AXNT20 KNHC 200522
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1222 AM EST Wed Nov 20 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
Tropical Storm Sebastien is near 20.7N 60.6W at 20/0300 UTC, or
about 205 nm NE of the northern Leeward Islands. Sebastien is
moving WNW at 8 kt. The estimated minimum central pressure is 1004
mb. Maximum sustained winds are 40 kt with gusts to 50 kt.
Numerous moderate with scattered strong convection extends outward
to 210 nm in the SE quadrant. Scattered moderate convection is
elsewhere within 330 nm in the SE quadrant. Sebastian will turn to
the north today and move to near 23N 61.5W this evening. The
cyclone is forecast to become extratropical Thu evening as it
reaches near 27N 56.5W. Some strengthening is forecast through
Thursday. Sebastien is expected to become absorbed by a cold
front early Friday. The Public Advisories for Sebastien are
available via the WMO header WTNT35 KNHC and the AWIPS header
MIATCPAT5. The Forecast/Advisories are available via the WMO
header WTNT25 KNHC and the AWIPS header MIATCMAT5.
An Atlantic Ocean tropical wave is along 40/41W, from 12N
southward, moving W at 10-15 kt. Scattered moderate convection is
from 06N-12N between 34W-41W.
A Caribbean Sea tropical wave is along 72W, from 09N-20N moving W
at 5 kt. No significant deep convective precipitation is apparent
with this tropical wave.
The monsoon trough passes through the coastal plains of southern
Sierra Leone near 07N12W to 05N19W. The ITCZ continues from 05N19W
to 04N30W to 06N39W. Isolated moderate to locally strong
convection is seen from 01N-12N between 24W-34W. Scattered
moderate to isolated strong convection is near the African coast
from 05N-08N between 09W-13W.
GULF OF MEXICO...
A 1018 mb surface high is near 28N90W. Weak surface ridging and
relatively dry air cover most of the basin. The latest ASCAT pass
shows that gentle to moderate anticyclonic winds cover the basin.
High pressure over the central Gulf will shift NE through today.
Fresh to strong SE return flow will develop over the NW Gulf today
through Thu ahead of the next cold front. The front will move off
the Texas coast late Fri, followed by fresh to strong northerly
winds Fri night into Sat. The front will rapidly move across the
basin and begin to weaken as it reaches the far SE Gulf this
A surface trough extends from the Turks and Caicos Islands through
the Windward Passage to 19N75W. Isolated light showers are
possible along and northwest of the surface trough. Isolated
showers are also present in the western Caribbean from 10N-20N
between 81W-85W in an area of slightly higher moisture content.
The latest ASCAT pass shows moderate N winds from 12N-21N between
The surface trough in the Windward Passage will dissipate this
morning. A tropical wave with axis across the central Caribbean
will weaken today as it moves across the basin. Fresh to strong
NE winds will pulse through the Windward Passage tonight through
A cold front passes through 32N71W to 27N75W to 26N80W. A pre-
frontal surface trough is from 29N71W to 24N72W. Another trough
extends from 22N71W to the Windward Passage. Scattered showers and
isolated tstorms are seen from 24N-32N between 58W-70W. Isolated
showers are noted west of 70W between the cold front and the SE
Bahamas. The latest ASCAT pass shows strong W winds northwest of
the cold front, north of 28N between 72W-80W.
In the far NE portion of the area, a cold front extends from the
Madeira Islands near 32N17W to 31N24W with no convection noted.
Fresh N winds are north of the front. Surface ridging dominates
elsewhere, anchored by a 1029 mb high near 32N38W.
The cold front from 32N71W to 26N80W will quickly move across the
northern waters through tonight, with fresh to strong W to NW
winds behind the front. Sebastien will become merged into the
frontal system early Fri. High pressure will build across the
northern waters Thu through Sat. The next cold front will move off
the NE Florida coast late by Sat night.