Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 240004

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Wed Aug 23 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.


The center of regenerated Tropical Depression Harvey at 23/2100 
UTC is near 21.6N 92.6W, or about 455 nm SSE of Port Oconnor,
Texas or about 400 nm SE of Port Mansfield, Texas. Maximum 
sustained wind speed is 30 kt with gusts to 40 kt. The estimated 
minimum central pressure is 1005 mb. Numerous moderate to strong
convection is within 90 nm of Harvey's center. Scattered moderate
to strong convection and isolated tstms are elsewhere from 17N to
29N between 87W and 84W. Some strengthening is forecast during the 
next 48 hours, and Harvey could become a hurricane on Friday. Please
see PUBLIC ADVISORIES issued under the WMO/AWIPS header WTNT34 
WTNT24 KNHC/MIATCMAT4 for more details.


A tropical wave came off the W coast of Africa associated with a
broad cyclonic circulation. The wave axis extends from 15N18W to
08N19W. The CIRA LPW imagery show abundant moisture at low levels
associated with this wave that is in a region of low to moderate
vertical wind shear. Upper level diffluence support numerous
moderate to isolated strong convection and isolated tstms from 08N
to 13N between 23W and 26W. Scattered moderate convection is
elsewhere from 05N to 16N E of 30W. 

A tropical wave is in the central Atlc associated with a 1010 mb
low near 17N37W. Its axis extends from 22N35W to the low to 09N37W
and it has been moving W at 10 kt within the last 24 hours. The
wave is in a region of strong vertical wind shear and RGB imagery
show Saharan dry air and dust in the wave environment, which is
currently hindering convection.

A tropical wave is in the central Caribbean with axis extending 
from 20N77W to 09N79W, moving W at 15-20 kt. Scattered to isolated
heavy showers and tstms are within 90 nm either side of the wave


The monsoon trough extends from 13N16W to 15N30W to 12N44W. The 
Intertropical Convergence Zone continues from there to 10N58W. Besides
the convection mentioned in the tropical wave section, scattered 
moderate convection is from 08N to 13N between 30W and 40W.



The main concern in the basin is tropical depression Harvey, which
is generating much of the weather basin-wide. Please, see the Special
Features section for details. Otherwise, a middle level low over
the Florida straits supports a surface trough across the central
and southern Florida Peninsula that along with upper level
diffluent flow have been supporting scattered to isolated showers
extending within 60 nm off the coast to the SE Gulf. Harvey 
should be approaching the Texas coast late Friday.


A tropical wave is moving across the central Caribbean Sea. 
Please, see Tropical Waves section for details. Scattered heavy
showers and tstms are along Cuba and adjacent waters being
supported by a broad area of diffluent flow aloft. In the SW
basin, a 1008 mb low is ahead of the tropical wave axis near
09N81W, which along the EPAC monsoon trough support scattered
showers and tstms S of 13N W of 75W. Another area of upper level
diffluence is over Hispaniola between N flow and a low centered
over SW N Atlc waters. This setting aloft is allowing for the
development of isolated showers along the southern half of the
Island. Isolated showers are noted over SW Puerto Rico and
adjacent waters as well as in the Leeward Islands where a surface
trough extends from central Atlc waters to 15N61W. Dry air
subsidence support fair weather elsewhere.


Upper level diffluence is over Hispaniola between N flow and a low
centered over SW N Atlc waters. This setting aloft is allowing 
for the development of isolated showers along the southern half of
the Island. This shower activity is forecast to continue through
early Friday.


A broad area of diffluent flow aloft is over the region supporting
instability and the continuation of scattered showers and tstms
across the Bahamas and the Great Bahama Bank. Farther east, an
upper level low reflects at the surface as a surface trough from
30N63W to 25N68W. NE of the Bahamas another surface trough is
analyzed along 21N57W to the Leeward Islands near 15N61W.
Scattered showers and tstms are NE of this trough from 21N to 26N
between 54W and 58W. Otherwise, surface ridging and fair weather
dominates elsewhere N of 20N. For tropical waves information, see
section above.

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Page last modified: Thursday, 24-Aug-2017 00:05:29 UTC