[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191747
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
147 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 1200 UTC surface analysis and satellite imagery through
1715 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. Although this system is
producing a widespread area of cloudiness and disorganized showers
and thunderstorms, interaction with land and proximity to dry air
in the mid-levels of the atmosphere over W Texas and NE Mexico
should prevent a tropical cyclone from forming. However, this
disturbance is likely to produce additional heavy rainfall and
flash flooding across portions of southern and southeastern Texas
during the next few days. As much as 7 to 10 inches of additional
rainfall is possible over south Texas along the Texas Coastal Bend
during the next 1 to 2 days. Strong SE to S winds can be expected
over the western Gulf N of 25N between 92W and 96W, primarily in
bands of deep convection through this evening. Winds and seas are
expected to subside Tonight and Wed as this system gradually
weakens. For more details on this disturbance and the threat for
heavy rainfall, please see products issued by your local weather
office and High Seas Forecasts issued by the National Weather
Service.

...TROPICAL WAVES...

A tropical wave over the eastern Atlc has an axis extending from
02N19W to 11N21W, moving W from Africa around 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 tropical wave over the central Atlc has an axis extending from
02N33W to 11N34W, moving W around 15 kt in a moderate shear
environment due to an upper-level trough over 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 tropical wave over the west-central Atlc has an axis extending
from 05N54W to 14N51W, moving W around 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 tropical wave entering the eastern Caribbean has an axis
extending from 09N66W to 19N63W, moving W at 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 extends from the border of Guinea and Sierra
Leone on the coast of Africa near 09N13W to 06N23W. The ITCZ
continues from 06N23W to 05N33W, then resumes from 04N35W to
05N47W to the coast of South America near 04N51W. 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

$$
McElroy
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