AXNT20 KNHC 151203
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
803 AM EDT Wed Aug 15 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
At 15/0900 UTC, the center of Subtropical Depression Five is
located near latitude 37.6 North, longitude 45.6 West, about 882 nm
W of the Azores. The estimated minimum central pressure is 1009
mb (29.80 inches). The subtropical depression is moving toward the
north near 4 kt, and this general motion with a slight increase
in forward speed is expected today. A faster northeastward motion
is forecast to occur on Thursday and Friday. Maximum sustained
winds are near 30 kt with higher gusts. Some strengthening is
forecast during the next day or so, and the subtropical depression
is expected to become a subtropical storm later today.
An Atlantic Ocean tropical wave is along 36W, from 22N southward,
moving W at 15 kt. Rainshowers are possible within 300 nm on
either side of the wave.
An Atlantic Ocean tropical wave is along 56W, from 20N southward,
moving W at 15 kt. Scattered showers are from 15N-18N between
A Caribbean Sea tropical wave is along 74W from 21N southward,
moving W at 15 kt. Scattered moderate convection is N of Jamaica
from 18N-20N between 75W-78W. Scattered moderate to isolated
strong convection is over N Colombia and NW Venezuela between
07N-12N between 70W-78W.
A Caribbean Sea tropical wave is along 86W, from 23N southward,
moving W at 15 kt. Scattered showers are within 120 nm of the wave
The monsoon trough passes through the coastal sections of Guinea-
Bissau near 12N16W, to 11N18W, 10N20W, and then to 10N33W. The
ITCZ is along 09N36W 08N43W 07N48W. Besides the convection
mentioned in the tropical wave section, scattered moderate to
isolated strong convection is from 05N-11N between 39W-47W.
GULF OF MEXICO...
NE upper level winds are over the Gulf of Mexico due to a large
upper level high centered over N Mexico near 29N106W. At the
surface, a 1022 mb high is centered over the W Atlantic near
30N70W. Surface ridging extends from the high to the NE Gulf of
Mexico. Isolated moderate convection is over the NE Gulf from 25N-
29N between 83W-88W. Elsewhere, scattered moderate convection is
over the Bay of Campeche from 17N-22N between 95W-98W.
The surface ridge, extending westward from the Atlantic Ocean
into the northern Gulf of Mexico will prevail across the region
for the rest of the week. A nocturnal surface trough will move
off the Yucatan Peninsula into the SW Gulf of Mexico each night,
accompanied by a surge of fresh NE to E winds.
Two tropical waves are over the Caribbean Sea. See above.
An upper level trough passes over Andros Island in the Bahamas,
to Belize in Central America. Isolated moderate rainshowers cover
the area that runs from Haiti to Cuba, and from Honduras to
Guatemala to SE Mexico into the SW corner of the Gulf of Mexico.
Rainshowers are possible also from 15N northward from 80W
westward, and elsewhere from 70W westward.
An upper level cyclonic circulation center is about 100 nm to the
north of the northern coast of Puerto Rico. Isolated moderate
rainshowers are within 360 nm of the center in NE semicircle.
The monsoon trough is along 08N/09N between 73W in Colombia and
84W in southern Costa Rica. Scattered moderate to isolated
strong convection is over Panama, N Colombia, and NW Venezuela
between 07N-12N between 70W-82W.
A surface ridge across the western Atlantic Ocean will maintain
fresh trade winds in the south central Caribbean Sea for the rest
of the week. Moderate to fresh trade winds are expected
An upper level trough is along the coast of the SE U.S.A.,
passing through 32N76W to Andros Island in the Bahamas, to Belize
in Central America. Isolated moderate rainshowers are to the NW of
the line that runs through 32N70W to 28N80W along the Florida
coast, from Haiti to Cuba, and from Honduras to Guatemala to SE
Mexico into the SW corner of the Gulf of Mexico. Rainshowers are
possible over the W Atlantic W of 73W to include the Bahamas.
An upper level trough passes through 32N37W in the north central
Atlantic Ocean, to 22N47W to 14N60W, just to the east of
Martinique and Saint Lucia. Isolated moderate rainshowers are
within 480 nm to the north of the trough between 49W and 60W.
A surface trough passes through 32N48W to 26N56W. Isolated
moderate to locally strong rainshowers are from 26N northward
between 44W and 60W.
Gentle to moderate trade winds, with a 30N surface ridge, will
prevail across the region for the rest of the week.
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