[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210534
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
134 AM EDT Fri Sep 21 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
0515 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 25W/26W from 20N
southward. Isolated moderate rainshowers are from 10N to 20N
between 20W and 30W.

An Atlantic Ocean tropical wave is along 48W/50W from 16N
southward. Widely scattered moderate to isolated strong
rainshowers are from 10N to 13N between 48W and 51W. Dry middle
level air and strong upper level winds are expected to hinder any
development of this disturbance while it moves toward the WNW.

A Caribbean Sea tropical wave is along 72W/73W, moving across
Hispaniola. Scattered moderate to isolated strong rainshowers are
within 120 nm to the south of Hispaniola between 70W and 73W.
Isolated moderate rainshowers are within 60 nm to the north of
Hispaniola between 70W and 73W, and elsewhere from 16N to 20N
between the Windward Passage and 81W. Satellite imagery has been
showing Saharan dust to the east of the wave from 12N to 24N
between 57W and 67W. Puerto Rico and the Virgin Islands have been
reporting hazy conditions. Strong wind gusts are possible near the
rainshowers that are associated with this wave through Friday as
it moves westward through the central Caribbean Sea. The wave is
expected to increase the likelihood of precipitation across
Hispaniola, Cuba, and Jamaica for the next 24 hours or so.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal border sections of
Guinea and Sierra Leone near 09N13W to 05N20W. The ITCZ continues
from 05N20W to 06N28W, to 05N38W, and 08N44W. Scattered to
numerous strong rainshowers are inland and in the coastal sections
of Africa from 04N to 13N between 13W and 18W. Isolated moderate
rainshowers are elsewhere from 15N southward between Africa and
60W.

...DISCUSSION...

GULF OF MEXICO...

An upper level cyclonic circulation center is near 28N80W, moving
from the Atlantic Ocean toward Florida. Upper level cyclonic wind
flow covers Florida, the Gulf of Mexico, and the Atlantic Ocean
from the Florida Straits to 32N between 75W and 85W. Isolated
moderate rainshowers are in the area of upper level cyclonic wind
flow. Other isolated moderate rainshowers are in the Atlantic
Ocean from 25N to 30N between 70W and 75W.

A cold front extends from 1006 mb low pressure center that is near
33N64W, to 30N66W 28N70W 28N74W, and 29N81W near the coast of
Florida. Isolated moderate to locally strong rainshowers cover the
area that is from 28N northward between 46W and 66W.

High pressure building in the eastern U.S.A. will support gentle
to moderate E to SE winds, and sea heights ranging from 1 foot to
4 feet, across the basin through Sunday. It is possible that a
surface trough, that will be moving westward across the
southwestern corner of the Gulf of Mexico, may produce locally
fresh winds through Saturday.

CARIBBEAN SEA...

Broad upper level cyclonic wind flow, with a trough, covers the
Caribbean Sea from Hispaniola westward. Isolated moderate
rainshowers are in the area of upper level cyclonic wind flow.

The monsoon trough is along 08N/09N from 75W in Colombia
beyond southern Costa Rica. Isolated moderate to locally strong
rainshowers are from 13N southward from 78W westward.

The Hispaniola tropical wave will move westward into Central
America through Sunday. Gusty winds are possible near rainshowers
associated with this wave. High pressure building westward from
the central Atlantic Ocean into the Bahamas will support moderate
to fresh trade winds and building seas through Friday. The wind
speeds will diminish across most of the basin during the upcoming
weekend.

ATLANTIC OCEAN...

An upper level cyclonic circulation center is near 28N80W, moving
from the Atlantic Ocean toward Florida. Upper level cyclonic wind
flow covers Florida, the Gulf of Mexico, and the Atlantic Ocean
from the Florida Straits to 32N between 75W and 85W. Isolated
moderate rainshowers are in the area of upper level cyclonic wind
flow. Other isolated moderate rainshowers are in the Atlantic
Ocean from 25N to 30N between 70W and 75W.

A cold front extends from 1006 mb low pressure center that is near
33N64W, to 30N66W 28N70W 28N74W, and 29N81W near the coast of
Florida. Isolated moderate to locally strong rainshowers cover the
area that is from 28N northward between 46W and 66W. Dry air, that
is associated with a weakening frontal system, and strong upper
level winds, are expected to inhibit any significant development
during the next couple of days. It is possible that conditions may
become a bit more conducive for the 1006 mb low pressure center
to acquire some tropical characteristics, gradually, early next
week, while the system moves southward on Sunday, and then drifts
westward to the southwest of Bermuda on Monday.

A surface trough is along 33W/35W, from 24N to 32N. A 1018 mb low
pressure center is along the trough near 30N. The 1018 mb low
pressure center is the remnant of Joyce. Rainshowers are possible
from 24N northward between 30W and 37W.

An upper level trough extends from a 31N24W cyclonic circulation
center, to a second upper level cyclonic circulation center that
is near 28N40W, to 21N47W, to a third upper level cyclonic
circulation center that is near 14N52W, to 14N60W. Isolated
moderate rainshowers are within 180 nm on either side of the line
that runs from 33N19W to 30N30W to 27N40W, and within 600 nm on
either side of the line that runs from 27N40W to 17N47W.

The current Bermuda-to-29N81W cold front will reach 27N on Friday,
and then dissipate through Saturday. The low pressure center that
is associated with the front will drift southward through Saturday,
and then it will move northwestward early next week. NE swell
will affect the waters E of the Bahamas through early next week.

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

$$
MT
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