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FXCA20 KWBC 141858
PMDCA

Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
257 PM EDT Mon Sep 14 2026

Forecast Bulletin 14 September 2026 at 1900 UTC:

Across Central America, the Caribbean, and the Bahamas...

A dynamic low-to-upper level will be present across the region,
helping support the development of convection. The first
atmospheric feature of interest is an upper level trough that is
currently situated across the northwest Caribbean Sea. This upper
trough will support a divergent pattern across Nicaragua, Costa
Rica, Colombia, and Hispaniola for today and Tuesday. The trough
is expected to deepen, extending into the interior of the
countries of Honduras, Costa Rica, Nicaragua, and Panama for
Tuesday. Thereafter, the upper trough will continue extending
northwestward for Wednesday before merging with another
strengthening upper trough, which is expected to intensify in the
vicinity of Florida, Cuba, and the Bahamas.

The upper trough center will be in the vicinity of Hispaniola on
Monday and Tuesday, helping destabilize the atmosphere and
supporting divergence. On Monday, a low level trough that is being
accompanied by a weak moisture plume will be moving across the
island, leading to moderate total precipitation maxima. On
Tuesday, isolated convection will still be likely across the
island. Starting on Wednesday morning, anticipate the development
of an induced low level trough across the central Greater Antilles
region. This low level trough will be accompanied with above
normal precipitable water values and will be reflected in the
mid-levels as well. Thus, anticipate an increase in total
precipitation maxima across Hispaniola and Jamaica for Wednesday
as the induced trough moves overhead.

Meanwhile in the Caribbean, the dynamic upper level pattern will
support the continuous development of mid-level vorticity maxima
and low level troughs in the south Caribbean Sea for Monday and
Tuesday. Convection is likely with these conditions across the
region, in particular, across the Caribbean coast of Costa Rica
and the southern Caribbean coast of Nicaragua for today and
Tuesday. This region will have enhanced low level convergence due
to the presence of prevailing easterly low level winds. The upper
level support will dwindle by Wednesday as the upper trough moves
away from the region. Thus, there will be a subtle decrease of
total precipitation maxima compared to the days prior.

Another feature of interest is an incoming tropical wave that is
expected to arrive into the Lesser Antilles on Wednesday and
continue moving westward through the rest of the work week.
Precipitation chances will increase for Wednesday across Barbados
and across the Leeward Islands on Thursday. At this time, there is
uncertainty in the upper level support that will be present in the
region. The presence of upper divergence in the eastern Greater
Antilles region and the Leeward Islands will be influenced by the
location of a developing upper ridge in the east Caribbean Sea. A
more eastward development of the upper ridge will translate to
there being more upper divergence across the Leeward Island,
Puerto Rico, and the Virgin Islands. Regardless, convection will
be likely across the region and it will bring moderate to heavy
total precipitation maxima for Wednesday into Thursday.

Meanwhile in the Bahamas, also anticipate an uptick in total
precipitation maxima on Wednesday into Thursday. Convection will
be reinforced by the presence of a deepening upper level trough
that is expected to destabilize the environment and help increase
moisture levels in response. At the same time, a low level trough
will be present. These conditions will favor the development and
sustenance of deep convection in this region with moderate to high
total precipitation maxima likely.

Across South America...

The precipitable water values across the Pacific coasts of
Colombia and Ecuador will remain high through the forecast cycle.
Daily convection is likely to occur across the region as the
environment is already highly unstable. Furthermore, the low level
winds from the west will be converging in the region, further
reinforcing precipitation processes. Moderate to high total
precipitation maxima is likely for the next three days in this
region.  East of the Andes, expect a persistent easterly low to
mid level wind regime that will support moisture convergence.
Light to moderate total precipitation maxima is thus expected for
the next three days.

Across the rest of the region...

Diurnal convection and showers are likely across the Sierra Madre
Occidental and Sierra Madre del Sur in Mexico for Monday and
Tuesday. During the afternoon on Monday, there will be an uptick
in upper divergence across the Sierra Madre del Sur, which will be
driven by the presence of an upper trough to the west. Upper level
support will subside for Tuesday. Starting on Wednesday, another
moisture plume will be advancing towards the Gulf coast (Veracruz,
Tamaulipas), though convection and showers will remain shallow.
Otherwise, seasonal conditions will prevail through the rest of
the tropical domain.



Tropical Waves Initialized at 12 UTC:
expect SOF  INIT 15/00 15/12 16/00 16/12 17/00 17/12 18/00 18/12
TW  12N   42W  45W  48W  50W  52W  54W  56W  58W  60W
TW  20N   49W  52W  55W  58W  61W  64W  67W  70W  73W
TW  15N   53W  56W  59W  62W  65W  68W  70W  72W  74W
TW  12N   64W  66W  69W  72W  74W  76W  78W  80W  83W
TW  20N   93W  96W  99W  102W 105W 107W 109W Diss  ---
TW  17N   101W  103W  105W  107W  109W  110W  111W  112W 113W
TW  20N   117W  Exits ---  ---



Tinoco-Morales...(WPC)
Rivera-Torres...(WPC)


$$