 
and gusty winds will continue to affect mainly western Cuba and 
the Cayman Islands tonight, and will continue to spread westward 
across Belize, northern Guatemala, and the Yucatan Peninsula 
during the next couple of days. The system is forecast to move 
into the Bay of Campeche on Wednesday, where environmental 
conditions are expected to be conducive for redevelopment into a 
tropical cyclone. 

A tropical wave extends from 23N24W to 10N29W moving W at 15-20 
kt. A 1009 mb low pressure precedes the wave centered near 
13N33W. Scattered moderate convection is noted within 120 nm SE of
a line from 13N23W to 10N31W. This wave in a moist area based on 
TPW imagery and has a well pronounced 700 mb trough.

A tropical wave is over the far eastern Caribbean and extends 
from near Antigua to eastern Venezuela at 08N63W moving W at 
20-25 kt. Isolated showers are near the northern end of the wave 
axis. The wave is expected to move across the eastern Caribbean 
Sea and portions of Venezuela through Tuesday helping to induce 
some convective activity. Subtle troughing is noted on 700 mb 
streamline analysis, but some moisture is observed on either side 
of the wave axis based on the TPW animation. This wave will cross 
the central Caribbean through mid-week.

The monsoon trough extends from 10N31W to 08N40W to 07N43W. The 
Intertropical Convergence Zone axis continues from 07N43W to 
08N51W. Scattered moderate convection is within about 90 nm south 
of trough between 31W-39W.


A large and well defined upper-level low centered over the central 
Gulf near 26N90W continues to generate scattered to numerous 
showers and thunderstorms, mainly across the NE and central Gulf.
A surface trough is analyzed over the SW Gulf and extends from
25N97W to the Bay of Campeche near 19N94W where some shower
activity is noted. The upper-low will drift WNW across the western
Gulf on Tuesday and will continue to enhance the development of 
showers and tstms across the Gulf waters through mid-week. 
Looking ahead, the remnant low of Harvey, currently moving across 
the western Caribbean is forecast to move into the Bay of Campeche
on Wednesday, where environmental conditions are expected to be 
conducive for redevelopment into a tropical cyclone.

The remnant low of Harvey currently located over the NW Caribbean 
continues to be the primary area of concern across the basin.
Please, see Special Features section for more details. A tropical 
wave is over the far eastern Caribbean. Please, see the Tropical 
Waves section for details. Patches of low-level moisture embedded
in the trade wind flow are noted over parts of the east and
central Caribbean. Fresh SE winds are observed per scatterometer 
data across the central Caribbean, but maninly N of 13N. These 
winds are the result of the pressure gradient between the Atlantic
ridge and the remnant low of Harvey. 

Daytime heating, local sea breezes and mountain upslope lifting 
will combined with available moisture to produce isolated to
scattered showers and thunderstorms mainly during the afternnon 
and evening hours. The next tropical wave is forecast to pass just
south of the island Tuesday night into Wednesday.

A trough of low pressure continues to move westward across the
Bahamas and now extends from 28N74W across the central Bahamas to
near 22N76W. This system continues to produce disorganized 
showers and thunderstorms, with fresh to strong winds mainly on 
its NW side based on scatterometer data. Only slow development of 
this system is anticipated during the next several days while it 
moves west-northwestward across the Bahamas and then turns 
northwestward or northward near Florida and the adjacent waters.
Farther east, there is another surface trough that extends 25N52W
to 16N55W. This trough is likely the surface reflection of an 
upper-level low spinning near 26N57W. The remainder of the 
forecast area is under the influence of the Atlantic ridge. 

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Page last modified: Monday, 21-Aug-2017 23:53:35 UTC