AXNT20 KNHC 201207
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Mon Aug 20 2018
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
A far eastern Atlantic tropical wave has its axis along 32W/33W
from 05N to 17N, moving westward at 10-15 kt. Isolated moderate
convection is from 05N-17N. Scattered moderate convection is
within 180 nm east of the wave from 05N-08N. Isolated showers and
thunderstorms are elsewhere within 180 nm either side of the wave
A central Atlantic tropical wave has its axis extending from
05N51W to 12N50.5W to 18N49W, moving westward at 10-15 kt.
Isolated showers and thunderstorms are within 120 nm either side
of the wave from 08N-11N.
A Caribbean Sea tropical wave has its axis extending from far
southern Costa Rica northward to 15N77W and to eastern Cuba near
20N76W. It is moving westward at 10-15 kt. Isolated moderate
convection is within 60 nm east of the wave from 20N-21N.
The northern portion of an eastern Pacific tropical wave extends
along 91W northward to the far eastern Bay of Campeche, moving
westward near 15 kt. Only isolated showers are noted within 60 nm
of the wave.
The monsoon trough axis extends from western Africa at 13N17W to
10N28W to 08N40W, where scatterometer data indicates the ITCZ axis
begins and extends to 08N49W where it briefly ends just east to
the east of the central Atlantic tropical wave. It resumes at
09N52W to just inland the coast of S America at 07N58W. Scattered
moderate convection is within 60 nm south of the axis between
17W-20W. Widely scattered moderate convection is seen from 05N-
09N between 26W- 29W. Isolated moderate convection is within 60 nm
of the ITCZ axis between 53W-58W.
GULF OF MEXICO...
A 1023 mb high is centered over the W Atlantic at 32N59W, with a
ridge axis extending WSW from the high to central Florida and to
the eastern gulf waters. The associated gradient is allowing for
generally moderate southerly flow to persist over much of the
gulf, except for lighter SW to W flow, in the 5-10 kt range over
the far northeastern gulf waters. Widely scattered moderate
convection is over the N Florida Peninsula N of 27N. The northern
portion of a tropical wave is over the eastern Bay of Campeche.
No deep convection is occurring with this wave. See above for
details. Scattered moderate to isolated strong convection is from
15N-21N between 92W-95W. An upper level low is centered over the
Yucatan Channel near 22N86W enhancing the convection over western
Cuba and the NW Caribbean Sea.
Expect, a surface high to develop over the Gulf near 27N91W on
Tue. This high will meander over the western gulf waters through
Thu. A weak trough will stalls over the eastern Gulf waters, then
drifts west and dissipates on Fri.
Two tropical waves are over the Caribbean Sea and Central America.
See above. Scattered moderate convection is noted over E Cuba,
Panama, and Costa Rica. Similar convection is S of Puerto Rico
from 15N-17N between 65W-68W. Otherwise, surface ridging
extending from the Atlantic to the northern half of the basin
support fresh to strong winds in the south-central Caribbean.
Expect showers and convection to persist over the SW Caribbean
for the next several days. Also expect strong to near gale force
nocturnal easterly trades expected along the northwestern coast
of Colombia and across the Gulf of Venezuela through the middle of
A surface trough is N of the central Bahamas from 28N70W to
23N73W. Scattered showers are within 90 nm of the trough. A
1023 mb high is centered over the W Atlantic near 32N59W. Another
surface trough is over the W Atlantic from 32N50W to 27N60W.
Scattered showers are within 90 nm of this trough. A surface
trough is analyzed along a position from near 28N69W to the
southeastern Bahamas near 22N74W. A shortwave trough passing just
to its northwest is providing additional atmospheric lift leading
to clusters of scattered moderate convection from 26N-29N between
71W-74W. Isolated showers and thunderstorms are elsewhere within
90 nm of the surface trough from 22N to 26N. Scattered moderate
convection is within 30 nm either side of a line from 09N58W to
11N61W. A 1026 mb high is centered over the Azores near 38N29W
producing ridging and fair weather over the eastern Atlantic.
The trough north of the central Bahamas is forecast to move
westward across the Bahamas through Tue night.
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