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Atlantic Tropical Weather Discussion

AXNT20 KNHC 222333

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
733 PM EDT Sat Jul 22 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 
2330 UTC.

Please refer to the METEO-FRANCE High Seas Forecast listed under 
winds are forecast for the AGADIR area through tonight.


A tropical wave came off the African coast this morning. It axis 
extends from 15N19W to 06N19W, moving wet at about 10 kt. At this
time, abundant moisture combined with the presence of the monsoon
trough are enhancing scattered moderate convection south of 10N
between 16W-24W.

A tropical wave is in the central Atlantic with axis extending 
from 20N35W to 10N35W, moving west at 5-10 kt during the last 24 
hours. The wave is in a region of Saharan dry air and dust that is
hindering deep convection at the time.

A low amplitude tropical wave is in the central Atlantic with 
axis extending from 15N45W to 06N46W, moving west at 10-15 kt. 
Middle to upper-level diffluence is supporting isolated showers 
from 08N-12N between 45W-48W.

A tropical wave is in the east Caribbean with axis extending from
21N65W to 10N67W, moving west at 10 kt within the last 24 hours. 
Strong dry air subsidence from aloft seems to be hindering the 
development of deep convection at this time. Isolated showers are
observed along the northern portion of the wave affecting portions
of Puerto Rico and adjacent waters north of 18N between 60W-67W.

A tropical wave is in the central Caribbean with axis extending
from 20N76W to 09N80W, moving west at 15 kt within the last 24 
hours. Shallow moisture over the northern portion of the wave is 
supporting isolated moderate convection affecting Jamaica, eastern
Cuba and adjacent waters north of 17N between 75W-79W.


The monsoon trough extends from 11N15W to 09N22W to 12N35W to
11N43W. The ITCZ begins near 08N48W to 08N61W. Aside from the 
convection associated with the tropical waves, scattered showers 
are south of 10N between 50W-60W.



Weak surface ridging continues to dominate the Gulf anchored by a
1021 mb high centered over the west Atlantic. A light to gentle
anticyclonic flow prevails across the area. Abundant moisture 
along with a very unstable environment aloft supports an area of
scattered to numerous showers and thunderstorms north of 26N
and east of 95W affecting the coastal Gulf states and the Florida
Peninsula. Scatterometer data show fresh to near-gale winds within
this activity. No significant changes are expected during the 
rest of the weekend.


The main features across the basin are two tropical waves. Please
refer to the section above for details. In the southwest portion 
of the basin, the monsoon trough supports scattered moderate
convection along Panama, Costa Rica and adjacent waters south of
10N between 78W-83W. The remainder basin is under the influence 
of dry air subsidence, which is supporting fair weather. The high
pressure over the Atlantic extends across the basin supporting a 
pressure gradient strong enough to maintain fresh to strong trades 
over the south-central Caribbean. These winds are forecast to 
prevail during the next two days.


Fair weather prevails across the island at this time. A tropical 
wave has moved across the island this morning, while another one 
is coming from the east. This wave will allow for the re-
development of showers and thunderstorms through the weekend. 


Aside from the tropical activity associated with the waves, the
remainder basin remains under the influence of a broad surface 
ridge that is anchored by a stationary 1021 mb high centered near 
30N62W. No significant changes are expected during the next few 
days. See the section above for details about the waves and
associated convection.

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