[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101746
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
146 PM EDT Mon Jul 10 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...TROPICAL WAVES...

A tropical wave is in the eastern Atlantic southwest of the Cabo
Verde Islands with axis extending from 14N31W to 06N31W, moving
west at 15 kt. Abundant moisture prevails within this wave, as
noted in TPW imagery. Satellite imagery shows an area of moderate
convection along the wave axis from 10N to 12.5N between 30W and
33W. Some gradual development of this system is possible through
the week while it moves westward across the tropical Atlantic
Ocean.

Another tropical wave extends from 15N42W to 05N42W, moving west
at 10 kt. Scattered showers are on either side of the wave axis.
A large area of moisture is noted on the TPW animation to the NE
of the wave, and on the east side of an upper-level trough
extending well north into the subtropics to 25N. A large area of
Saharan dust is noted to the east of the moisture plume. The wave
is forecast to reach 55W by Tuesday night.

A broad area of lower to mid level cyclonic turning is noted in
satellite derived winds farther west, with an axis roughly along
50W. Scatterometer and buoy data hint a very broad trough at the
surface. This feature is on the drier subsident side of the above
mentioned upper-level trough, and little to no sensible weather
is noted, other than a few showers. Moisture associated with this
trough will reach the Leeward and Windward Islands Tuesday night
into Wednesday.

A tropical wave is analyzed over the eastern Caribbean with axis
extending from Dominican Republic to western Venezuela. The wave
will enter the central Caribbean this afternoon and continue to
move westward across this area on Tuesday enhancing convection
over Hispaniola.

Another tropical wave extends from the westernmost tip of Cuba to
the Gulf of Honduras, and then across Honduras and Nicaragua
moving west at 10 kt. The wave is on the west and dry side of an
upper level low spinning over the Cayman Islands. Clusters of
moderate to isolated strong convection are over the SW Caribbean,
and just behind the wave axis covering the area S of 13N and W of
80W. This wave will be over the Yucatan Peninsula early Tuesday
morning.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from 15N17W to 10N26W to 08N31W to
09N40W. The intertropical convergence zone extends from 09N44W to
the coast of Guyana at 07N59W. Outside of the convection associated
with the tropical waves, an area of moderate to isolated strong
convection is noted along the west coast of Africa from 07N to 10N
E of 16W.

...DISCUSSION...

GULF OF MEXICO...

The combination of a tropical wave, with axis near the westernmost
tip of Cuba and the northern periphery of an upper-level low
located over the Cayman Islands is producing scattered showers and
thunderstorms across south Florida and the Florida Keys since
early this morning. Mosaic Doppler Radar from the SE U.S. confirmed
the presence of this convective activity affecting also parts of
the Straits of Florida. Isolated showers are noted over the NE
Gulf. Weak ridge extended from the western Atlantic across the
Florida peninsula into the eastern Gulf where a 1018 mb high
pressure is analyzed. Light to gentle winds and slight seas are
noted across the region as a result, with the exception of
moderate to fresh east winds in the Straits of Florida. Earlier
scatterometer data indicated the wind shift related to the thermal
trough emerging off the west coast of the Yucatan Peninsula.
Fresh to locally strong winds were associated with this trough
forecast to develop each evening over the Yucatan peninsula, then
move across the SW Gulf each night and dissipate each morning.

CARIBBEAN SEA...

Two tropical waves are moving across the Caribbean. See Tropical
Waves section for details. As perviously mentioned, an upper-level
low is spinning over the Cayman Islands generating some shower
activity. Clusters of moderate to isolated strong convection are
over the SW Caribean likely associated with the Monsoon Trough and
a tropical wave with axis over Central America. Shallow moisture
embedded in the trade wind flow is noted elsewhere. A ridge, with
axis north of the area, combined with the Colombian/Panamanian low
will continue to support fresh to strong winds across the south-
central Caribbean through midweek, with moderate to locally fresh
trades prevailing elsewhere.

...HISPANIOLA...

The interaction of a tropical wave (with axis across the island)
with the aforementioned upper-level low over the western Caribbean
will maintain the risk of scattered showers and thunderstorms
across Hispaniola this afternoon and early evening hours. Similar
weather conditions are expected on Tuesday.

ATLANTIC OCEAN...

Two tropical waves and a trough are analyzed over the tropical
Atlantic. See Tropical Waves section above for details. In
addition, a 1012 mb low pressure, associated with the remnants of
T.D. Four, is added to the 1200 UTC analysis/surface map near
22.5N64W. A cluster of moderate to isolated strong convection is
within about 150 nm east semicircle of low center. A trough
extends from the low center to near 30N64W. Experimental GOES-16
shows some inverted-V pattern in the cloud field in association
with this trough. To the east of the trough, an upper level low
located near 28N57W is also producing some shower activity. The
Bermuda-Azores high extends a ridge across the remainder of the
forecast region. An extensive area of African Saharan dust is
reaching 40W based on the Saharan Air Layer Tracking Product from
CIMSS.

For additional information please visit
http://www.hurricanes.gov/marine

$$
GR
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