Tropical Weather Discussion
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AXNT20 KNHC 220541

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
141 AM EDT Tue Aug 22 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.


A tropical wave extends from 23N86W to 12N87W moving W-NW at
15-20 kt. The remnant circulation of Harvey continues to be
analyzed as a 1011 mb low pressure along the wave axis near
18N87W. Scattered moderate to strong convection is from 18N-22N
between 79W-89W. Satellite images and surface observations
indicate that the system has not become better organized and
tropical cyclone development is not expected before the system
moves inland over the Yucatan peninsula this morning. However,
environmental conditions are expected to be conducive for
development when the system moves over the Bay of Campeche tonight
or early Wednesday, and a tropical depression is likely to form
over the southwestern Gulf of Mexico on Wednesday or Thursday.
Regardless of development, locally heavy rainfall and gusty winds
are expected to spread westward across Belize and the Yucatan
peninsula during the next day or so. There is a high chance for
this system to become a tropical cyclone within 48 hours.


A tropical wave extends from 22N28W to 11N30W moving W at 15-20
kt. A 1012 mb low pressure precedes the wave centered near
13N34W. Scattered moderate convection is from 08N-12N between
28W-33W. This wave in a moist area based on TPW imagery and has a
well pronounced 700 mb trough.

A tropical wave extends over the eastern Caribbean from 17N65W to
10N66W, moving W at 20-25 kt. Isolated showers are near the
northern end of the wave axis. The wave is expected to move across
the eastern Caribbean Sea and portions of Venezuela through
Tuesday helping to induce some convective activity. Subtle
troughing is noted on 700 mb streamline analysis. Some moisture
is observed on either side of the wave axis based on the SSMI TPW
animation. This wave will cross the central Caribbean through


The monsoon trough extends from 14N17W to 17N23W to 13N34W to
07N43W. The Intertropical Convergence Zone axis continues from
07N43W to 06N57W. Scattered moderate convection is within about
90 nm south of trough between 31W-39W. Besides the convection
mentioned in the tropical wave section, scattered moderate
convection is from 09N-14N between 21W-27W, and from 06N-08N
between 37W-40W.



Weak surface ridging is over the Gulf of Mexico with axis along
30N. 10-15 kt easterly surface flow is over the N Gulf. The
northern extent of a tropical wave is producing scattered moderate
to strong convection over the Yucatan Channel, and the N Yucatan
Peninsula. Scattered showers and isolated thunderstorms are also
advecting over S Florida from the Atlantic. In the upper levels,
an upper level low is centered over the W Gulf near 27N91W
enhancing showers. Expect over the next 24 hours for the upper
level low to remain quasi-stationary and continue to produce
convection. Looking ahead, the remnant low of Harvey and tropical
wave, currently moving across the Caribbean Sea is expected to
traverse the Yucatan Peninsula this morning and Tuesday, and then
move into the Bay of Campeche Wednesday, where redevelopment to a
tropical cyclone appears likely.


The remnant low of Harvey currently located over the NW Caribbean
continues to be the primary area of concern across the basin.
Please, see Special Features section for more details. A tropical
wave is over the far eastern Caribbean. Please, see the Tropical
Waves section for details. Patches of low-level moisture embedded
in the trade wind flow are noted over parts of the east and
central Caribbean. Fresh SE winds are observed per scatterometer
data across the central Caribbean, but mainly N of 13N. These
winds are the result of the pressure gradient between the Atlantic
ridge and the remnant low of Harvey.


Presently, showers have full dissipated. However,daytime heating,
local sea breezes and mountain upslope lifting will combined with
available moisture to produce isolated to scattered showers and
thunderstorms during the afternoon and evening hours Tuesday. The
next tropical wave is forecast to pass just south of the island
Tuesday night into Wednesday.


A trough of low pressure continues to move westward across the
Bahamas and now extends from 29N77W across the N Bahamas to
central Cuba near 22N79W. This system continues to produce
disorganized showers and thunderstorms, with fresh to strong winds
mainly on its NW side based on scatterometer data. Only slow
development of this system is anticipated during the next several
days while it moves west-northwestward across the Bahamas and
then turns northwestward or northward near Florida and the
adjacent waters. Farther east, there is another surface trough
that extends 25N54W to 17N55W. This trough is likely the surface
reflection of an upper-level low spinning near 27N58W. The
remainder of the forecast area is under the influence of the
Atlantic ridge.

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