AXNT20 KNHC 231705
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 PM EDT Mon Jul 23 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 |1200 UTC surface analysis and satellite imagery through
A tropical wave is moving across the far east Atlantic with axis
extending from 05N-20N along 29W, moving W at 10-15 kt. A large
area of Saharan dust is noted along the wave mainly north of 10N.
Widely scattered moderate convection is noted where the tropical
wave intersects the monsoon trough from 08N-11N between 22W-29W.
A tropical wave is in the central Atlantic with axis extending
from 06N-22N along 48W, moving W at 10-15 kt. This tropical wave
continues to be on the leading edge of a large area of Saharan dry
air and dust, inhibiting large scale convection at this time.
Scattered moderate convection is noted on the southern end of the
tropical wave where it intersects the monsoon trough from 05N-
09N between 40W-47W.
A tropical wave is in the western tropical Atlantic with axis
extending from 10N-24N along 60W, moving W at 10-15 kt. The
tropical wave is accompanied by Saharan dry air and dust,
inhibiting convection. Scattered showers are over the Leeward
A low amplitude and low latitude tropical wave is moving across
Costa Rica and adjacent waters, along 83W and south of 11N. The
tropical wave may be interacting with monsoon flow over Costa Rica
and Panama. Scattered moderate to isolated strong convection is
from 07N-11N between 76W-86W.
The monsoon trough extends from the coast of Africa near 15N17W
to 10N23W to 08N36W. The ITCZ extends from 08N36W to the coast of
South America near 07N58W. Besides the convection mentioned in
the tropical wave section, scattered showers are within 120 nm of
the remainder of the monsoon and ITCZ axis.
GULF OF MEXICO...
A cold front extends from the Florida Panhandle at 30N84W to
beyond SE Louisiana at 30N89W, with scattered moderate to
isolated strong convection from 26N-30N between 82W-89W. A squall
line is along the forward extent of the convection from Tampa
Florida at 28N83W to 26N87W. 20-30 kt winds and 7 ft seas are
being reported along the squall line. The remainder of the basin
is under the influence of a surface ridge, anchored by a 1016 mb
high centered over the Yucatan Channel near 21N85W. This feature
is maintaining fair weather, light to gentle winds, and 1 to 3 ft
seas across remainder of the basin.
The cold front over the Florida Panhandle will be followed by
another weak cold front that will move over the northern Gulf
waters early this week. This front will become stationary and
weaken Thu. A surface trough will move off the Yucatan Peninsula
into the Bay of Campeche each evening, accompanied by fresh
nocturnal winds. Elsewhere, surface ridging will prevail.
The northern portion of a tropical wave is moving across the far
southwestern Caribbean today, just north of Costa Rica. Another
tropical wave is entering the E Caribbean. See above. Widely
scattered moderate convection is S of Cuba from 18N-20N between
76W-82W. Dry conditions persist elsewhere. Earlier scatterometer
pass indicated fresh to strong trade winds over the south central
Caribbean, mainly off Colombia. Maximum seas are estimated to be 8
to 9 ft. Seas are 2 to 3 ft in the northwest Caribbean, and 5 to
7 ft elsewhere.
Two more tropical waves are moving across the basin. Refer to the
section above for details.
Scattered moderate to isolated strong convection is over the
northern Bahamas and adjacent waters from 23N-26N between 77W-80W,
related to divergent flow aloft. Gusty winds are possible with
these thunderstorms. Moderate S to SW winds are noted west of 70W
with 4 to 6 ft seas in open waters. A broad high prevails across
the remainder of the basin, centered near 40N48W. For the
forecast, the Atlantic high pressure along with the low pressure
system over the southeast U.S. will continue to produce moderate
to fresh southerly winds across the waters just offshore the
central and northeast Florida through Wed. Moderate to fresh winds
are also expected south of 22N, including approaches to the
Windward Passage. Ridging will dominate the area most of the
forecast period, with a surface trough reaching the E part of the
region by Thu.
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