[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111751
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
151 PM EDT Tue Jul 11 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.

A tropical wave is analyzed over the far eastern Atlantic along
21N from 05N to 13N. Deep layer moisture is associated with the
tropical wave south of 11N, with Saharan dust prevaling north and
ahead of the wave. A cluster of moderate to isolated strong
convection is noted ahead of the wave axis from 07N to 10N between
21W and 24W.

The tropical wave previously located along 34W/35W is relocated
farther west along 37W based on visible satellite imagery and the
TPW animation. This tropical wave remains well defined in satellite
derived wind fields. Scattered showers are near the wave axis
between 35W and 40W.

A tropical wave is analyzed along 56W/57W on the 1200 UTC
analysis/surface map based also on visible satellite imagery,
that shows some inverted-V pattern in the cloud field, and the
TPW product where a sharp inverted trough is noted. This wave
coincides with a broad trough previously located along 55W. A
patch of moisture with embedded showers is related to this wave
forecast to reach the Lesser Antilles late today.

A tropical wave is over the central Caribbean Sea and extends from
eastern Cuba to the coast of Colombia near 10.5N75W. No significant
convection is noted with it.

...ITCZ/MONSOON TROUGH...

The monsoon trough passes through Senegal near 14N16W to 10N19W to
09N35W. The ITCZ extends from 08N38W to 09N60W. Scattered moderate
convection is observed within about 150 nm N of ITCZ axis between
49W and 55W. A small cluster of moderate to isolated strong
convection is from 09N to 11N between 17W and 18.5W.

...DISCUSSION...

...THE GULF OF MEXICO...

A ridge continues to dominate the Gulf waters producing mainly
gentle winds and slight seas. The ridge will persist through
Thursday. A trough is over the NE Gulf and extends from 27N85W to
23N86W. Scattered showers and thunderstorms are over the NE Gulf
associated with this trough forecast to dissipate by tonight.
Similar convective activity is noted over the western Gulf, and
mainly from 21N to 24N west of 95W, including also the mexican
coastline. A diffluent pattern aloft ahead of an upper-level low
centered over NE Mexico is helping to induce this activity. As
usual, a thermal trough will develop over the Yucatan Peninsula
during the late afternoons, move NW during the overnight hours
dissipating over the SW Gulf by late each morning. A surge of
moderate to locally fresh winds will be associated with this
thermal trough. Looking ahead, a surface trough, associated with
the remnants of T.D Four, currently located along 68W, will move
across south Florida on Thursday, and across the E Gulf Thursday
night into Friday, reaching the central Gulf later on Friday. This
trough is expected to increase the likelihood of showers with
embedded thunderstorms.

...THE CARIBBEAN SEA...

A recent scatterometer pass provided observations of fresh to
strong winds over the south-central Caribbean ahead of and in the
wake of a passing tropical wave. The area of strong trade winds
is shrinking slightly however as high pressure north of the region
weakens. A large area of showers and thunderstorms is over the SW
Caribbean, and covers the region South of 14N west of 80W, and
south of 13N between a tropical wave with axis along 75W and 80W.
This convective activity is likely associated with a weak low
pressure system located along the monsoon trough near 10N79W. In
addition, a very well defined diffluent pattern aloft supports
this strong convective activity. An upper-level low persists near
the Cayman Islands and continues to enhance some shower activity
over eastern Cuba and the Cayman Islands. This upper-level low is
forecast to persist on Wednesday while weakening. Looking ahead, a
stronger tropical wave is forecast to approach the Windward
Islands late Thursday and enter the eastern Caribbean early on
Friday.

...HISPANIOLA...

Available moisture will combined with the local effects to produce
scattered showers and isolated and thunderstorms during the
afternoon and early evening hours. The upper-level low located
west of the area, that was enhancing convection across the island
is forecast to weaken on Wednesday, then dissipate over the next
24 hours.

...THE ATLANTIC OCEAN...

A 1014 mb low pressure, remnants of T.D. Four is situated near
23N68.5W. Scattered showers and thunderstorms area near the low
center, with another area of cloudiness with embedded showers and
thunderstorms to the SE of the low center. This low is forecast to
approach the SE Bahamas by early Wednesday morning. So far, the
GFS Computer Model suggests that a trough associated with the
remnants of T.D. Four will move across the Bahamas through
Wednesday night, reaching south Florida on Thursday. A surface
trough extends from 24N45W to 19N46W. Scattered showers are near
the northern end of the trough axis. Another surface trough is
along 73W from 26N to 30N. Isolated showers and thunderstorms are
near the trough axis. Farther east, an upper-level low is centered
near 28N58W, supporting scattered showers and thunderstorms from
26N to 29N between 57W and 61W. The Bermuda-Azores high extends a
ridge across the remainder of the forecast region. An extensive
area of African Saharan dust is reaching 45W 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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