Tropical Weather Discussion

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Tropical Weather Discussion (NHC/TPC):
NWS National Hurricane Center Miami FL
656 AM 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 0600 UTC surface analysis and satellite imagery through 
1040 UTC.

...SPECIAL FEATURES...

Tropical Storm Humberto is centered near 28.3N 77.7W at 15/0900 
UTC, or 150 nm E of Cape Canaveral Florida, moving NNW at 6 kt. 
Estimated minimum central pressure is 1000 mb. Maximum sustained 
wind speed is 50 kt with gusts to 60 kt. Numerous moderate to 
scattered strong convection extends outward from the center 180 
nm NE quad, from 90 to 240 nm SE quad, 45 nm SW quad and 105 nm 
NW quad. On the forecast track, the center of Humberto should 
continue to move well offshore of the east coast of Florida during
the next day or so and then move away from the U.S. Humberto is 
forecast to become a hurricane by tonight. 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 is along 20W from 19N southward,
moving W around 15 kt. The wave shows up well in 700 mb trough 
diagnostics and TPW imagery. Scattered moderate convection is from
13N-16N between 90 nm E and 210 nm W of the wave axis. Scattered 
showers are from 04N-07N between 16W-21W.

A tropical wave with axis along 38W from 04N-16N, is moving W 
at 10-15 kt. The wave is well depicted in satellite imagery and 
TPW imagery. Scattered moderate convection is within 270 nm of the
wave axis from 07N-13N. Conditions are forecast to be conducive 
for gradual development through the middle of next week, and a 
tropical depression could form while the system moves slowly 
westward or west-northwestward.

A central Atlantic tropical wave with axis along 53W from 07N-21N
is moving W around 20 kt. This wave is well depicted in model 
guidance and satellite imagery. Scattered moderate convection is
seen from 12N-17N between 51W-56W, and from 07N-12N between 54W-
59W. The wave will bring enhanced rain to the Lesser Antilles and
eastern Caribbean on Monday.

An eastern Caribbean tropical wave extends its axis from 20N61W 
to 06N63W, moving west around 15 kt. Scattered moderate convection
covers the area from 14N-18N between 61W-65W, including the 
islands of Dominica, Guadeloupe, St. Kitts, and other nearby 
islands.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from Guinea-Bissau near 12N16W to 
08N44W. Aside from the convection already discussed in the 
Tropical Waves section above, scattered moderate convection is
noted within 210 nm of the monsoon trough between 20W-44W.

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 central portion of the 
basin near 26N92W. The GFS model analysis and 6-hr forecast 
indicates that the low is closed from 250-700 mb, and there is a 
sharp trough at 850 and 925 mb over the south-central Gulf. A
surface trough is now being analyzed from the western Yucatan
Peninsula near 18N89.5W to 22N90.5W to 26N93.5W. Another surface
trough extends from the NW Bahamas to the Florida Keys to 24.5N84W
to 22N88W. Upper-level diffluence and divergence on the east side
of the upper-low are enhancing scattered to numerous moderate 
convection from 26N-29.5N between 84.5W-91.5W. Scattered showers
and isolated tstorms are in the NW Gulf north of 25N west of
91.5W. Additional scattered showers are along the trough from Key
West to just north of the Yucatan Peninsula. Scattered showers and
tstorms are seen in the southern Bay of Campeche from 18N-20N
between 90.5W-94W. The latest ASCAT pass depicts fresh easterly 
winds across the northern half of the basin north of 24N, while 
gentle winds prevail south of 24N.

The mid to upper-level low in the Gulf has a low chance of
developing into a tropical cyclone during the next 48 hours while
it moves westward over the western Gulf. The system is forecast to
move inland along the northwestern Gulf coast by late Monday or
Tuesday. Moderate to fresh east to northeast winds are expected 
across the northern Gulf through Mon associated with the area of 
low pressure.

CARIBBEAN SEA...

A tropical wave is currently producing scattered moderate
convection over portions of the Lesser Antilles and eastern
Caribbean. See the Tropical Waves section for details.

Mid-level anti-cyclonic flow is over Cuba and Jamaica, and
relatively dry air covers the central Caribbean. In the SW 
Caribbean, scattered moderate with embedded isolated strong
convection is southwest of a line from 10N75W to 14N83W, including
over northern Colombia, Panama and Costa Rica. The latest ASCAT 
pass depicts fresh to strong trades in the south-central 
Caribbean.

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 from a large, storm-force mid-latitude low
currently centered near 41N45W, will reach the Atlantic passages 
into the Caribbean Sea late on Monday and continuing into mid-
week.

ATLANTIC OCEAN...

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

A surface trough extends from the NW Bahamas to the Florida Keys.
Scattered showers and tstorms just E of the Keys are being
enhanced by the trough and by T.S. Humberto. A mid to upper- 
level low near 26N58W is producing isolated showers from 22N-30N
between 55W-64W. A cold front extends over the discussion area 
from 32N43W to 29.5N54W to 31N62W. Scattered showers are south of
the front between 55W-61W. A surface trough extends from 30N43W 
to 26N49W. Isolated showers are within 90 nm of this trough.
Numerous moderate convection is seen within 120 nm of a line from
29N41W to 32N38.5W due to forcing ahead of a cold front.

Tropical Storm Humberto is near 28.3N 77.7W, 1000 mb, at 5 AM EDT
moving NNW at 6 kt. Maximum sustained winds are 50 kt with gusts 
of 60 kt. Humberto is forecast to become a hurricane tonight
29.5N77.5W, move to near 31N71W by Tuesday night as a 90 kt 
hurricane, to near 33N65W Wed night and near 38N58W Thu night.

Northerly swell from a large, storm-force mid-latitude low 
currently centered near 41N45W, will reach the Atlantic passages 
into the Caribbean Sea late on Monday and continuing into mid- 
week.

$$
Graphical representation of waves, etc. on this image (NCEP/OPC) [more].
Various tropical satellite imagery available here

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