[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091752
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
152 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 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...TROPICAL WAVES...

Currently, two tropical waves are observed between the coast of
Africa and the Lesser Antilles. Two tropical waves are moving
across the Caribbean Sea.

A tropical wave is along 21W from 4N-13N moving westward 15 to 20
kt. 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 tropical wave extends its axis along 35W/36W south of
15N, moving westward 10 to 15 kt. Isolated moderate convection is
seen where the waves axis meets the ITCZ. Saharan dust surrounds
the wave.

A tropical wave has entered the Caribbean Sea. Its axis is along
62W south of 18N, moving westward 15 to 20 kt. A patch of low
level moisture with embedded showers is associated with the wave,
affecting parts of the Lesser Antilles. The wave will pass south
of Puerto Rico tonight, and reach Hispaniola on Sun.

A tropical wave is moving across the western Caribbean Sea around
10 kt. Its axis is along 86W, south of 18N. The wave will pass
west through the Gulf of Honduras through this evening and interact
with an upper-level trough resulting in continued thunderstorm
development across parts of the western Caribbean and northern
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 mid to upper-level low will meander over the Gulf of Mexico
through the middle of next week and enhance convection over the
eastern Gulf waters. 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
95W/96W during the late mornings, accompanied by a fresh to
locally strong wind shift. An east to west ridge will meander
across the northern Gulf waters through the period accompanied by
a moderate southeast return flow, except increasing to fresh
southeast breeze late Sun through Mon evening.

CARIBBEAN SEA...

Recent scatterometer data provide observations of 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.

Two tropical waves are moving across the Caribbean Sea. Refer to
the Tropical Waves section above for details.

Strong SW flow ahead of a mid to upper-level trough over the
eastern Gulf of Mexico and the Yucatan Peninsula continues to
transport abundant mid-upper level moisture across the NW Caribbean
into central Cuba and the Bahamas. Convection continues to flare
up over the SW Caribbean, likely related to the proximity of the
Monsoon Trough. Patches of low level moisture embedded in the
trade winds flow are noted elsewhere across the basin.

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.

An east to west ridge is forecast to meander between 27N and 29N
through Wed. Fresh to locally strong nocturnal easterly winds are
forecast along the northern coast of Hispaniola, with moderate
easterly expected elsewhere south of the ridge. Gentle to moderate
southerly flow is forecast north of the ridge.

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.

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

$$
GR
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