Tropical Weather Discussion
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AXNT20 KNHC 230938

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
538 AM EDT Fri Jun 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 0600 UTC surface analysis and satellite imagery through
0930 UTC.


A tropical wave is in the E Atlc associated with a 1010 mb low
centered S of the Cape Verde Islands near 13N24W. The wave axis
extends from 19N22W to the low to 06N24W and it has been moving
at 5-10 kt within the last 24 hours. The wave is in a region of
favorable to neutral wind shear. However, the CIRA LPW imagery
show extensive dry air around the low while moderate moisture
with patches of dry air is S of the low. Meteosat enhanced
imagery confirm the presence of Saharan dry air and dust around
the low where there is lack of convection. Upper level divergence
support scattered showers and tstms S of the low from 07N to 11N
between 21W and 27W.

A tropical wave is in the central Atlc associated with a 1010 mb
low centered near 09N43W. Its axis extends from 14N43W to the low
to 04N43W, moving W at 5 kt within the last 24 hours. The wave is
in a region of favorable wind shear S of 11N, is mainly in a very
moist environment with some patches of dry air according to CIRA
LPW, and is under a region of upper level divergence. These
factors support scattered heavy showers and tstms from 0N to 05N
W of 41W, and isolated showers within 210 nm of the low center.

A tropical wave is in the E Caribbean with axis extending from
16N62W to inland Venezuela, moving west at 5-10 knots within the
last 24 hours. The wave is in a region of favorable to neutral
wind shear. However, extensive intrusion of Saharan dry air and
dust hinder convection at the time.

A tropical wave is in the western Caribbean with axis extending
from 21N84W to inland Honduras and Nicaragua, moving west at 20
knots within the past 24 hours. The wave is in a region of
favorable to neutral wind shear. CIRA LPW imagery show patches of
dry air ahead of the wave axis, which limit the convection to
scattered to isolated showers S of 22N. Scattered showers and
tstms are E of the wave axis from 13N to 22N between 78W and 85W.


The Monsoon Trough is not present over E Atlc waters. The
Intertropical Convergence Zone begins near 08N25W to 04N40W to
04N51W. For information regarding convection see the tropical
waves section.



Stable weather conditions are basin-wide being supported by
surface high pressure extending SW from the W Atlc and dry air
subsidence from aloft as indicated by Water Vapor imagery. Latest
scatterometer data show fresh to strong S-SE winds in the
northern Gulf N of 23N W of 88W. Fresh winds are also noted in
the far W Bay of Campeche and in the Florida straits S of 24N.
Moderate gentle to moderate SE winds are elsewhere. A tropical
wave will enter the Yucatan Peninsula later today with scattered
showers and thunderstorms. An upper level low ahead of this wave
will move over the Bay of Campeche supporting heavy showers and
tstms over the W Gulf W of 90W over the weekend.


An upper-level low is centered over the NW Caribbean ahead of a
tropical wave along 85W. Scattered heavy showers and tstms are E
of the wave axis from 15N to 22N. See the tropical waves section
for further details. The upper level low also supports scattered
to isolated showers over western Cuba and across the Windward
Passage. A 1009 mb low is over NW Colombia linked to the EPAC
monsoon trough, which support isolated showers 120 nm off the
Colombia coast S of 11N. Fresh to strong winds are in the vicinity
of the wave while moderate trades dominate elsewhere. The upper-
level low is forecast to move northwest toward the southwest Gulf
of Mexico by Saturday with the tropical wave moving westward into
the East Pacific waters during the weekend. Increased probability
of convection and precipitation is expected across Central
America and southern Mexico through this period.


Isolated showers and tstms are over SW Haiti and the Windward
Passage associated with a broad upper level low over the NW
Caribbean and a tropical wave moving across Honduras and the
Yucatan Channel. An upper-level anticyclone centered N of the
Bahamas continue to provide overall subsidence elsewhere, thus
supporting fair weather across the remainder Island.


There are three tropical waves in the basin. See that section
above for further details. Otherwise, the Azores high prevails
across the basin being anchored by a 1025 mb high near 40N26W.
A weakness in the ridge is being analyzed as a surface trough from
27N54W to 24N56W per the latest scatterometer pass. No
significant areas of convection are occurring away from the
ITCZ/monsoon trough/tropical waves. Little change is expected for
the next couple of days.

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