[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141104
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
704 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 0600 UTC surface analysis and satellite imagery through
1050 UTC.

...SPECIAL FEATURES...

Tropical Storm Humberto is centered near 26.3N 76.0W at 14/0900
UTC or 60 nm E of Great Abaco Island moving NW at 6 kt. Minimum
central pressure is 1007 mb. Maximum sustained wind speed is 35 kt
with gusts to 45 kt. Scattered moderate to isolated strong
convection extends outward 180 nm NE quad. Numerous moderate to
scattered strong convection extends outward 270 nm SE quad. Little
to no convection is in the western semicircle. On the forecast
track, the system is anticipated to move near or over 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 by
Sunday night. 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 34N from 05N-16N,
moving W at 15-20 kt. The wave is well depicted in satellite
imagery and TPW imagery. Scattered moderate convection is from
07N-13N between 30W-38W. 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 45W from 06N-21N,
moving W at 15-20 kt. Scattered showers are within 180 nm of the
wave axis from 12N-23N. 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 57/58W, from 08N-21N, moving
west around 15 kt. Scattered moderate showers are within 180 nm of
the wave axis from 13N-18N. TPW imagery and 700 mb streamline
analysis depict the wave well.

A western Caribbean tropical wave is along 86W 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 11N20W to
08N44W. The ITCZ is from 08N46W 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-41W. Another area of scattered moderate
convection, associated with a surface trough, is just N of the
ITCZ from 08N-13N between 47W-52W. Scattered showers are within
180 nm N and 360 nm S of the monsoon trough between the W coast of
Africa and 30W.

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 26N90W, but spans nearly the entire Gulf. Upper-level
diffluence on the east side of the upper low is producing
numerous moderate with embedded isolated strong convection from
23N-28N between 82W-85W. Scattered moderate convection is from
27N-30N between 85W-91W. Elsewhere N of 22N and E of 93W,
scattered showers and tstorms are seen. 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 18N-22N, west of 94W due to enhanced moisture in the
area. The latest ASCAT pass shows moderate to fresh ENE winds
across much of the Gulf.

Fresh to strong NE to E winds will persist over the eastern Gulf
today, between high pressure over the Mississippi Valley and
Tropical Storm Humberto near the Bahamas. Winds and seas will
diminish tonight into Sun as Humberto moves farther north off the
northeast coast of Florida. Scattered to numerous showers and
thunderstorms will continue across much of the eastern Gulf
through Sun as an upper-level low lingers over the central Gulf. A
weak pressure pattern will persist from late Sun through mid week
as high pressure builds over the area.

CARIBBEAN SEA...

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

Relatively dry air covers much of the Caribbean Sea, including
the central Caribbean. In the SW Caribbean, a line of scattered
moderate to strong convection is within 45 nm of a line from
09N76W to 10.5N79W to 13.5N83W. A surface trough extends over Cuba
and the NW Caribbean from 23N78W to 21N85W. Isolated showers are
over the NW Caribbean N of 19N between 73W-87W. Scattered showers
and tstorms are also seen over the NE Caribbean due to an
approaching tropical wave. 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,
pulsing to fresh to strong in the south central Caribbean mainly
at night. A tropical wave over the Gulf of Honduras will move
inland today. Another tropical wave nearing Barbados will move
across the eastern Caribbean today, through the central Caribbean
Sun and Mon, and through the western Caribbean mid week. A third
and stronger tropical wave will approach the Barbados Sun, move
across the eastern Caribbean Mon, and into the central Caribbean
through mid week, bringing widespread showers and thunderstorms,
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 52W-
65W. Upper-level diffluence near the base of this trough is giving
way to scattered moderate convection from 21N-26N between 58W-65W.
An area of scattered moderate convection from 25N-30N between
41W-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 31N49W 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 26.3N 76.0W at 5 AM EDT, is moving
NW at 6 kt. Humberto will gradually intensify as it moves to near
29.0N 77.9W Sunday afternoon, before strengthening to a hurricane
near 29.8N 77.4W W Monday morning. Humberto is then forecast to
turn east to near 31N74.5W by Tuesday morning. Farther south, long
long period NE swell will reach the waters northeast of the Leeward
Islands early next week.

$$
Hagen
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