[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200004
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Tue Jun 19 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.

...SPECIAL FEATURE...

Surface observations and NOAA Doppler weather radar data indicate
that a deep layer low pressure system has consolidated W of
Corpus Christi Texas near 28N98W. This system has been producing
widespread cloudiness and disorganized rainshowers. Interaction
with land and proximity to dry air in the mid-levels of the
atmosphere in W Texas and NE Mexico should prevent a tropical
cyclone from forming. It is likely that this disturbance may
produce additional heavy rainfall and flash flooding across
parts of southern and southeastern Texas during the next few
days. As much as 7 to 10 inches of additional rainfall are
possible in south Texas along the Texas Coastal Bend during the
next 1 to 2 days. Strong SE to S winds can be expected in the
western Gulf N of 25N between 92W and 96W, primarily in bands of
deep convective precipitation through this evening. Winds and
seas are expected to subside tonight and Wednesday as this system
gradually weakens. Numerous strong rainshowers are in Texas and
northeastern parts of Mexico from 24N to 27N between the coast and
99W. Scattered moderate to isolated strong rainshowers are in the
Gulf of Mexico from 26N northward from 91W westward. Please read
bulletins and forecasts that are issued by your local weather
office, and High Seas Forecasts issued by the National Weather
Service for more details on this disturbance and the threat for
heavy rainfall.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 21W/22W from 11N
southward, moving W about 20 kt, in a low vertical shear
environment. Composite TPW satellite imagery shows this system is
embedded in deep layer moisture. Scattered moderate and isolated
strong convection is found from 03N to 06N between 18W and 21W.

A second Atlantic Ocean tropical wave is along 34W/35W from 11N
southward, moving W about 15 kt, in a moderate shear environment
due to an upper-level trough in the Atlc near 40W. Dry Saharan
air and dust are limiting convection on the W side of this wave.
Scattered moderate and isolated strong convection is found from
03N to 06N between 27W and 36W.

A third Atlantic Ocean tropical wave is along 51W/54W from 14N
southward, moving W about 10 kt. GOES-16 RGB imagery shows dry
air and dust surrounding the N side of the wave. Convergent upper-
level winds are also inhibiting deep convection. Consequently,
only spotty cloudiness and isolated showers are observed within 90
nm of the wave axis.

A Caribbean Sea tropical wave is along 63W/67W from 19N southward,
moving W 15 to 20 kt. This wave is within a very moist
environment and upper level diffluent flow, supporting scattered
moderate and isolated strong convection over the Virgin Islands
and Leeward Islands from 12N to 19N between 61W and 65W.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Guinea
near 10N14W, to 06N23W. The ITCZ continues from 06N23W to 04N31W
05N33W, to 04N53W in NE French Guiana. Scattered moderate and
isolated strong convection is present from 03N to 07N between 10W
and 18W.

...DISCUSSION...

GULF OF MEXICO...

Scattered to numerous showers and thunderstorms are occurring over
the Gulf of Mexico W of 92W. This convection is associated with
deep layer low pressure centered over S Texas. See the Special
Features Section for more details on this system. The pressure
gradient between the area of low pressure and a ridge across the
SE CONUS extending into the NE Gulf supports fresh to strong SE to
S winds W of 87W. Light to moderate E to SE winds are observed
over the eastern Gulf. The ridge over the Gulf will gradually
shift E over the western Atlc during then next couple of days,
helping winds over the western Gulf to diminishing below 20 kt.
Gentle to moderate return flow will dominate the basin thereafter
through Wed night, with strongest winds focusing west of 90W.

CARIBBEAN SEA...

Strong trades across the S central Caribbean will gradually
decrease in areal coverage today through Wed as high pressure in
the SW N Atlc shifts east. Fresh to strong winds will pulse at
night in the Gulf of Honduras through early Wed morning.
Otherwise, a tropical wave passing west of the Windward Islands
will move across the E Caribbean today along with showers. The
wave will move S of Puerto Rico, then into the central Caribbean
on Wed. Winds and seas over the S Central Caribbean will increase
toward the end of the week as high pressure over the western Atlc
rebuilds and low pressure over northern S America deepens
slightly.

ATLANTIC OCEAN...

A stationary front extends SW from 32N56W to 26N63W, then
continues W as a weakening stationary front to end just east of
the Bahamas near 25N74W. Weak surface ridging north of the front
supports light to gentle NE to E winds and mostly fair weather.
Scattered moderate and isolated strong convection is seen from 24N
to 29N between 55W and 68W. A mid to upper-level low continues to
support convection in the vicinity of the front. The remainder of
the Atlantic remains under the influence of the subtropical ridge
anchored by a 1027 mb high centered just SW of the Azores
Islands. The front will continue to weaken through Tue and
dissipate by Wed. Surface ridging will continue to extend SW over
the western Atlc from near the Azores through the end of the
week.

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

$$
MT
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