[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112308
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Mon Sep 12 2022

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...TROPICAL WAVES...

A central Atlantic tropical wave has its axis along 39W from 04N
to 22N. It is moving westward at 15-20 kt. The wave is depicted
latest available ASCAT data pass as a having a sharp axis, with
mainly gentle to moderate southeast to south winds behind it to
near 32W, and moderate to fresh north to northeast winds ahead of
it to near 42W. Satellite imagery shows scattered moderate to
isolated strong convection from 06N to 18N between 32W-39W, and
scattered moderate convection from 06N to 14N between 39W-44W.

Another central Atlantic tropical wave has its axis along 59W
south of 21N also moving westward at 15-20 kt. The wave is
surrounded by a dry and dusty Saharan airmass that is inhibiting
the development of deep convection. Only isolated showers are
south of 09N between 56W-60W. Light to gentle winds are in its
vicinity.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic through the coast of
extreme northwest Bissau near new and continues southwestward to
10N21W and northwestward to 13N26W, then to 12N37W to 09N41W and
to 07N48W. Aside from convection associated to the tropical wave
that is along 22N36W to 13N39W to 04N41W, clusters of increasing
numerous moderate to strong convection is along and just inland
the coast of Africa from 11N to 15N and is spreading westward to
18W. This activity is in advance of the next tropical wave.
Scattered moderate convection is noted near the coast of Africa
from 05N to 10N between 14W-18W, from 04N to 09N between 17W-24W
and within 60 nm of the trough between 41W-44W.

GULF OF MEXICO...

Water vapor imagery shows a persistent a deep-layer trough over
the central Gulf. It reaches from the Mississippi/Alabama border
southwestward into the Bay of Campeche. This feature supports
a surface trough that extends from near Destin, Florida southwestward
to 26N90W and to near 21N93W. Numerous moderate to isolated
strong convection is along and within about 180 nm southeast of
the surface north of 23N. Similar activity is over the Florida
panhandle east of the trough. Scattered showers and a few
thunderstorms are over the eastern Bay of Campeche. Dry sinking
air west of the upper trough is maintaining rather tranquil
weather conditions over just about the entire western Gulf, with
the exception of pockets of low clouds, with possible isolated
showers south of 28N between 95W and the coast of Texas and
Mexico. Moderate to locally fresh southeast to south winds are
east of the trough to near 86W and light to gentle east to
southeast winds are east of 86W. Seas are relatively low east of
the trough, in the 2-4 ft range. Gentle to moderate north to
northeast winds and low seas of 1-3 ft are west of the surface
trough as were noted in a recent altimeter data pass.

For the forecast, the surface trough extending from near Destin,
Florida to 26N90W and to 21N93W will linger over the southwest
Gulf into mid-week, ahead of a cold front that will move across
the northern Gulf Mon. The weak cold front will shift slowly
south then stall from near Tampa, Florida to Corpus Christi,
Texas by mid-week then dissipate.

CARIBBEAN SEA...

A large area of numerous moderate convection is confined to
the southwestern part of the Caribbean, mainly south of 13N
and west of northwest Colombia to inland Nicaragua, Costa Rica
and Panama. This is associated with abundant tropical moisture
interacting with the east segment of the eastern Pacific monsoon
trough that protrudes eastward through central Costa Rica and to
northwest Colombia. Patches of low-level clouds moving westward,
with scattered showers and few thunderstorms are over the
central Caribbean from 15N to 18N between 69W-79W, and over the
western Caribbean from 16N to 20N between 81W-87W. Low-level
cloud streamers, with possible isolated showers are seen over the
eastern Caribbean north of 12N. Scattered showers and thunderstorms
are developing over eastern Cuba, Jamaica, over sections of Hispaniola
and over the southwestern section of Puerto Rico. The rest of
the basin enjoys fairly tranquil weather conditions. ASCAT data
passes from this afternoon reveal fresh to locally strong trade
winds over the south-central Caribbean Sea from 11N to 13N west
of 73W, including offshore Honduras. Gentle to moderate trade
winds are elsewhere. Seas are 4-6 ft south of 15N west of 68W,
and 3-5 ft elsewhere except for lower seas of 2-4 ft north of 15N
between 64W-68W, south of 18N west of 85W including the Gulf of
Honduras and near the Windward Passage area.

For the forecast, mainly moderate east to southeast winds will
continue across the basin through tonight, except for fresh to
locally strong winds in the south-central Caribbean and offshore
Honduras. Gentle to moderate winds and slight to moderate seas
will continue Mon through Tue over the Caribbean as a tropical
wave moves across the eastern and central portions of the basin.
Winds and seas will start to increase from east to west starting
late Tue as high pressure builds north of the area in the wake of
the tropical wave. Northerly swell will propagate through the
Atlantic passages early on Tue, and will gradually subside late
Wed.

ATLANTIC OCEAN...

A cold front extends southward and southwestward from a nearly
stationary extratropical cyclone, former Hurricane Earl, located
south of Newfoundland, and enters the tropical Atlantic through
31N50W to 26N63W and northwestward to 31N74W, where it becomes
a stationary front to the Outer Banks of North Carolina. A
surface trough is out ahead of the cold front from near 31N46W
to 26N51W. No convection is occurring with this trough, however,
scattered showers and thunderstorms are along and within 60 nm
southeast of the cold front north of 27N. Isolated showers and
thunderstorms are elsewhere within 60 nm southeast and south of
the cold front east of 74W. Partial ASCAT data passes received
today have light to gentle winds to the southeast and south of
the front, except for fresh to strong southerly winds ahead of it
north of 26N between 40W-47W. Seas in these waters are 6-10 ft.
Seas are 8-12 ft north of the cold front due to a northeast
swell, with the highest seas occurring near 31N57W.

Scattered showers and thunderstorms are some sections of the
interior of the Florida peninsula.

The rest of the tropical Atlantic is under the influence of
high pressure ridging anchored by a 1022 mb high center that
is near 30N36W. It allowing for fairly tranquil weather
conditions. Fresh to strong northerly winds are present off the
coast of Western Sahara and northwestern Mauritania due to a
tight pressure gradient between the 1022 mb and low pressures
in western Africa. Seas with these winds are in the 5-7 ft range.
Farther north, northwest swell associated with the remnants of
former Hurricane Danielle are producing seas of 6-8 ft north
of 28N. Elsewhere over the basin, moderate or weaker winds and
seas of 3-6 ft are present.

For the forecast west of 55W, the aforementioned cold front
will continue to move southward to 24N west of 65W through Mon,
then stall and dissipate through from Mon evening into Tue. The
northeast swell north of the cold front will spread across the
open waters east of the Bahamas through late Mon, then subside
into mid week. Looking ahead, the northern end of a tropical wave
will pass 55W south of 22N by Thu, bringing fresh east winds and
locally rough seas to the area northeast of the northern Leeward
Islands.

$$
Aguirre
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