Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 181039

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.


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.


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.


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.



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. 


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.


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.


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. 

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Page last modified: Friday, 18-Aug-2017 10:40:15 UTC