Tropical Weather Discussion
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AXNT20 KNHC 252356

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
756 PM EDT Sun Jun 25 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
2315 UTC.


A tropical wave is in the far eastern Atlantic with the axis
extending along 25W south of 12N and is moving W at 15 to 20 kt.
Scattered moderate isolated strong convection was noted from
04N to 09N between 27W and 30W. Scattered moderate was noted
elsewhere within 240 nm W of the axis.

A large amplitude tropical wave is in the central Atlantic with
the axis extending from 15N38W to 03N44W and is moving W at 15-20
kt. The wave is easily identifiable on the latest visible
satellite imagery. Scattered moderate convection was noted from
10N to 12N between 38W and 40W, and from 08N to 10N between 44w
and 46W.

Another fairly large amplitude tropical wave is located over the
Lesser Antilles with the axis extending along 62W/63W S of 19N
and is moving W at 15 kt. The wave is in a region of favorable to
neutral wind shear. Scattered moderate isolated strong convection
was noted from 12N to 16N within 240 nm W of the wave axis.

A tropical wave is located in the central Caribbean with the
axis extending along 76W/77W south of 20N to Colombia and is
moving west at 15 kt. Water vapor imagery indicates that the wave
is in a region of unfavorable wind shear and convection is


The Monsoon Trough extends from the Africa coast near 12N15W to
07N23W. The Intertropical Convergence Zone axis begins near
07N27W and continues to 07N40W to 04N51W. For convection
information see the tropical waves section.



A sharp middle/upper level trough over the NW gulf extends from
the coast of Louisiana southward through 26N91W 22N94W. The trough
is moving eastward at 15 kt across the northern half of the gulf.
Moderate SW winds aloft are located on the east side of the
trough. Diffluent flow aloft SE of the trough was maintaining
scattered moderate to strong convection within 120-180 nm E of a
surface trough over the Bay of Campeche from 25N93W to 18N95W.
Additional scattered to numerous strong convection was emerging
off the coast of Yucatan into the Bay of Campeche. At the surface
a weak cold front extended from near Apalachicola, Florida to
28N91W to near Corpus Christi, Texas. The portion of the front W
of 90W was in the process of dissipating. Light and variable
winds prevailed over the Gulf south of the cold front with light
to locally moderate NE winds north of the front.


A fairly large upper level cyclone covered the Caribbean W of
76W with moderate subsidence within 240 nm of the core of the
upper low. Further east, broad anticyclonic flow prevailed over
the remainder of the Caribbean in the vicinity of the tropical
wave along 62W/63W with some of the subsidence in the area
becoming entrained into the convection associated with the
tropical wave allowing the convection to weaken. At the surface,
an ASCAT scatterometer pass from 1450 UTC showed moderate to
strong trades of 20-25 kt from 11N to 16N between 69W and 75W and
also over the Windward islands. Light winds prevailed over the NW


Moderate upper level southwesterly winds amidst some subsidence
aloft was noted over Hispaniola. A cluster of strong
thunderstorms was in progress over Haiti and in interior portions
of the Dominican Republic. The 12Z rawinsonde from Santo Domingo
showed low to mid level moisture to about 550 mb with precipitable
water values approaching 2.00 inches.


An expansive mid-to upper level cyclonic circulation is located
over the west central Atlantic near 27N54W drifting to the WSW.
Further east,a fairly sharp middle/upper level trough has its
axis along 29W/30W north of 26N and is digging to the southeast.
A large anticyclone dominated the flow over the tropical Atlantic
between 30W and 60W with strong deep layered subsidence noted
from 10N to 20N between 40W and 52W. The strongest subsidence
coincided with an area of extensive Saharan dust as noted in the
Seviri dust imagery. At the surface a trough extended from 31N52W
to 25N54W. A 1026 mb high is centered near 32N47W. This high
dominated the surface flow over a majority of the subtropical

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