[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122356
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 13 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 2345 UTC.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis analyzed from
near 20N19W to 13N20W to 05N21W. It is moving westward at 15 kt.
Scattered moderate to isolated strong convection is increasing
from 12N to 18N between 19W-22W. Scattered moderate convection
is east of the wave from 09N to 12N between 16W-20W. Environmental
conditions appear only marginally favorable, and any development
of this wave should be slow to occur while it moves westward or
west-northwestward across the eastern tropical Atlantic through
the end of the week.

A central Atlantic tropical wave has its axis extending from
21N42W to 13N44W to 04N44W. It is moving westward at 15-20 kt.
Latest ASCAT data shows a rather sharp northeast to southeast
wind shift across the wave axis consisting of mainly fresh wind
speeds. Satellite imagery shows an increasing area of numerous
moderate to strong convection east-northeast of the wave from
14N to 18N between 34W-44W. Scattered moderate convection is
from 8N to 11N between 37W-44W. Some slow development of this
system is possible over the next several days while it moves
generally westward to west-northwestward over the central
tropical Atlantic and approaches the Windward Islands by
the end of the week.

An eastern Caribbean tropical wave has its axis along 66W south
of 21N moving westward near 20 kt. This position is extrapolated
from a time series analysis of the latest available upper-air
data from Barbados, St. Martin, San Juan and the Dominican
Republic. This wave is void of deep convection, however, low-
level clouds moving westward with possible isolated showers are
noted north of 13N within 180 nm either side of the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic through the coast of
Mauritania near 18N16W, and continues southwestward to 12N24W and
to 13N30W to 14N40W and to 09N46W to 09N53W. Aside from convection
associated with the tropical waves, an area of scattered moderate
to isolated strong convection is south of the trough axis from
06N to 09N between 23W-31W. Scattered moderate convection is
within 120 nm south of the trough axis between 34W-39W, and
within 60 nm north of the trough axis between 51W-53W.

GULF OF MEXICO...

A cold front is analyzed from near New Orleans, Louisiana
southwestward to 28N93W and to inland southern Texas just north
of Brownsville. Noticeably drier air is following in behind it.
To its east, a surface trough extends from southeastern Georgia
southwestward to near Panama City, Florida and continues to
27N90W to 23N93W and to the Bay of Campeche near 18N95W. The base
of a broad upper- level trough is noted on water vapor imagery
to reach south to roughly along 28N and between 88W-99W.
Scattered moderate convection is over the NE Gulf north of 27N
and east of the surface trough to inland the Florida peninsula.
Scattered showers and isolated thunderstorms are seen south of
27N and east of the surface trough. Skies west of the cold front
are mostly clear, while between the cold front and surface trough
there are pockets of scattered showers and thunderstorms. Per
the latest ASCAT data pass, gentle to moderate north to northeast
winds are between the surface trough and front, except for
moderate to fresh north winds in the western Bay of Campeche
south of 22N and west of 94W, including offshore Veracruz. Light
and variable winds are east of the surface trough north of 24N,
and gentle east to southeast winds are south of 24N. Seas
relatively low throughout, in the 1-3 ft range except 2-4 ft in
the southwestern Gulf area.

For the forecast, the surface trough extending from near Panama
City, Florida to 27N90W to 23N93W and to the Bay of Campeche
near 18N95W will linger over the southwestern Gulf into mid-week,
ahead of a cold front currently moving through across the
northwest Gulf. The weak cold front will shift slowly south then
stall from near Tampa, Florida to Corpus Christi, Texas by mid
week then dissipate. Looking ahead to later in the week, high
pressure will build over the southeast U.S. following the front,
maintaining gentle to moderate easterly breezes and slight seas.

CARIBBEAN SEA...

An upper-level low is identified on water vapor to near near
21N68W, while a smaller one is over Cuba near 23N81W. With plenty
of Atmospheric already in place, these features are helping to
maintain active weather in the form of scattered to numerous
showers and thunderstorms across Cuba, Hispaniola and over some
sections of western Puerto Rico. Upper-level diffluent flow
between the upper-level low near 21N68W and upper anticyclonic
flow west of 79W is helping to sustain isolated to scattered
showers and few thunderstorms over the central and western
Caribbean waters. Scattered showers and thunderstorms are also
over the southwestern Caribbean south of 13N between 76W-82W.
This activity is being further aided by the eastern extension of
the eastern Pacific monsoon trough that extends along 11N to low
pressure of 1010 mb over northwestern Colombia near 11N75W.
Isolated showers moving westward are over the eastern Caribbean
moving. Some of this activity is associated to the tropical wave
along 66W. Weak high pressure north of the basin is allowing
for moderate to locally fresh trade winds in the south-central
Caribbean, while moderate or weaker winds are found elsewhere.
Seas of 3-5 ft are over the south-central Caribbean and also
north of 15N between 64W-72W. Seas of 2-4 ft are 15N to 18N
between 72W-85W, and lower seas of 1-3 ft are elsewhere over
the basin.

For the forecast, gentle to moderate winds and slight to moderate
seas will continue into Tue over the Caribbean as a tropical
wave moves across the eastern and central portions of the basin.
Winds and seas will begin to increase from east to west starting
late Wed over the central Caribbean 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. Looking ahead, another
tropical wave will move into the eastern Caribbean Fri, and
reach the central Caribbean by Sat.

ATLANTIC OCEAN...

A cold front enters the area through 31N46W and continues to
27N51W, where it transitions into a dissipating stationary front
that extends to 24N65W to 25N70W and northwestward to 31N75W.
Scattered showers and thunderstorms are seen along and within
120 nm south of the stationary front between 70W-75W and along
and within 30 of the stationary front between 65W-70W. Scattered
showers and thunderstorms are within 30-60 nm southeast of the
cold front north of 26N. Fresh southerly winds are north of 29N
and east of the cold front to near 40W. Northerly swell
associated with the remnants of former Hurricane Earl are
generating seas of 8-10 ft N of 22N and between 40W and 74W.

In the central Atlantic, a surface trough extends from 25N59W to
21N53W and to 17N54W. Isolated showers are along and just west
of the trough. In the eastern Atlantic, high pressure of 1020 mb
is analyzed near 30N34W, with a ridge stretching west-southwestward
to 24N50W and another ridge east-northeastward to 30N18W. This
feature controls the wind regime over the eastern Atlantic waters
north of 20N maintaining generally mostly fair skies there.

The remnants of former Hurricane Danielle are located a couple
hundred miles east of Portugal and are generating a large swell
region that extends into the tropical Atlantic. Seas of 8-11 ft
are present north of 27N and east of 31W. Moderate to locally
fresh northerly winds are north of 15N and east of 31W. Seas of
5-8 ft are north of of 15N and east of 31W. Elsewhere, moderate
or weaker winds and seas of 4-6 ft continue.

For the forecast west of 55W, northerly swell of 8 to 12 ft
spreading across the waters east of the Bahamas is expected to
subside into Wed. Looking ahead, the northern end of a tropical
wave will pass 55W south of 22N by early on Fri bringing fresh
east winds and locally rough seas to the area northeast of the
northern Leeward Islands. The wave may weaken as it continues
westward toward the Turks and Caicos Islands and southern Bahamas
through Sat.

$$
Aguirre
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