AXNT20 KNHC 150522
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
122 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 0000 UTC surface analysis and satellite imagery through
A 1012 mb low pressure center is near 37N46W. The precipitation
pattern has become comparatively better organized during the last
6 hours. Satellite-derived wind data also indicate that the
surface circulation has become better defined since yesterday.
Conditions appear conducive for some additional development
during the next day or so. It is possible that a subtropical
depression or subtropical storm may form overnight or on
Wednesday, while the low moves northward to northeastward. The
low pressure center is expected to move northeastward over colder
waters and merge with a frontal zone that is in the northern
Atlantic Ocean later this week. The potential for this feature to
become a subtropical cyclone during the next 48 hours is medium.
An Atlantic Ocean tropical wave is along 34W/35W, from 22N
southward. 15 kt. Rainshowers are possible within 300 nm on either
side of the wave.
An Atlantic Ocean tropical wave is along 55W, from 20N southward.
The wave is moving through the area of a pre-existing upper level
trough. Please read the first paragraph in the ATLANTIC OCEAN
section for more details about precipitation.
A Caribbean Sea tropical wave is along 72W/73W from 21N
southward. Areas of upper level cyclonic wind flow are nearby. It
is possible that any precipitation may be more related to the
areas of upper level cyclonic wind flow.
A Caribbean Sea tropical wave is along 84W/85W, from 23N
southward. The wave is moving through a pre-existing area of upper
level cyclonic wind flow. It is possible that any precipitation
may be more related to the upper level cyclonic wind flow.
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. Widely scattered moderate to
isolated strong rainshowers cover the Atlantic Ocean from 03N to
13N between 34W and 60W.
GULF OF MEXICO...
Broad upper level anticyclonic wind flow spans the Gulf of Mexico.
A surface ridge extends from Lake Okeechobee in south Florida to
24N91W, to the coastal plains of Mexico near 21N97W.
Isolated moderate rainshowers are from 24N northward from 90W
A surface ridge, extending westward from the Atlantic Ocean into
the northern Gulf of Mexico, will prevail across the region
through the weekend. 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.
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. Numerous strong rainshowers are in
Colombia and Venezuela from 07N to 11N between 71W and 75W. Isolated
moderate rainshowers are from 13N southward between 75W and land,
in the SW corner of the Caribbean Sea.
A surface ridge across the western Atlantic Ocean will maintain
fresh trade winds in the south central Caribbean Sea through the
weekend. Moderate to fresh trade winds are expected elsewhere.
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 also from 15N northward from 80W westward, and elsewhere
from 70W westward.
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 through the weekend.
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