Tropical Weather Discussion

axnt20 knhc 191802

Tropical weather discussion
NWS National Hurricane Center Miami FL
202 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 1200 UTC surface analysis and satellite imagery through 
1745 UTC.

...Tropical waves...

A tropical wave is coming off west Africa. Its axis extends from
06n to 19n along 17w. 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 15n E of
20w. The wave is forecast to move at 5-10 kt within the next 24

A tropical wave is in the central Atlc with axis extending from
05n34w to 17n33w, moving westward at 10-15 kt. The wave is moving
across an extensive Saharan air layer outbreak, which dry air and
dust hinder convection.

A tropical wave is in the E Caribbean with axis S of 20n along
68w, moving westward at 15 to 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 62w and 71w. 

...Monsoon trough/ITCZ...

the monsoon trough axis extends from W Africa near 16n16w to 
09n23w to 07n40w, where the ITCZ begins and continues to South 
America near 06n57w. Scattered moderate convection is from 06n to
10n between 20w and 30w, and from 04n to 07n W of 45w.


Gulf of Mexico...

The Azores high continues to extend a ridge axis SW across the
southern half of the Florida Peninsula then westward to 90w. This
is supporting maily south to southwest light to gentle winds S of
27n. In the NE Gulf, a surface pre-frontal trough continues to
generate scattered moderate convection and isolated tstms being
supported by middle level diffluent flow. Except for the Bay of
Campeche where both CIRA lpw and GOES-16 low level water vapor
imagery show shallow moisture, 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 over the remainder weekend. Otherwise, a 
surface trough will move westward off the Yucatan Peninsula at
night, enhancing nocturnal winds over the eastern half of the Bay
of Campeche.

Caribbean Sea...

A tropical wave is between Puerto Rico and the eastern Dominican
Republic with axis along the Mona Passage to NW Venezuela. Upper
level diffluent flow over Puerto Rico and eastern Hispaniola along
with abundant shallow moisture associated with this wave support
scattered showers and tstms N of 13n between 62w and 72w. The
remainder basin is under dry, stable air as indicated by the low
level water vapor imagery of GOES-16. Rgb imagery from GOES-16
also show 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. 

Atlantic Ocean...

The base of a middle to upper level trough extends to nearly 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 moving between Puerto Rico and Hispaniola
support scattered showers and tstms S of 22n between 61w and 70w.
The remainder Atlc N of 18n is under the influence of the Azores
high, which in part is supporting fair weather conditions. No
major changes expected during the next two days.

For additional information 
please visit http://www.Hurricanes.Gov/marine



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