[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181039
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
639 AM EDT Fri Aug 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

...SPECIAL FEATURES...

At 18/0900 UTC, Tropical Storm Harvey is located near 13.1N
59.1W, moving west at 16 kt. Estimated minimum central pressure
is 1004 mb. Maximum sustained wind speed has increased to 35 kt
with gusts to 45 kt. A cluster of moderate to strong convection is
noted from 11N-16N between 58W-64W. Harvey should move through
the Windward Islands then enter the eastern Caribbean today. Slow
strengthening is possible during the next 48 hours. Harvey is
expected to produce rainfall totals of 2 to 4 inches across
portions of the Windward Islands from Martinique southward to
Grenada. These rains could cause life-threatening flash floods and
mudslides. See see the latest NHC Intermediate Public Advisory
under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC, and the full
Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC
for more details.

A tropical wave extends its axis from 20N48W to a 1010 mb low
near 16N49W to 09N48W. Scattered moderate convection is noted
from 16N-20N between 47W-51W. The shower and thunderstorm activity
is mostly associated with the area of low pressure. Only a slight
increase in the organization of the shower activity could lead to
the formation of a tropical depression during the next couple of
days before upper-level winds become less favorable for development
early next week. The low is expected to move west-northwestward
at about 15-20 kt during the next few days, and interests in the
northern Leeward Islands should monitor the progress of this
disturbance. This system has a high change of becoming a tropical
cyclone during the next 48 hours.

...TROPICAL WAVES...

A tropical wave is moving across the eastern Atlantic with axis
extending from 17N30W to a 1010 mb near 13N31W to 06N31W.
Scattered moderate convection is from 12N-18N between 30W-35W.
This wave is in a very moist area based on TPW imagery and has a
well pronounced 700 mb trough. Gradual development of this system
is possible through the middle of next week while the wave moves
westward to westward at about 15-20 kt. Currently, this system has
a low change of becoming a tropical cyclone through 5 days.

A broad tropical wave is moving westward across the Caribbean
extending its axis from 23N72W to 11N73W. Scattered moderate
convection is noted over the northern part of the wave axis from
18N-25N between 67W-75W. This activity is affecting the western
part of Hispaniola. The wave shows up very well in the TPW
animation and 700 mb streamline analysis. Moisture associated with
this wave will spread across the Turks and Caicos Islands, the
southern Bahamas, and the remainder of Hispaniola tonight
increasing the likelihood of rain. Fresh to locally strong
northeast winds are noted over waters ahead of the wave axis.

A tropical wave extends its axis across the southern portion of
the Bay of Campeche and into the EPAC from 21N94W to 09N94W. The
wave is enhancing isolated showers over southeast Mexico and
adjacent waters south of 20N between 92W-96W. The wave coincides
with a 700 mb trough, and is well depicted in TPW imagery.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 16N17W to
a 1010 mb low pressure 13N31W to 07N40W. Scattered moderate
convection is observed within 100 nm on either side of the axis
between 31W-43W.

...DISCUSSION...

GULF OF MEXICO...

A 1018 mb surface high centered over northeast Gulf near 27N86W
and extends its ridge across the region producing mainly gentle to
moderate winds based on scatterometer data. The tropical wave
currently moving across the Bay of Campeche will enhance the
convection today. A broad upper-level low is centered over
eastern Cuba enhancing convection in its periphery mostly
affecting Southern Florida and adjacent waters. Little change in
this weather pattern is expected through early next week.

CARIBBEAN SEA...

A tropical wave is along 73W enhancing convection over Hispaniola.
Please, see the Tropical Waves section for details. Tropical
Storm Harvey should move through the Windward Islands and into the
eastern Caribbean today. Refer to the Special Features section
for more details. Upper-level diffluent flow between an anticyclonic
circulation centered over the southeast CONUS and an upper-level
low spinning over central Cuba supports isolated showers across
the island. Scatterometer data depicts moderate to fresh trades
across the basin. The previously mentioned tropical wave will
bring showers and thunderstorms over eastern Cuba today, and over
western Cuba on Saturday. Scattered moderate convection is also
noted over the southwest Caribbean, likely associated with the
eastern extent of the Pacific's monsoon trough combined with a
diffluent pattern aloft.

...HISPANIOLA...

A broad tropical wave is moving across western Hispaniola keeping
showers and thunderstorms and gusty winds prevailing over the
island. This activity has the potential of locally heavy rain
through today.


ATLANTIC OCEAN...

A pair of tropical waves and Tropical Storm Harvey are moving
westward across the tropical Atlantic. The northern portion of
a strong tropical wave is affecting the waters north of Hispaniola.
Please, see Special Features and Tropical Wave sections above for
details. The remainder of the Atlantic is under the influence of
a surface ridge, with a center of 1024 mb located near 35N34W. A
belt of fresh to locally strong easterly winds is noted per
scatterometer data roughly between 15N-23N due to the pressure
gradient between the ridge and the tropical systems located
between the coast of Africa and the Lesser Antilles.

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

$$

ERA
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