AXNT20 KNHC 211205
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Thu Jun 21 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
There are four tropical waves between the west coast of Africa
and the Lesser Antilles.
A tropical wave is along 24W from 03N-12N. The Hovmoller Diagram
shows the westward propagation of the wave, that coincides with a
modest surge of moistened air based on the TPW product. Convection
is limited near the wave's axis.
A tropical wave is along 33W/34W from 3N-11N, moving W at 20
knots. This wave shows up well as a low amplitude moisture surge
on the TPW animation. Scattered moderate convection is noted where
the wave meets the ITCZ.
A tropical wave is along 42W from 3N-11N, moving W at about 15
knots. The wave is well depicted in the moisture product.
Scattered moderate convection is noted on either side of the
wave's axis from 6N-8N between 38W-45W.
Another tropical wave is approaching the Lesser Antilles. Its axis
is along 58W from 6N-17N, moving W at about 10 knots. The TPW
animation shows a surge of moistened air near the wave's axis. A
cluster of moderate convection is already affecting Trinidad and
Tobago. Scattered moderate convection is seen near 13N58W, and
near the southern end of the wave's axis, from 6N-8N between 55W-
58W. Moisture associated with this feature will continue to
affect the Windward Islands this morning. The wave will then move
across the eastern Caribbean this afternoon through Fri night.
The associated moisture is forecast by the GFS computer model to
spread out reaching the Leeward Islands later today and tonight,
and Puerto Rico on Fri.
A tropical wave is moving across the Caribbean. Its axis is along
70W, and extends from Hispaniola to western Venezuela. The wave,
combined with an upper-level trough crossing eastern Cuba, is
producing scattered showers and tstms across the Windward Passage
and parts of Haiti. Lingering moisture from this tropical wave
will continue to support showers and isolated thunderstorms across
Hispaniola today. Moisture and instability related to this wave
will also affect the Windward Passage and eastern Cuba later
The monsoon trough passes through the coastal sections of Guinea
near 10N13W to 06N21W. The ITCZ continues from 06N21W to 06N30W
05N40W to 05N51W. Outside of the convection associated with the
tropical waves, isolated moderate convection is from 3N-7N
between 24W-35W. Scattered moderate convection is from 4N-7N
GULF OF MEXICO...
An area of low pressure over southern Texas will continue to support
strong gusty winds, widespread showers and scattered thunderstorms
in Texas coastal waters, and over parts of NE Mexico, including
coastal waters this morning. Winds and seas in the NW Gulf will
diminish further today as the low weakens. A broad ridge across
the SE Gulf will support light winds and seas less than 3 ft east
of 88W through Tue.
A surface trough will develop in the Yucatan Peninsula each
afternoon, then move westward across the SW Gulf during the
overnight hours, accompanied by fresh east to southeast winds.
A tropical wave passing south of Hispaniola will move into the
western Caribbean today. A tropical wave along 59W will reach the
Lesser Antilles later this morning. Fresh to strong winds are
expected in the Gulf of Honduras Fri night through Sun night.
Trade winds across the south-central Caribbean will strengthen
tonight, then expand in coverage across the basin this weekend as
high pressure builds in the central Atlantic. Seas will build to
10-11 ft in the central Caribbean Sat night through Mon night.
An upper-level trough extends from a cyclonic circulation centered
near 27N65W to eastern Cuba. Scattered showers and tstms are
noted on the SE semicircle of the low affecting mainly the waters
from 24N-29N between 60W and 70W. A diffluent pattern aloft
between the aforementioned upper-level trough and an anticyclonic
circulation located E of the Lesser Antilles is helping to induce
this convective activity.
High pressure over the east-central Atlantic near 34N33W will
slowly shift westward through Sat night, then remain nearly
stationary near 30N55W through Tue. The pressure gradient in the
central Atlantic associated with this high will support fresh
trade winds S of 23N west of 50W, and allow seas to build to 6-7
ft in southern waters E of the Bahamas this weekend.
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