[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 140601
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
201 AM EDT Sat Sep 14 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
0530 UTC.

...SPECIAL FEATURES...

Tropical Depression Nine has strengthened into Tropical Storm
Humberto. Tropical Storm Humberto is centered near 25.8N 75.6W at
14/0600 UTC or 85 nm ESE of Great Abaco Island moving NW at 5 kt.
Minimum central pressure is 1007 mb. Maximum sustained wind speed
is 35 kt with gusts to 45 kt. Scattered moderate to strong
convection extends from 30-210 nm from the center NE quad, 90-180
nm from the center SE quad and 150-270 nm from the center SW quad,
with very little convection near the center. On the forecast
track, the system is anticipated to move very near the
northwestern Bahamas today, and offshore of the east coast of
Florida this weekend and early next week. Gradual strengthening is
forecast, and Humberto is expected to become a hurricane in 2 or
3 days. Please read the latest NHC forecast/advisory under
AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC, or go to the website
hurricanes.gov for more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave is along 32N from 06N-16N,
moving W at 15-20 kt. The wave is well depicted in satellite
imagery and TPW imagery. Scattered moderate to isolated strong
convection is from 07N-13N between 30W-35W. Gradual development
of this system is possible during the next several days, and a
tropical depression could form early next week while it moves
westward across the tropical Atlantic.

A central Atlantic tropical wave is along 43W from 06N-21N, moving
W at 15-20 kt. Scattered showers are within 180 nm of the wave
axis. This wave is well depicted in model guidance, and satellite
imagery shows turning. Conditions could become a little more
conducive for development in a few days when the wave moves over
the eastern Caribbean Sea.

An Atlantic tropical wave is along 56W, from 08N-21N, moving west
around 15 kt. Scattered moderate showers are within 180 nm W and
within 240 nm E of the wave axis from 14N-18N. TPW imagery and
700 mb streamline analysis depict the wave well.

A western Caribbean tropical wave is along 85W from 18N southward,
moving W around 15 kt. Scattered moderate showers are over the SW
Caribbean S of 15N and W of 76W, and over portions of Central
America.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from Senegal near 14N17W to 10N24W to
07N45W. The ITCZ is from 07N45W to 06N57W. Aside from the
convection already discussed in the Tropical Waves section, an
area of convection embedded in the monsoon trough near 39W is
being monitored with a low chance of tropical cyclone formation
during the next 48 hours. Scattered moderate convection is from
08N-10N between 38W-40W. Another area of scattered moderate
convection is just N of the ITCZ from 07N-11N between 47W-51W.
Scattered showers are within 180 nm N and 360 nm S of the monsoon
trough between the W coast of Africa and 29W.

GULF OF MEXICO...

The weather over the Gulf of Mexico is dominated by a large
upper-level low that is centered over the central portion of the
basin near 26N89W, but spans nearly the entire Gulf. Upper-level
diffluence in the east side of the upper low is producing numerous
moderate with embedded scattered strong convection from 23N-29N
between 82W-87W. Scattered showers and tstorms are elsewhere from
22N-29N between 82W-92W. Only slow development of this system is
likely during the next couple of days. However, conditions could
become more conducive for tropical cyclone development early next
week as the system moves over the western Gulf of Mexico.

Elsewhere across the basin, scattered showers are seen in the SW
Gulf from 19N-22N, west of 94.5W due to enhanced moisture in the
area. The latest ASCAT pass shows moderate to fresh ENE winds
across much of the Gulf.

The gradient between high pressure north of the area and Tropical
Storm Humberto just east of the central Bahamas will maintain
enhanced winds of fresh speeds over the eastern Gulf and over the
eastern part of the central Gulf through the weekend. Tropical
Storm Humberto will track northwestward, staying well off the
east coast of Florida through early next week while gradually
strengthening. Scattered to numerous showers and thunderstorms
will continue across much of the eastern Gulf through Sunday as an
upper-level low lingers over the central Gulf.

CARIBBEAN SEA...

Refer to the Tropical Waves section above for details on the
tropical wave moving across the western Caribbean.

Relatively dry air and mid to upper-level anticyclonic flow cover
much of the Caribbean Sea. A few areas with slightly higher
moisture content and scattered showers include the SW Caribbean
south of 15N and west of 76W, the Greater Antilles, the NW
Caribbean west of 84W due to a tropical wave, and the Lesser
Antilles due to an approaching tropical wave to the east. The
latest ASCAT pass shows fresh trades over the south-central
Caribbean, south of 16N between 64W-77W.

High pressure north of the area will maintain moderate trades,
that will at times pulse to fresh to strong in the south central
Caribbean. A tropical wave, with axis near 85W will continue to
move inland across Central America today. Another tropical wave,
with axis along 56W will enter the eastern Caribbean later today.
A third and stronger tropical wave will approach the eastern
Caribbean late Sunday and move through the area into early next
week. It is expected to bring widespread showers and tstorms,
gusty winds and building seas.

ATLANTIC OCEAN...

Refer to the sections above for details on T.S. Humberto and the
three tropical waves moving across the basin.

Upper-level troughing covers the area north of 23N between 53W-
65W. Upper-level diffluence near the base of this trough is giving
way to scattered moderate to isolated strong convection from
21N-24N between 60W-64W. An area of scattered moderate convection
from 23N-28N between 42W-45W is being caused by upper-level
diffluence to the NW of an upper-level anticyclone and also likely
due to the presence of a high amplitude tropical wave passing just
to the south. Some additional showers are seen within 150 nm of a
line extending from 25N57W to 28N53W to 31N49.5W due to low-level
troughing and upper-level diffluence in the area. Surface ridging
and fair weather cover E Atlantic north of 20N and east of 40W.

Tropical Storm Humberto, near 25.8N 75.6W at 2 AM EDT, is moving
NW at 5 kt. Humberto will gradually intensify as it moves to near
28.8N 78.2W Sunday morning, and strengthen to a hurricane near
31.0N 75.5W Monday evening. Humberto is then forecast to turn east
to near 32N 67W Wednesday evening. Meanwhile, a tropical wave may
approach the waters south of 22N west of 65W early next week.

$$
Hagen
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