[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211205
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 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 0600 UTC surface analysis and satellite imagery through
1145 UTC.

...TROPICAL WAVES...

A tropical wave likely to be analyzed today near the coast of
Africa based on model guidance and satellite imagery. The present
satellite imagery shows a broad canopy of multilayer clouds with
scattered moderate to strong convection ahead of the wave from 04N
to 13N between 16W and 21W. The imagery also shows pretty good
upper- level outflow with this activity as marked by the cirrus
clouds fanning outward away from convection.

Another far eastern Atlantic Ocean has its axis along 26W/27W
from 03N to 20N, moving westward at 10 to 15 kt. Only isolated
showers and weak thunderstorms are within 60 nm either side of the
wave axis from 04N to 08N.

A central Atlantic tropical wave has its axis along 50W/51W from
05N to 19N, moving westward at 10 to 15 kt. Scattered moderate to
isolated strong convection is within 60 nm either side of the wave
from 11N to 14N. Scattered moderate convection is within 30 nm of
12N48W and within 30 nm of 11N49W. Dry mid-level air and strong
upper level winds are expected to hinder any development of this
disturbance while it moves toward the WNW.

A central Caribbean Sea tropical wave has its axis along 74W south
of 20N, moving westward at 10 to 15 kt. Scattered showers and
isolated thunderstorms are seen within 240 nm east of the wave
north of 15N to across the Dominican Republic. Isolated showers
and thunderstorms are north of 15N and west of the wave to 75W.
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.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the coastal border sections
of Guinea and Sierra Leone near 09N13W to 05N20W. The ITCZ
continues from 05N20W to 06N28W, to 05N38W, and 08N44W. Other than
convection associated with the wave along the coast of Africa,
and with the one along 26W/27W, scattered moderate convection is
seen within 210 nm north of the ITCZ between 40W and 45W.

...DISCUSSION...

GULF OF MEXICO...

An upper-level cyclonic circulation center is moving westward over
S Florida near 26N81W. Associated 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. Scattered showers
and thunderstorms are over the eastern gulf waters from 24N to
27N east of 85W. Isolated showers and thunderstorms are elsewhere
over the basin.

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 Sun. It is possible that typical
nocturnal 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 eastern Pacific monsoon trough axis is along 08N/09N from 75W
in Colombia beyond southern Costa Rica. Scattered mdoerate to
strong convection is over the far western portion of the
southwestern Caribbean south of 14N and west of 80W.

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 1008 mb low pressure center that is
near 33N63W, 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 Sat, and then it will move northwestward early next week.
NE swell is forecast to affect the waters E of the Bahamas
through early next week.

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

$$
MT/Aguirre
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