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Atlantic Tropical Weather Discussion

AXNT20 KNHC 210521

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
121 AM EDT Sat Jul 21 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 0000 UTC surface analysis and satellite imagery through 
0515 UTC.


A tropical wave is in the E Atlc with axis extending from 05N-18N
along 28W, moving W at 10-15 kt. Saharan dry air and dust 
continue to prevail in the wave's environment as shown by CIRA 
LPW and GOES-16 RGBs imagery. This is inhibiting convection at 
this time. 

A tropical wave is in the central Atlantic with axis extending 
from 05N-21N along 45W, moving W at 10-15 kt. The wave is moving 
across an extensive area of Saharan dry air, which is hindering 
convection at the time.

A low amplitude tropical wave is moving across Venezuela with 
axis extending from 00N-10N along 66W, moving W at 10-15 kt. 
Scattered moderate convection is observed with this wave between
62W-70W. This wave is forecast to move to EPAC waters on Mon.

A tropical wave is in the west-central Caribbean with axis along 
81W, moving W at 15-20 kt. Scattered showers are noted along the 
wave's axis in the vicinity of the monsoon trough mainly south of 


The monsoon trough axis extends from the coast of W Africa near 
14N17W and continues to 09N40W. The ITCZ begins near 07N47W and 
continues to South America near 08N59W. No significant convection
is observed along these boundaries at this time.



A surface trough continues over the northeast Gulf waters from 
northern Florida near 30N83W to 28N86W. This feature is being 
supported by a mid-level trough that extends over the eastern 
CONUS, which also supports a frontal system north of the area. 
Scattered showers are noted along the trough at this time. Latest
scatterometer data show gentle to moderate winds in the vicinity 
of the trough. Elsewhere, the remainder Gulf is under the 
influence of a surface ridge, anchored by a 1016 mb high centered
near 27N92W. This is providing light to moderate anticyclonic 
winds across the basin. The trough is forecast to lift NE of the 
area this morning and surface ridging will prevail thereafter 
through the weekend. A surface trough will move off the Yucatan 
Peninsula into the Bay of Campeche each evening, accompanied by 
fresh nocturnal winds and scattered showers. 


The majority of the basin is pretty quiet as very dry air prevails
across the area. A tropical wave is moving across the west-
central portion of the basin, however lacks convection due to the 
aforementioned conditions. The only region of convection is within
150 nm off the coast of Costa Rica and northern Panama where the 
EPAC monsoon flow supports scattered showers and tstms. For more 
information about the wave, refer to the section above. 
Otherwise, the southwestern periphery of the Azores high continue 
to tighten the pressure gradient in the south-central basin, thus
supporting fresh winds between 65W and 83W. Strong to near-gale 
winds are forecast at night along the Colombia coast and adjacent 
waters. No major changes expected through early next week. 


Mid to upper-level diffluent flow between a ridge in the west
Atlantic and a trough along the E CONUS continue to support 
scattered showers and tstms N of 25N W of 70W. The remainder basin
is under the influence of the Azores high, which is anchored by a
1036 mb high near 40N37W. Fair weather is elsewhere, however hazy
conditions are expected S of 26N as an extensive Saharan Air 
Layer outbreak moves across the Atlantic tropical waters.

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