Tropical Weather Discussion
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AXNT20 KNHC 130519

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
119 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 0000 UTC surface analysis and satellite imagery through
0515 UTC.


Newly formed Tropical Depression Eight was centered near 25.3N
70.3W at 13/0300 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 330 degrees,
at 11 kt. Numerous moderate and scattered strong convection is
noted within 120 nm eastern 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.


The axis of a tropical wave is near 29W from 05N 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 08N- 13N between 25W- 35W.

The axis of a tropical wave is near 49W from 07N 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 82W
from 06N to 22N. The wave is moving W at 20 kt. Scattered
moderate to isolated strong convection is over the SW Caribbean
from 10N-15N between 76W- 83W.


The monsoon trough extends from the coast of African near 13.5N17W
to 12N19W to 08N45W. The Intertropical Convergence Zone continues
from 08N45W 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-14N between
17W- 24W.



High pressure of 1016 mb is centered over the Gulf of Mexico near
25N91W. Light to gentle anticyclonic flow is observed over
the Gulf waters, with the exception of moderate winds noted west
of a thermal trough moving off the Yucatan into the southwest
Gulf. The high pressure center will remain nearly stationary
across the Gulf waters today. The ridge is forecast to shift
early next week allowing fresh southerly return flow to set up
over the western Gulf Tue and Wed.

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.


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


The earlier convection over Hispaniola has dissipated during the
evening hours. Moisture will decrease across the area today.
Expect isolated showers and tstms today due to daytime heating,
local sea breezes and mountain upslope lifting.


Please see the special features section above for more on recently
developed Tropical Depression Eight and the tropical wave
section above for more on the tropical waves propagating across
the tropical Atlantic waters. A weak surface trough persists
across the central Atlantic and extends from 31N51W to 27N54W.
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.

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