AXNT20 KNHC 192357
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
757 PM EDT Thu Jul 19 2018
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
A tropical wave is off the coast of west Africa from 06N to 18N
along 19W, moving W at 10-15 kt. The wave is being engulfed by
Saharan dry air and dust and is mainly in a strong deep layer wind
shear environment. However, shallow moisture and upper level
diffluence is supporting scattered moderate convection from 06N to
13N E of 24W.
A tropical wave is in the central Atlantic with axis extending
from 18N34W to 04N34W, moving W at 15 kt. The wave is moving
across an extensive Saharan Air Layer Outbreak with dry air and
dust hindering convection.
A low amplitude tropical wave is over the central Atlantic with
axis extending from 12N52W to 02N53W, moving W at 15 kt. Scattered
moderate comvection is within 180 nm of the wave axis.
A tropical wave is in the E Caribbean with axis S of 20N along
70W, moving W at 20 kt. The wave is in a strong deep layer wind
shear environment. However, abundant shallow moisture and upper
level diffluence in the NE Caribbean support scattered showers and
tstms N of 13N between 66W and 73W.
The monsoon trough axis extends from W Africa near 15N17W to
08N26W to 07N40W, where the ITCZ begins and continues to South
America near 05N55W. Scattered moderate convection is from 06N to
10N between 24W and 30W, and from 04N to 08N between 46W and 50W.
GULF OF MEXICO...
The Azores high continues to extend a ridge axis SW across the
southern half of the Florida Peninsula to the central Gulf of
Mexico. This is supporting maily light to gentle winds over the
Gulf S of 27N. In the NE Gulf, a surface trough continues to
generate scattered moderate convection and isolated tstms. The
trough is being supported by upper level level diffluent flow.
The Bay of Campeche has shallow moisture as depicted by low
level water vapor imagery. The remainder of the Gulf is under dry
stable air which supports fair weather. The trough is forecast to
dissipate late Friday night and convection associated with it
will cease by early Sat. However, an upper level trough will
extend from the SE CONUS into the E Gulf, and will support the
development of showers for the remainder of the weekend. In
addition, a surface trough will move westward off the Yucatan
Peninsula each night, enhancing nocturnal winds over the eastern
half of the Bay of Campeche.
A tropical wave is over the E Caribbean. See above. Upper level
diffluent flow over Puerto Rico and eastern Hispaniola along with
abundant shallow moisture supports this wave. The remainder of the
basin is under dry, stable, air as indicated by the low level
water vapor imagery of GOES-16. RGB imagery from GOES-16 also
shows a thin layer of Saharan Dust moving across the central and
western portions of the basin. These factors along with strong
deep layer wind shear contribute to a lack of convection
elsewhere. The wave will cross Hispaniola tonight and continue to
bring showers at the island and adjacent waters through early
Friday. The convection will then shift to the SW basin during the
weekend as the wave continues to move westward. Otherwise, fresh
to strong winds will prevail in the central basin through the
weekend as the Azores high remains nearly-stationary. Near gale
force winds will be likely along the coast of Colombia.
The base of an upper level trough is over the W Atlantic at 30N.
This upper trough supports a cold front N of the area. Diffluent
flow between the trough and a middle to upper level anticyclone
over the Bahamas support scattered showers and tstms N of 28N W of
69W. Isolated showers are also across Andros Island and adjacent
waters. A tropical wave over E Hispaniola supports scattered
showers and tstms S of 22N between 61W and 70W. The remainder of
the Atlantic N of 18N is under the influence of the Azores high
supporting fair weather conditions. No major changes expected
during the next two days.
For additional information
please visit http://www.hurricanes.gov/marine