Tropical Weather Discussion
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471
AXNT20 KNHC 212333
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Fri Jul 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.

...TROPICAL WAVES...

A tropical wave over the eastern Atlantic extends from near
17N33W to 04N35W and is moving westward 15 to 20 kt.  The 18Z
GFS guidance shows a well-defined 700 mb trough associated with
this wave.  Scattered moderate isolated strong convection covers
a large area primarily east of the wave axis from 06N to 14N
between 28W and 37W.

A large amplitude tropical wave is over the central Atlantic
with its axis extending from near 24N59W to 15N58W and is moving
westward at 15 kt.  This wave exhibits a well-defined inverted-v
shape structure.  Scattered moderate isolated strong convection
is located from 18N to 23N between 55W and 60W with the deepest
convection from 22N to 23N.  Scattered showers and isolated
thunderstorms are elsewhere within 120 to 180 nm either side of
the wave axis.

A well-defined tropical wave is easily identifiable on the
latest visible satellite imagery with its axis located along
68W/69W south of 19N into Venezuela.  It is moving westward 15
to 20 kt.  Scattered showers and isolated thunderstorms are
located up to 180 nm either side of the wave axis.

A tropical wave is located over the western Caribbean with its
axis along 85W south of 18N across Nicaragua and into the
eastern Pacific waters near 05N85W.  It is moving westward near
15 kt.  This wave is the remnant of former Tropical Storm Don.
Abundant low level moisture is to the south of 16N west of 80W,
and has resulted in scattered moderate to isolated strong
convection from 08N to 16N west of 80W into Central America.

...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 16N16W to 10N36W.  The ITCZ
then extends from 10N36W to a weak low pressure of 1013 mb near
09N42W to 08N52W.  Aside from the convection associated with the
tropical waves, scattered moderate to strong convection is
located within a 90 nm radius of 11.5N21W.  Scattered moderate
isolated strong convection is located from 06N to 11N between
43W and 53W.

...DISCUSSION...

GULF OF MEXICO...

An elongated middle/upper level cyclonic circulation is centered
over the north central Gulf near 28N90W and is forecast to move
into the northwest Gulf in 24 hours.  Another middle/upper level
cyclonic circulation is centered off the Yucatan Peninsula near
22N92W and is drifting northward.  Abundant moisture and
instability is in place over much of the northern half of the
Gulf.  Also, a surface trough extends through the central
Florida panhandle to 26N88W.

CARIBBEAN SEA...

Light southerly flow aloft covers most of the eastern half of
the Caribbean with water vapor imagery showing subsidence east
of about 68W.  These conditions are allowing for mainly fair
weather conditions outside the shower and thunderstorm activity
related to the tropical waves.

...HISPANIOLA...

Light to moderate southerly winds aloft cover Hispaniola early
this evening.  A tropical wave is approaching the eastern
Dominican Republic with an increase in showers and thunderstorms
expected.  Broken to overcast layered clouds with scattered
showers and isolated thunderstorms cover most of the
island.

ATLANTIC OCEAN...

A well-defined middle/upper level cyclonic circulation is
located just north of the central Bahamas near 25N74.5W and is
forecast to move north about 15 kt over the next 24 hours.
Another large middle/upper level cyclonic circulation is located
in the central Atlantic near 28N46W and will move south about 10
kt over the next day or so.  At the surface, a 1023 mb high is
centered near 29N55W with a ridge extending westward to near
27N75W.  Aside from the convection associated with the above
described tropical waves, scattered to numerous showers and
thunderstorms are observed over the far western part of the
basin north of 24N west 75W including the Bahamas.

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

$$
CAB



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