[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Tue Jul 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 1800 UTC surface analysis and satellite imagery through
2345 UTC.

...SPECIAL FEATURES...

Tropical Storm Don is centered near 11.7N 60.0W at 18/2100 UTC
moving westward or 275 degrees at 19 kt. Estimated minimum
central pressure is 1010 mb with maximum sustained winds of 35 kt
with gusts to 45 kt. Scattered moderate convection associated
with Don is from 09N to 14N between 59W and 68W. The center of
Don will move across the Windward Islands this evening, and then
move westward across the southeastern Caribbean Sea late tonight
and Wednesday. Don is expected to produce total rain
accumulations of 3 to 6 inches, with isolated higher amounts
across Barbados, Trinidad and Tobago, and the southern Windward
Islands through Wednesday. Therefore, there is a high potential
for life-threatening flash floods and mudslides, especially in
mountainous areas. Please refer to the latest NHC
forecast/advisory under AWIPS/WMO headers MIATCPAT5/WTNT35 KNHC
for more details.

...TROPICAL WAVES...

A tropical wave associated with a center of low pressure is in
the central Atlc. Its axis extends from 17N38W a 1012 mb low near
10N39W to 04N39W, moving westward at 5-10 kt within the last 24
hours. The wave is in a region of favorable wind shear. However,
its environment continue to be affected by intrusion of Saharan
dry air and dust, which is limiting the convection to scattered
showers from 07N to 13N between 38W and 48W. Some slow
development of this system is possible during the next day or two
while it moves toward the west-northwest or northwest. Potential
for tropical cyclone development from this system remain low
through the next two days.

A tropical wave is in the E Caribbean with axis extending from
20N65W to inland Venezuela near 08N65W, moving west at 20 kt
within the last 24 hours. The wave is in a region of unfavorable
wind shear, and Saharan dry air and dust are affecting the
northern half of the wave environment. This set up is limiting
the convection to isolated showers across Puerto Rico and adjacent
waters as well as the Dominican Republic.

...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 12N16W to 11N30W to 07N45W.
The ITCZ then extends from 07N45W to 07N57W. Aside from the
convection associated with the tropical wave and attendant low,
scattered moderate to isolated strong convection is from 05N to
11N between 15W and 26W.

...DISCUSSION...

GULF OF MEXICO...

The atmosphere across the Gulf remains very moist and unstable as
low to middle level southeasterly flow continue to advect moisture
from the Caribbean. Latest scatterometer data showed the presence
of a surface trough along the northern Gulf waters from 29N84W to
28N88W to 27N92W with fresh to strong northerly flow between the
trough axis and the Florida Panhandle. Scattered to isolated
showers are within 90 nm either side of the trough. Former scattered
showers and thunderstorms over the SW Gulf are now reaching the NW
Gulf waters underneath diffluent flow. This area of showers and
tstms are over adjacent waters of S Texas from 23N to 26N W of
93W. Similar shower activity is across Florida being supported by
a surface trough. Little change is expected in the shower and
thunderstorm activity over the next couple of days as moist and
unstable conditions continue, and a mid to upper trough just
north of the basin begins to shift southward.

CARIBBEAN SEA...

The main feature of concern for the SE Caribbean is Tropical Storm
Don that is moving across the Windward Islands. Don is expected
to produce total rain accumulations of 3 to 6 inches, with
isolated higher amounts, which may result in potential life-threatening
flash floods and mudslides, especially in mountainous areas. See
the special features section for details. Scattered to isolated
heavy showers and tstms are confined to the far SW Caribbean. This
activity is being supported by the combination of diffluence
aloft along with low-level forcing from low-level wind speed
convergence. In addition, the presence of the the eastern segment
of the eastern Pacific monsoon trough across much of Costa Rica
and Panama is providing added instability to this convective
activity. This activity will remain quite active through the next
24-48 hours.

...HISPANIOLA...

A fast moving tropical wave over the eastern Caribbean Sea is
supporting isolated showers across the Dominican Republic and
adjacent waters, including the Mona Passage. The wave will move
into the vicinity of the island tonight and into Wednesday
morning. Shower and thunderstorm activity associated with the wave
are to be mainly of the scattered to isolated nature. However,
any moisture from the wave that does mix in with local effects may
result in a bit more shower and thunderstorm activity in some
locations of the island through Wednesday.

ATLANTIC OCEAN...

Middle level diffluence continue to support scattered showers
across the northern Bahamas and northward adjacent waters beyond
30N. Central Atlantic high pressure centered near 34N50W extends
a ridge south across the entire basin N of 20N. Otherwise, a tropical
wave with low potential of tropical cyclone development within the
next two days is in the central tropical basin. See the waves
section for further details.

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

$$
Ramos
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