Tropical Discussion - International Desks
NWS Weather Prediction Center College Park MD
332 PM EDT Mon Oct 20 2025

Forecast Bulletin 20 October 2025 at 1900 UTC:

The Bahamas and the Caribbean:

Most of the precipitation in the region for the next three days is
going to be associated with the tropical wave (AL98) currently
being monitored by the National Hurricane Center (NHC) with a 80%
chance of tropical cyclone formation in the next seven days. The
most significant impacts associated with this system will be
towards the end of the forecast period, as the system may develop
a low-level closed circulation center. There is uncertainty
regarding the track of the system and therefore the location of
the highest rainfall accumulations. Heavy rainfall may occur
across the Greater Antilles over the next three days regardless.
The tropical wave is expected to cause precipitation over Puerto
Rico from today through Thursday, particularly on the eastern
portion of Puerto Rico. As the system propagates westward it is
expected to impact southern Hispaniola and Jamaica, with the
highest precipitation from Wednesday into Thursday. Local and
diurnal effects may favor isolated higher rainfall accumulations.
Aruba, Curacao and Bonaire may also receive some precipitation
associated with this tropical wave, particularly from today
through Wednesday.

Another region of interest for the next three days is eastern
Bahamas and northeastern Cuba. The presence of an eastward
propagating upper tropospheric trough with its base extending into
Yucatan, a stationary front extending into the south-central
Bahamas and the presence of low-level troughs will favor the
development of convective activity and precipitation in the area
from today through Wednesday. Rainfall is expected to continue
from Wednesday through Thursday as precipitable water remains high
with the AL98 tropical wave approaching the region and the upper
level trough enhancing speed divergence in the area.

From Wednesday through Thursday, Trinidad and Tobago, and the
Windward Islands may also experience some rainfall as a low-level
trough moves into the region. Although there is disagreement
between the models in regards to the amount of moisture being
advected into the region, instability is expected and
thunderstorms are likely to develop.

Mexico and Central America:

Over Mexico the synoptic pattern will be dominated by a mid- to
upper-level high over the next three days. A series of low-level
troughs may advect some moisture over eastern Mexico, causing some
precipitation each day. However, precipitable water is expected to
decrease from Tuesday through Thursday, limiting precipitation and
establishing a drying tendency towards the end of the forecast
period.

Belize, Guatemala and portions of Honduras should expect rainfall
today through Thursday, with moisture being advected from the
Caribbean, The presence of a low-level trough throughout the
forecast period and enhanced low-level moisture convergence will
favor the increase in precipitation chances in this sector.

An area of interest in Central America is Nicaragua, as a
low-level trough approaches the region today, expect increasing
low-level moisture convergence in the area. A mid- and upper-
level trough are also in the region, increasing instability and
favoring the development of convective activity, particularly from
today through Tuesday. Precipitation may continue from Tuesday
into Wednesday due to moisture advection. Less precipitation is
expected from Wednesday through Thursday with a high dominating at
the mid- and upper-levels.

Over Costa Rica, and Panama rainfall is expected each day with the
presence of the monsoon trough over the region and the development
of a surface low that will favor moist onshore flow from the
Pacific Ocean and from the Caribbean.

Tropical South America:

Across tropical South America, showers and thunderstorms will be
observed each day. The primary drivers will be low-level moisture
convergence, diurnal heating, and local effects.

Most of the precipitation will be over the western region of
Colombia as long-fetch Pacific moisture feeds into the region,
maximum total accumulated rainfall around 30-60mm is expected each
day.

A low-level trough may enhance rainfall and thunderstorms over
Guyana from Tuesday through Wednesday. Heavy rainfall is expected
to continue as the low-level trough propagates westward into
eastern Venezuela, from Wednesday through Thursday

Another region of interest in South America is the northeastern
portion of the Andes and Caribbean region in Colombia and
northwestern Venezuela with deep moisture available in the region,
the presence of a low-level trough and enhanced low-level moisture
allowing the development of thunderstorms each day.



Positions of Tropical/Easterly Waves Initialized at 12 UTC
TYP SOF INIT 21/00 21/12 22/00 22/12 23/00 23/12 24/00
TW  17N  66W   67W   69W  71W  73W   74W   74W   74W 
EW  15N  94W   97W   99W  102W  104W  106W  108W  110W

For the latest available charts please visit:
https://www.wpc.ncep.noaa.gov/international/crb_day1-3.shtml

Rivera-Torres...(WPC)