[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100003
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
803 PM EDT Sat Jun 9 2018

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
2300 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 21W/22W from 13N
southward, moving westward 15 knots. The Hovmoller Diagram
indicates the westward propagation of the wave, and model
diagnostics guidance also suggests the presence of this system.
This wave shows up well as a low amplitude moisture surge on the
TPW product. Currently, convection is limited along the wave's
axis due to the presence of African dust.

A second Atlantic Ocean tropical wave extends its axis along
36W/37W south of 15N, moving westward 10 to 15 knots. Isolated
moderate convection is seen where the waves axis meets the ITCZ.
Saharan dust surrounds the wave.

A Caribbean Sea tropical wave is along 63W/64W from 19N southward
moving westward 15 to 20 knots. A patch of low level moisture
with embedded showers is associated with the wave, affecting parts
of the Lesser Antilles. The wave will pass to the south of Puerto
Rico tonight, and reach Hispaniola on Sunday.

A Caribbean Sea tropical wave is along 86W/87W from 19N southward,
moving westward 10 knots. The wave is moving through an area of
upper level cyclonic wind flow. Continued rainshowers are possible
in parts of the western Caribbean Sea and northern sections of
Central America.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through Guinea, and
continues to 09N21W to 07N34W. The ITCZ stretches from 07N37W to
06N45W to the coast of Guyana near 08N59W. A cluster of moderate
convection is from 6.5N-8N between 14N-16N. Similar convection is
noted within about 120 nm N of the ITCZ axis between 52W and 57W.

...DISCUSSION...

GULF OF MEXICO...

A mid to upper level low located over the NE Gulf continues to
enhance the development of scattered showers and thunderstorms
across the eastern Gulf, and over parts of Florida. A surface
trough is analyzed over northern Florida and the NE Gulf in
association with this system aloft. The remainder of the Gulf is
under the influence of a ridge anchored by a 1022 mb high
pressure situated over central Florida. Scattered showers and
tstms are also noted just of the coast of Mexico, roughly between
Tampico and Veracruz, where a diffluent pattern aloft prevails.

The middle to upper level cyclonic circulation center will
meander in the eastern Gulf of Mexico through Tuesday, supporting
rainshowers. A surface trough will develop along the Yucatan
Peninsula late each afternoon, drift westward across the southwest
Gulf during the overnight hours, then dissipate along 96W during
the late mornings. Fresh northeast to east to southeast wind shift
is expected in the vicinity of the trough. An east to west ridge
will meander across the northern Gulf waters through the period
accompanied by a moderate southeast return flow in the W Gulf.
Fresh to strong winds and associated seas are expected in the
Yucatan Channel Wed evening associated with a tropical wave or
developing area of low pressure that will move into the SW Gulf
Thu.

CARIBBEAN SEA...

Scatterometer data have been showing near gale force trade winds
across the south-central Caribbean, particularly S of 13N between
73W and 77W. The most recent altimeter data indicated sea heights
of near 14 ft in association with these winds. Fresh to strong
trade winds area noted elsewhere from 11N- 17N between 68W- 80W.
Moderate to locally fresh trades prevail across the remainder of
the eastern Caribbean, with gentle to moderate NE-E winds across
the NW part of the basin. The pressure gradient between high
pressure N of area and the Colombian/Panamanian low will continue
to support fresh to strong winds across the central Caribbean, and
the eastern Caribbean S of 15N, but mainly W of 64W. These
conditions will persist through at least Mon.

The Saharan Air Layer (SAL) from CIMSS shows abundant Saharan dust
covering the area between the west coast of Africa and the Lesser
Antilles. The Saharan dust is expected to reach Puerto Rico and
the Virgin Islands on Sun, bringing haze conditions across the
area.

A tropical wave will move west across the Gulf of
Honduras through tonight. The wave interacts with an upper
trough that supports the continuation of rainshowers across the
NW Caribbean. A second tropical wave is in the E Caribbean
supporting showers in the NE basin, including the Leeward
Islands. Strong high pressure N of the area will support fresh to
strong trades in the south-central basin continuing through Thu,
however increasing in areal coverage Wed and Thu. A tropical wave
is forecast to move across Honduras Tue night into Wed tightening
the pressure gradient, thus resulting in fresh to strong winds in
the Gulf of Honduras and NW Caribbean.

ATLANTIC OCEAN...

Abundant moisture continues to prevail across the west Atlantic,
on the eastern side of the Gulf of Mexico-Yucatan Peninsula mid to
upper-level trough. A band of multi-layer clouds extends from
central Cuba across the NW and central Bahamas. Lightning data and
Doppler Radar indicate the presence of tstms over S Florida and
the NW Bahamas. A ridge dominates the remainder of the Atlantic
Ocean with a 1027 mb high pressure located near 31N41W. Moderate
to locally fresh winds are noted along the southern periphery of
the ridge per scatterometer data.

Surface ridging extending from the central Atlc will
prevail across the region, thus supporting moderate ESE winds in
the vicinity of the southern Bahamas. Fresh to locally strong
nocturnal easterly winds are forecast to continue along the
northern coast of Hispaniola through Sunday. These winds will
resume Tue night and continue through Thu. Gentle to moderate
southwesterly flow is expected N of 30N of the ridge.

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

$$
MT
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