Tropical Weather Discussion
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407
AXNT20 KNHC 290005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
804 PM EDT Sun May 28 2017

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
2345 UTC.

...TROPICAL WAVES...

A tropical wave came off the W coast of Africa earlier today. Its
axis extends from 16N16W to 05N16W and is expected to move at 10
kt within the next 24 hours. Even though the wave is in a
favorable wind shear environment, the CIRA LPW imgery show shallow
moisture with large patches of dry air, which in part hinder
convection at the time.

A tropical wave is in the central Atlc with axis extending from
09N30W to 01S30W, moving W at 10-15 kt within the last 24 hours.
Unfavorable wind shear is N of 05N, and dry air intrusion is seen
on enhanced satelite imagery in the NW wave environment. However,
CIRA LPW imagery show shallow moisture and large patches of dry
air in the wave environment. Middle to upper level diffluece
support scattered to isolated showers from 01N-06N between 25W-
35W.

A tropical wave is in the W Atlc with axis extending
from 15N51W to 05N52W, moving W at 20-25 kt within the last 24
hours. The wave is in an unfavorable wind shear environment and
satellite enhanced imagery show Saharan dry air and dust in the
wave environment, which in part inhibit convection at the time.

A tropical wave is in the E Caribbean with axis extending from
17N62W to 10N63W, moving W at 20-25 kt within the last 24
hours. Cira LPW show mainly moderate low level moisture in the
wave environment with small patches of dry air associated with the
Saharan Air Layer. Even though the wave is in a region of
unfavorable wind shear, upper level divergence support scattered
heavy showers and tstms across the Lesser Antilles and the Virgin
Islands. This showers will start affecting Puerto Rico tonight as
the wave continues a westward track.

...ITCZ/MONSOON TROUGH...

The monsoon trough is inland Africa. The ITCZ begins near 04N18W
to 04N30W...then resumes W of a tropical wave near 04N32W and
continues to 06N46W. For information about convection see the
tropical waves section.

...DISCUSSION...

GULF OF MEXICO...

A weak surface ridge prevails in the eastern Gulf anchored by a
1017 mb high near 26N84W, which is forecast to stall through
Monday evening. Scattered showers are off the Florida Panhandle
coast N of 28N ahead of a cluster of heavy showers and tstms that
is being supported by low level moisture being advected from the
Caribbean by SE flow. This cluster of heavy showers is located S
of Louisiana to 26N between 88W and 92W and is also being supported
by upper level diffluence between a trough with base over the
northern Gulf and a ridge that covers the remainder basin. GOES
IFR show medium to high chances of dense fog in the NW basin,
which is confirmed by surface observations. Low visibility is in
that region...caution should be excercised by vessels. A thermal
trough will is over the W Yucatan Peninsula, which will move west
across the SW Gulf tonight and then will dissipate near 94W by
late in the morning. A surge of fresh to locally strong winds
will follow the trough. Little change in this weather pattern is
expected through Tuesday.

CARIBBEAN SEA...

A tropical wave is in the E Caribbean supporting scattered heavy
showers and tstms. See the tropical waves section for additional
details. Shallow moisture along with a weak and broad upper level
trough support scattered showers along Cuba and isolated showers
over Jamaica and central Hispaniola. Heavy showers and tstms are
in the SW basin S of 12N being supported by the EPAC monsoon
trough that extends from Costa Rica to Panama to a low over NW
Colombia. Strong dry air subsidence is elsewhere, which supports
fair weather. Otherwise, high pressure over the central Atlantic
extends a ridge SW across the northern Caribbean Sea, which will
support fresh to strong easterly winds across the south-central
Caribbean between 74W and 77W at night through Tuesday. Pulsing
fresh to strong E to SE winds are also expected over the Gulf of
Honduras through this period. Moderate trades are expected
elsewhere.

HISPANIOLA...

A broad and weak upper level trough, middle level diffluent flow
and shallow moisture in the vicinity of the Island support
isolated showers and tstms mainly in the W Dominican Republic and
Haiti. Scattered heavy showers are forecast Tuesday associated
with the tropical wave currently over the eastern Caribbean.

ATLANTIC OCEAN...

Fair weather conditions are in the SW N Atlc with no significant
surface features at the time. The remainder central and eastern
Atlc is under the influence of a broad surface ridge anchored by a
1025 mb high near 29N44W, which is expected to move slightly SW to
near 27N46W by Monday evening. A dissipating cold front extends
from 30N20W to 26N30W to 28N40W with no associated convection.
Otherwise, four tropical waves are passing over the tropical
Atlc. Please refer to the Tropical Waves section for more details.

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

$$
Ramos



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