Tropical Weather Discussion
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AXNT20 KNHC 200559

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
159 AM EDT Thu Jul 20 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 0000 UTC surface analysis and satellite imagery through
0515 UTC.


A tropical wave is over the far eastern Atlc with its axis
extending from near 17N23W to 05N23W, moving W at 15 kt. SSMI
imagery shows a moist area from 05N-17N between 12W-26W. There is
also a well defined 700 mb trough associated with the wave.
Saharan dry air and dust is NW of the wave environment. Scattered
moderate to isolated strong convection is from 10N-14N between

A tropical wave with an embedded low pressure is in the central
Atlantic. The axis extends from 19N47W to a 1014 mb low near
12N48W to 08N48W, moving W at 15 kt. The SSMI total precipitable
water imagery shows a very large moist area over from 02N-24N
between 38W-51W. The embedded surface low is well defined. Saharan
dry air and dust is NW of the wave environment. Potential for
tropical cyclone development from this system remains low through
the next two days. Widely scattered moderate convection is from
09N-16N between 47W-51W.

A tropical wave is over the central Caribbean Sea, which denotes
the remnants of former Tropical Storm Don. The wave axis extends
from 19N69W to 10N69W, moving W at 20 kt. The wave is in an
unfavorable wind shear environment. However, abundant low to mid
level moisture along with divergent flow aloft support scattered
showers within 120 nm of the wave axis. Moreover, scattered
moderate to strong convection has recently developed over W
Venezuela and N Colombia from 07N-10N between 71W-76W.

A tropical wave is in the W Caribbean with axis extending from
19N79W to Panama near 07N81W, moving W at 20 kt. SSMI TPW imagery
depict abundant moisture associated with this wave. The wave is
however, in a region of unfavorable wind shear, and Saharan dry
air and dust are affecting the western periphery of the wave
environment. Scattered moderate convection is off the coast of
Nicaragua from 10N-15N between 80W-85W.


The monsoon trough axis extends from 14N17W to 10N23W to 09N30W to
07N35W. The ITCZ then extends from 07N35W to 05N43W. The ITCZ
resumes W of a tropical wave near 10N50W and extends to the coast
of South America near 08N60W. Aside from the convection
associated with the tropical waves, scattered moderate convection
is from 05N-12N between 26W-37W.



A surface trough is over the Yucatan Peninsula from 21N88W to
16N94W. Scattered showers are within 90 nm of the trough axis.
Further W, scattered moderate convection is inland over S Mexico
from 16N-18N between 93W-96W. A 1019 mb high is centered over the
NE Gulf of Mexico near 28N85W. 5 kt anticyclonic winds are noted
around the high. The NW Gulf has 5-10 kt SW flow. Radar imagery
shows isolated showers over the Straits of Florida, and Florida.
In the upper levels, an upper level low is centered over Mexico
near 24N100W enhancing convection over Mexico. Another upper level
low is centered off the coast of Georgia near 31N79W. Expect in
24 hours for the latter upper level low to move to NE Florida, and
to the NE Gulf of Mexico in 48 hours, with convection. Also
expect scattered showers and thunderstorms to form over the Bay
of Campeche, during maximum heating Thursday.


The main features in the basin are the remnants of former tropical
storm Don, currently analyzed as an open tropical wave, and a
tropical wave in the W Caribbean. In addition, isolated moderate
convection is over the NW Caribbean from 19N-22N between 80W-88W.


A fast moving tropical wave is moving across the western portion
of the island. Scattered showers are noted over Haiti. These
showers are expected to cease by Thursday as the wave races
westward tonight.


Scattered showers are over the N Bahamas and the W Atlantic, N of
25N and W of 73W. A large 1025 mb high is centered over the
central Atlantic near 32N59W. Of note in the upper levels, two
upper level lows are over the W Atlantic at 31N79W and 26N69W
enhancing showers. Another upper level low is also centered over
the central Atlantic near 30N49W enhancing showers W of center.

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