[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152319
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
719 PM EDT Sun Sep 15 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

Tropical Storm Humberto is centered near 29.3N 78.0W at 15/2100
UTC or 180 nm NNW of Great Abaco Island moving N at 5 kt.
Estimated minimum central pressure is 989 mb. Maximum sustained
wind speed is 60 kt with gusts to 75 kt. Numerous moderate to
scattered strong convection extends outward from the center 100 nm
NW quad, from 90 nm NE quad, 80 nm SE quad. On the forecast
track, the center of Humberto will continue to move away from the
Bahamas and remain well offshore of the southeastern coast of the
United States through Wednesday. Please read the latest NHC
forecast/advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC,
or at the website hurricanes.gov for more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave with axis along 23W from 04N-18N,
is moving W around 15 kt. The wave shows up well in 700 mb trough
diagnostics, the TPW imagery and latest ASCAT pass. Scattered
showers are present in the vicinity of the wave axis.

A central Atlantic tropical wave with axis along 40W from 04N-
16N, is moving W at around 15 kt. A 1008 mb surface low is
centered along the wave axis near 09N40W. The wave is well
depicted in satellite imagery and TPW imagery. Scattered moderate
convection is noted from 08N- 12N between 38W-43W. Slow
development is anticipated during the next day or two.
Environmental conditions are forecast to become more conducive for
development by the middle of the week, and a tropical depression
is likely to form by the end of the week while the system moves
slowly west-northwestward to northwestward. There is a low chance
of development in the next 48 hours.

A west-central Atlantic tropical wave with axis along 55W from
07N-21N, is moving W around 15-20 kt. This wave is well depicted
in model guidance and satellite imagery. Scattered moderate
convection is seen from 12N-21N between 55W-60W. The wave will
bring enhanced rain to the Lesser Antilles and eastern Caribbean
on Monday.

An eastern Caribbean tropical wave extends its axis along 62W from
20N, moving west around 15 kt. This wave is well depicted in
model guidance and satellite imagery also. Scattered moderate
convection covers the area from 14N-18N between 62W-69W affecting
the northern Leeward Islands and Puerto Rico.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from Guinea-Bissau near 15N17W to
11N32W to 08N44W. The ITCZ continues from 08N44W to 09N51W. Aside
from the convection already discussed in the Tropical Waves
section above, scattered moderate convection is noted within 90
nm on either side of the monsoon trough between 26W-35W.

GULF OF MEXICO...

The weather over the Gulf of Mexico is dominated by a large mid to
upper-level low that is centered over the western portion of the
basin. A surface trough is now being analyzed from the western
Yucatan Peninsula near 25N90W to 18N91W. Upper- level diffluence
and divergence on the east side of the upper-low are enhancing
scattered to numerous moderate convection from 25N- 28N between
82W-93W. Scattered showers and tstorms are seen in the southern
Bay of Campeche from 19N-21N between 90W-92W. The latest ASCAT
pass and nearby observations depict gentle to moderate easterly
winds across the northern half of the basin north of 24N, while
gentle winds prevail south of 25N.

The broad area of disorganized showers and thunderstorms over the
northern Gulf of Mexico has some slight development possible
during the next couple of days while it moves westward over the
western Gulf of Mexico. The system is forecast to move inland
along the northwestern Gulf coast by late Monday or Tuesday, and
further development is not expected after that time. High pressure
will gradually build over the Gulf Tue through Fri.

CARIBBEAN SEA...

Refer to the Tropical Waves section above for details on the
tropical waves moving and approaching the basin.

Relatively dry air covers the central Caribbean. In the SW
Caribbean, scattered moderate to strong convection is noted int he
vicinity of the monsoon trough affecting the Caribbean waters and
portions of Central America south of 13N and west of 77W. The
latest ASCAT pass depicts moderate to fresh trades in the south-
central Caribbean, while gentle to moderate easterly winds prevail
elsewhere.

Moderate to fresh trade winds will dominate much of
the basin. A tropical wave moving across the eastern Caribbean
today will reach the central Caribbean on Mon. Another tropical
wave will approach Barbados late today, move across the eastern
Caribbean Mon, and into the central Caribbean through mid week,
bringing widespread showers and thunderstorms, gusty winds and
building seas. Northerly swell will reach the Atlantic passages
into the Caribbean Sea late on Mon and then gradually subside
through Wed.

ATLANTIC OCEAN...

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

A mid-latitude low currently centered near 41N43W extends its
cold front south entering the forecast area near 31N39W to
28N57W. The front becomes stationary from that point to 31N65W. A
pre-frontal trough is analyzed from 30N37W to 25N48W with
scattered showers. To the east, 1027 mb surface high centered to
the north remains in control over this area.

Humberto will strengthen to a hurricane near 29.8N 77.6W Mon
morning, move to 30.1N 76.7W Mon afternoon, 30.4N 75.4W Tue
morning, 30.7N 73.6W Tue afternoon, and 31.7N 68.9W Wed afternoon.
Humberto will change little in intensity as it moves near 35.0N
62.0W Thu afternoon, and weaken to a tropical storm over 39.6N
56.1W Fri. Northerly swell will reach the Atlantic passages into
the Caribbean Sea late on Mon and subside by Wed.

$$

ERA
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