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Atlantic Tropical Weather Discussion

AXNT20 KNHC 220538

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1238 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 0000 UTC surface analysis and satellite imagery through 
0520 UTC.


Tropical Storm Sebastien is near 24.7N 57.8W at 22/0300 UTC, or
about 490 nm NE of the northern Leeward Islands, moving NE at 16
kt. Minimum central pressure is 999 mb. Maximum sustained wind 
speeds are 50 kt with gusts to 60 kt. Numerous moderate with
scattered strong convection is within 120 nm of the center in the
NE quadrant and 150 nm NW quad. Scattered moderate with isolated 
strong convection is elsewhere within 210 nm of the center in the
NE, SE and NW quads, and only within 30 nm SW quad. The cold front
approaching Sebastien is now only about 80 nm west of Sebastien.
Sebastien is forecast to continue moving NE with an increase in
forward speed, with little change in strength. 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 MIATCMAT5/WTNT25 KNHC.


An eastern Atlantic Ocean tropical wave has been added to the map
along 32W, moving W around 10 kt. The wave shows up well in TPW
imagery and model diagnostics. Numerous moderate with scattered 
strong convection is seen from 02N-08N between 27W-33W.

Another, weaker tropical wave has also been added to the map along
41/42W from 05N-12N, moving W-NW around 5-10 kt. Scattered 
moderate convection from 10N-15N between 35W-41W may be more due 
to the upper-level low near 20N41W rather than the tropical wave.

An Atlantic Ocean tropical wave is along 52W from 12N southward, 
moving W at 10-15 kt. Isolated showers are within 120 nm of the
wave axis.

A Caribbean Sea tropical wave is along 79/80W, from 07N-16N, 
moving W around 10 kt. Isolated showers and tstorms are within 60 
nm of the wave axis from 11N-16N.


The monsoon trough passes through the coastal plains of Sierra 
Leone near 07N12W to 07N15. The ITCZ continues from 07N15W to
02N31W, then continues W of a tropical wave from 03N33W to 02N47W.
Aside from the convection mentioned above in the Tropical Waves
section, isolated moderate convection is seen from 02N-06N between


Deep-layered anticyclonic wind flow covers the basin. Scattered
showers are over SE Texas, well ahead of a cold front over north-
central Texas. The latest ASCAT pass shows moderate to fresh SE
winds across the basin.

A surface ridge will prevail across the area through today, with 
fresh SE return flow persisting over the western Gulf. A cold 
front will move off the Texas coast and into the NW Gulf tonight,
cross the northern and central waters this weekend, then weaken 
and stall over the southern Gulf Sun night.


As of 22/0300 UTC, a stationary front extends from the Mona 
Passage to the north coast of Jamaica to 20N85W. Isolated moderate
showers and tstorms are present along and south of the front, 
north of 14.5N between 64.5W-72W. The latest ASCAT pass shows 
strong N-NE winds in the Mona and Windward Passages, and south of 
the Dominican Republic and Cuba.

The stationary front will weaken today. Fresh NE winds will 
prevail across much of the western Caribbean through today, with 
the strongest winds expected through the Windward and Mona 
passages as high pressure builds behind the front. Easterly 
trades will freshen across the south-central Caribbean early next


A cold front passes through 32N56W to 24N62W to the Mona Passage.
The front is only 80 nm west of T.S. Sebastien. Aside from the
convection mentioned in the section above associated with
Sebastien, scattered moderate convection is along and within 210
nm E of the cold front north of Sebastien to 32N. To the west of
the cold front, surface high pressure ridging prevails, thanks to
a 1025 mb high centered near the coast of South Carolina. Fresh N
to NE winds are throughout the Bahamas region. Strong N winds are
from 20N-30N between 63W-70W.

Farther east, an upper-level low near 20N41W is inducing scattered
showers and isolated tstorms from about 15N-25N between 30W-43W.
North of that, fair weather prevails due to a 1023 mb high
centered near 32N36W. A cold front extends from 32N12W to the
Canary Islands near 28N16W to 26N20W to 26N26W with no significant
precipitation noted.

The cold front from 32N56W to the Mona Passage will continue
moving eastward and steer Sebastien into the central Atlantic. 
High pressure will build behind the cold front across the northern
waters through Sat, then shift eastward Sat night. The next cold 
front will cross the western Atlantic Sun through Mon.