Tropical Weather Discussion
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000
AXNT20 KNHC 180004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Mon Jul 17 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
2345 UTC.

...SPECIAL FEATURES...

Tropical Storm Don formed east of the Windward Islands at 2100
UTC. The location of the storm center is near 11N52W or about 515
nm east of Trinidad and has a minimum central pressure of 1009 mb.
Don is moving westward at 15 kt. Maximum sustained winds are 35
kt with gusts to 45 kt. Numerous heavy showers are from 10N to 12N
between 51W and 54W. Scattered heavy showers are elsewhere from
08N to 13N between 51W and 56W. The center of Don will move
through the Windward Islands late Tuesday and Tuesday night. Don
is expected to produce total rain accumulations of 2 to 4 inches
across the Windward Islands through Wednesday morning. Please
refer to the latest NHC forecast/advisory under AWIPS/WMO headers
MIATCPAT5/WTNT35 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is in the central Atlc with axis extending from
17N36W to a 1012 mb low near 09N37W to 05N37W, moving west 20 kt
within the last 24 hours. The wave is in a region of neutral to
unfavorable wind shear and dry air intrusion to its environment is
noted in CIRA LPW imagery. This is limiting convection to
scattered showers from 04N to 12N between 32W and 49W. Some
gradual development of this system is possible over the next few
days while it moves slowly toward the west-northwest or northwest
over the open Atlantic Ocean.

A tropical wave is east of the Lesser Antilles with axis
extending from 19N56W to 07N58W, moving west at 20 kt within the
last 24 hours. The wave is mainly in a region of neutral to
unfavorable wind shear, and extensive Saharan dry air and dust
intrusion to its environment is noted in satellite enhanced
imagery. This is limiting convection to isolated showers from 13N
to 16N between 56W and 60W.

A tropical wave is in the west Caribbean with axis extending from
23N83W across eastern Nicaragua and Costa Rica to 06N84W, moving
west at 5 to 10 kt within the last 24 hours. Favorable wind shear
N of 20N and middle to upper level divergence support heavy
showers and tstms across the western half of Cuba and adjacent
waters. Similar shower activity over the eastern half of Honduras,
across Nicaragua and northern Costa Rica. Over SW Caribbean
waters, heavy showers and tstms are from 09N to 14N W of 78W being
supported by the EPAC monsoon trough.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 13N17W to 13N30W to 09N40W to
11N49W. No ITCZ noted at the time. Aside from the convection
associated with the tropical waves, scattered showers are from 08N
to 13N E of 20W.

...DISCUSSION...

GULF OF MEXICO...

Generally low pressure dominates the western half of the Gulf
while weak high pressure prevails E of 90W being where is anchored
by a 1016 mb high near 27N84W. This scenario is providing variable
gentle to light winds in the E Gulf and E-SE winds of similar
magnitude across the remainder basin, except N of 27N between 87W
and 92W. In this region, latest scatterometer data show NW fresh
to strong winds associated with scattered showers and tstms. No
major changes expected basin-wide through the middle of the week.

CARIBBEAN SEA...

A tropical wave is moving through the western Caribbean, helping
enhance convection mainly inland with the exception of the SW
Caribbean where convection is being amplified by the EPAC monsoon
trough. See the tropical waves section for further details. Upper
level divergence over Hispaniola supports scattered heavy showers
and tstms across Haiti, and scattered to isolated showers in the
Dominican Republic. A moderate pressure pattern will continue to
support fresh to strong winds in the south-central Caribbean
during the next two days while moderate to fresh winds will
prevail over the eastern and the remainder central Caribbean.
Otherwise, a tropical wave is forecast to move across the Lesser
Antilles late tonight through Tuesday morning with scattered to
isolated showers. Otherwise, tropical storm Don will move through
the Windward Islands late Tuesday and Tuesday night potentially
producing total rain accumulations of 2 to 4 inches through
Wednesday morning.

...HISPANIOLA...

Upper level divergence over Hispaniola supports scattered heavy
showers and tstms across Haiti, and scattered to isolated showers
in the Dominican Republic. Conditions are forecast to improve by
Tuesday.

ATLANTIC OCEAN...

Central Atlantic high pressure centered near 34N44W extends a
ridge westward to the southeast United States. As typical for this
time of year, tropical waves are moving through the tropical
Atlantic waters. Low pressure has developed within the monsoon
trough near 09N37W. Active convection associated to this low is
described in the tropical waves section.

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

$$
MT



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