149
AXNT20 KNHC 210610
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Sat Sep 21 2024

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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Potential Heavy Rainfall in Central America:
A Central American Gyre (CAG) is forecast to gradually develop
over Central America this weekend, possibly near Costa Rica and
Panama this weekend. It will slowly drift northwestward across
Nicaragua, Honduras and the Yucatan Peninsula through midweek
next week. Aided by abundant tropical moisture already in the
region, this system can produce significant rainfall near Panama
this weekend, Costa Rica and eastern Nicaragua this weekend
through early next week. Afterward, heavy rain will spread over
central and northern Guatemala and western Honduras during the
first half of next week, Belize and the Yucatan Peninsula after
midweek next week. This will lead to increased potential for life-
threatening flash flooding and mudslides in these areas. It is
recommended that residents in the aforementioned areas stay alert
on the latest information from their local meteorological
agencies. Please refer to the Tropical Weather Discussion for the
Eastern Pacific at website:
https://www.hurricanes.gov/text/MIATWDEP.shtml for rainfall across
El Salvador and the Pacific coast of Nicaragua, Guatemala and
southern Mexico.

...TROPICAL WAVES...

The western Caribbean tropical wave has moved into the Yucatan
Peninsula and East Pacific. Refer to the Tropical Weather
Discussion for the Eastern Pacific mentioned above for more
information.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic along the coast of Gambia,
then extends southwestward through 10N29W to 08N35W. An ITCZ
curves northwestward from 08N35W to 10N51W. Scattered moderate
convection is noted near and south of the trough from 06N to 14N
between the central Africa coast and 18W. Widely scattered
moderate convection is found farther west south of the trough but
near the ITCZ from 04N to 09N between 18W and 40W.

The eastern end of the East Pacific monsoon trough is producing
scattered heavy showers and strong thunderstorms across the
Caribbean waters near northwestern Colombia.

...GULF OF MEXICO...

A surface trough extending westward from the Great Bahama Bank to
the Florida Straits is causing isolated thunderstorms over the
southeastern Gulf, including the Yucatan Channel. Otherwise, a
modest surface ridge runs southwestward from a 1012 mb high over
southern Louisiana to near Veracruz, Mexico. Gentle to moderate
ENE to SE winds and seas at 2 to 4 ft are present at the western
and south-central Gulf. Mostly gentle ENE to E winds with 1 to 3
ft seas prevail for the rest of the Gulf.

For the forecast, a broad area of low pressure could form by the
early to middle part of next week over the northwestern Caribbean
Sea. Thereafter, gradual development of this system is possible,
and a tropical depression could form as the system moves slowly north
to northwestward across the northwestern Caribbean Sea and into
the southern Gulf of Mexico through the end of next week. There is
a medium chance of tropical cyclone formation in the next seven
days. Regardless of development, winds and seas will start
increasing across the southeastern Gulf early next week.

...CARIBBEAN SEA...

Please refer to the SPECIAL FEATURES section above for potential
heavy rainfall associated with a developing Central American Gyre
(CAG).

Convergent surface winds are coupling with strong divergent winds
aloft to trigger scattered moderate convection near Haiti and
over the northwestern basin, including the Gulf of Honduras. An
upper-level trough over the eastern basin is generating isolated
strong thunderstorms near Puerto Rico and the Leeward Islands.
Refer to the Monsoon Trough/ITCZ section for additional convection
in the Caribbean Sea. Gentle to moderate with locally fresh E to
SE winds and seas at 3 to 5 ft are present across the south-
central and southeastern basin. Light to gentle winds and 1 to 3
ft seas are noted near Costa Rica and Panama. Mainly gentle ENE to
SE winds and seas of 2 to 4 ft prevail elsewhere in the Caribbean
Sea.

For the forecast, moderate to fresh winds and moderate seas are
expected across the eastern and central basin through Sat night.
Looking ahead, a broad area of low pressure could form early to
midweek next week over the northwestern basin. Thereafter,
gradual development of this system is possible, and a tropical
depression could form as the system moves slowly north to
northwestward over the northwestern basin and into the southern
Gulf of Mexico through the end of next week. There is a medium
chance of tropical cyclone formation in the next seven days.

...ATLANTIC OCEAN...

A surface trough meanders southwestward from 31N73W across the
central Bahamas to the Great Bahama Bank. Convergent southeasterly
winds feeding toward this feature are enhanced by strong
divergent flow aloft, causing scattered heavy showers and strong
thunderstorms across the southeast Bahamas and nearby waters. At
the central Atlantic, a surface trough curves southeastward from
31N64W to a 1006 mb low near 25N55W, then turns eastward through a
1005 mb low near 27N42W to 28N33W. Scattered moderate convection
is evident from 23N to 29N between 51W and 64W, and from 20N to
27N between 35W and 41W. Refer to the Monsoon Trough/ITCZ section
for additional convection in the Atlantic Basin.

Tighter gradient between the aforementioned low pressure systems
and the Atlantic Ridge across the north-central Atlantic is
sustaining moderate to fresh with locally strong ENE to SE winds
and seas of 6 to 9 ft north of 25N between 35W and 60W. To the
south, gentle to moderate S to SE winds with 4 to 6 ft seas are
present from 16N to 25N between 35W and 60W/Leeward Islands.
Farther west, Light to gentle winds and seas at 3 to 5 ft in
moderate NE swell are noted north of 20N between 60W and the
Florida-Georgia coast. Gentle to moderate E to SE winds and seas
of 4 to 6 ft prevail for the remainder of the Atlantic Basin west
of 35W.

For the forecast W of 55W, for the aforementioned low pressure
near 25N55W, environmental conditions do not appear conducive for
significant development of this system during the next couple of
days while it drifts northwestward over the central or western
subtropical Atlantic. Otherwise, a weak cold front will exit the
southeast coast of the US tonight and slowly move across the
waters north of 25N into Mon night.

$$

Chan