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000
AXNT20 KNHC 202353
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
753 PM EDT Fri Oct 20 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 is in the central Atlantic with axis extending from 18N39W to 09N43W, moving W at 10-15 kt. The wave is embedded in abundant moisture as seen on SSMI Imagery. There are distinct surface and 700 mb troughs. Scattered moderate convection is from 13N-17N between 37W-41W.

A tropical wave is in the central Caribbean with axis extending from 20N74W to 09N76W, moving W at 15 kt. The wave is embedded in abundant moisture as seen on SSMI Imagery. There is a well defined surface trough, and a broad 700 mb trough. Widely scattered moderate convection is from 13N-20N between 73W-80W.

A tropical wave is in the western Caribbean with axis extending from 21N82W to 09N84W, moving W at 15 kt. The wave is embedded in abundant moisture as seen on SSMI Imagery. There are distinct surface and 700 mb troughs. Scattered moderate convection is from 12N-18N between 81W-86W.


...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 09N13W to 08N20W. The Intertropical Convergence Zone axis extends from 08N20W to 06N30W to 08N40W. The ITCZ continues W of a tropical wave from 09N46W to 08N60W. Aside from the convection associated with the tropical wave in the central Atlantic, scattered moderate convection is from 07N-10N between 33W-38W, and from 08N-10N between 60W-62W.


...DISCUSSION...

GULF OF MEXICO...

A 1025 mb high is centered over North Carolina near 35N80W producing surface ridging over the N Gulf of Mexico. A Surface trough is over the W Gulf from 26N94W to 18N92W. Scattered moderate convection is N of the trough from 26N-32N between 92W- 95W. Isolated moderate convection is elsewhere within 120 nm of the trough axis. Further E, scattered moderate convection is over the Yucatan Peninsula, the Yucatan Channel, and W Cuba, all moving N from the Caribbean Sea. In addition, radar imagery shows scattered showers are over S Florida and the Straits of Florida, moving SW from the Atlantic. In the upper levels, an upper level trough is over Texas and the W Gulf with axis along 100W. Upper level diffluence E of the axis is enhancing the convection over the W Gulf of Mexico. An upper level ridge is over the E Gulf with axis along 82W. Strong subsidence is over north and central Florida. Expect moderate to occasional fresh E-SE winds over the Gulf through Saturday as the surface ridge remains in place.

CARIBBEAN SEA...

Two tropical waves are over the Caribbean Sea. See above. In addition, the eastern extent of the E Pacific monsoon trough is over Costa Rica and Panama producing isolated moderate convection. In the upper levels, a large upper level high is centered over the NW Caribbean near 19N81W with abundant upper level moisture. Scattered moderate convection is over most of Cuba. Further E, very strong subsidence is over the E Caribbean E of 70W, to include Puerto Rico and the Virgin Islands. Expect the tropical waves to move W with convection. Also expect fair weather to continue over Puerto Rico and the Leeward Islands for the next 24 hours.


...HISPANIOLA...

Hispaniola is presently E of the two tropical waves that are moving W. Fair weather is over E Hispaniola. Scattered showers are over W Hispaniola mostly due to the upper level high. Fresh to strong trades are expected through the weekend as high pressure builds in N of the region. Scattered showers will be possible in the afternoon and evening hours.

ATLANTIC OCEAN...

A cold front is over the W Atlantic from 31N62W to 25N73W. Scattered showers are within 120 nm of the front. A 1030 mb high is centered over the E Atlantic near 39N34W producing fair weather. Of note in the upper levels, an upper level trough is over the W Atlantic with axis along 73W. Upper level diffluence E of the axis is enhancing the showers over the W Atlantic. An upper level low is centered over the central Atlantic near 22N42W producing scattered showers within 600 nm E of the center due to upper level diffluence.

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

$$ Formosa

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