Tropical Weather Discussion
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974
AXNT20 KNHC 131030
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
630 AM EDT Sun Aug 13 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

...SPECIAL FEATURES...

Tropical Depression Eight was centered near 26.5N 70.9W at
13/0900 UTC with maximum sustained winds of 30 kt gusting to 40
kt and a minimum sea level pressure of 1011 mb. The depression is
moving toward the north-northwest, or 335 degrees, at 12 kt.
Numerous moderate and scattered strong convection is noted within
120 nm southeastern semicircle of the low. The system is expected
to remain east of the United States, moving in a north-
northwestward direction today as it reaches tropical storm
intensity, then remaining at tropical storm intensity while moving
northward tonight, then northeastward by Monday night. See latest
NHC forecast/ advisory under AWIPS/WMO headers MIATCMAT3/WTNT23
KNHC for more details.

...TROPICAL WAVES...

The axis of a tropical wave is near 32W from 07N to 21N, moving W
at 15-20 kt. This wave is very evident in low-mid level satellite
cloud wind vectors. Scattered moderate convection is noted from
07N- 14N between 30W- 37W.

The axis of a tropical wave is near 52W from 05N to 21N. The wave
is moving W at 15-20 kt. There is limited convection associated
to this wave.

The axis of a tropical wave in the western Caribbean is near 83W
from 06N to 22N. The wave is moving W at 20 kt. Scattered moderate
to isolated strong convection is over the SW Caribbean south of 14N
and west of 75W.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the coast of African near 19N16W
to 13N22W to 09N45W. The Intertropical Convergence Zone continues
from 09N45W to 08.5N50W. It resumes from 08N53W to the coast of
South America near 07.5N58.5W. Aside from convection associated
with the tropical waves, scattered moderate isolated strong
convection is noted from 10N- 15N between 17W- 25W. This
convection is ahead of the next tropical wave which is just moving
off the coast of Africa.

...DISCUSSION...

GULF OF MEXICO...

A ridge of high pressure prevails over the Gulf of Mexico with
light to gentle anticyclonic flow covering much of the Gulf
waters. The one exception is an area of moderate winds west of a
thermal trough that moved off the Yucatan Peninsula into the
southwest Gulf. The ridge will remain across the Gulf waters
the next several days. Southerly return flow will freshen over
western Gulf by midweek.

A thermal trough will develop each evening over the Yucatan
Peninsula, shifting westward into the southwest Gulf during the
overnight hours, and dissipating over this area each morning.
Locally higher winds can be expected west of the trough axis.

CARIBBEAN SEA...

Please see above for more on the tropical wave moving through the
western Caribbean. The tropical wave will continue to propagate
westward, moving west of the area late tonight. Fresh to strong
winds prevail over the south central Caribbean, gentle to
moderate winds are noted over the western Caribbean, and moderate
to fresh winds prevail elsewhere. These general conditions will
continue across the Caribbean through midweek. Ample moisture
associated to a tropical wave is helping produce active convection
over the southwest Caribbean as well as the surrounding land
masses.

...HISPANIOLA...

Moisture will decrease across the area today. Expect isolated
showers and tstms today due to daytime heating, local sea breezes
and mountain upslope lifting.

ATLANTIC OCEAN...

Please see the special features section above for more on Tropical
Depression Eight and the tropical wave section above for more on
the tropical waves propagating across the tropical Atlantic
waters. Outside of Tropical Depression Eight, gentle to moderate
winds prevail across much of the area, except freshening winds
noted between the eastern tropical wave and strengthening
subtropical high to the north. The fresh winds will shift along
with the tropical wave as it propagates westward the next couple
of days.

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

$$
AL



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