[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161053
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
653 AM EDT Mon Sep 16 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 0600 UTC surface analysis and satellite imagery through
1040 UTC.

...SPECIAL FEATURES...

Hurricane Humberto is near 29.7N 77.3W at 16/0900 UTC or 660 nm W
of Bermuda moving NE at 4 kt. Estimated minimum central pressure
is 980 mb. Maximum sustained wind speed is 75 kt with gusts to 90
kt. Numerous moderate to scattered strong convection extends
outward from the center 270 nm NE quad, 180 nm SE quad, 90 nm SW
quad and 120 nm NW quad. A trailing rainband affecting portions of
the NW Bahamas with heavy rain is not as strong as it was several
hours ago, but is still producing convection in the area south of
Great Abaco, west of Eleuthera and north of Nassau. An ENE motion
with a gradual increase in forward speed is expected tonight
through early Thursday. The center of Humberto is forecast to
approach Bermuda late Wed or Wed night. Additional strengthening
is expected during the next couple of days along with an expansion
of the wind radii. Please read the latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC, or at the website
hurricanes.gov for more details.

Showers and thunderstorms have increased in association with an
area of low pressure along a tropical wave in the central tropical
Atlantic. A 1008 mb surface low is centered near 09N41W along a
wave that extends along 41W from 04N-16N. The low and wave are
moving W at 5-10 kt. Scattered moderate convection is seen from
06N-13N between 38W-46W. Environmental conditions are forecast to
be conducive for gradual development, and a tropical depression
is likely to form within the next two to three days while the
system moves slowly west-northwestward to northwestward.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has an axis along 28W S of 19N,
moving W around 20 kt. The wave shows up well in model diagnostics
and TPW imagery. Scattered moderate convection is from 10N-15N
between 26W-33W.

See section above for information on the tropical wave along 41W.

A tropical wave moving through the Lesser Antilles today has its
axis along 58/59W from 06N-22N, moving W around 15 kt. Scattered
to numerous moderate with embedded isolated strong convection is
from 12N-17N between 57W-63W, affecting islands from St. Vincent
to Guadeloupe. Barbados recently recorded sustained winds of 31 kt
at 0800 UTC. Scattered showers are over the Lesser Antilles
elsewhere from 11N-19N. This wave is well depicted in model
guidance and TPW imagery. The wave will continue to bring
enhanced rain to the Lesser Antilles and eastern Caribbean today.

An eastern Caribbean tropical wave extends its axis along 68/69W
from 19N southward, moving west around 15 kt. This wave is well
depicted in TPW imagery. Scattered showers are within 60 nm of the
wave axis from 15N-18N and also inland over Venezuela.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from northern Mauritania near 21N16W
to 13N24W to 09N48. The ITCZ continues from 09N48W to 10N57W.
Aside from the convection already discussed in the Tropical Waves
section above, scattered moderate with embedded isolated strong
convection is noted from 03N-15N between the coast of Africa and
22W.

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, as well as a surface trough. The low is closed down to 850
mb, according to the GFS model. The surface trough is analyzed
from 26N86W to 26N92W to 22.5N96.5W. Scattered moderate convection
is seen north of the surface trough from 27N-29N between 89W-95W.
In the eastern Bay of Campeche, upper-level diffluence has
induced an area of scattered moderate convection from 18N-21N
between 90W-93W. The latest ASCAT pass from late Sunday evening
shows fresh to strong E winds from 27N-29.5N between 89W-94W.
Light winds are over the south-central Gulf. A 1016 mb high is
over western Cuba near 23N83W.

An elongated trough extending across the central and western Gulf
will become a broad low pressure center over the northwest Gulf
later today, before moving inland over Texas tonight. Weak high
pressure will build over the north central Gulf through mid week,
before dissipating later in the week ahead of a weak cold front
moving across the eastern Gulf.

CARIBBEAN SEA...

Refer to the Tropical Waves section above for details on the two
tropical waves currently impacting the eastern Caribbean.

Relatively dry air covers the central and NW Caribbean. Deep-
layered ridging is over Cuba. A 1016 mb surface high is analyzed
near 23N83W. Scattered showers and tstorms cover portions of the
SW Caribbean and Central America, including the waters near
eastern Honduras and northern Nicaragua as well as the waters
north of western Colombia and eastern Panama. The latest ASCAT
pass from Sunday evening depicts moderate to fresh trades in the
south-central Caribbean.

Moderate to fresh trade winds will dominate much of the basin.
Long period northerly swell will starting pushing through Atlantic
passages by early Tue. A tropical wave entering the central
Caribbean will move through the western Caribbean by late Tue, and
west of the basin by mid week. Scattered thunderstorms and gusty
winds accompany another tropical wave currently impacting the
Lesser Antilles. This wave will move through the eastern Caribbean
today, across the central Caribbean through mid week, and into
the western Caribbean by late week. Looking ahead, low pressure
developing east of the area will move toward the Atlantic offshore
waters of the Leeward Islands by late Fri, possibly as a tropical
cyclone.

ATLANTIC OCEAN...

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

A cold front enters the discussion area near 32N35W to 27N43W to
26N49W to 26N52W. It continues as a stationary front from that
point to 29N60W to Bermuda. A pre-frontal trough is analyzed from
30N35W to 26N40W to 24N45W with scattered showers. Scattered
showers are also seen within 180 nm of the stationary front from
23.5N-29N between 49W-62W.

Hurricane Humberto will strengthen as it moves to near 30.5N 74W
Tue afternoon, and the wind radii will expand as it moves to near
33N 66.5W late Wed night or early Thu morning. Northerly swell
will follow across the open waters in the wake of Humberto.

$$
Hagen
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