Tropical Weather Discussion
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AXNT20 KNHC 141028

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
628 AM EDT Mon Aug 14 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.


Tropical Storm Gert is centered near 29.7N 72.2W at 14/0900 UTC,
moving toward the north-northwest, or 345 degrees, at 8 kt. Estimated
minimum central pressure is 1009 mb. Maximum sustained wind speed
is 40 kt with gusts to 50 kt. Numerous moderate and scattered
strong convection is noted within 90 nm southeast and 30 nm
northwest semicircles of Gert. Scattered moderate isolated strong
convection is noted elsewhere within 210 nm southeast and 60 nm
northwest semicircles of Gert. The system is expected to remain
east of the United States, taking a turn toward the north today,
followed by a turn toward the north- northeast tonight. See latest
NHC forecast/ advisory under AWIPS/WMO headers MIATCMAT3/WTNT23
KNHC for more details.


The axis of a tropical wave is near 24W from 05N to 21N, with low
pressure centered along the wave axis near 13N24W, moving W at 15
kt. Environmental conditions are expected to become more
conducive for development of this low later this week, and there
is a medium chance for tropical cyclone formation within 5 days.
Scattered showers are noted from 10N to 16N between 20W and 27W.

The axis of a tropical wave is near 39W from 06N to 21N, moving W
at 20 kt. This wave is very evident in low-mid level satellite
cloud wind vectors. Scattered showers are within 90 nm of the
wave axis south of 13N.

The axis of a tropical wave is near 57W from 07N to 21N, moving W
at 15-20 kt. There is limited convection associated with this
wave, with isolated showers noted near the southern end of the
wave axis, from 08N- 11N between 55W- 58W.

The axis of a tropical wave has moved west of the Caribbean
waters, and is currently moving across the Yucatan Peninsula. This
wave is helping produce active convection over the western
Caribbean as well as the Yucatan Peninsula, Belize, Guatemala,
Honduras, and Nicaragua.


The monsoon trough extends from the coast of Africa near 19N16W
to 14N22W to 09N47W. The Intertropical Convergence Zone continues
from 09N47W to 08N57W. Aside from the convection associated with
the tropical waves, scattered moderate isolated strong convection
is noted from 06N- 14N between 27W- 36W, and from 05N- 12N
between 40W- 47W.



A ridge of high pressure prevails over the Gulf of Mexico, except
for a thermally induced trough which has moved off the Yucatan
Peninsula into the southwest Gulf. Latest surface observations
indicate with light to gentle anticyclonic flow covering much of
the Gulf waters, with two exceptions. The first is an area of
moderate to fresh winds west of the trough in the southwest Gulf.
The second is over the far western Gulf where moderate to fresh
winds prevail due to a tighter pressure gradient between the ridge
and a trough of low pressure over Mexico. The ridge will remain
across the Gulf waters the next several days with these general
conditions prevailing.

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.


The western Atlantic ridge has started to build westward south of
T.S. Gert, which has tightened the pressure gradient over the
area. Latest surface observations indicate fresh to strong winds
over the south central Caribbean, moderate to fresh winds over the
north central Caribbean, moderate winds over the eastern
Caribbean, and gentle to moderate winds over the western
Caribbean. The ridge will continue to build as Gert moves further
north. This will bring an increase in coverage of fresh winds
across the north central and eastern Caribbean through midweek.


Expect daytime heating, local sea breezes and mountain upslope
lifting to produce scattered showers and thunderstorms during the
afternoon and evening hours across the island the next couple of


Please see the Special Features section above for more on
Tropical Storm Gert, and the Tropical Wave section above for more
on the tropical waves propagating across the tropical Atlantic
waters. Outside of these areas, the forecast area is under the
influence of the subtropical high. This high pressure area has
started to build westward into the southwest north Atlantic waters
in the wake of T.S. Gert as the system moves northward. Moderate
to fresh winds prevail over the eastern waters between the two
easternmost tropical waves and the subtropical high, with gentle
to moderate winds elsewhere. The area of fresh winds will spread
westward along with the tropical waves the next couple of days.

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