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338
AXNT20 KNHC 150522
TWDAT

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 0500 UTC.


...SPECIAL FEATURE...

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.


...TROPICAL WAVES...

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.


...MONSOON TROUGH/ITCZ...

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.


...DISCUSSION...

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 eastward.

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.

CARIBBEAN SEA...

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.

ATLANTIC OCEAN...

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.

For additional information please visit http://www.hurricanes.gov/marine

$$ MT

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