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057
AXNT20 KNHC 200005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Wed Sep 19 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 1800 UTC surface analysis and satellite imagery through 2330 UTC.


...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 19W/22W from 20N southward, moving W at 10 kt. This wave is associated with a distinct 700 mb trough. Isolated moderate rainshowers are within 180 nm on either side of the wave.

An Atlantic Ocean surface trough is along 19N29W 10N31W. Rainshowers are possible within 150 nm of the western side of the trough. The trough is associated with a distinct 700 mb trough.

An Atlantic Ocean surface trough is along 46W/48W, from 02N to 11N. Scattered to numerous strong rainshowers are from 08N to 11N between 45W and 48W.

A Caribbean Sea tropical wave is along 65W/66W from 20N southward, moving W at 15 kt. Widely scattered moderate to isolated strong rainshowers are from 20N southward between 60W and 69W.


...MONSOON TROUGH/ITCZ...

The monsoon trough passes from W Africa near 14N17W to 11N20W. The ITCZ continues from 09N23W to 08N37W to 05N52W. Scattered moderate convection is from 04N-10N between 25W- 35W.


...DISCUSSION...

GULF OF MEXICO...

The northern extent of a surface trough, the remnants of Isaac, is over the Yucatan Peninsula. Scattered moderate convection is over the Yucatan Channel and the eastern Yucatan Peninsula. Weak surface ridging is over the remainder of the Gulf of Mexico with axis along 28N.

In the upper levels an upper level low is centered over S Texas near 28N98W. Upper level diffluence is over the W Gulf. Scattered showers are from 20N-25N between 95W-98W. The remainder of the Gulf has mostly fair weather.

High pressure will build over the eastern United States through tonight, allowing gentle to moderate E to SE breezes and 2 to 4 ft seas across the Gulf through Sun. A trough over the northwest Caribbean and Yucatan Channel will shift westward across the south central Gulf and Yucatan Peninsula through tonight, and across the southwest Gulf Thu and Fri, before dissipating Sat.

CARIBBEAN SEA...

The remnant trough of Isaac extends from 22N86W to the Gulf of Honduras near 16N88W. Widely scattered moderate convection is over the NW Caribbean N of 15N between 79W-89W.

Scattered moderate to isolated strong convection is over the SW Caribbean S of 15N between 77W-87W. The monsoon trough is along 09N over Costa Rica and Panama enhancing convection.

An eastern Caribbean Sea tropical wave will move westward, across the central Caribbean Sea from Thu into Fri. The wave will pass west of the area through late Sat into Sun. Strong gusts are possible near showers and thunderstorms associated with this tropical wave near the Lesser Antilles and eastern Caribbean through this evening. Meanwhile high pressure building from the central Atlantic Ocean into the central Bahamas will support moderate to fresh trade winds and building seas across the entire basin from late Wed through Fri.

ATLANTIC OCEAN...

A quasi-stationary front is off the coast of Georgia. Scattered moderate convection is from 29N-31N between 74W-78W. A surface trough is further E from 34N64W to 28N68W. Scattered showers are within 90 nm of this trough. A 1022 mb high is centered over the central Atlantic near 28N49W. The remnant low of Joyce is over the E Atlantic near 30N29W. Scattered showers are within 120 nm of the center.

Of note in the upper levels, an upper level low is centered over the W Atlantic near 31N66W enhancing convection.

A surface trough reaching from roughly Bermuda to the central Bahamas will shift slowly NW and weaken this evening as the central Atlantic ridge builds into the southern Bahamas. Low pressure moving off the Carolinas tonight will drag an weakening frontal boundary across the waters north of 27N Thu and Fri. The low will sink to near 31N67W Fri evening then drift W and slowly weaken Sat and Sun. NE swell will move into the open waters east of the Bahamas Fri through early next week.

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

$$ mrf/ec/mt

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