[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250558
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
158 AM EDT Wed Jul 25 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 0000 UTC surface analysis and satellite imagery through
0545 UTC.

...TROPICAL WAVES...

A tropical wave is over the far eastern Atlantic just to the west
of the Cape Verde Islands with its axis along 30W extending from
06N-20N, moving westward at 15-20 kt. A large area of Saharan dry
air and dust is hindering convective activity from developing at
the time.

A tropical wave is over the central Atlantic with axis along 42W
from 04N-15N, moving westward at 15-20 kt. A large area of
Saharan dry air and dust is hindering convective activity from
developing at the time.

A tropical wave is SE of the Lesser Antilles with its along 57W
from 05N-16N, moving westward at 15 kt. A large area of Saharan
dry air and dust is hindering convective activity from developing
at the time.

A tropical wave is over the central Caribbean with axis along 78W
from E Cuba to inland Panama, moving westward at 15-20 kt.
Shallow moisture in the northern wave environment along with a
region of middle to upper level diffluence ahead of the wave is
supporting isolated showers off the coast of SW Cuba and W coast
of Jamaica.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coast of Africa near
13.5N16.5W to 10.5N30W and ends just to the east of the tropical
wave with axis along 42W. The ITCZ extends from 07.5N44W to the
coast of South America near 06N56W. Scattered moderate convection
is seen within 60 nm north of the monsoon trough between 31W-37W.

...DISCUSSION...

GULF OF MEXICO...

A deep layer trough extends from southern Georgia through the
central Gulf of Mexico as seen in water vapor imagery. This upper
feature supports a dissipating stationary front that extends from
a 1011 mb low pressure over SE Georgia to 29N85W to 27N89W. A
pre-frontal trough extends from Tampa Bay SW to 25N85W to 23N90W. Diffluence
aloft ahead of this boundary is sustaining convection, moving
southeastward over the waters from 24N-27N between 81W-95W. The
front will vanish later this morning, leaving a surface trough
over the E Gulf. With upper diffluence and shallow moisture
remaining in place, convection is expected to continue over the
east-southeast Gulf through Thu morning. The Atlc subtropical
ridge will then extend an axis SW across the eastern Gulf.
Surface ridging is forecast to continue through the weekend, thus
providing light to gentle variable flow across the basin.
Elsewhere, a surface trough will move off the Yucatan Peninsula
into the Bay of Campeche each evening, accompanied by fresh
nocturnal winds. Scattered to isolated showers are possible in the
Bay of Campeche with the surface trough.

CARIBBEAN SEA...

A tropical wave is in the central Caribbean with axis along 78W.
For further details see tropical waves section. Scattered
moderate convection and isolated tstms are off the coast of
Colombia associated with a 1011 mb low near 09N73W. Isolated
showers are located over waters S of Puerto Rico and Hispaniola
between 65W and 75W. This convection is being sustained by a small
region of shallow moisture and diffluence aloft. Relatively dry
and stable conditions persist elsewhere.

The 1011 mb low over Colombia is expected to move westward over
SW Caribbean waters today, bringing showers and tstms to Panama,
Costa Rica and southern Nicaragua as well as adjacent waters. This
shower activity in this region will continue through the weekend
being enhanced by the EPAC monsoon trough and a tropical wave that
will move into SW Caribbean waters Friday night. With forecasted
diffluence aloft and shallow moisture present in the north-central
Caribbean, scattered showers are expected through the weekend as
well. Otherwise, the Atlc subtropical ridge will continue to
extend an axis S-SW into the NE Caribbean, thus supporting fresh
to strong winds in the south-central basin through Fri. Elsewhere,
stable conditions with light to moderate winds are expected.

ATLANTIC OCEAN...

Three tropical waves are moving across the basin, however all
lacking convection due in part to the presence of the dry air of
the Saharan Air Layer. Refer to the tropical waves section above
for more details. Isolated showers are across the central and
northern Bahamas extending N of 30N and to 75W being supported by
diffluent flow aloft. Farther east, a middle to upper level low
supports an area of scattered showers and tstms from 24N-29N
between 55W-62W. Otherwise, the Atlc subtropical ridge dominates
the remainder basin being anchored by a 1032 mb high centered
near 37N54.5W.

With ample moisture and diffluence aloft associated with an upper
level feature, scattered moderate to isolated strong convection
is expected north of the Bahamas through the weekend. The
aforementioned 1032 mb subtropical high along with low pressure
over the southeast U.S. will produce moderate to fresh southerly
winds across the waters north of 25N and west of 70W including
Florida coastal waters through today. Moderate to fresh winds are
also expected south of 22N, including approaches to the Windward
Passage. Ridging will dominate the area through the end of the
week providing stable and dry conditions in the central Atlantic.

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

$$
Sangster/Ramos
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