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Atlantic Tropical Weather Discussion

AXNT20 KNHC 221804

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 AM EST Fri Nov 22 2019

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 1200 UTC surface analysis and satellite imagery through 
1745 UTC.


Tropical Storm Sebastien is centered near 25.2N 55.3W at 22/1500 
UTC or 600 nm NE of the Northern Leeward Islands moving ENE at 
13 kt. Estimated minimum central pressure is 1000 mb. Maximum 
sustained wind speed is 45 kt with gusts to 55 kt. Numerous 
moderate with isolated strong convection is from 25N to 30N 
between 49W and 55W. An ENE to NE motion is expected during the 
next few days. Continued gradual weakening is anticipated and 
Sebastien is forecast to dissipate by early next week. The 
Public Advisories for Sebastien are available via AWIPS/WMO 
headers MIATCPAT5/WTNT35 KNHC. The Forecast/Advisories for 
Sebastien are available via the AWIPS/WMO headers 


A tropical wave is in the central Atlc from 01N to 10N with axis 
near 36W, moving W at 10-15 kt. Scattered moderate isolated 
strong convection is from 0N to 11N between 25W and 38W.

A tropical wave is to the SE of the Windward Islands from 06N to 
14N with axis near 56W, moving W around 10 kt. Isolated showers 
are S of 10N between 51W and 60W.


The monsoon trough passes through the coastal plains of Sierra 
Leone near 07N12W to 07N14W. The ITCZ continues from 07N14W to 
05N20W to 05N32W, then continues W of a tropical wave from 
02N37W to 01N46W to 0N50W. For information on convection, see 
the Tropical Waves section.


Except for isolated showers and patchy fog along the NW Gulf 
coast, the remainder basin is under fair weather conditions 
being supported by a deep-layered anticyclone centered near the 
Yucatan Peninsula in the middle to upper levels. At the surface, 
the ridge is anchored by a 1022 mb high over the SW N Atlc and 
provides gentle to fresh return flow to the gulf as seen in the 
latest ASCAT pass.

The surface ridge will prevail across the area through today. A 
cold front will move off the Texas coast and into the NW Gulf 
this evening, cross the northern and central waters this 
weekend, then weaken and stall over the southern Gulf Sun night 
into Mon. Another cold front may move into the NW Gulf by Tue 


A surface trough, remnants of a former tropical wave, is over 
the NW Caribbean waters extending from 19N82W to Nicaragua 
adjacent waters. Isolated showers are in the vicinity of this 
trough. The remnants of a former cold front are analyzed as a 
shearline extending from Guadeloupe SW to 15N67W to 14N73W. 
Scattered to isolated showers are within 60 nm either side of 
the shearline. This line of showers and tstms will gradually 
move SSE through Sat and then dissipate. Otherwise, the pressure 
gradient between T.S. Sebastien in the central Atlc and high 
pressure building over the SW N Atlc waters is supporting a 
swath of fresh winds N of 14N between the Mona Passage and the 
Dominican Republic. These winds will diminish Sat as Sebastian 
is expected to continue a NE track, which will weaken the 
pressure gradient.

Easterly trades will freshen across the south-central Caribbean 
early next week, increasing to strong Tue into Tue night.


Please, see the Special Features section above for details on 
T.S. Sebastien.

A cold front is just west of T.S. Sebastien extending from 
22N61W to near Puerto Rico. The front will continue moving 
eastward and steer Sebastien into the north-central Atlantic.
Surface high pressure is over the SW N Atlc waters and will 
prevail through Sat, then shift eastward Sat night. The next 
cold front will cross the region Sun through Mon, weakening near 
70W Tue and Tue night. Otherwise, surface ridging domintes the 
northeastern Atlc waters.