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Atlantic Tropical Weather Discussion (Text)



000
AXNT20 KNHC 231801
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
201 PM EDT Sun Jul 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 1200 UTC surface analysis and satellite imagery through 
1745 UTC.

...TROPICAL WAVES...

A tropical wave is in the E Atlc with axis extending from 16N22W 
to 05N22W, moving W at 15 kt within the last 24 hours. The wave 
is in a region of favorable to neutral vertical shear, however
continue to be severely affected by Saharan dry air dust. Both CIRA
LPW and SSMI TPW imagery confirm the extensive presence of the 
dry air mainly in the northern wave environment. Shallow moisture
associated with the African monsoon along with upper level 
diffluence support scattered showers from 04N to 10N between 20W
and 31W.

A tropical wave is in the central Atlc with axis extending from
19N35W to 09N36W, moving W at 5 kt within the last 24 hours. The 
wave is in a region of favorable vertical shear, however the
prevailing intrusion of Saharan dry air dust to its environment 
support lack of deep convection at the time.

A tropical wave is in the central Atlc with axis extending from 
16N49W to 06N50W, moving W at 15-20 kt within the last 24 hours. 
The wave is in a region of favorable vertical shear S of 14N, 
however it continues being severely affected by intrusion of 
Saharan dry air dust to its northern environment. Middle to upper
level diffluence and shallow moisture as seen in CIRA LPW support
scattered to isolated showers from 10N to 13.5N between 48W and 
53W.

A tropical wave is in the far W Caribbean and moving across 
Central America. This wave has been relocalized from the Central
Caribbean to the present location based on satellite and models
Hovmoller data as well as on surface observations. The wave axis
extends from 20N86W to 10N86W. The wave is in a region of
unfavorable vertical wind shear, however shallow moisture and
upper level diffluent flow within a narrow ridge over the W
Caribbean support scattered showers and isolated tstms in the Gulf
of Honduras S of 18N W of 84W. 

...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 10N14W and continues along
08N26W to 12N38W to 10N52W. The ITCZ begins near 10N52W and 
continues to 10N61W. For information about convection see the
tropical waves sections above.

...DISCUSSION...

GULF OF MEXICO...

Weak surface ridging continues to dominate across the Gulf waters with
gentle to light variable winds E of 91W and moderate southerly
flow elsewhere. Instability aloft prevails in the form of
divergent flow generated by a broad upper level low centered near
the central Gulf at 24N89W and another upper low centered over
Georgia adjacent waters near 31N76W. This is supporting a weakness
in the surface ridge analyzed as a trough along 30N84W to 29N90W 
to 29N94W, which continues to generate scattered heavy showers and
tstms along S Louisiana and adjacent waters to 28N. A col of low 
pressure between the upper level lows continue to support similar 
convection in the NE Gulf N of 26N E of 86W, including portions of
central and NE Florida. Latest surface and scatterometer data 
show fresh to near gale winds in the area of convection S of 
Louisiana. Otherwise, shallow moisture and middle level diffluent 
flow in the SW Gulf support scattered showers in the Bay of 
Campeche. No major changes expected during the next two to three 
days.

CARIBBEAN SEA...

An upper level low centered near the central Gulf of Mexico and a
narrow upper ridge in the NW Caribbean generate diffluent flow
aloft, which along with abundant low level moisture support 
scattered showers and tstms over southern Cuba adjacent waters to
18N. Similar shower activity is in the Gulf of Honduras due in
part to a tropical wave that will be entering Belize and the
Yucatan Peninsula tonight. For further details see the tropical 
waves section above. The northern portion of this wave still
lingers in the SW N Atlc as a surface trough just in the SW
periphery of the Azores ridge. This trough that extends from
24N68W to 17N69W is supporting isolated showers across the E
Dominican Republic. Another surface trough is in the SE Caribbean
just moving across the Windward Islands where it is supporting
scattered to isolated showers. In the SW basin, the eastern
extension of the E Pacific monsoon trough support numerous to
scattered heavy showers and tstms within 90 nm off the coast of
Costa Rica and northern Panama. The remainder basin prevails 
under the influence of unfavorable vertical wind shear and dry 
air subsidence, which is supporting fair weather. Otherwise, 
strong high pressure over the Atlc extending a ridge along the 
northern basin increase the pressure gradient enough to maintain 
the continuation of fresh to near gale-force winds in the south- 
central Caribbean. These winds are forecast to prevail the next 
two days.

...HISPANIOLA...

The northern energy associated with a tropical wave currently 
moving across the NW Caribbean and northern Central America still 
lingers in the SW N Atlc as a surface trough just in the SW 
periphery of the Azores ridge. This trough that extends from 
24N68W to 17N69W is supporting isolated showers across the E 
Dominican Republic. Model guidance indicate this shower activity
will persist through tonight and then fair weather will set in
through at least Monday night.

ATLANTIC OCEAN...

An upper level low centered over adjacent waters of Georgia and S
Carolina continue to support scattered showers and tstms just N of
the Bahamas W of 76W. E of the S Bahamas, a surface trough,
remnant energy of a tropical wave currently moving across Central
America, support scattered showers from 22N to 25N between 67W
and 70W. Otherwise, the Azores high continues to cover the
remainder Atlc waters providing stability. For tropical waves
activity see the waves section above. No major changes expected 
the two to three days.

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

$$
Ramos

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Page last modified: Sunday, 23-Jul-2017 18:02:10 UTC