Tropical Weather Discussion
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000
AXNT20 KNHC 181806
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
206 PM EDT Sun Jun 18 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 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

A tropical wave is in the central Atlantic associated with a 1009
mb low centered near 06N47W. Its axis extends from 10N46W to the
low to 02N47W, moving W at 20 kt within the last 24 hours. The
wave is in a region of favorable wind shear and is embedded in a
moderate moist environment at the lower levels according to CIRA
LPW imagery. However, Saharan dry air and dust continue to enter
its environment, thus limiting the convection to scattered
moderate from 06N to 10N between the wave axis and 52W. Upper
level divergence support this convection. Some development of
this system is possible during the next couple of days before
environmental conditions become less favorable for tropical
cyclone formation. This system is forecast to move to the west-
northwest towards the Windward Islands and northeastern South
America during the next two days. This system has a medium chance
of becoming a tropical cyclone during the next two days. See the
latest NHC Tropical Weather Outlook under AWISP/WMO headers
MIATWOAT/ABNT20 KNHC for more details.

A broad area of low pressure in the northwestern Caribbean Sea is
centered by a 1006 mb low near 18N87W. This system is generating
clusters of heavy showers with embedded tstms N of 13N W of 77W,
including inland western Cuba. Gale force SE winds are N of 19N
between 81W and 83W with seas of 9 to 11 ft. Fresh to near gale
force winds are elsewhere N of 16N between 78W and 84W with seas
to 10 ft. Gale conditions are forecast to continue through Monday
morning. Gradual development of this system is expected while it
moves slowly northwestward across the Yucatan Peninsula later
today and over the southern or central Gulf of Mexico on Monday
and Tuesday, where a tropical or subtropical cyclone is likely to
form. Regardless of development, heavy rains are expected over
portions of Central America, the Yucatan Peninsula, Jamaica, the
Cayman Islands, and western Cuba during the next several days. The
chance of formation into a tropical cyclone during the next two
days is medium. Please read the latest NHC Tropical Weather
Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more
details.

...TROPICAL WAVES...

A tropical wave is in the E Atlc associated with a 1011 mb low
near 08N21W. Its axis extends from 11N21W to the low to 02N21W. The
wave is in a region of favorable wind shear and CIRA LPW show a
moderate moist environment with some patches of dry associated
with Saharan dry air and dust intrusion. Upper level divergence
support scattered moderate convection from 08N to 12N between 20W
and 25W.

A tropical wave is in the central Atlc with axis extending from
10N33W to 02N34W, moving W at 20 kt within the last 24 hours. The
wave is in a region of favorable wind shear. However, extensive
intrusion of Saharan dry air and dust to its environment limit the
convection to isolated showers within 120 nm either side of its
axis from 05N to 08N.

A tropical wave is in the W Atlc around 270 nm E of the Lesser
Antilles. Its axis extends from 17N55W to 08N55W and has been moving
W at 20 kt within the last 24 hours. The wave is in a region of
unfavorable wind shear and its environment is being affected by
extensive Saharan dry air intrusion. Shallow moisture and a middle
level divergent environment ahead of the wave support scattered
showers and tstms S of 16N between 57W and 65W.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough extends from the coast of west Africa near
10N14W to a 1011 mb low near 08N21W to 06N31W. The ITCZ extends
from 04N36W to 05N43W, then resumes W of a tropical wave near
05N52W to 06N58W. Three tropical waves are embedded within the
Monsoon trough/ITCZ. See tropical waves and special features
sections for information about convection.

...DISCUSSION...

GULF OF MEXICO...

Broad surface high press covering great portions of the Atlc
waters extends a ridge axis SW across the Florida peninsula to the
NE Gulf, which continue to provide gentle to moderate SE flow
across the basin, except for the SE gulf. Latest scatterometer
data and surface observations show fresh to near gale force winds
in the SE basin S of 24N E of 88W associated with a broad area of
low pressure in the NW Caribbean with medium chances of becoming a
tropical cyclone in the next two days as it moves slowly
northwestward across the Yucatan Peninsula later today and over
the southern or central Gulf of Mexico on Monday and Tuesday.
Scattered showers associated with the rainbands of this systems
are already affecting the Florida straits and the Yucatan channel.
See the special features section and the latest NHC Tropical
Weather Outlook under AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for
more details.

CARIBBEAN SEA...

The major concern in the basin is a broad area of low pressure in
the NW Caribbean, which is generating numerous heavy showers and
strong to gale force winds. Gradual development of this system is
expected while it moves slowly northwestward across the Yucatan
Peninsula later today and over the southern or central Gulf of
Mexico on Monday and Tuesday, where a tropical or subtropical
cyclone is likely to form. See the special features section and
the latest NHC Tropical Weather Outlook under AWIPS/WMO headers
MIATWOAT/ABNT20 KNHC for more details. Scattered heavy showers and
tstms are in the SE basin ahead of a tropical wave with axis near
270 nm E of the Lesser Antilles. See tropical waves section for
further details. Otherwise, a surface trough off the coast of
Colombia is supporting scattered heavy showers and tstms S of 14N
between 75W and 79W.

...HISPANIOLA...

Isolated showers are across the island being influenced by the
broad area of low pressure in the NW Caribbean. Showers are
forecast to continue through later today.

ATLANTIC OCEAN...

Four tropical waves are moving westward between the coast of
Africa and the Lesser Antilles. Please refer to the Tropical Waves
section above for details. Otherwise, broad high pressure covers
the Atlantic from the Azores to the Florida Peninsula, with a 1025
mb high pressure near 29N44W.

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

$$
Ramos



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