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000
AXNT20 KNHC 212333
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Fri Jul 21 2017

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 1800 UTC surface analysis and satellite imagery through 2315 UTC.


...TROPICAL WAVES...

A tropical wave over the eastern Atlantic extends from near 17N33W to 04N35W and is moving westward 15 to 20 kt. The 18Z GFS guidance shows a well-defined 700 mb trough associated with this wave. Scattered moderate isolated strong convection covers a large area primarily east of the wave axis from 06N to 14N between 28W and 37W.

A large amplitude tropical wave is over the central Atlantic with its axis extending from near 24N59W to 15N58W and is moving westward at 15 kt. This wave exhibits a well-defined inverted-v shape structure. Scattered moderate isolated strong convection is located from 18N to 23N between 55W and 60W with the deepest convection from 22N to 23N. Scattered showers and isolated thunderstorms are elsewhere within 120 to 180 nm either side of the wave axis.

A well-defined tropical wave is easily identifiable on the latest visible satellite imagery with its axis located along 68W/69W south of 19N into Venezuela. It is moving westward 15 to 20 kt. Scattered showers and isolated thunderstorms are located up to 180 nm either side of the wave axis.

A tropical wave is located over the western Caribbean with its axis along 85W south of 18N across Nicaragua and into the eastern Pacific waters near 05N85W. It is moving westward near 15 kt. This wave is the remnant of former Tropical Storm Don. Abundant low level moisture is to the south of 16N west of 80W, and has resulted in scattered moderate to isolated strong convection from 08N to 16N west of 80W into Central America.


...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 16N16W to 10N36W. The ITCZ then extends from 10N36W to a weak low pressure of 1013 mb near 09N42W to 08N52W. Aside from the convection associated with the tropical waves, scattered moderate to strong convection is located within a 90 nm radius of 11.5N21W. Scattered moderate isolated strong convection is located from 06N to 11N between 43W and 53W.


...DISCUSSION...

GULF OF MEXICO...

An elongated middle/upper level cyclonic circulation is centered over the north central Gulf near 28N90W and is forecast to move into the northwest Gulf in 24 hours. Another middle/upper level cyclonic circulation is centered off the Yucatan Peninsula near 22N92W and is drifting northward. Abundant moisture and instability is in place over much of the northern half of the Gulf. Also, a surface trough extends through the central Florida panhandle to 26N88W.

CARIBBEAN SEA...

Light southerly flow aloft covers most of the eastern half of the Caribbean with water vapor imagery showing subsidence east of about 68W. These conditions are allowing for mainly fair weather conditions outside the shower and thunderstorm activity related to the tropical waves.


...HISPANIOLA...

Light to moderate southerly winds aloft cover Hispaniola early this evening. A tropical wave is approaching the eastern Dominican Republic with an increase in showers and thunderstorms expected. Broken to overcast layered clouds with scattered showers and isolated thunderstorms cover most of the island.

ATLANTIC OCEAN...

A well-defined middle/upper level cyclonic circulation is located just north of the central Bahamas near 25N74.5W and is forecast to move north about 15 kt over the next 24 hours. Another large middle/upper level cyclonic circulation is located in the central Atlantic near 28N46W and will move south about 10 kt over the next day or so. At the surface, a 1023 mb high is centered near 29N55W with a ridge extending westward to near 27N75W. Aside from the convection associated with the above described tropical waves, scattered to numerous showers and thunderstorms are observed over the far western part of the basin north of 24N west 75W including the Bahamas.

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

$$ CAB

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